/*
 *  TLS shared functions
 *
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
 */
/*
 *  http://www.ietf.org/rfc/rfc2246.txt
 *  http://www.ietf.org/rfc/rfc4346.txt
 */

#include "common.h"

#if defined(MBEDTLS_SSL_TLS_C)

#include "mbedtls/platform.h"

#include "mbedtls/ssl.h"
#include "ssl_client.h"
#include "ssl_debug_helpers.h"
#include "ssl_misc.h"
#include "ssl_tls13_keys.h"

#include "debug_internal.h"
#include "mbedtls/error.h"
#include "mbedtls/platform_util.h"
#include "mbedtls/version.h"
#include "mbedtls/constant_time.h"

#include <string.h>

#if defined(MBEDTLS_USE_PSA_CRYPTO)
#include "mbedtls/psa_util.h"
#include "md_psa.h"
#include "psa_util_internal.h"
#include "psa/crypto.h"
#endif

#if defined(MBEDTLS_X509_CRT_PARSE_C)
#include "mbedtls/oid.h"
#endif

#if defined(MBEDTLS_USE_PSA_CRYPTO)
/* Define local translating functions to save code size by not using too many
 * arguments in each translating place. */
static int local_err_translation(psa_status_t status)
{
    return psa_status_to_mbedtls(status, psa_to_ssl_errors,
                                 ARRAY_LENGTH(psa_to_ssl_errors),
                                 psa_generic_status_to_mbedtls);
}
#define PSA_TO_MBEDTLS_ERR(status) local_err_translation(status)
#endif

#if defined(MBEDTLS_TEST_HOOKS)
static mbedtls_ssl_chk_buf_ptr_args chk_buf_ptr_fail_args;

void mbedtls_ssl_set_chk_buf_ptr_fail_args(
    const uint8_t *cur, const uint8_t *end, size_t need)
{
    chk_buf_ptr_fail_args.cur = cur;
    chk_buf_ptr_fail_args.end = end;
    chk_buf_ptr_fail_args.need = need;
}

void mbedtls_ssl_reset_chk_buf_ptr_fail_args(void)
{
    memset(&chk_buf_ptr_fail_args, 0, sizeof(chk_buf_ptr_fail_args));
}

int mbedtls_ssl_cmp_chk_buf_ptr_fail_args(mbedtls_ssl_chk_buf_ptr_args *args)
{
    return (chk_buf_ptr_fail_args.cur  != args->cur) ||
           (chk_buf_ptr_fail_args.end  != args->end) ||
           (chk_buf_ptr_fail_args.need != args->need);
}
#endif /* MBEDTLS_TEST_HOOKS */

#if defined(MBEDTLS_SSL_PROTO_DTLS)

#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
/* Top-level Connection ID API */

int mbedtls_ssl_conf_cid(mbedtls_ssl_config *conf,
                         size_t len,
                         int ignore_other_cid)
{
    if (len > MBEDTLS_SSL_CID_IN_LEN_MAX) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    if (ignore_other_cid != MBEDTLS_SSL_UNEXPECTED_CID_FAIL &&
        ignore_other_cid != MBEDTLS_SSL_UNEXPECTED_CID_IGNORE) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    conf->ignore_unexpected_cid = ignore_other_cid;
    conf->cid_len = len;
    return 0;
}

int mbedtls_ssl_set_cid(mbedtls_ssl_context *ssl,
                        int enable,
                        unsigned char const *own_cid,
                        size_t own_cid_len)
{
    if (ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    ssl->negotiate_cid = enable;
    if (enable == MBEDTLS_SSL_CID_DISABLED) {
        MBEDTLS_SSL_DEBUG_MSG(3, ("Disable use of CID extension."));
        return 0;
    }
    MBEDTLS_SSL_DEBUG_MSG(3, ("Enable use of CID extension."));
    MBEDTLS_SSL_DEBUG_BUF(3, "Own CID", own_cid, own_cid_len);

    if (own_cid_len != ssl->conf->cid_len) {
        MBEDTLS_SSL_DEBUG_MSG(3, ("CID length %u does not match CID length %u in config",
                                  (unsigned) own_cid_len,
                                  (unsigned) ssl->conf->cid_len));
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    memcpy(ssl->own_cid, own_cid, own_cid_len);
    /* Truncation is not an issue here because
     * MBEDTLS_SSL_CID_IN_LEN_MAX at most 255. */
    ssl->own_cid_len = (uint8_t) own_cid_len;

    return 0;
}

int mbedtls_ssl_get_own_cid(mbedtls_ssl_context *ssl,
                            int *enabled,
                            unsigned char own_cid[MBEDTLS_SSL_CID_IN_LEN_MAX],
                            size_t *own_cid_len)
{
    *enabled = MBEDTLS_SSL_CID_DISABLED;

    if (ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    /* We report MBEDTLS_SSL_CID_DISABLED in case the CID length is
     * zero as this is indistinguishable from not requesting to use
     * the CID extension. */
    if (ssl->own_cid_len == 0 || ssl->negotiate_cid == MBEDTLS_SSL_CID_DISABLED) {
        return 0;
    }

    if (own_cid_len != NULL) {
        *own_cid_len = ssl->own_cid_len;
        if (own_cid != NULL) {
            memcpy(own_cid, ssl->own_cid, ssl->own_cid_len);
        }
    }

    *enabled = MBEDTLS_SSL_CID_ENABLED;

    return 0;
}

int mbedtls_ssl_get_peer_cid(mbedtls_ssl_context *ssl,
                             int *enabled,
                             unsigned char peer_cid[MBEDTLS_SSL_CID_OUT_LEN_MAX],
                             size_t *peer_cid_len)
{
    *enabled = MBEDTLS_SSL_CID_DISABLED;

    if (ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM ||
        mbedtls_ssl_is_handshake_over(ssl) == 0) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    /* We report MBEDTLS_SSL_CID_DISABLED in case the CID extensions
     * were used, but client and server requested the empty CID.
     * This is indistinguishable from not using the CID extension
     * in the first place. */
    if (ssl->transform_in->in_cid_len  == 0 &&
        ssl->transform_in->out_cid_len == 0) {
        return 0;
    }

    if (peer_cid_len != NULL) {
        *peer_cid_len = ssl->transform_in->out_cid_len;
        if (peer_cid != NULL) {
            memcpy(peer_cid, ssl->transform_in->out_cid,
                   ssl->transform_in->out_cid_len);
        }
    }

    *enabled = MBEDTLS_SSL_CID_ENABLED;

    return 0;
}
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */

#endif /* MBEDTLS_SSL_PROTO_DTLS */

#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
/*
 * Convert max_fragment_length codes to length.
 * RFC 6066 says:
 *    enum{
 *        2^9(1), 2^10(2), 2^11(3), 2^12(4), (255)
 *    } MaxFragmentLength;
 * and we add 0 -> extension unused
 */
static unsigned int ssl_mfl_code_to_length(int mfl)
{
    switch (mfl) {
        case MBEDTLS_SSL_MAX_FRAG_LEN_NONE:
            return MBEDTLS_TLS_EXT_ADV_CONTENT_LEN;
        case MBEDTLS_SSL_MAX_FRAG_LEN_512:
            return 512;
        case MBEDTLS_SSL_MAX_FRAG_LEN_1024:
            return 1024;
        case MBEDTLS_SSL_MAX_FRAG_LEN_2048:
            return 2048;
        case MBEDTLS_SSL_MAX_FRAG_LEN_4096:
            return 4096;
        default:
            return MBEDTLS_TLS_EXT_ADV_CONTENT_LEN;
    }
}
#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */

int mbedtls_ssl_session_copy(mbedtls_ssl_session *dst,
                             const mbedtls_ssl_session *src)
{
    mbedtls_ssl_session_free(dst);
    memcpy(dst, src, sizeof(mbedtls_ssl_session));
#if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C)
    dst->ticket = NULL;
#if defined(MBEDTLS_SSL_PROTO_TLS1_3) && \
    defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
    dst->hostname = NULL;
#endif
#endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */

#if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_ALPN) && \
    defined(MBEDTLS_SSL_EARLY_DATA)
    dst->ticket_alpn = NULL;
#endif

#if defined(MBEDTLS_X509_CRT_PARSE_C)

#if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
    if (src->peer_cert != NULL) {
        int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

        dst->peer_cert = mbedtls_calloc(1, sizeof(mbedtls_x509_crt));
        if (dst->peer_cert == NULL) {
            return MBEDTLS_ERR_SSL_ALLOC_FAILED;
        }

        mbedtls_x509_crt_init(dst->peer_cert);

        if ((ret = mbedtls_x509_crt_parse_der(dst->peer_cert, src->peer_cert->raw.p,
                                              src->peer_cert->raw.len)) != 0) {
            mbedtls_free(dst->peer_cert);
            dst->peer_cert = NULL;
            return ret;
        }
    }
#else /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
    if (src->peer_cert_digest != NULL) {
        dst->peer_cert_digest =
            mbedtls_calloc(1, src->peer_cert_digest_len);
        if (dst->peer_cert_digest == NULL) {
            return MBEDTLS_ERR_SSL_ALLOC_FAILED;
        }

        memcpy(dst->peer_cert_digest, src->peer_cert_digest,
               src->peer_cert_digest_len);
        dst->peer_cert_digest_type = src->peer_cert_digest_type;
        dst->peer_cert_digest_len = src->peer_cert_digest_len;
    }
#endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */

#endif /* MBEDTLS_X509_CRT_PARSE_C */

#if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_ALPN) && \
    defined(MBEDTLS_SSL_EARLY_DATA)
    {
        int ret = mbedtls_ssl_session_set_ticket_alpn(dst, src->ticket_alpn);
        if (ret != 0) {
            return ret;
        }
    }
#endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_ALPN && MBEDTLS_SSL_EARLY_DATA */

#if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C)
    if (src->ticket != NULL) {
        dst->ticket = mbedtls_calloc(1, src->ticket_len);
        if (dst->ticket == NULL) {
            return MBEDTLS_ERR_SSL_ALLOC_FAILED;
        }

        memcpy(dst->ticket, src->ticket, src->ticket_len);
    }

#if defined(MBEDTLS_SSL_PROTO_TLS1_3) && \
    defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
    if (src->endpoint == MBEDTLS_SSL_IS_CLIENT) {
        int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
        ret = mbedtls_ssl_session_set_hostname(dst, src->hostname);
        if (ret != 0) {
            return ret;
        }
    }
#endif /* MBEDTLS_SSL_PROTO_TLS1_3 &&
          MBEDTLS_SSL_SERVER_NAME_INDICATION */
#endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */

    return 0;
}

#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
MBEDTLS_CHECK_RETURN_CRITICAL
static int resize_buffer(unsigned char **buffer, size_t len_new, size_t *len_old)
{
    unsigned char *resized_buffer = mbedtls_calloc(1, len_new);
    if (resized_buffer == NULL) {
        return MBEDTLS_ERR_SSL_ALLOC_FAILED;
    }

    /* We want to copy len_new bytes when downsizing the buffer, and
     * len_old bytes when upsizing, so we choose the smaller of two sizes,
     * to fit one buffer into another. Size checks, ensuring that no data is
     * lost, are done outside of this function. */
    memcpy(resized_buffer, *buffer,
           (len_new < *len_old) ? len_new : *len_old);
    mbedtls_zeroize_and_free(*buffer, *len_old);

    *buffer = resized_buffer;
    *len_old = len_new;

    return 0;
}

static void handle_buffer_resizing(mbedtls_ssl_context *ssl, int downsizing,
                                   size_t in_buf_new_len,
                                   size_t out_buf_new_len)
{
    int modified = 0;
    size_t written_in = 0, iv_offset_in = 0, len_offset_in = 0, hdr_in = 0;
    size_t written_out = 0, iv_offset_out = 0, len_offset_out = 0;
    if (ssl->in_buf != NULL) {
        written_in = ssl->in_msg - ssl->in_buf;
        iv_offset_in = ssl->in_iv - ssl->in_buf;
        len_offset_in = ssl->in_len - ssl->in_buf;
        hdr_in = ssl->in_hdr - ssl->in_buf;
        if (downsizing ?
            ssl->in_buf_len > in_buf_new_len && ssl->in_left < in_buf_new_len :
            ssl->in_buf_len < in_buf_new_len) {
            if (resize_buffer(&ssl->in_buf, in_buf_new_len, &ssl->in_buf_len) != 0) {
                MBEDTLS_SSL_DEBUG_MSG(1, ("input buffer resizing failed - out of memory"));
            } else {
                MBEDTLS_SSL_DEBUG_MSG(2, ("Reallocating in_buf to %" MBEDTLS_PRINTF_SIZET,
                                          in_buf_new_len));
                modified = 1;
            }
        }
    }

    if (ssl->out_buf != NULL) {
        written_out = ssl->out_msg - ssl->out_buf;
        iv_offset_out = ssl->out_iv - ssl->out_buf;
        len_offset_out = ssl->out_len - ssl->out_buf;
        if (downsizing ?
            ssl->out_buf_len > out_buf_new_len && ssl->out_left < out_buf_new_len :
            ssl->out_buf_len < out_buf_new_len) {
            if (resize_buffer(&ssl->out_buf, out_buf_new_len, &ssl->out_buf_len) != 0) {
                MBEDTLS_SSL_DEBUG_MSG(1, ("output buffer resizing failed - out of memory"));
            } else {
                MBEDTLS_SSL_DEBUG_MSG(2, ("Reallocating out_buf to %" MBEDTLS_PRINTF_SIZET,
                                          out_buf_new_len));
                modified = 1;
            }
        }
    }
    if (modified) {
        /* Update pointers here to avoid doing it twice. */
        ssl->in_hdr = ssl->in_buf + hdr_in;
        mbedtls_ssl_update_in_pointers(ssl);
        mbedtls_ssl_reset_out_pointers(ssl);

        /* Fields below might not be properly updated with record
         * splitting or with CID, so they are manually updated here. */
        ssl->out_msg = ssl->out_buf + written_out;
        ssl->out_len = ssl->out_buf + len_offset_out;
        ssl->out_iv = ssl->out_buf + iv_offset_out;

        ssl->in_msg = ssl->in_buf + written_in;
        ssl->in_len = ssl->in_buf + len_offset_in;
        ssl->in_iv = ssl->in_buf + iv_offset_in;
    }
}
#endif /* MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH */

#if defined(MBEDTLS_SSL_PROTO_TLS1_2)

#if defined(MBEDTLS_SSL_CONTEXT_SERIALIZATION)
typedef int (*tls_prf_fn)(const unsigned char *secret, size_t slen,
                          const char *label,
                          const unsigned char *random, size_t rlen,
                          unsigned char *dstbuf, size_t dlen);

static tls_prf_fn ssl_tls12prf_from_cs(int ciphersuite_id);

#endif /* MBEDTLS_SSL_CONTEXT_SERIALIZATION */

/* Type for the TLS PRF */
typedef int ssl_tls_prf_t(const unsigned char *, size_t, const char *,
                          const unsigned char *, size_t,
                          unsigned char *, size_t);

MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls12_populate_transform(mbedtls_ssl_transform *transform,
                                        int ciphersuite,
                                        const unsigned char master[48],
#if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC_ETM)
                                        int encrypt_then_mac,
#endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC_ETM */
                                        ssl_tls_prf_t tls_prf,
                                        const unsigned char randbytes[64],
                                        mbedtls_ssl_protocol_version tls_version,
                                        unsigned endpoint,
                                        const mbedtls_ssl_context *ssl);

#if defined(MBEDTLS_MD_CAN_SHA256)
MBEDTLS_CHECK_RETURN_CRITICAL
static int tls_prf_sha256(const unsigned char *secret, size_t slen,
                          const char *label,
                          const unsigned char *random, size_t rlen,
                          unsigned char *dstbuf, size_t dlen);
static int ssl_calc_verify_tls_sha256(const mbedtls_ssl_context *, unsigned char *, size_t *);
static int ssl_calc_finished_tls_sha256(mbedtls_ssl_context *, unsigned char *, int);

#endif /* MBEDTLS_MD_CAN_SHA256*/

#if defined(MBEDTLS_MD_CAN_SHA384)
MBEDTLS_CHECK_RETURN_CRITICAL
static int tls_prf_sha384(const unsigned char *secret, size_t slen,
                          const char *label,
                          const unsigned char *random, size_t rlen,
                          unsigned char *dstbuf, size_t dlen);

static int ssl_calc_verify_tls_sha384(const mbedtls_ssl_context *, unsigned char *, size_t *);
static int ssl_calc_finished_tls_sha384(mbedtls_ssl_context *, unsigned char *, int);
#endif /* MBEDTLS_MD_CAN_SHA384*/

MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls12_session_load(mbedtls_ssl_session *session,
                                  const unsigned char *buf,
                                  size_t len);
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */

static int ssl_update_checksum_start(mbedtls_ssl_context *, const unsigned char *, size_t);

#if defined(MBEDTLS_MD_CAN_SHA256)
static int ssl_update_checksum_sha256(mbedtls_ssl_context *, const unsigned char *, size_t);
#endif /* MBEDTLS_MD_CAN_SHA256*/

#if defined(MBEDTLS_MD_CAN_SHA384)
static int ssl_update_checksum_sha384(mbedtls_ssl_context *, const unsigned char *, size_t);
#endif /* MBEDTLS_MD_CAN_SHA384*/

int  mbedtls_ssl_tls_prf(const mbedtls_tls_prf_types prf,
                         const unsigned char *secret, size_t slen,
                         const char *label,
                         const unsigned char *random, size_t rlen,
                         unsigned char *dstbuf, size_t dlen)
{
    mbedtls_ssl_tls_prf_cb *tls_prf = NULL;

    switch (prf) {
#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
#if defined(MBEDTLS_MD_CAN_SHA384)
        case MBEDTLS_SSL_TLS_PRF_SHA384:
            tls_prf = tls_prf_sha384;
            break;
#endif /* MBEDTLS_MD_CAN_SHA384*/
#if defined(MBEDTLS_MD_CAN_SHA256)
        case MBEDTLS_SSL_TLS_PRF_SHA256:
            tls_prf = tls_prf_sha256;
            break;
#endif /* MBEDTLS_MD_CAN_SHA256*/
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
        default:
            return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
    }

    return tls_prf(secret, slen, label, random, rlen, dstbuf, dlen);
}

#if defined(MBEDTLS_X509_CRT_PARSE_C)
static void ssl_clear_peer_cert(mbedtls_ssl_session *session)
{
#if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
    if (session->peer_cert != NULL) {
        mbedtls_x509_crt_free(session->peer_cert);
        mbedtls_free(session->peer_cert);
        session->peer_cert = NULL;
    }
#else /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
    if (session->peer_cert_digest != NULL) {
        /* Zeroization is not necessary. */
        mbedtls_free(session->peer_cert_digest);
        session->peer_cert_digest      = NULL;
        session->peer_cert_digest_type = MBEDTLS_MD_NONE;
        session->peer_cert_digest_len  = 0;
    }
#endif /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
}
#endif /* MBEDTLS_X509_CRT_PARSE_C */

uint32_t mbedtls_ssl_get_extension_id(unsigned int extension_type)
{
    switch (extension_type) {
        case MBEDTLS_TLS_EXT_SERVERNAME:
            return MBEDTLS_SSL_EXT_ID_SERVERNAME;

        case MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH:
            return MBEDTLS_SSL_EXT_ID_MAX_FRAGMENT_LENGTH;

        case MBEDTLS_TLS_EXT_STATUS_REQUEST:
            return MBEDTLS_SSL_EXT_ID_STATUS_REQUEST;

        case MBEDTLS_TLS_EXT_SUPPORTED_GROUPS:
            return MBEDTLS_SSL_EXT_ID_SUPPORTED_GROUPS;

        case MBEDTLS_TLS_EXT_SIG_ALG:
            return MBEDTLS_SSL_EXT_ID_SIG_ALG;

        case MBEDTLS_TLS_EXT_USE_SRTP:
            return MBEDTLS_SSL_EXT_ID_USE_SRTP;

        case MBEDTLS_TLS_EXT_HEARTBEAT:
            return MBEDTLS_SSL_EXT_ID_HEARTBEAT;

        case MBEDTLS_TLS_EXT_ALPN:
            return MBEDTLS_SSL_EXT_ID_ALPN;

        case MBEDTLS_TLS_EXT_SCT:
            return MBEDTLS_SSL_EXT_ID_SCT;

        case MBEDTLS_TLS_EXT_CLI_CERT_TYPE:
            return MBEDTLS_SSL_EXT_ID_CLI_CERT_TYPE;

        case MBEDTLS_TLS_EXT_SERV_CERT_TYPE:
            return MBEDTLS_SSL_EXT_ID_SERV_CERT_TYPE;

        case MBEDTLS_TLS_EXT_PADDING:
            return MBEDTLS_SSL_EXT_ID_PADDING;

        case MBEDTLS_TLS_EXT_PRE_SHARED_KEY:
            return MBEDTLS_SSL_EXT_ID_PRE_SHARED_KEY;

        case MBEDTLS_TLS_EXT_EARLY_DATA:
            return MBEDTLS_SSL_EXT_ID_EARLY_DATA;

        case MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS:
            return MBEDTLS_SSL_EXT_ID_SUPPORTED_VERSIONS;

        case MBEDTLS_TLS_EXT_COOKIE:
            return MBEDTLS_SSL_EXT_ID_COOKIE;

        case MBEDTLS_TLS_EXT_PSK_KEY_EXCHANGE_MODES:
            return MBEDTLS_SSL_EXT_ID_PSK_KEY_EXCHANGE_MODES;

        case MBEDTLS_TLS_EXT_CERT_AUTH:
            return MBEDTLS_SSL_EXT_ID_CERT_AUTH;

        case MBEDTLS_TLS_EXT_OID_FILTERS:
            return MBEDTLS_SSL_EXT_ID_OID_FILTERS;

        case MBEDTLS_TLS_EXT_POST_HANDSHAKE_AUTH:
            return MBEDTLS_SSL_EXT_ID_POST_HANDSHAKE_AUTH;

        case MBEDTLS_TLS_EXT_SIG_ALG_CERT:
            return MBEDTLS_SSL_EXT_ID_SIG_ALG_CERT;

        case MBEDTLS_TLS_EXT_KEY_SHARE:
            return MBEDTLS_SSL_EXT_ID_KEY_SHARE;

        case MBEDTLS_TLS_EXT_TRUNCATED_HMAC:
            return MBEDTLS_SSL_EXT_ID_TRUNCATED_HMAC;

        case MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS:
            return MBEDTLS_SSL_EXT_ID_SUPPORTED_POINT_FORMATS;

        case MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC:
            return MBEDTLS_SSL_EXT_ID_ENCRYPT_THEN_MAC;

        case MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET:
            return MBEDTLS_SSL_EXT_ID_EXTENDED_MASTER_SECRET;

        case MBEDTLS_TLS_EXT_RECORD_SIZE_LIMIT:
            return MBEDTLS_SSL_EXT_ID_RECORD_SIZE_LIMIT;

        case MBEDTLS_TLS_EXT_SESSION_TICKET:
            return MBEDTLS_SSL_EXT_ID_SESSION_TICKET;

    }

    return MBEDTLS_SSL_EXT_ID_UNRECOGNIZED;
}

uint32_t mbedtls_ssl_get_extension_mask(unsigned int extension_type)
{
    return 1 << mbedtls_ssl_get_extension_id(extension_type);
}

#if defined(MBEDTLS_DEBUG_C)
static const char *extension_name_table[] = {
    [MBEDTLS_SSL_EXT_ID_UNRECOGNIZED] = "unrecognized",
    [MBEDTLS_SSL_EXT_ID_SERVERNAME] = "server_name",
    [MBEDTLS_SSL_EXT_ID_MAX_FRAGMENT_LENGTH] = "max_fragment_length",
    [MBEDTLS_SSL_EXT_ID_STATUS_REQUEST] = "status_request",
    [MBEDTLS_SSL_EXT_ID_SUPPORTED_GROUPS] = "supported_groups",
    [MBEDTLS_SSL_EXT_ID_SIG_ALG] = "signature_algorithms",
    [MBEDTLS_SSL_EXT_ID_USE_SRTP] = "use_srtp",
    [MBEDTLS_SSL_EXT_ID_HEARTBEAT] = "heartbeat",
    [MBEDTLS_SSL_EXT_ID_ALPN] = "application_layer_protocol_negotiation",
    [MBEDTLS_SSL_EXT_ID_SCT] = "signed_certificate_timestamp",
    [MBEDTLS_SSL_EXT_ID_CLI_CERT_TYPE] = "client_certificate_type",
    [MBEDTLS_SSL_EXT_ID_SERV_CERT_TYPE] = "server_certificate_type",
    [MBEDTLS_SSL_EXT_ID_PADDING] = "padding",
    [MBEDTLS_SSL_EXT_ID_PRE_SHARED_KEY] = "pre_shared_key",
    [MBEDTLS_SSL_EXT_ID_EARLY_DATA] = "early_data",
    [MBEDTLS_SSL_EXT_ID_SUPPORTED_VERSIONS] = "supported_versions",
    [MBEDTLS_SSL_EXT_ID_COOKIE] = "cookie",
    [MBEDTLS_SSL_EXT_ID_PSK_KEY_EXCHANGE_MODES] = "psk_key_exchange_modes",
    [MBEDTLS_SSL_EXT_ID_CERT_AUTH] = "certificate_authorities",
    [MBEDTLS_SSL_EXT_ID_OID_FILTERS] = "oid_filters",
    [MBEDTLS_SSL_EXT_ID_POST_HANDSHAKE_AUTH] = "post_handshake_auth",
    [MBEDTLS_SSL_EXT_ID_SIG_ALG_CERT] = "signature_algorithms_cert",
    [MBEDTLS_SSL_EXT_ID_KEY_SHARE] = "key_share",
    [MBEDTLS_SSL_EXT_ID_TRUNCATED_HMAC] = "truncated_hmac",
    [MBEDTLS_SSL_EXT_ID_SUPPORTED_POINT_FORMATS] = "supported_point_formats",
    [MBEDTLS_SSL_EXT_ID_ENCRYPT_THEN_MAC] = "encrypt_then_mac",
    [MBEDTLS_SSL_EXT_ID_EXTENDED_MASTER_SECRET] = "extended_master_secret",
    [MBEDTLS_SSL_EXT_ID_SESSION_TICKET] = "session_ticket",
    [MBEDTLS_SSL_EXT_ID_RECORD_SIZE_LIMIT] = "record_size_limit"
};

static const unsigned int extension_type_table[] = {
    [MBEDTLS_SSL_EXT_ID_UNRECOGNIZED] = 0xff,
    [MBEDTLS_SSL_EXT_ID_SERVERNAME] = MBEDTLS_TLS_EXT_SERVERNAME,
    [MBEDTLS_SSL_EXT_ID_MAX_FRAGMENT_LENGTH] = MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH,
    [MBEDTLS_SSL_EXT_ID_STATUS_REQUEST] = MBEDTLS_TLS_EXT_STATUS_REQUEST,
    [MBEDTLS_SSL_EXT_ID_SUPPORTED_GROUPS] = MBEDTLS_TLS_EXT_SUPPORTED_GROUPS,
    [MBEDTLS_SSL_EXT_ID_SIG_ALG] = MBEDTLS_TLS_EXT_SIG_ALG,
    [MBEDTLS_SSL_EXT_ID_USE_SRTP] = MBEDTLS_TLS_EXT_USE_SRTP,
    [MBEDTLS_SSL_EXT_ID_HEARTBEAT] = MBEDTLS_TLS_EXT_HEARTBEAT,
    [MBEDTLS_SSL_EXT_ID_ALPN] = MBEDTLS_TLS_EXT_ALPN,
    [MBEDTLS_SSL_EXT_ID_SCT] = MBEDTLS_TLS_EXT_SCT,
    [MBEDTLS_SSL_EXT_ID_CLI_CERT_TYPE] = MBEDTLS_TLS_EXT_CLI_CERT_TYPE,
    [MBEDTLS_SSL_EXT_ID_SERV_CERT_TYPE] = MBEDTLS_TLS_EXT_SERV_CERT_TYPE,
    [MBEDTLS_SSL_EXT_ID_PADDING] = MBEDTLS_TLS_EXT_PADDING,
    [MBEDTLS_SSL_EXT_ID_PRE_SHARED_KEY] = MBEDTLS_TLS_EXT_PRE_SHARED_KEY,
    [MBEDTLS_SSL_EXT_ID_EARLY_DATA] = MBEDTLS_TLS_EXT_EARLY_DATA,
    [MBEDTLS_SSL_EXT_ID_SUPPORTED_VERSIONS] = MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS,
    [MBEDTLS_SSL_EXT_ID_COOKIE] = MBEDTLS_TLS_EXT_COOKIE,
    [MBEDTLS_SSL_EXT_ID_PSK_KEY_EXCHANGE_MODES] = MBEDTLS_TLS_EXT_PSK_KEY_EXCHANGE_MODES,
    [MBEDTLS_SSL_EXT_ID_CERT_AUTH] = MBEDTLS_TLS_EXT_CERT_AUTH,
    [MBEDTLS_SSL_EXT_ID_OID_FILTERS] = MBEDTLS_TLS_EXT_OID_FILTERS,
    [MBEDTLS_SSL_EXT_ID_POST_HANDSHAKE_AUTH] = MBEDTLS_TLS_EXT_POST_HANDSHAKE_AUTH,
    [MBEDTLS_SSL_EXT_ID_SIG_ALG_CERT] = MBEDTLS_TLS_EXT_SIG_ALG_CERT,
    [MBEDTLS_SSL_EXT_ID_KEY_SHARE] = MBEDTLS_TLS_EXT_KEY_SHARE,
    [MBEDTLS_SSL_EXT_ID_TRUNCATED_HMAC] = MBEDTLS_TLS_EXT_TRUNCATED_HMAC,
    [MBEDTLS_SSL_EXT_ID_SUPPORTED_POINT_FORMATS] = MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS,
    [MBEDTLS_SSL_EXT_ID_ENCRYPT_THEN_MAC] = MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC,
    [MBEDTLS_SSL_EXT_ID_EXTENDED_MASTER_SECRET] = MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET,
    [MBEDTLS_SSL_EXT_ID_SESSION_TICKET] = MBEDTLS_TLS_EXT_SESSION_TICKET,
    [MBEDTLS_SSL_EXT_ID_RECORD_SIZE_LIMIT] = MBEDTLS_TLS_EXT_RECORD_SIZE_LIMIT
};

const char *mbedtls_ssl_get_extension_name(unsigned int extension_type)
{
    return extension_name_table[
        mbedtls_ssl_get_extension_id(extension_type)];
}

const char *mbedtls_ssl_get_hs_msg_name(int hs_msg_type)
{
    switch (hs_msg_type) {
        case MBEDTLS_SSL_HS_CLIENT_HELLO:
            return "ClientHello";
        case MBEDTLS_SSL_HS_SERVER_HELLO:
            return "ServerHello";
        case MBEDTLS_SSL_TLS1_3_HS_HELLO_RETRY_REQUEST:
            return "HelloRetryRequest";
        case MBEDTLS_SSL_HS_NEW_SESSION_TICKET:
            return "NewSessionTicket";
        case MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS:
            return "EncryptedExtensions";
        case MBEDTLS_SSL_HS_CERTIFICATE:
            return "Certificate";
        case MBEDTLS_SSL_HS_SERVER_KEY_EXCHANGE:
            return "ServerKeyExchange";
        case MBEDTLS_SSL_HS_CERTIFICATE_REQUEST:
            return "CertificateRequest";
        case MBEDTLS_SSL_HS_CERTIFICATE_VERIFY:
            return "CertificateVerify";
        case MBEDTLS_SSL_HS_CLIENT_KEY_EXCHANGE:
            return "ClientKeyExchange";
        case MBEDTLS_SSL_HS_FINISHED:
            return "Finished";
    }
    return "Unknown";
}

void mbedtls_ssl_print_extension(const mbedtls_ssl_context *ssl,
                                 int level, const char *file, int line,
                                 int hs_msg_type, unsigned int extension_type,
                                 const char *extra_msg0, const char *extra_msg1)
{
    const char *extra_msg;
    if (extra_msg0 && extra_msg1) {
        mbedtls_debug_print_msg(
            ssl, level, file, line,
            "%s: %s(%u) extension %s %s.",
            mbedtls_ssl_get_hs_msg_name(hs_msg_type),
            mbedtls_ssl_get_extension_name(extension_type),
            extension_type,
            extra_msg0, extra_msg1);
        return;
    }

    extra_msg = extra_msg0 ? extra_msg0 : extra_msg1;
    if (extra_msg) {
        mbedtls_debug_print_msg(
            ssl, level, file, line,
            "%s: %s(%u) extension %s.", mbedtls_ssl_get_hs_msg_name(hs_msg_type),
            mbedtls_ssl_get_extension_name(extension_type), extension_type,
            extra_msg);
        return;
    }

    mbedtls_debug_print_msg(
        ssl, level, file, line,
        "%s: %s(%u) extension.", mbedtls_ssl_get_hs_msg_name(hs_msg_type),
        mbedtls_ssl_get_extension_name(extension_type), extension_type);
}

void mbedtls_ssl_print_extensions(const mbedtls_ssl_context *ssl,
                                  int level, const char *file, int line,
                                  int hs_msg_type, uint32_t extensions_mask,
                                  const char *extra)
{

    for (unsigned i = 0;
         i < sizeof(extension_name_table) / sizeof(extension_name_table[0]);
         i++) {
        mbedtls_ssl_print_extension(
            ssl, level, file, line, hs_msg_type, extension_type_table[i],
            extensions_mask & (1 << i) ? "exists" : "does not exist", extra);
    }
}

#if defined(MBEDTLS_SSL_PROTO_TLS1_3) && defined(MBEDTLS_SSL_SESSION_TICKETS)
static const char *ticket_flag_name_table[] =
{
    [0] = "ALLOW_PSK_RESUMPTION",
    [2] = "ALLOW_PSK_EPHEMERAL_RESUMPTION",
    [3] = "ALLOW_EARLY_DATA",
};

void mbedtls_ssl_print_ticket_flags(const mbedtls_ssl_context *ssl,
                                    int level, const char *file, int line,
                                    unsigned int flags)
{
    size_t i;

    mbedtls_debug_print_msg(ssl, level, file, line,
                            "print ticket_flags (0x%02x)", flags);

    flags = flags & MBEDTLS_SSL_TLS1_3_TICKET_FLAGS_MASK;

    for (i = 0; i < ARRAY_LENGTH(ticket_flag_name_table); i++) {
        if ((flags & (1 << i))) {
            mbedtls_debug_print_msg(ssl, level, file, line, "- %s is set.",
                                    ticket_flag_name_table[i]);
        }
    }
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_3 && MBEDTLS_SSL_SESSION_TICKETS */

#endif /* MBEDTLS_DEBUG_C */

void mbedtls_ssl_optimize_checksum(mbedtls_ssl_context *ssl,
                                   const mbedtls_ssl_ciphersuite_t *ciphersuite_info)
{
    ((void) ciphersuite_info);

#if defined(MBEDTLS_MD_CAN_SHA384)
    if (ciphersuite_info->mac == MBEDTLS_MD_SHA384) {
        ssl->handshake->update_checksum = ssl_update_checksum_sha384;
    } else
#endif
#if defined(MBEDTLS_MD_CAN_SHA256)
    if (ciphersuite_info->mac != MBEDTLS_MD_SHA384) {
        ssl->handshake->update_checksum = ssl_update_checksum_sha256;
    } else
#endif
    {
        MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
        return;
    }
}

int mbedtls_ssl_add_hs_hdr_to_checksum(mbedtls_ssl_context *ssl,
                                       unsigned hs_type,
                                       size_t total_hs_len)
{
    unsigned char hs_hdr[4];

    /* Build HS header for checksum update. */
    hs_hdr[0] = MBEDTLS_BYTE_0(hs_type);
    hs_hdr[1] = MBEDTLS_BYTE_2(total_hs_len);
    hs_hdr[2] = MBEDTLS_BYTE_1(total_hs_len);
    hs_hdr[3] = MBEDTLS_BYTE_0(total_hs_len);

    return ssl->handshake->update_checksum(ssl, hs_hdr, sizeof(hs_hdr));
}

int mbedtls_ssl_add_hs_msg_to_checksum(mbedtls_ssl_context *ssl,
                                       unsigned hs_type,
                                       unsigned char const *msg,
                                       size_t msg_len)
{
    int ret;
    ret = mbedtls_ssl_add_hs_hdr_to_checksum(ssl, hs_type, msg_len);
    if (ret != 0) {
        return ret;
    }
    return ssl->handshake->update_checksum(ssl, msg, msg_len);
}

int mbedtls_ssl_reset_checksum(mbedtls_ssl_context *ssl)
{
#if defined(MBEDTLS_MD_CAN_SHA256) || \
    defined(MBEDTLS_MD_CAN_SHA384)
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    psa_status_t status;
#else
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
#endif
#else /* SHA-256 or SHA-384 */
    ((void) ssl);
#endif /* SHA-256 or SHA-384 */
#if defined(MBEDTLS_MD_CAN_SHA256)
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    status = psa_hash_abort(&ssl->handshake->fin_sha256_psa);
    if (status != PSA_SUCCESS) {
        return mbedtls_md_error_from_psa(status);
    }
    status = psa_hash_setup(&ssl->handshake->fin_sha256_psa, PSA_ALG_SHA_256);
    if (status != PSA_SUCCESS) {
        return mbedtls_md_error_from_psa(status);
    }
#else
    mbedtls_md_free(&ssl->handshake->fin_sha256);
    mbedtls_md_init(&ssl->handshake->fin_sha256);
    ret = mbedtls_md_setup(&ssl->handshake->fin_sha256,
                           mbedtls_md_info_from_type(MBEDTLS_MD_SHA256),
                           0);
    if (ret != 0) {
        return ret;
    }
    ret = mbedtls_md_starts(&ssl->handshake->fin_sha256);
    if (ret != 0) {
        return ret;
    }
#endif
#endif
#if defined(MBEDTLS_MD_CAN_SHA384)
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    status = psa_hash_abort(&ssl->handshake->fin_sha384_psa);
    if (status != PSA_SUCCESS) {
        return mbedtls_md_error_from_psa(status);
    }
    status = psa_hash_setup(&ssl->handshake->fin_sha384_psa, PSA_ALG_SHA_384);
    if (status != PSA_SUCCESS) {
        return mbedtls_md_error_from_psa(status);
    }
#else
    mbedtls_md_free(&ssl->handshake->fin_sha384);
    mbedtls_md_init(&ssl->handshake->fin_sha384);
    ret = mbedtls_md_setup(&ssl->handshake->fin_sha384,
                           mbedtls_md_info_from_type(MBEDTLS_MD_SHA384), 0);
    if (ret != 0) {
        return ret;
    }
    ret = mbedtls_md_starts(&ssl->handshake->fin_sha384);
    if (ret != 0) {
        return ret;
    }
#endif
#endif
    return 0;
}

static int ssl_update_checksum_start(mbedtls_ssl_context *ssl,
                                     const unsigned char *buf, size_t len)
{
#if defined(MBEDTLS_MD_CAN_SHA256) || \
    defined(MBEDTLS_MD_CAN_SHA384)
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    psa_status_t status;
#else
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
#endif
#else /* SHA-256 or SHA-384 */
    ((void) ssl);
    (void) buf;
    (void) len;
#endif /* SHA-256 or SHA-384 */
#if defined(MBEDTLS_MD_CAN_SHA256)
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    status = psa_hash_update(&ssl->handshake->fin_sha256_psa, buf, len);
    if (status != PSA_SUCCESS) {
        return mbedtls_md_error_from_psa(status);
    }
#else
    ret = mbedtls_md_update(&ssl->handshake->fin_sha256, buf, len);
    if (ret != 0) {
        return ret;
    }
#endif
#endif
#if defined(MBEDTLS_MD_CAN_SHA384)
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    status = psa_hash_update(&ssl->handshake->fin_sha384_psa, buf, len);
    if (status != PSA_SUCCESS) {
        return mbedtls_md_error_from_psa(status);
    }
#else
    ret = mbedtls_md_update(&ssl->handshake->fin_sha384, buf, len);
    if (ret != 0) {
        return ret;
    }
#endif
#endif
    return 0;
}

#if defined(MBEDTLS_MD_CAN_SHA256)
static int ssl_update_checksum_sha256(mbedtls_ssl_context *ssl,
                                      const unsigned char *buf, size_t len)
{
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    return mbedtls_md_error_from_psa(psa_hash_update(
                                         &ssl->handshake->fin_sha256_psa, buf, len));
#else
    return mbedtls_md_update(&ssl->handshake->fin_sha256, buf, len);
#endif
}
#endif

#if defined(MBEDTLS_MD_CAN_SHA384)
static int ssl_update_checksum_sha384(mbedtls_ssl_context *ssl,
                                      const unsigned char *buf, size_t len)
{
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    return mbedtls_md_error_from_psa(psa_hash_update(
                                         &ssl->handshake->fin_sha384_psa, buf, len));
#else
    return mbedtls_md_update(&ssl->handshake->fin_sha384, buf, len);
#endif
}
#endif

static void ssl_handshake_params_init(mbedtls_ssl_handshake_params *handshake)
{
    memset(handshake, 0, sizeof(mbedtls_ssl_handshake_params));

#if defined(MBEDTLS_MD_CAN_SHA256)
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    handshake->fin_sha256_psa = psa_hash_operation_init();
#else
    mbedtls_md_init(&handshake->fin_sha256);
#endif
#endif
#if defined(MBEDTLS_MD_CAN_SHA384)
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    handshake->fin_sha384_psa = psa_hash_operation_init();
#else
    mbedtls_md_init(&handshake->fin_sha384);
#endif
#endif

    handshake->update_checksum = ssl_update_checksum_start;

#if defined(MBEDTLS_DHM_C)
    mbedtls_dhm_init(&handshake->dhm_ctx);
#endif
#if !defined(MBEDTLS_USE_PSA_CRYPTO) && \
    defined(MBEDTLS_KEY_EXCHANGE_SOME_ECDH_OR_ECDHE_1_2_ENABLED)
    mbedtls_ecdh_init(&handshake->ecdh_ctx);
#endif
#if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    handshake->psa_pake_ctx = psa_pake_operation_init();
    handshake->psa_pake_password = MBEDTLS_SVC_KEY_ID_INIT;
#else
    mbedtls_ecjpake_init(&handshake->ecjpake_ctx);
#endif /* MBEDTLS_USE_PSA_CRYPTO */
#if defined(MBEDTLS_SSL_CLI_C)
    handshake->ecjpake_cache = NULL;
    handshake->ecjpake_cache_len = 0;
#endif
#endif

#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)
    mbedtls_x509_crt_restart_init(&handshake->ecrs_ctx);
#endif

#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
    handshake->sni_authmode = MBEDTLS_SSL_VERIFY_UNSET;
#endif

#if defined(MBEDTLS_X509_CRT_PARSE_C) && \
    !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
    mbedtls_pk_init(&handshake->peer_pubkey);
#endif
}

void mbedtls_ssl_transform_init(mbedtls_ssl_transform *transform)
{
    memset(transform, 0, sizeof(mbedtls_ssl_transform));

#if defined(MBEDTLS_USE_PSA_CRYPTO)
    transform->psa_key_enc = MBEDTLS_SVC_KEY_ID_INIT;
    transform->psa_key_dec = MBEDTLS_SVC_KEY_ID_INIT;
#else
    mbedtls_cipher_init(&transform->cipher_ctx_enc);
    mbedtls_cipher_init(&transform->cipher_ctx_dec);
#endif

#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    transform->psa_mac_enc = MBEDTLS_SVC_KEY_ID_INIT;
    transform->psa_mac_dec = MBEDTLS_SVC_KEY_ID_INIT;
#else
    mbedtls_md_init(&transform->md_ctx_enc);
    mbedtls_md_init(&transform->md_ctx_dec);
#endif
#endif
}

void mbedtls_ssl_session_init(mbedtls_ssl_session *session)
{
    memset(session, 0, sizeof(mbedtls_ssl_session));
    /* Set verify_result to -1u to indicate 'result not available'. */
    session->verify_result = 0xFFFFFFFF;
}

MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_handshake_init(mbedtls_ssl_context *ssl)
{
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    /* Clear old handshake information if present */
#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
    if (ssl->transform_negotiate) {
        mbedtls_ssl_transform_free(ssl->transform_negotiate);
    }
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
    if (ssl->session_negotiate) {
        mbedtls_ssl_session_free(ssl->session_negotiate);
    }
    if (ssl->handshake) {
        mbedtls_ssl_handshake_free(ssl);
    }

#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
    /*
     * Either the pointers are now NULL or cleared properly and can be freed.
     * Now allocate missing structures.
     */
    if (ssl->transform_negotiate == NULL) {
        ssl->transform_negotiate = mbedtls_calloc(1, sizeof(mbedtls_ssl_transform));
    }
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */

    if (ssl->session_negotiate == NULL) {
        ssl->session_negotiate = mbedtls_calloc(1, sizeof(mbedtls_ssl_session));
    }

    if (ssl->handshake == NULL) {
        ssl->handshake = mbedtls_calloc(1, sizeof(mbedtls_ssl_handshake_params));
    }
#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
    /* If the buffers are too small - reallocate */

    handle_buffer_resizing(ssl, 0, MBEDTLS_SSL_IN_BUFFER_LEN,
                           MBEDTLS_SSL_OUT_BUFFER_LEN);
#endif

    /* All pointers should exist and can be directly freed without issue */
    if (ssl->handshake           == NULL ||
#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
        ssl->transform_negotiate == NULL ||
#endif
        ssl->session_negotiate   == NULL) {
        MBEDTLS_SSL_DEBUG_MSG(1, ("alloc() of ssl sub-contexts failed"));

        mbedtls_free(ssl->handshake);
        ssl->handshake = NULL;

#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
        mbedtls_free(ssl->transform_negotiate);
        ssl->transform_negotiate = NULL;
#endif

        mbedtls_free(ssl->session_negotiate);
        ssl->session_negotiate = NULL;

        return MBEDTLS_ERR_SSL_ALLOC_FAILED;
    }

#if defined(MBEDTLS_SSL_EARLY_DATA)
#if defined(MBEDTLS_SSL_CLI_C)
    ssl->early_data_state = MBEDTLS_SSL_EARLY_DATA_STATE_IDLE;
#endif
#if defined(MBEDTLS_SSL_SRV_C)
    ssl->discard_early_data_record = MBEDTLS_SSL_EARLY_DATA_NO_DISCARD;
#endif
    ssl->total_early_data_size = 0;
#endif /* MBEDTLS_SSL_EARLY_DATA */

    /* Initialize structures */
    mbedtls_ssl_session_init(ssl->session_negotiate);
    ssl_handshake_params_init(ssl->handshake);

#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
    mbedtls_ssl_transform_init(ssl->transform_negotiate);
#endif

    /* Setup handshake checksums */
    ret = mbedtls_ssl_reset_checksum(ssl);
    if (ret != 0) {
        MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_reset_checksum", ret);
        return ret;
    }

#if defined(MBEDTLS_SSL_PROTO_TLS1_3) && \
    defined(MBEDTLS_SSL_SRV_C) && \
    defined(MBEDTLS_SSL_SESSION_TICKETS)
    ssl->handshake->new_session_tickets_count =
        ssl->conf->new_session_tickets_count;
#endif

#if defined(MBEDTLS_SSL_PROTO_DTLS)
    if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
        ssl->handshake->alt_transform_out = ssl->transform_out;

        if (ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT) {
            ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_PREPARING;
        } else {
            ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_WAITING;
        }

        mbedtls_ssl_set_timer(ssl, 0);
    }
#endif

/*
 * curve_list is translated to IANA TLS group identifiers here because
 * mbedtls_ssl_conf_curves returns void and so can't return
 * any error codes.
 */
#if defined(MBEDTLS_ECP_C)
#if !defined(MBEDTLS_DEPRECATED_REMOVED)
    /* Heap allocate and translate curve_list from internal to IANA group ids */
    if (ssl->conf->curve_list != NULL) {
        size_t length;
        const mbedtls_ecp_group_id *curve_list = ssl->conf->curve_list;

        for (length = 0;  (curve_list[length] != MBEDTLS_ECP_DP_NONE); length++) {
        }

        /* Leave room for zero termination */
        uint16_t *group_list = mbedtls_calloc(length + 1, sizeof(uint16_t));
        if (group_list == NULL) {
            return MBEDTLS_ERR_SSL_ALLOC_FAILED;
        }

        for (size_t i = 0; i < length; i++) {
            uint16_t tls_id = mbedtls_ssl_get_tls_id_from_ecp_group_id(
                curve_list[i]);
            if (tls_id == 0) {
                mbedtls_free(group_list);
                return MBEDTLS_ERR_SSL_BAD_CONFIG;
            }
            group_list[i] = tls_id;
        }

        group_list[length] = 0;

        ssl->handshake->group_list = group_list;
        ssl->handshake->group_list_heap_allocated = 1;
    } else {
        ssl->handshake->group_list = ssl->conf->group_list;
        ssl->handshake->group_list_heap_allocated = 0;
    }
#endif /* MBEDTLS_DEPRECATED_REMOVED */
#endif /* MBEDTLS_ECP_C */

#if defined(MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED)
#if !defined(MBEDTLS_DEPRECATED_REMOVED)
#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
    /* Heap allocate and translate sig_hashes from internal hash identifiers to
       signature algorithms IANA identifiers.  */
    if (mbedtls_ssl_conf_is_tls12_only(ssl->conf) &&
        ssl->conf->sig_hashes != NULL) {
        const int *md;
        const int *sig_hashes = ssl->conf->sig_hashes;
        size_t sig_algs_len = 0;
        uint16_t *p;

        MBEDTLS_STATIC_ASSERT(MBEDTLS_SSL_MAX_SIG_ALG_LIST_LEN
                              <= (SIZE_MAX - (2 * sizeof(uint16_t))),
                              "MBEDTLS_SSL_MAX_SIG_ALG_LIST_LEN too big");

        for (md = sig_hashes; *md != MBEDTLS_MD_NONE; md++) {
            if (mbedtls_ssl_hash_from_md_alg(*md) == MBEDTLS_SSL_HASH_NONE) {
                continue;
            }
#if defined(MBEDTLS_KEY_EXCHANGE_ECDSA_CERT_REQ_ALLOWED_ENABLED)
            sig_algs_len += sizeof(uint16_t);
#endif

#if defined(MBEDTLS_RSA_C)
            sig_algs_len += sizeof(uint16_t);
#endif
            if (sig_algs_len > MBEDTLS_SSL_MAX_SIG_ALG_LIST_LEN) {
                return MBEDTLS_ERR_SSL_BAD_CONFIG;
            }
        }

        if (sig_algs_len < MBEDTLS_SSL_MIN_SIG_ALG_LIST_LEN) {
            return MBEDTLS_ERR_SSL_BAD_CONFIG;
        }

        ssl->handshake->sig_algs = mbedtls_calloc(1, sig_algs_len +
                                                  sizeof(uint16_t));
        if (ssl->handshake->sig_algs == NULL) {
            return MBEDTLS_ERR_SSL_ALLOC_FAILED;
        }

        p = (uint16_t *) ssl->handshake->sig_algs;
        for (md = sig_hashes; *md != MBEDTLS_MD_NONE; md++) {
            unsigned char hash = mbedtls_ssl_hash_from_md_alg(*md);
            if (hash == MBEDTLS_SSL_HASH_NONE) {
                continue;
            }
#if defined(MBEDTLS_KEY_EXCHANGE_ECDSA_CERT_REQ_ALLOWED_ENABLED)
            *p = ((hash << 8) | MBEDTLS_SSL_SIG_ECDSA);
            p++;
#endif
#if defined(MBEDTLS_RSA_C)
            *p = ((hash << 8) | MBEDTLS_SSL_SIG_RSA);
            p++;
#endif
        }
        *p = MBEDTLS_TLS_SIG_NONE;
        ssl->handshake->sig_algs_heap_allocated = 1;
    } else
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
    {
        ssl->handshake->sig_algs_heap_allocated = 0;
    }
#endif /* !MBEDTLS_DEPRECATED_REMOVED */
#endif /* MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED */
    return 0;
}

#if defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY) && defined(MBEDTLS_SSL_SRV_C)
/* Dummy cookie callbacks for defaults */
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_cookie_write_dummy(void *ctx,
                                  unsigned char **p, unsigned char *end,
                                  const unsigned char *cli_id, size_t cli_id_len)
{
    ((void) ctx);
    ((void) p);
    ((void) end);
    ((void) cli_id);
    ((void) cli_id_len);

    return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
}

MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_cookie_check_dummy(void *ctx,
                                  const unsigned char *cookie, size_t cookie_len,
                                  const unsigned char *cli_id, size_t cli_id_len)
{
    ((void) ctx);
    ((void) cookie);
    ((void) cookie_len);
    ((void) cli_id);
    ((void) cli_id_len);

    return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
}
#endif /* MBEDTLS_SSL_DTLS_HELLO_VERIFY && MBEDTLS_SSL_SRV_C */

/*
 * Initialize an SSL context
 */
void mbedtls_ssl_init(mbedtls_ssl_context *ssl)
{
    memset(ssl, 0, sizeof(mbedtls_ssl_context));
}

MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_conf_version_check(const mbedtls_ssl_context *ssl)
{
    const mbedtls_ssl_config *conf = ssl->conf;

#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
    if (mbedtls_ssl_conf_is_tls13_only(conf)) {
        if (conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
            MBEDTLS_SSL_DEBUG_MSG(1, ("DTLS 1.3 is not yet supported."));
            return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
        }

        MBEDTLS_SSL_DEBUG_MSG(4, ("The SSL configuration is tls13 only."));
        return 0;
    }
#endif

#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
    if (mbedtls_ssl_conf_is_tls12_only(conf)) {
        MBEDTLS_SSL_DEBUG_MSG(4, ("The SSL configuration is tls12 only."));
        return 0;
    }
#endif

#if defined(MBEDTLS_SSL_PROTO_TLS1_2) && defined(MBEDTLS_SSL_PROTO_TLS1_3)
    if (mbedtls_ssl_conf_is_hybrid_tls12_tls13(conf)) {
        if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
            MBEDTLS_SSL_DEBUG_MSG(1, ("DTLS not yet supported in Hybrid TLS 1.3 + TLS 1.2"));
            return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
        }

        MBEDTLS_SSL_DEBUG_MSG(4, ("The SSL configuration is TLS 1.3 or TLS 1.2."));
        return 0;
    }
#endif

    MBEDTLS_SSL_DEBUG_MSG(1, ("The SSL configuration is invalid."));
    return MBEDTLS_ERR_SSL_BAD_CONFIG;
}

MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_conf_check(const mbedtls_ssl_context *ssl)
{
    int ret;
    ret = ssl_conf_version_check(ssl);
    if (ret != 0) {
        return ret;
    }

    if (ssl->conf->f_rng == NULL) {
        MBEDTLS_SSL_DEBUG_MSG(1, ("no RNG provided"));
        return MBEDTLS_ERR_SSL_NO_RNG;
    }

    /* Space for further checks */

    return 0;
}

/*
 * Setup an SSL context
 */

int mbedtls_ssl_setup(mbedtls_ssl_context *ssl,
                      const mbedtls_ssl_config *conf)
{
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
    size_t in_buf_len = MBEDTLS_SSL_IN_BUFFER_LEN;
    size_t out_buf_len = MBEDTLS_SSL_OUT_BUFFER_LEN;

    ssl->conf = conf;

    if ((ret = ssl_conf_check(ssl)) != 0) {
        return ret;
    }
    ssl->tls_version = ssl->conf->max_tls_version;

    /*
     * Prepare base structures
     */

    /* Set to NULL in case of an error condition */
    ssl->out_buf = NULL;

#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
    ssl->in_buf_len = in_buf_len;
#endif
    ssl->in_buf = mbedtls_calloc(1, in_buf_len);
    if (ssl->in_buf == NULL) {
        MBEDTLS_SSL_DEBUG_MSG(1, ("alloc(%" MBEDTLS_PRINTF_SIZET " bytes) failed", in_buf_len));
        ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
        goto error;
    }

#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
    ssl->out_buf_len = out_buf_len;
#endif
    ssl->out_buf = mbedtls_calloc(1, out_buf_len);
    if (ssl->out_buf == NULL) {
        MBEDTLS_SSL_DEBUG_MSG(1, ("alloc(%" MBEDTLS_PRINTF_SIZET " bytes) failed", out_buf_len));
        ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
        goto error;
    }

    mbedtls_ssl_reset_in_pointers(ssl);
    mbedtls_ssl_reset_out_pointers(ssl);

#if defined(MBEDTLS_SSL_DTLS_SRTP)
    memset(&ssl->dtls_srtp_info, 0, sizeof(ssl->dtls_srtp_info));
#endif

    if ((ret = ssl_handshake_init(ssl)) != 0) {
        goto error;
    }

    return 0;

error:
    mbedtls_free(ssl->in_buf);
    mbedtls_free(ssl->out_buf);

    ssl->conf = NULL;

#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
    ssl->in_buf_len = 0;
    ssl->out_buf_len = 0;
#endif
    ssl->in_buf = NULL;
    ssl->out_buf = NULL;

    ssl->in_hdr = NULL;
    ssl->in_ctr = NULL;
    ssl->in_len = NULL;
    ssl->in_iv = NULL;
    ssl->in_msg = NULL;

    ssl->out_hdr = NULL;
    ssl->out_ctr = NULL;
    ssl->out_len = NULL;
    ssl->out_iv = NULL;
    ssl->out_msg = NULL;

    return ret;
}

/*
 * Reset an initialized and used SSL context for re-use while retaining
 * all application-set variables, function pointers and data.
 *
 * If partial is non-zero, keep data in the input buffer and client ID.
 * (Use when a DTLS client reconnects from the same port.)
 */
void mbedtls_ssl_session_reset_msg_layer(mbedtls_ssl_context *ssl,
                                         int partial)
{
#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
    size_t in_buf_len = ssl->in_buf_len;
    size_t out_buf_len = ssl->out_buf_len;
#else
    size_t in_buf_len = MBEDTLS_SSL_IN_BUFFER_LEN;
    size_t out_buf_len = MBEDTLS_SSL_OUT_BUFFER_LEN;
#endif

#if !defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) || !defined(MBEDTLS_SSL_SRV_C)
    partial = 0;
#endif

    /* Cancel any possibly running timer */
    mbedtls_ssl_set_timer(ssl, 0);

    mbedtls_ssl_reset_in_pointers(ssl);
    mbedtls_ssl_reset_out_pointers(ssl);

    /* Reset incoming message parsing */
    ssl->in_offt    = NULL;
    ssl->nb_zero    = 0;
    ssl->in_msgtype = 0;
    ssl->in_msglen  = 0;
    ssl->in_hslen   = 0;
    ssl->keep_current_message = 0;
    ssl->transform_in  = NULL;

    /* TLS: reset in_hsfraglen, which is part of message parsing.
     * DTLS: on a client reconnect, don't reset badmac_seen. */
    if (!partial) {
        ssl->badmac_seen_or_in_hsfraglen = 0;
    }

#if defined(MBEDTLS_SSL_PROTO_DTLS)
    ssl->next_record_offset = 0;
    ssl->in_epoch = 0;
#endif

    /* Keep current datagram if partial == 1 */
    if (partial == 0) {
        ssl->in_left = 0;
        memset(ssl->in_buf, 0, in_buf_len);
    }

    ssl->send_alert = 0;

    /* Reset outgoing message writing */
    ssl->out_msgtype = 0;
    ssl->out_msglen  = 0;
    ssl->out_left    = 0;
    memset(ssl->out_buf, 0, out_buf_len);
    memset(ssl->cur_out_ctr, 0, sizeof(ssl->cur_out_ctr));
    ssl->transform_out = NULL;

#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
    mbedtls_ssl_dtls_replay_reset(ssl);
#endif

#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
    if (ssl->transform) {
        mbedtls_ssl_transform_free(ssl->transform);
        mbedtls_free(ssl->transform);
        ssl->transform = NULL;
    }
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */

#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
    mbedtls_ssl_transform_free(ssl->transform_application);
    mbedtls_free(ssl->transform_application);
    ssl->transform_application = NULL;

    if (ssl->handshake != NULL) {
#if defined(MBEDTLS_SSL_EARLY_DATA)
        mbedtls_ssl_transform_free(ssl->handshake->transform_earlydata);
        mbedtls_free(ssl->handshake->transform_earlydata);
        ssl->handshake->transform_earlydata = NULL;
#endif

        mbedtls_ssl_transform_free(ssl->handshake->transform_handshake);
        mbedtls_free(ssl->handshake->transform_handshake);
        ssl->handshake->transform_handshake = NULL;
    }

#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
}

int mbedtls_ssl_session_reset_int(mbedtls_ssl_context *ssl, int partial)
{
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    mbedtls_ssl_handshake_set_state(ssl, MBEDTLS_SSL_HELLO_REQUEST);
    ssl->tls_version = ssl->conf->max_tls_version;

    mbedtls_ssl_session_reset_msg_layer(ssl, partial);

    /* Reset renegotiation state */
#if defined(MBEDTLS_SSL_RENEGOTIATION)
    ssl->renego_status = MBEDTLS_SSL_INITIAL_HANDSHAKE;
    ssl->renego_records_seen = 0;

    ssl->verify_data_len = 0;
    memset(ssl->own_verify_data, 0, MBEDTLS_SSL_VERIFY_DATA_MAX_LEN);
    memset(ssl->peer_verify_data, 0, MBEDTLS_SSL_VERIFY_DATA_MAX_LEN);
#endif
    ssl->secure_renegotiation = MBEDTLS_SSL_LEGACY_RENEGOTIATION;

    ssl->session_in  = NULL;
    ssl->session_out = NULL;
    if (ssl->session) {
        mbedtls_ssl_session_free(ssl->session);
        mbedtls_free(ssl->session);
        ssl->session = NULL;
    }

#if defined(MBEDTLS_SSL_ALPN)
    ssl->alpn_chosen = NULL;
#endif

#if defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY) && defined(MBEDTLS_SSL_SRV_C)
    int free_cli_id = 1;
#if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE)
    free_cli_id = (partial == 0);
#endif
    if (free_cli_id) {
        mbedtls_free(ssl->cli_id);
        ssl->cli_id = NULL;
        ssl->cli_id_len = 0;
    }
#endif

    if ((ret = ssl_handshake_init(ssl)) != 0) {
        return ret;
    }

    return 0;
}

/*
 * Reset an initialized and used SSL context for re-use while retaining
 * all application-set variables, function pointers and data.
 */
int mbedtls_ssl_session_reset(mbedtls_ssl_context *ssl)
{
    return mbedtls_ssl_session_reset_int(ssl, 0);
}

/*
 * SSL set accessors
 */
void mbedtls_ssl_conf_endpoint(mbedtls_ssl_config *conf, int endpoint)
{
    conf->endpoint   = endpoint;
}

void mbedtls_ssl_conf_transport(mbedtls_ssl_config *conf, int transport)
{
    conf->transport = transport;
}

#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
void mbedtls_ssl_conf_dtls_anti_replay(mbedtls_ssl_config *conf, char mode)
{
    conf->anti_replay = mode;
}
#endif

void mbedtls_ssl_conf_dtls_badmac_limit(mbedtls_ssl_config *conf, unsigned limit)
{
    conf->badmac_limit = limit;
}

#if defined(MBEDTLS_SSL_PROTO_DTLS)

void mbedtls_ssl_set_datagram_packing(mbedtls_ssl_context *ssl,
                                      unsigned allow_packing)
{
    ssl->disable_datagram_packing = !allow_packing;
}

void mbedtls_ssl_conf_handshake_timeout(mbedtls_ssl_config *conf,
                                        uint32_t min, uint32_t max)
{
    conf->hs_timeout_min = min;
    conf->hs_timeout_max = max;
}
#endif

void mbedtls_ssl_conf_authmode(mbedtls_ssl_config *conf, int authmode)
{
    conf->authmode   = authmode;
}

#if defined(MBEDTLS_X509_CRT_PARSE_C)
void mbedtls_ssl_conf_verify(mbedtls_ssl_config *conf,
                             int (*f_vrfy)(void *, mbedtls_x509_crt *, int, uint32_t *),
                             void *p_vrfy)
{
    conf->f_vrfy      = f_vrfy;
    conf->p_vrfy      = p_vrfy;
}
#endif /* MBEDTLS_X509_CRT_PARSE_C */

void mbedtls_ssl_conf_rng(mbedtls_ssl_config *conf,
                          int (*f_rng)(void *, unsigned char *, size_t),
                          void *p_rng)
{
    conf->f_rng      = f_rng;
    conf->p_rng      = p_rng;
}

void mbedtls_ssl_conf_dbg(mbedtls_ssl_config *conf,
                          void (*f_dbg)(void *, int, const char *, int, const char *),
                          void  *p_dbg)
{
    conf->f_dbg      = f_dbg;
    conf->p_dbg      = p_dbg;
}

void mbedtls_ssl_set_bio(mbedtls_ssl_context *ssl,
                         void *p_bio,
                         mbedtls_ssl_send_t *f_send,
                         mbedtls_ssl_recv_t *f_recv,
                         mbedtls_ssl_recv_timeout_t *f_recv_timeout)
{
    ssl->p_bio          = p_bio;
    ssl->f_send         = f_send;
    ssl->f_recv         = f_recv;
    ssl->f_recv_timeout = f_recv_timeout;
}

#if defined(MBEDTLS_SSL_PROTO_DTLS)
void mbedtls_ssl_set_mtu(mbedtls_ssl_context *ssl, uint16_t mtu)
{
    ssl->mtu = mtu;
}
#endif

void mbedtls_ssl_conf_read_timeout(mbedtls_ssl_config *conf, uint32_t timeout)
{
    conf->read_timeout   = timeout;
}

void mbedtls_ssl_set_timer_cb(mbedtls_ssl_context *ssl,
                              void *p_timer,
                              mbedtls_ssl_set_timer_t *f_set_timer,
                              mbedtls_ssl_get_timer_t *f_get_timer)
{
    ssl->p_timer        = p_timer;
    ssl->f_set_timer    = f_set_timer;
    ssl->f_get_timer    = f_get_timer;

    /* Make sure we start with no timer running */
    mbedtls_ssl_set_timer(ssl, 0);
}

#if defined(MBEDTLS_SSL_SRV_C)
void mbedtls_ssl_conf_session_cache(mbedtls_ssl_config *conf,
                                    void *p_cache,
                                    mbedtls_ssl_cache_get_t *f_get_cache,
                                    mbedtls_ssl_cache_set_t *f_set_cache)
{
    conf->p_cache = p_cache;
    conf->f_get_cache = f_get_cache;
    conf->f_set_cache = f_set_cache;
}
#endif /* MBEDTLS_SSL_SRV_C */

#if defined(MBEDTLS_SSL_CLI_C)
int mbedtls_ssl_set_session(mbedtls_ssl_context *ssl, const mbedtls_ssl_session *session)
{
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    if (ssl == NULL ||
        session == NULL ||
        ssl->session_negotiate == NULL ||
        ssl->conf->endpoint != MBEDTLS_SSL_IS_CLIENT) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    if (ssl->handshake->resume == 1) {
        return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
    }

#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
    if (session->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
        const mbedtls_ssl_ciphersuite_t *ciphersuite_info =
            mbedtls_ssl_ciphersuite_from_id(session->ciphersuite);

        if (mbedtls_ssl_validate_ciphersuite(
                ssl, ciphersuite_info, MBEDTLS_SSL_VERSION_TLS1_3,
                MBEDTLS_SSL_VERSION_TLS1_3) != 0) {
            MBEDTLS_SSL_DEBUG_MSG(4, ("%d is not a valid TLS 1.3 ciphersuite.",
                                      session->ciphersuite));
            return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
        }
#else
        /*
         * If session tickets are not enabled, it is not possible to resume a
         * TLS 1.3 session, thus do not make any change to the SSL context in
         * the first place.
         */
        return 0;
#endif
    }
#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */

    if ((ret = mbedtls_ssl_session_copy(ssl->session_negotiate,
                                        session)) != 0) {
        return ret;
    }

    ssl->handshake->resume = 1;

    return 0;
}
#endif /* MBEDTLS_SSL_CLI_C */

void mbedtls_ssl_conf_ciphersuites(mbedtls_ssl_config *conf,
                                   const int *ciphersuites)
{
    conf->ciphersuite_list = ciphersuites;
}

#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
void mbedtls_ssl_conf_tls13_key_exchange_modes(mbedtls_ssl_config *conf,
                                               const int kex_modes)
{
    conf->tls13_kex_modes = kex_modes & MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_ALL;
}

#if defined(MBEDTLS_SSL_EARLY_DATA)
void mbedtls_ssl_conf_early_data(mbedtls_ssl_config *conf,
                                 int early_data_enabled)
{
    conf->early_data_enabled = early_data_enabled;
}

#if defined(MBEDTLS_SSL_SRV_C)
void mbedtls_ssl_conf_max_early_data_size(
    mbedtls_ssl_config *conf, uint32_t max_early_data_size)
{
    conf->max_early_data_size = max_early_data_size;
}
#endif /* MBEDTLS_SSL_SRV_C */

#endif /* MBEDTLS_SSL_EARLY_DATA */
#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */

#if defined(MBEDTLS_X509_CRT_PARSE_C)
void mbedtls_ssl_conf_cert_profile(mbedtls_ssl_config *conf,
                                   const mbedtls_x509_crt_profile *profile)
{
    conf->cert_profile = profile;
}

static void ssl_key_cert_free(mbedtls_ssl_key_cert *key_cert)
{
    mbedtls_ssl_key_cert *cur = key_cert, *next;

    while (cur != NULL) {
        next = cur->next;
        mbedtls_free(cur);
        cur = next;
    }
}

/* Append a new keycert entry to a (possibly empty) list */
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_append_key_cert(mbedtls_ssl_key_cert **head,
                               mbedtls_x509_crt *cert,
                               mbedtls_pk_context *key)
{
    mbedtls_ssl_key_cert *new_cert;

    if (cert == NULL) {
        /* Free list if cert is null */
        ssl_key_cert_free(*head);
        *head = NULL;
        return 0;
    }

    new_cert = mbedtls_calloc(1, sizeof(mbedtls_ssl_key_cert));
    if (new_cert == NULL) {
        return MBEDTLS_ERR_SSL_ALLOC_FAILED;
    }

    new_cert->cert = cert;
    new_cert->key  = key;
    new_cert->next = NULL;

    /* Update head if the list was null, else add to the end */
    if (*head == NULL) {
        *head = new_cert;
    } else {
        mbedtls_ssl_key_cert *cur = *head;
        while (cur->next != NULL) {
            cur = cur->next;
        }
        cur->next = new_cert;
    }

    return 0;
}

int mbedtls_ssl_conf_own_cert(mbedtls_ssl_config *conf,
                              mbedtls_x509_crt *own_cert,
                              mbedtls_pk_context *pk_key)
{
    return ssl_append_key_cert(&conf->key_cert, own_cert, pk_key);
}

void mbedtls_ssl_conf_ca_chain(mbedtls_ssl_config *conf,
                               mbedtls_x509_crt *ca_chain,
                               mbedtls_x509_crl *ca_crl)
{
    conf->ca_chain   = ca_chain;
    conf->ca_crl     = ca_crl;

#if defined(MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK)
    /* mbedtls_ssl_conf_ca_chain() and mbedtls_ssl_conf_ca_cb()
     * cannot be used together. */
    conf->f_ca_cb = NULL;
    conf->p_ca_cb = NULL;
#endif /* MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK */
}

#if defined(MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK)
void mbedtls_ssl_conf_ca_cb(mbedtls_ssl_config *conf,
                            mbedtls_x509_crt_ca_cb_t f_ca_cb,
                            void *p_ca_cb)
{
    conf->f_ca_cb = f_ca_cb;
    conf->p_ca_cb = p_ca_cb;

    /* mbedtls_ssl_conf_ca_chain() and mbedtls_ssl_conf_ca_cb()
     * cannot be used together. */
    conf->ca_chain   = NULL;
    conf->ca_crl     = NULL;
}
#endif /* MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK */
#endif /* MBEDTLS_X509_CRT_PARSE_C */

#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
const unsigned char *mbedtls_ssl_get_hs_sni(mbedtls_ssl_context *ssl,
                                            size_t *name_len)
{
    *name_len = ssl->handshake->sni_name_len;
    return ssl->handshake->sni_name;
}

int mbedtls_ssl_set_hs_own_cert(mbedtls_ssl_context *ssl,
                                mbedtls_x509_crt *own_cert,
                                mbedtls_pk_context *pk_key)
{
    return ssl_append_key_cert(&ssl->handshake->sni_key_cert,
                               own_cert, pk_key);
}

void mbedtls_ssl_set_hs_ca_chain(mbedtls_ssl_context *ssl,
                                 mbedtls_x509_crt *ca_chain,
                                 mbedtls_x509_crl *ca_crl)
{
    ssl->handshake->sni_ca_chain   = ca_chain;
    ssl->handshake->sni_ca_crl     = ca_crl;
}

#if defined(MBEDTLS_KEY_EXCHANGE_CERT_REQ_ALLOWED_ENABLED)
void mbedtls_ssl_set_hs_dn_hints(mbedtls_ssl_context *ssl,
                                 const mbedtls_x509_crt *crt)
{
    ssl->handshake->dn_hints = crt;
}
#endif /* MBEDTLS_KEY_EXCHANGE_CERT_REQ_ALLOWED_ENABLED */

void mbedtls_ssl_set_hs_authmode(mbedtls_ssl_context *ssl,
                                 int authmode)
{
    ssl->handshake->sni_authmode = authmode;
}
#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */

#if defined(MBEDTLS_X509_CRT_PARSE_C)
void mbedtls_ssl_set_verify(mbedtls_ssl_context *ssl,
                            int (*f_vrfy)(void *, mbedtls_x509_crt *, int, uint32_t *),
                            void *p_vrfy)
{
    ssl->f_vrfy = f_vrfy;
    ssl->p_vrfy = p_vrfy;
}
#endif

#if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)

#if defined(MBEDTLS_USE_PSA_CRYPTO)
static const uint8_t jpake_server_id[] = { 's', 'e', 'r', 'v', 'e', 'r' };
static const uint8_t jpake_client_id[] = { 'c', 'l', 'i', 'e', 'n', 't' };

static psa_status_t mbedtls_ssl_set_hs_ecjpake_password_common(
    mbedtls_ssl_context *ssl,
    mbedtls_svc_key_id_t pwd)
{
    psa_status_t status;
    psa_pake_cipher_suite_t cipher_suite = psa_pake_cipher_suite_init();
    const uint8_t *user = NULL;
    size_t user_len = 0;
    const uint8_t *peer = NULL;
    size_t peer_len = 0;
    psa_pake_cs_set_algorithm(&cipher_suite, PSA_ALG_JPAKE);
    psa_pake_cs_set_primitive(&cipher_suite,
                              PSA_PAKE_PRIMITIVE(PSA_PAKE_PRIMITIVE_TYPE_ECC,
                                                 PSA_ECC_FAMILY_SECP_R1,
                                                 256));
    psa_pake_cs_set_hash(&cipher_suite, PSA_ALG_SHA_256);

    status = psa_pake_setup(&ssl->handshake->psa_pake_ctx, &cipher_suite);
    if (status != PSA_SUCCESS) {
        return status;
    }

    if (ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER) {
        user = jpake_server_id;
        user_len = sizeof(jpake_server_id);
        peer = jpake_client_id;
        peer_len = sizeof(jpake_client_id);
    } else {
        user = jpake_client_id;
        user_len = sizeof(jpake_client_id);
        peer = jpake_server_id;
        peer_len = sizeof(jpake_server_id);
    }

    status = psa_pake_set_user(&ssl->handshake->psa_pake_ctx, user, user_len);
    if (status != PSA_SUCCESS) {
        return status;
    }

    status = psa_pake_set_peer(&ssl->handshake->psa_pake_ctx, peer, peer_len);
    if (status != PSA_SUCCESS) {
        return status;
    }

    status = psa_pake_set_password_key(&ssl->handshake->psa_pake_ctx, pwd);
    if (status != PSA_SUCCESS) {
        return status;
    }

    ssl->handshake->psa_pake_ctx_is_ok = 1;

    return PSA_SUCCESS;
}

int mbedtls_ssl_set_hs_ecjpake_password(mbedtls_ssl_context *ssl,
                                        const unsigned char *pw,
                                        size_t pw_len)
{
    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
    psa_status_t status;

    if (ssl->handshake == NULL || ssl->conf == NULL) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    /* Empty password is not valid  */
    if ((pw == NULL) || (pw_len == 0)) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_DERIVE);
    psa_set_key_algorithm(&attributes, PSA_ALG_JPAKE);
    psa_set_key_type(&attributes, PSA_KEY_TYPE_PASSWORD);

    status = psa_import_key(&attributes, pw, pw_len,
                            &ssl->handshake->psa_pake_password);
    if (status != PSA_SUCCESS) {
        return MBEDTLS_ERR_SSL_HW_ACCEL_FAILED;
    }

    status = mbedtls_ssl_set_hs_ecjpake_password_common(ssl,
                                                        ssl->handshake->psa_pake_password);
    if (status != PSA_SUCCESS) {
        psa_destroy_key(ssl->handshake->psa_pake_password);
        psa_pake_abort(&ssl->handshake->psa_pake_ctx);
        return MBEDTLS_ERR_SSL_HW_ACCEL_FAILED;
    }

    return 0;
}

int mbedtls_ssl_set_hs_ecjpake_password_opaque(mbedtls_ssl_context *ssl,
                                               mbedtls_svc_key_id_t pwd)
{
    psa_status_t status;

    if (ssl->handshake == NULL || ssl->conf == NULL) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    if (mbedtls_svc_key_id_is_null(pwd)) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    status = mbedtls_ssl_set_hs_ecjpake_password_common(ssl, pwd);
    if (status != PSA_SUCCESS) {
        psa_pake_abort(&ssl->handshake->psa_pake_ctx);
        return MBEDTLS_ERR_SSL_HW_ACCEL_FAILED;
    }

    return 0;
}
#else /* MBEDTLS_USE_PSA_CRYPTO */
int mbedtls_ssl_set_hs_ecjpake_password(mbedtls_ssl_context *ssl,
                                        const unsigned char *pw,
                                        size_t pw_len)
{
    mbedtls_ecjpake_role role;

    if (ssl->handshake == NULL || ssl->conf == NULL) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    /* Empty password is not valid  */
    if ((pw == NULL) || (pw_len == 0)) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    if (ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER) {
        role = MBEDTLS_ECJPAKE_SERVER;
    } else {
        role = MBEDTLS_ECJPAKE_CLIENT;
    }

    return mbedtls_ecjpake_setup(&ssl->handshake->ecjpake_ctx,
                                 role,
                                 MBEDTLS_MD_SHA256,
                                 MBEDTLS_ECP_DP_SECP256R1,
                                 pw, pw_len);
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
#endif /* MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */

#if defined(MBEDTLS_SSL_HANDSHAKE_WITH_PSK_ENABLED)
int mbedtls_ssl_conf_has_static_psk(mbedtls_ssl_config const *conf)
{
    if (conf->psk_identity     == NULL ||
        conf->psk_identity_len == 0) {
        return 0;
    }

#if defined(MBEDTLS_USE_PSA_CRYPTO)
    if (!mbedtls_svc_key_id_is_null(conf->psk_opaque)) {
        return 1;
    }
#endif /* MBEDTLS_USE_PSA_CRYPTO */

    if (conf->psk != NULL && conf->psk_len != 0) {
        return 1;
    }

    return 0;
}

static void ssl_conf_remove_psk(mbedtls_ssl_config *conf)
{
    /* Remove reference to existing PSK, if any. */
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    if (!mbedtls_svc_key_id_is_null(conf->psk_opaque)) {
        /* The maintenance of the PSK key slot is the
         * user's responsibility. */
        conf->psk_opaque = MBEDTLS_SVC_KEY_ID_INIT;
    }
#endif /* MBEDTLS_USE_PSA_CRYPTO */
    if (conf->psk != NULL) {
        mbedtls_zeroize_and_free(conf->psk, conf->psk_len);
        conf->psk = NULL;
        conf->psk_len = 0;
    }

    /* Remove reference to PSK identity, if any. */
    if (conf->psk_identity != NULL) {
        mbedtls_free(conf->psk_identity);
        conf->psk_identity = NULL;
        conf->psk_identity_len = 0;
    }
}

/* This function assumes that PSK identity in the SSL config is unset.
 * It checks that the provided identity is well-formed and attempts
 * to make a copy of it in the SSL config.
 * On failure, the PSK identity in the config remains unset. */
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_conf_set_psk_identity(mbedtls_ssl_config *conf,
                                     unsigned char const *psk_identity,
                                     size_t psk_identity_len)
{
    /* Identity len will be encoded on two bytes */
    if (psk_identity               == NULL ||
        psk_identity_len           == 0    ||
        (psk_identity_len >> 16) != 0    ||
        psk_identity_len > MBEDTLS_SSL_OUT_CONTENT_LEN) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    conf->psk_identity = mbedtls_calloc(1, psk_identity_len);
    if (conf->psk_identity == NULL) {
        return MBEDTLS_ERR_SSL_ALLOC_FAILED;
    }

    conf->psk_identity_len = psk_identity_len;
    memcpy(conf->psk_identity, psk_identity, conf->psk_identity_len);

    return 0;
}

int mbedtls_ssl_conf_psk(mbedtls_ssl_config *conf,
                         const unsigned char *psk, size_t psk_len,
                         const unsigned char *psk_identity, size_t psk_identity_len)
{
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    /* We currently only support one PSK, raw or opaque. */
    if (mbedtls_ssl_conf_has_static_psk(conf)) {
        return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
    }

    /* Check and set raw PSK */
    if (psk == NULL) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }
    if (psk_len == 0) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }
    if (psk_len > MBEDTLS_PSK_MAX_LEN) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    if ((conf->psk = mbedtls_calloc(1, psk_len)) == NULL) {
        return MBEDTLS_ERR_SSL_ALLOC_FAILED;
    }
    conf->psk_len = psk_len;
    memcpy(conf->psk, psk, conf->psk_len);

    /* Check and set PSK Identity */
    ret = ssl_conf_set_psk_identity(conf, psk_identity, psk_identity_len);
    if (ret != 0) {
        ssl_conf_remove_psk(conf);
    }

    return ret;
}

static void ssl_remove_psk(mbedtls_ssl_context *ssl)
{
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    if (!mbedtls_svc_key_id_is_null(ssl->handshake->psk_opaque)) {
        /* The maintenance of the external PSK key slot is the
         * user's responsibility. */
        if (ssl->handshake->psk_opaque_is_internal) {
            psa_destroy_key(ssl->handshake->psk_opaque);
            ssl->handshake->psk_opaque_is_internal = 0;
        }
        ssl->handshake->psk_opaque = MBEDTLS_SVC_KEY_ID_INIT;
    }
#else
    if (ssl->handshake->psk != NULL) {
        mbedtls_zeroize_and_free(ssl->handshake->psk,
                                 ssl->handshake->psk_len);
        ssl->handshake->psk_len = 0;
        ssl->handshake->psk = NULL;
    }
#endif /* MBEDTLS_USE_PSA_CRYPTO */
}

int mbedtls_ssl_set_hs_psk(mbedtls_ssl_context *ssl,
                           const unsigned char *psk, size_t psk_len)
{
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    psa_key_attributes_t key_attributes = psa_key_attributes_init();
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_algorithm_t alg = PSA_ALG_NONE;
    mbedtls_svc_key_id_t key = MBEDTLS_SVC_KEY_ID_INIT;
#endif /* MBEDTLS_USE_PSA_CRYPTO */

    if (psk == NULL || ssl->handshake == NULL) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    if (psk_len > MBEDTLS_PSK_MAX_LEN) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    ssl_remove_psk(ssl);

#if defined(MBEDTLS_USE_PSA_CRYPTO)
#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
    if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_2) {
        if (ssl->handshake->ciphersuite_info->mac == MBEDTLS_MD_SHA384) {
            alg = PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_384);
        } else {
            alg = PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_256);
        }
        psa_set_key_usage_flags(&key_attributes, PSA_KEY_USAGE_DERIVE);
    }
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */

#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
    if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
        alg = PSA_ALG_HKDF_EXTRACT(PSA_ALG_ANY_HASH);
        psa_set_key_usage_flags(&key_attributes,
                                PSA_KEY_USAGE_DERIVE | PSA_KEY_USAGE_EXPORT);
    }
#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */

    psa_set_key_algorithm(&key_attributes, alg);
    psa_set_key_type(&key_attributes, PSA_KEY_TYPE_DERIVE);

    status = psa_import_key(&key_attributes, psk, psk_len, &key);
    if (status != PSA_SUCCESS) {
        return MBEDTLS_ERR_SSL_HW_ACCEL_FAILED;
    }

    /* Allow calling psa_destroy_key() on psk remove */
    ssl->handshake->psk_opaque_is_internal = 1;
    return mbedtls_ssl_set_hs_psk_opaque(ssl, key);
#else
    if ((ssl->handshake->psk = mbedtls_calloc(1, psk_len)) == NULL) {
        return MBEDTLS_ERR_SSL_ALLOC_FAILED;
    }

    ssl->handshake->psk_len = psk_len;
    memcpy(ssl->handshake->psk, psk, ssl->handshake->psk_len);

    return 0;
#endif /* MBEDTLS_USE_PSA_CRYPTO */
}

#if defined(MBEDTLS_USE_PSA_CRYPTO)
int mbedtls_ssl_conf_psk_opaque(mbedtls_ssl_config *conf,
                                mbedtls_svc_key_id_t psk,
                                const unsigned char *psk_identity,
                                size_t psk_identity_len)
{
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    /* We currently only support one PSK, raw or opaque. */
    if (mbedtls_ssl_conf_has_static_psk(conf)) {
        return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
    }

    /* Check and set opaque PSK */
    if (mbedtls_svc_key_id_is_null(psk)) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }
    conf->psk_opaque = psk;

    /* Check and set PSK Identity */
    ret = ssl_conf_set_psk_identity(conf, psk_identity,
                                    psk_identity_len);
    if (ret != 0) {
        ssl_conf_remove_psk(conf);
    }

    return ret;
}

int mbedtls_ssl_set_hs_psk_opaque(mbedtls_ssl_context *ssl,
                                  mbedtls_svc_key_id_t psk)
{
    if ((mbedtls_svc_key_id_is_null(psk)) ||
        (ssl->handshake == NULL)) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    ssl_remove_psk(ssl);
    ssl->handshake->psk_opaque = psk;
    return 0;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */

#if defined(MBEDTLS_SSL_SRV_C)
void mbedtls_ssl_conf_psk_cb(mbedtls_ssl_config *conf,
                             int (*f_psk)(void *, mbedtls_ssl_context *, const unsigned char *,
                                          size_t),
                             void *p_psk)
{
    conf->f_psk = f_psk;
    conf->p_psk = p_psk;
}
#endif /* MBEDTLS_SSL_SRV_C */

#endif /* MBEDTLS_SSL_HANDSHAKE_WITH_PSK_ENABLED */

#if defined(MBEDTLS_USE_PSA_CRYPTO)
static mbedtls_ssl_mode_t mbedtls_ssl_get_base_mode(
    psa_algorithm_t alg)
{
#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
    if (alg == PSA_ALG_CBC_NO_PADDING) {
        return MBEDTLS_SSL_MODE_CBC;
    }
#endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */
    if (PSA_ALG_IS_AEAD(alg)) {
        return MBEDTLS_SSL_MODE_AEAD;
    }
    return MBEDTLS_SSL_MODE_STREAM;
}

#else /* MBEDTLS_USE_PSA_CRYPTO */

static mbedtls_ssl_mode_t mbedtls_ssl_get_base_mode(
    mbedtls_cipher_mode_t mode)
{
#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
    if (mode == MBEDTLS_MODE_CBC) {
        return MBEDTLS_SSL_MODE_CBC;
    }
#endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */

#if defined(MBEDTLS_GCM_C) || \
    defined(MBEDTLS_CCM_C) || \
    defined(MBEDTLS_CHACHAPOLY_C)
    if (mode == MBEDTLS_MODE_GCM ||
        mode == MBEDTLS_MODE_CCM ||
        mode == MBEDTLS_MODE_CHACHAPOLY) {
        return MBEDTLS_SSL_MODE_AEAD;
    }
#endif /* MBEDTLS_GCM_C || MBEDTLS_CCM_C || MBEDTLS_CHACHAPOLY_C */

    return MBEDTLS_SSL_MODE_STREAM;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */

static mbedtls_ssl_mode_t mbedtls_ssl_get_actual_mode(
    mbedtls_ssl_mode_t base_mode,
    int encrypt_then_mac)
{
#if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC_ETM)
    if (encrypt_then_mac == MBEDTLS_SSL_ETM_ENABLED &&
        base_mode == MBEDTLS_SSL_MODE_CBC) {
        return MBEDTLS_SSL_MODE_CBC_ETM;
    }
#else
    (void) encrypt_then_mac;
#endif
    return base_mode;
}

mbedtls_ssl_mode_t mbedtls_ssl_get_mode_from_transform(
    const mbedtls_ssl_transform *transform)
{
    mbedtls_ssl_mode_t base_mode = mbedtls_ssl_get_base_mode(
#if defined(MBEDTLS_USE_PSA_CRYPTO)
        transform->psa_alg
#else
        mbedtls_cipher_get_cipher_mode(&transform->cipher_ctx_enc)
#endif
        );

    int encrypt_then_mac = 0;
#if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC_ETM)
    encrypt_then_mac = transform->encrypt_then_mac;
#endif
    return mbedtls_ssl_get_actual_mode(base_mode, encrypt_then_mac);
}

mbedtls_ssl_mode_t mbedtls_ssl_get_mode_from_ciphersuite(
#if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC_ETM)
    int encrypt_then_mac,
#endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC_ETM */
    const mbedtls_ssl_ciphersuite_t *suite)
{
    mbedtls_ssl_mode_t base_mode = MBEDTLS_SSL_MODE_STREAM;

#if defined(MBEDTLS_USE_PSA_CRYPTO)
    psa_status_t status;
    psa_algorithm_t alg;
    psa_key_type_t type;
    size_t size;
    status = mbedtls_ssl_cipher_to_psa((mbedtls_cipher_type_t) suite->cipher,
                                       0, &alg, &type, &size);
    if (status == PSA_SUCCESS) {
        base_mode = mbedtls_ssl_get_base_mode(alg);
    }
#else
    const mbedtls_cipher_info_t *cipher =
        mbedtls_cipher_info_from_type((mbedtls_cipher_type_t) suite->cipher);
    if (cipher != NULL) {
        base_mode =
            mbedtls_ssl_get_base_mode(
                mbedtls_cipher_info_get_mode(cipher));
    }
#endif /* MBEDTLS_USE_PSA_CRYPTO */

#if !defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC_ETM)
    int encrypt_then_mac = 0;
#endif
    return mbedtls_ssl_get_actual_mode(base_mode, encrypt_then_mac);
}

#if defined(MBEDTLS_USE_PSA_CRYPTO) || defined(MBEDTLS_SSL_PROTO_TLS1_3)

psa_status_t mbedtls_ssl_cipher_to_psa(mbedtls_cipher_type_t mbedtls_cipher_type,
                                       size_t taglen,
                                       psa_algorithm_t *alg,
                                       psa_key_type_t *key_type,
                                       size_t *key_size)
{
#if !defined(MBEDTLS_SSL_HAVE_CCM)
    (void) taglen;
#endif
    switch (mbedtls_cipher_type) {
#if defined(MBEDTLS_SSL_HAVE_AES) && defined(MBEDTLS_SSL_HAVE_CBC)
        case MBEDTLS_CIPHER_AES_128_CBC:
            *alg = PSA_ALG_CBC_NO_PADDING;
            *key_type = PSA_KEY_TYPE_AES;
            *key_size = 128;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_AES) && defined(MBEDTLS_SSL_HAVE_CCM)
        case MBEDTLS_CIPHER_AES_128_CCM:
            *alg = taglen ? PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, taglen) : PSA_ALG_CCM;
            *key_type = PSA_KEY_TYPE_AES;
            *key_size = 128;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_AES) && defined(MBEDTLS_SSL_HAVE_GCM)
        case MBEDTLS_CIPHER_AES_128_GCM:
            *alg = PSA_ALG_GCM;
            *key_type = PSA_KEY_TYPE_AES;
            *key_size = 128;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_AES) && defined(MBEDTLS_SSL_HAVE_CCM)
        case MBEDTLS_CIPHER_AES_192_CCM:
            *alg = taglen ? PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, taglen) : PSA_ALG_CCM;
            *key_type = PSA_KEY_TYPE_AES;
            *key_size = 192;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_AES) && defined(MBEDTLS_SSL_HAVE_GCM)
        case MBEDTLS_CIPHER_AES_192_GCM:
            *alg = PSA_ALG_GCM;
            *key_type = PSA_KEY_TYPE_AES;
            *key_size = 192;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_AES) && defined(MBEDTLS_SSL_HAVE_CBC)
        case MBEDTLS_CIPHER_AES_256_CBC:
            *alg = PSA_ALG_CBC_NO_PADDING;
            *key_type = PSA_KEY_TYPE_AES;
            *key_size = 256;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_AES) && defined(MBEDTLS_SSL_HAVE_CCM)
        case MBEDTLS_CIPHER_AES_256_CCM:
            *alg = taglen ? PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, taglen) : PSA_ALG_CCM;
            *key_type = PSA_KEY_TYPE_AES;
            *key_size = 256;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_AES) && defined(MBEDTLS_SSL_HAVE_GCM)
        case MBEDTLS_CIPHER_AES_256_GCM:
            *alg = PSA_ALG_GCM;
            *key_type = PSA_KEY_TYPE_AES;
            *key_size = 256;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_ARIA) && defined(MBEDTLS_SSL_HAVE_CBC)
        case MBEDTLS_CIPHER_ARIA_128_CBC:
            *alg = PSA_ALG_CBC_NO_PADDING;
            *key_type = PSA_KEY_TYPE_ARIA;
            *key_size = 128;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_ARIA) && defined(MBEDTLS_SSL_HAVE_CCM)
        case MBEDTLS_CIPHER_ARIA_128_CCM:
            *alg = taglen ? PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, taglen) : PSA_ALG_CCM;
            *key_type = PSA_KEY_TYPE_ARIA;
            *key_size = 128;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_ARIA) && defined(MBEDTLS_SSL_HAVE_GCM)
        case MBEDTLS_CIPHER_ARIA_128_GCM:
            *alg = PSA_ALG_GCM;
            *key_type = PSA_KEY_TYPE_ARIA;
            *key_size = 128;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_ARIA) && defined(MBEDTLS_SSL_HAVE_CCM)
        case MBEDTLS_CIPHER_ARIA_192_CCM:
            *alg = taglen ? PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, taglen) : PSA_ALG_CCM;
            *key_type = PSA_KEY_TYPE_ARIA;
            *key_size = 192;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_ARIA) && defined(MBEDTLS_SSL_HAVE_GCM)
        case MBEDTLS_CIPHER_ARIA_192_GCM:
            *alg = PSA_ALG_GCM;
            *key_type = PSA_KEY_TYPE_ARIA;
            *key_size = 192;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_ARIA) && defined(MBEDTLS_SSL_HAVE_CBC)
        case MBEDTLS_CIPHER_ARIA_256_CBC:
            *alg = PSA_ALG_CBC_NO_PADDING;
            *key_type = PSA_KEY_TYPE_ARIA;
            *key_size = 256;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_ARIA) && defined(MBEDTLS_SSL_HAVE_CCM)
        case MBEDTLS_CIPHER_ARIA_256_CCM:
            *alg = taglen ? PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, taglen) : PSA_ALG_CCM;
            *key_type = PSA_KEY_TYPE_ARIA;
            *key_size = 256;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_ARIA) && defined(MBEDTLS_SSL_HAVE_GCM)
        case MBEDTLS_CIPHER_ARIA_256_GCM:
            *alg = PSA_ALG_GCM;
            *key_type = PSA_KEY_TYPE_ARIA;
            *key_size = 256;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_CAMELLIA) && defined(MBEDTLS_SSL_HAVE_CBC)
        case MBEDTLS_CIPHER_CAMELLIA_128_CBC:
            *alg = PSA_ALG_CBC_NO_PADDING;
            *key_type = PSA_KEY_TYPE_CAMELLIA;
            *key_size = 128;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_CAMELLIA) && defined(MBEDTLS_SSL_HAVE_CCM)
        case MBEDTLS_CIPHER_CAMELLIA_128_CCM:
            *alg = taglen ? PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, taglen) : PSA_ALG_CCM;
            *key_type = PSA_KEY_TYPE_CAMELLIA;
            *key_size = 128;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_CAMELLIA) && defined(MBEDTLS_SSL_HAVE_GCM)
        case MBEDTLS_CIPHER_CAMELLIA_128_GCM:
            *alg = PSA_ALG_GCM;
            *key_type = PSA_KEY_TYPE_CAMELLIA;
            *key_size = 128;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_CAMELLIA) && defined(MBEDTLS_SSL_HAVE_CCM)
        case MBEDTLS_CIPHER_CAMELLIA_192_CCM:
            *alg = taglen ? PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, taglen) : PSA_ALG_CCM;
            *key_type = PSA_KEY_TYPE_CAMELLIA;
            *key_size = 192;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_CAMELLIA) && defined(MBEDTLS_SSL_HAVE_GCM)
        case MBEDTLS_CIPHER_CAMELLIA_192_GCM:
            *alg = PSA_ALG_GCM;
            *key_type = PSA_KEY_TYPE_CAMELLIA;
            *key_size = 192;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_CAMELLIA) && defined(MBEDTLS_SSL_HAVE_CBC)
        case MBEDTLS_CIPHER_CAMELLIA_256_CBC:
            *alg = PSA_ALG_CBC_NO_PADDING;
            *key_type = PSA_KEY_TYPE_CAMELLIA;
            *key_size = 256;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_CAMELLIA) && defined(MBEDTLS_SSL_HAVE_CCM)
        case MBEDTLS_CIPHER_CAMELLIA_256_CCM:
            *alg = taglen ? PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, taglen) : PSA_ALG_CCM;
            *key_type = PSA_KEY_TYPE_CAMELLIA;
            *key_size = 256;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_CAMELLIA) && defined(MBEDTLS_SSL_HAVE_GCM)
        case MBEDTLS_CIPHER_CAMELLIA_256_GCM:
            *alg = PSA_ALG_GCM;
            *key_type = PSA_KEY_TYPE_CAMELLIA;
            *key_size = 256;
            break;
#endif
#if defined(MBEDTLS_SSL_HAVE_CHACHAPOLY)
        case MBEDTLS_CIPHER_CHACHA20_POLY1305:
            *alg = PSA_ALG_CHACHA20_POLY1305;
            *key_type = PSA_KEY_TYPE_CHACHA20;
            *key_size = 256;
            break;
#endif
        case MBEDTLS_CIPHER_NULL:
            *alg = MBEDTLS_SSL_NULL_CIPHER;
            *key_type = 0;
            *key_size = 0;
            break;
        default:
            return PSA_ERROR_NOT_SUPPORTED;
    }

    return PSA_SUCCESS;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO || MBEDTLS_SSL_PROTO_TLS1_3 */

#if defined(MBEDTLS_DHM_C) && defined(MBEDTLS_SSL_SRV_C)
int mbedtls_ssl_conf_dh_param_bin(mbedtls_ssl_config *conf,
                                  const unsigned char *dhm_P, size_t P_len,
                                  const unsigned char *dhm_G, size_t G_len)
{
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    mbedtls_mpi_free(&conf->dhm_P);
    mbedtls_mpi_free(&conf->dhm_G);

    if ((ret = mbedtls_mpi_read_binary(&conf->dhm_P, dhm_P, P_len)) != 0 ||
        (ret = mbedtls_mpi_read_binary(&conf->dhm_G, dhm_G, G_len)) != 0) {
        mbedtls_mpi_free(&conf->dhm_P);
        mbedtls_mpi_free(&conf->dhm_G);
        return ret;
    }

    return 0;
}

int mbedtls_ssl_conf_dh_param_ctx(mbedtls_ssl_config *conf, mbedtls_dhm_context *dhm_ctx)
{
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    mbedtls_mpi_free(&conf->dhm_P);
    mbedtls_mpi_free(&conf->dhm_G);

    if ((ret = mbedtls_dhm_get_value(dhm_ctx, MBEDTLS_DHM_PARAM_P,
                                     &conf->dhm_P)) != 0 ||
        (ret = mbedtls_dhm_get_value(dhm_ctx, MBEDTLS_DHM_PARAM_G,
                                     &conf->dhm_G)) != 0) {
        mbedtls_mpi_free(&conf->dhm_P);
        mbedtls_mpi_free(&conf->dhm_G);
        return ret;
    }

    return 0;
}
#endif /* MBEDTLS_DHM_C && MBEDTLS_SSL_SRV_C */

#if defined(MBEDTLS_DHM_C) && defined(MBEDTLS_SSL_CLI_C)
/*
 * Set the minimum length for Diffie-Hellman parameters
 */
void mbedtls_ssl_conf_dhm_min_bitlen(mbedtls_ssl_config *conf,
                                     unsigned int bitlen)
{
    conf->dhm_min_bitlen = bitlen;
}
#endif /* MBEDTLS_DHM_C && MBEDTLS_SSL_CLI_C */

#if defined(MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED)
#if !defined(MBEDTLS_DEPRECATED_REMOVED) && defined(MBEDTLS_SSL_PROTO_TLS1_2)
/*
 * Set allowed/preferred hashes for handshake signatures
 */
void mbedtls_ssl_conf_sig_hashes(mbedtls_ssl_config *conf,
                                 const int *hashes)
{
    conf->sig_hashes = hashes;
}
#endif /* !MBEDTLS_DEPRECATED_REMOVED && MBEDTLS_SSL_PROTO_TLS1_2 */

/* Configure allowed signature algorithms for handshake */
void mbedtls_ssl_conf_sig_algs(mbedtls_ssl_config *conf,
                               const uint16_t *sig_algs)
{
#if !defined(MBEDTLS_DEPRECATED_REMOVED)
    conf->sig_hashes = NULL;
#endif /* !MBEDTLS_DEPRECATED_REMOVED */
    conf->sig_algs = sig_algs;
}
#endif /* MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED */

#if defined(MBEDTLS_ECP_C)
#if !defined(MBEDTLS_DEPRECATED_REMOVED)
/*
 * Set the allowed elliptic curves
 *
 * mbedtls_ssl_setup() takes the provided list
 * and translates it to a list of IANA TLS group identifiers,
 * stored in ssl->handshake->group_list.
 *
 */
void mbedtls_ssl_conf_curves(mbedtls_ssl_config *conf,
                             const mbedtls_ecp_group_id *curve_list)
{
    conf->curve_list = curve_list;
    conf->group_list = NULL;
}
#endif /* MBEDTLS_DEPRECATED_REMOVED */
#endif /* MBEDTLS_ECP_C */

/*
 * Set the allowed groups
 */
void mbedtls_ssl_conf_groups(mbedtls_ssl_config *conf,
                             const uint16_t *group_list)
{
#if defined(MBEDTLS_ECP_C) && !defined(MBEDTLS_DEPRECATED_REMOVED)
    conf->curve_list = NULL;
#endif
    conf->group_list = group_list;
}

#if defined(MBEDTLS_X509_CRT_PARSE_C)

/* A magic value for `ssl->hostname` indicating that
 * mbedtls_ssl_set_hostname() has been called with `NULL`.
 * If mbedtls_ssl_set_hostname() has never been called on `ssl`, then
 * `ssl->hostname == NULL`. */
static const char *const ssl_hostname_skip_cn_verification = "";

#if defined(MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED)
/** Whether mbedtls_ssl_set_hostname() has been called.
 *
 * \param[in]   ssl     SSL context
 *
 * \return \c 1 if mbedtls_ssl_set_hostname() has been called on \p ssl
 *         (including `mbedtls_ssl_set_hostname(ssl, NULL)`),
 *         otherwise \c 0.
 */
static int mbedtls_ssl_has_set_hostname_been_called(
    const mbedtls_ssl_context *ssl)
{
    return ssl->hostname != NULL;
}
#endif

/* Micro-optimization: don't export this function if it isn't needed outside
 * of this source file. */
#if !defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
static
#endif
const char *mbedtls_ssl_get_hostname_pointer(const mbedtls_ssl_context *ssl)
{
    if (ssl->hostname == ssl_hostname_skip_cn_verification) {
        return NULL;
    }
    return ssl->hostname;
}

static void mbedtls_ssl_free_hostname(mbedtls_ssl_context *ssl)
{
    if (ssl->hostname != NULL &&
        ssl->hostname != ssl_hostname_skip_cn_verification) {
        mbedtls_zeroize_and_free(ssl->hostname, strlen(ssl->hostname));
    }
    ssl->hostname = NULL;
}

int mbedtls_ssl_set_hostname(mbedtls_ssl_context *ssl, const char *hostname)
{
    /* Initialize to suppress unnecessary compiler warning */
    size_t hostname_len = 0;

    /* Check if new hostname is valid before
     * making any change to current one */
    if (hostname != NULL) {
        hostname_len = strlen(hostname);

        if (hostname_len > MBEDTLS_SSL_MAX_HOST_NAME_LEN) {
            return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
        }
    }

    /* Now it's clear that we will overwrite the old hostname,
     * so we can free it safely */
    mbedtls_ssl_free_hostname(ssl);

    if (hostname == NULL) {
        /* Passing NULL as hostname clears the old one, but leaves a
         * special marker to indicate that mbedtls_ssl_set_hostname()
         * has been called. */
        /* ssl->hostname should be const, but isn't. We won't actually
         * write to the buffer, so it's ok to cast away the const. */
        ssl->hostname = (char *) ssl_hostname_skip_cn_verification;
    } else {
        ssl->hostname = mbedtls_calloc(1, hostname_len + 1);
        if (ssl->hostname == NULL) {
            /* mbedtls_ssl_set_hostname() has been called, but unsuccessfully.
             * Leave ssl->hostname in the same state as if the function had
             * not been called, i.e. a null pointer. */
            return MBEDTLS_ERR_SSL_ALLOC_FAILED;
        }

        memcpy(ssl->hostname, hostname, hostname_len);

        ssl->hostname[hostname_len] = '\0';
    }

    return 0;
}
#endif /* MBEDTLS_X509_CRT_PARSE_C */

#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
void mbedtls_ssl_conf_sni(mbedtls_ssl_config *conf,
                          int (*f_sni)(void *, mbedtls_ssl_context *,
                                       const unsigned char *, size_t),
                          void *p_sni)
{
    conf->f_sni = f_sni;
    conf->p_sni = p_sni;
}
#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */

#if defined(MBEDTLS_SSL_ALPN)
int mbedtls_ssl_conf_alpn_protocols(mbedtls_ssl_config *conf, const char **protos)
{
    size_t cur_len, tot_len;
    const char **p;

    /*
     * RFC 7301 3.1: "Empty strings MUST NOT be included and byte strings
     * MUST NOT be truncated."
     * We check lengths now rather than later.
     */
    tot_len = 0;
    for (p = protos; *p != NULL; p++) {
        cur_len = strlen(*p);
        tot_len += cur_len;

        if ((cur_len == 0) ||
            (cur_len > MBEDTLS_SSL_MAX_ALPN_NAME_LEN) ||
            (tot_len > MBEDTLS_SSL_MAX_ALPN_LIST_LEN)) {
            return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
        }
    }

    conf->alpn_list = protos;

    return 0;
}

const char *mbedtls_ssl_get_alpn_protocol(const mbedtls_ssl_context *ssl)
{
    return ssl->alpn_chosen;
}
#endif /* MBEDTLS_SSL_ALPN */

#if defined(MBEDTLS_SSL_DTLS_SRTP)
void mbedtls_ssl_conf_srtp_mki_value_supported(mbedtls_ssl_config *conf,
                                               int support_mki_value)
{
    conf->dtls_srtp_mki_support = support_mki_value;
}

int mbedtls_ssl_dtls_srtp_set_mki_value(mbedtls_ssl_context *ssl,
                                        unsigned char *mki_value,
                                        uint16_t mki_len)
{
    if (mki_len > MBEDTLS_TLS_SRTP_MAX_MKI_LENGTH) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    if (ssl->conf->dtls_srtp_mki_support == MBEDTLS_SSL_DTLS_SRTP_MKI_UNSUPPORTED) {
        return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
    }

    memcpy(ssl->dtls_srtp_info.mki_value, mki_value, mki_len);
    ssl->dtls_srtp_info.mki_len = mki_len;
    return 0;
}

int mbedtls_ssl_conf_dtls_srtp_protection_profiles(mbedtls_ssl_config *conf,
                                                   const mbedtls_ssl_srtp_profile *profiles)
{
    const mbedtls_ssl_srtp_profile *p;
    size_t list_size = 0;

    /* check the profiles list: all entry must be valid,
     * its size cannot be more than the total number of supported profiles, currently 4 */
    for (p = profiles; *p != MBEDTLS_TLS_SRTP_UNSET &&
         list_size <= MBEDTLS_TLS_SRTP_MAX_PROFILE_LIST_LENGTH;
         p++) {
        if (mbedtls_ssl_check_srtp_profile_value(*p) != MBEDTLS_TLS_SRTP_UNSET) {
            list_size++;
        } else {
            /* unsupported value, stop parsing and set the size to an error value */
            list_size = MBEDTLS_TLS_SRTP_MAX_PROFILE_LIST_LENGTH + 1;
        }
    }

    if (list_size > MBEDTLS_TLS_SRTP_MAX_PROFILE_LIST_LENGTH) {
        conf->dtls_srtp_profile_list = NULL;
        conf->dtls_srtp_profile_list_len = 0;
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    conf->dtls_srtp_profile_list = profiles;
    conf->dtls_srtp_profile_list_len = list_size;

    return 0;
}

void mbedtls_ssl_get_dtls_srtp_negotiation_result(const mbedtls_ssl_context *ssl,
                                                  mbedtls_dtls_srtp_info *dtls_srtp_info)
{
    dtls_srtp_info->chosen_dtls_srtp_profile = ssl->dtls_srtp_info.chosen_dtls_srtp_profile;
    /* do not copy the mki value if there is no chosen profile */
    if (dtls_srtp_info->chosen_dtls_srtp_profile == MBEDTLS_TLS_SRTP_UNSET) {
        dtls_srtp_info->mki_len = 0;
    } else {
        dtls_srtp_info->mki_len = ssl->dtls_srtp_info.mki_len;
        memcpy(dtls_srtp_info->mki_value, ssl->dtls_srtp_info.mki_value,
               ssl->dtls_srtp_info.mki_len);
    }
}
#endif /* MBEDTLS_SSL_DTLS_SRTP */

#if !defined(MBEDTLS_DEPRECATED_REMOVED)
void mbedtls_ssl_conf_max_version(mbedtls_ssl_config *conf, int major, int minor)
{
    conf->max_tls_version = (mbedtls_ssl_protocol_version) ((major << 8) | minor);
}

void mbedtls_ssl_conf_min_version(mbedtls_ssl_config *conf, int major, int minor)
{
    conf->min_tls_version = (mbedtls_ssl_protocol_version) ((major << 8) | minor);
}
#endif /* MBEDTLS_DEPRECATED_REMOVED */

#if defined(MBEDTLS_SSL_SRV_C)
void mbedtls_ssl_conf_cert_req_ca_list(mbedtls_ssl_config *conf,
                                       char cert_req_ca_list)
{
    conf->cert_req_ca_list = cert_req_ca_list;
}
#endif

#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
void mbedtls_ssl_conf_encrypt_then_mac(mbedtls_ssl_config *conf, char etm)
{
    conf->encrypt_then_mac = etm;
}
#endif

#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
void mbedtls_ssl_conf_extended_master_secret(mbedtls_ssl_config *conf, char ems)
{
    conf->extended_ms = ems;
}
#endif

#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
int mbedtls_ssl_conf_max_frag_len(mbedtls_ssl_config *conf, unsigned char mfl_code)
{
    if (mfl_code >= MBEDTLS_SSL_MAX_FRAG_LEN_INVALID ||
        ssl_mfl_code_to_length(mfl_code) > MBEDTLS_TLS_EXT_ADV_CONTENT_LEN) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    conf->mfl_code = mfl_code;

    return 0;
}
#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */

void mbedtls_ssl_conf_legacy_renegotiation(mbedtls_ssl_config *conf, int allow_legacy)
{
    conf->allow_legacy_renegotiation = allow_legacy;
}

#if defined(MBEDTLS_SSL_RENEGOTIATION)
void mbedtls_ssl_conf_renegotiation(mbedtls_ssl_config *conf, int renegotiation)
{
    conf->disable_renegotiation = renegotiation;
}

void mbedtls_ssl_conf_renegotiation_enforced(mbedtls_ssl_config *conf, int max_records)
{
    conf->renego_max_records = max_records;
}

void mbedtls_ssl_conf_renegotiation_period(mbedtls_ssl_config *conf,
                                           const unsigned char period[8])
{
    memcpy(conf->renego_period, period, 8);
}
#endif /* MBEDTLS_SSL_RENEGOTIATION */

#if defined(MBEDTLS_SSL_SESSION_TICKETS)
#if defined(MBEDTLS_SSL_CLI_C)

void mbedtls_ssl_conf_session_tickets(mbedtls_ssl_config *conf, int use_tickets)
{
    conf->session_tickets &= ~MBEDTLS_SSL_SESSION_TICKETS_TLS1_2_MASK;
    conf->session_tickets |= (use_tickets != 0) <<
                             MBEDTLS_SSL_SESSION_TICKETS_TLS1_2_BIT;
}

#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
void mbedtls_ssl_conf_tls13_enable_signal_new_session_tickets(
    mbedtls_ssl_config *conf, int signal_new_session_tickets)
{
    conf->session_tickets &= ~MBEDTLS_SSL_SESSION_TICKETS_TLS1_3_MASK;
    conf->session_tickets |= (signal_new_session_tickets != 0) <<
                             MBEDTLS_SSL_SESSION_TICKETS_TLS1_3_BIT;
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
#endif /* MBEDTLS_SSL_CLI_C */

#if defined(MBEDTLS_SSL_SRV_C)

#if defined(MBEDTLS_SSL_PROTO_TLS1_3) && defined(MBEDTLS_SSL_SESSION_TICKETS)
void mbedtls_ssl_conf_new_session_tickets(mbedtls_ssl_config *conf,
                                          uint16_t num_tickets)
{
    conf->new_session_tickets_count = num_tickets;
}
#endif

void mbedtls_ssl_conf_session_tickets_cb(mbedtls_ssl_config *conf,
                                         mbedtls_ssl_ticket_write_t *f_ticket_write,
                                         mbedtls_ssl_ticket_parse_t *f_ticket_parse,
                                         void *p_ticket)
{
    conf->f_ticket_write = f_ticket_write;
    conf->f_ticket_parse = f_ticket_parse;
    conf->p_ticket       = p_ticket;
}
#endif
#endif /* MBEDTLS_SSL_SESSION_TICKETS */

void mbedtls_ssl_set_export_keys_cb(mbedtls_ssl_context *ssl,
                                    mbedtls_ssl_export_keys_t *f_export_keys,
                                    void *p_export_keys)
{
    ssl->f_export_keys = f_export_keys;
    ssl->p_export_keys = p_export_keys;
}

#if defined(MBEDTLS_SSL_ASYNC_PRIVATE)
void mbedtls_ssl_conf_async_private_cb(
    mbedtls_ssl_config *conf,
    mbedtls_ssl_async_sign_t *f_async_sign,
    mbedtls_ssl_async_decrypt_t *f_async_decrypt,
    mbedtls_ssl_async_resume_t *f_async_resume,
    mbedtls_ssl_async_cancel_t *f_async_cancel,
    void *async_config_data)
{
    conf->f_async_sign_start = f_async_sign;
    conf->f_async_decrypt_start = f_async_decrypt;
    conf->f_async_resume = f_async_resume;
    conf->f_async_cancel = f_async_cancel;
    conf->p_async_config_data = async_config_data;
}

void *mbedtls_ssl_conf_get_async_config_data(const mbedtls_ssl_config *conf)
{
    return conf->p_async_config_data;
}

void *mbedtls_ssl_get_async_operation_data(const mbedtls_ssl_context *ssl)
{
    if (ssl->handshake == NULL) {
        return NULL;
    } else {
        return ssl->handshake->user_async_ctx;
    }
}

void mbedtls_ssl_set_async_operation_data(mbedtls_ssl_context *ssl,
                                          void *ctx)
{
    if (ssl->handshake != NULL) {
        ssl->handshake->user_async_ctx = ctx;
    }
}
#endif /* MBEDTLS_SSL_ASYNC_PRIVATE */

/*
 * SSL get accessors
 */
uint32_t mbedtls_ssl_get_verify_result(const mbedtls_ssl_context *ssl)
{
    if (ssl->session != NULL) {
        return ssl->session->verify_result;
    }

    if (ssl->session_negotiate != NULL) {
        return ssl->session_negotiate->verify_result;
    }

    return 0xFFFFFFFF;
}

int mbedtls_ssl_get_ciphersuite_id_from_ssl(const mbedtls_ssl_context *ssl)
{
    if (ssl == NULL || ssl->session == NULL) {
        return 0;
    }

    return ssl->session->ciphersuite;
}

const char *mbedtls_ssl_get_ciphersuite(const mbedtls_ssl_context *ssl)
{
    if (ssl == NULL || ssl->session == NULL) {
        return NULL;
    }

    return mbedtls_ssl_get_ciphersuite_name(ssl->session->ciphersuite);
}

const char *mbedtls_ssl_get_version(const mbedtls_ssl_context *ssl)
{
#if defined(MBEDTLS_SSL_PROTO_DTLS)
    if (ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
        switch (ssl->tls_version) {
            case MBEDTLS_SSL_VERSION_TLS1_2:
                return "DTLSv1.2";
            default:
                return "unknown (DTLS)";
        }
    }
#endif

    switch (ssl->tls_version) {
        case MBEDTLS_SSL_VERSION_TLS1_2:
            return "TLSv1.2";
        case MBEDTLS_SSL_VERSION_TLS1_3:
            return "TLSv1.3";
        default:
            return "unknown";
    }
}

#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)

size_t mbedtls_ssl_get_output_record_size_limit(const mbedtls_ssl_context *ssl)
{
    const size_t max_len = MBEDTLS_SSL_OUT_CONTENT_LEN;
    size_t record_size_limit = max_len;

    if (ssl->session != NULL &&
        ssl->session->record_size_limit >= MBEDTLS_SSL_RECORD_SIZE_LIMIT_MIN &&
        ssl->session->record_size_limit < max_len) {
        record_size_limit = ssl->session->record_size_limit;
    }

    // TODO: this is currently untested
    /* During a handshake, use the value being negotiated */
    if (ssl->session_negotiate != NULL &&
        ssl->session_negotiate->record_size_limit >= MBEDTLS_SSL_RECORD_SIZE_LIMIT_MIN &&
        ssl->session_negotiate->record_size_limit < max_len) {
        record_size_limit = ssl->session_negotiate->record_size_limit;
    }

    return record_size_limit;
}
#endif /* MBEDTLS_SSL_RECORD_SIZE_LIMIT */

#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
size_t mbedtls_ssl_get_input_max_frag_len(const mbedtls_ssl_context *ssl)
{
    size_t max_len = MBEDTLS_SSL_IN_CONTENT_LEN;
    size_t read_mfl;

#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
    /* Use the configured MFL for the client if we're past SERVER_HELLO_DONE */
    if (ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT &&
        ssl->state >= MBEDTLS_SSL_SERVER_HELLO_DONE) {
        return ssl_mfl_code_to_length(ssl->conf->mfl_code);
    }
#endif

    /* Check if a smaller max length was negotiated */
    if (ssl->session_out != NULL) {
        read_mfl = ssl_mfl_code_to_length(ssl->session_out->mfl_code);
        if (read_mfl < max_len) {
            max_len = read_mfl;
        }
    }

    /* During a handshake, use the value being negotiated */
    if (ssl->session_negotiate != NULL) {
        read_mfl = ssl_mfl_code_to_length(ssl->session_negotiate->mfl_code);
        if (read_mfl < max_len) {
            max_len = read_mfl;
        }
    }

    return max_len;
}

size_t mbedtls_ssl_get_output_max_frag_len(const mbedtls_ssl_context *ssl)
{
    size_t max_len;

    /*
     * Assume mfl_code is correct since it was checked when set
     */
    max_len = ssl_mfl_code_to_length(ssl->conf->mfl_code);

    /* Check if a smaller max length was negotiated */
    if (ssl->session_out != NULL &&
        ssl_mfl_code_to_length(ssl->session_out->mfl_code) < max_len) {
        max_len = ssl_mfl_code_to_length(ssl->session_out->mfl_code);
    }

    /* During a handshake, use the value being negotiated */
    if (ssl->session_negotiate != NULL &&
        ssl_mfl_code_to_length(ssl->session_negotiate->mfl_code) < max_len) {
        max_len = ssl_mfl_code_to_length(ssl->session_negotiate->mfl_code);
    }

    return max_len;
}
#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */

#if defined(MBEDTLS_SSL_PROTO_DTLS)
size_t mbedtls_ssl_get_current_mtu(const mbedtls_ssl_context *ssl)
{
    if (ssl->handshake == NULL || ssl->handshake->mtu == 0) {
        return ssl->mtu;
    }

    if (ssl->mtu == 0) {
        return ssl->handshake->mtu;
    }

    return ssl->mtu < ssl->handshake->mtu ?
           ssl->mtu : ssl->handshake->mtu;
}
#endif /* MBEDTLS_SSL_PROTO_DTLS */

int mbedtls_ssl_get_max_out_record_payload(const mbedtls_ssl_context *ssl)
{
    size_t max_len = MBEDTLS_SSL_OUT_CONTENT_LEN;

#if !defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH) && \
    !defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT) && \
    !defined(MBEDTLS_SSL_PROTO_DTLS)
    (void) ssl;
#endif

#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
    const size_t mfl = mbedtls_ssl_get_output_max_frag_len(ssl);

    if (max_len > mfl) {
        max_len = mfl;
    }
#endif

#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)
    const size_t record_size_limit = mbedtls_ssl_get_output_record_size_limit(ssl);

    if (max_len > record_size_limit) {
        max_len = record_size_limit;
    }
#endif

    if (ssl->transform_out != NULL &&
        ssl->transform_out->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
        /*
         * In TLS 1.3 case, when records are protected, `max_len` as computed
         * above is the maximum length of the TLSInnerPlaintext structure that
         * along the plaintext payload contains the inner content type (one byte)
         * and some zero padding. Given the algorithm used for padding
         * in mbedtls_ssl_encrypt_buf(), compute the maximum length for
         * the plaintext payload. Round down to a multiple of
         * MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY and
         * subtract 1.
         */
        max_len = ((max_len / MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY) *
                   MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY) - 1;
    }

#if defined(MBEDTLS_SSL_PROTO_DTLS)
    if (mbedtls_ssl_get_current_mtu(ssl) != 0) {
        const size_t mtu = mbedtls_ssl_get_current_mtu(ssl);
        const int ret = mbedtls_ssl_get_record_expansion(ssl);
        const size_t overhead = (size_t) ret;

        if (ret < 0) {
            return ret;
        }

        if (mtu <= overhead) {
            MBEDTLS_SSL_DEBUG_MSG(1, ("MTU too low for record expansion"));
            return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
        }

        if (max_len > mtu - overhead) {
            max_len = mtu - overhead;
        }
    }
#endif /* MBEDTLS_SSL_PROTO_DTLS */

#if !defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH) &&        \
    !defined(MBEDTLS_SSL_PROTO_DTLS) &&                 \
    !defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)
    ((void) ssl);
#endif

    return (int) max_len;
}

int mbedtls_ssl_get_max_in_record_payload(const mbedtls_ssl_context *ssl)
{
    size_t max_len = MBEDTLS_SSL_IN_CONTENT_LEN;

#if !defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
    (void) ssl;
#endif

#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
    const size_t mfl = mbedtls_ssl_get_input_max_frag_len(ssl);

    if (max_len > mfl) {
        max_len = mfl;
    }
#endif

    return (int) max_len;
}

#if defined(MBEDTLS_X509_CRT_PARSE_C)
const mbedtls_x509_crt *mbedtls_ssl_get_peer_cert(const mbedtls_ssl_context *ssl)
{
    if (ssl == NULL || ssl->session == NULL) {
        return NULL;
    }

#if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
    return ssl->session->peer_cert;
#else
    return NULL;
#endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
}
#endif /* MBEDTLS_X509_CRT_PARSE_C */

#if defined(MBEDTLS_SSL_CLI_C)
int mbedtls_ssl_get_session(const mbedtls_ssl_context *ssl,
                            mbedtls_ssl_session *dst)
{
    int ret;

    if (ssl == NULL ||
        dst == NULL ||
        ssl->session == NULL ||
        ssl->conf->endpoint != MBEDTLS_SSL_IS_CLIENT) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    /* Since Mbed TLS 3.0, mbedtls_ssl_get_session() is no longer
     * idempotent: Each session can only be exported once.
     *
     * (This is in preparation for TLS 1.3 support where we will
     * need the ability to export multiple sessions (aka tickets),
     * which will be achieved by calling mbedtls_ssl_get_session()
     * multiple times until it fails.)
     *
     * Check whether we have already exported the current session,
     * and fail if so.
     */
    if (ssl->session->exported == 1) {
        return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
    }

    ret = mbedtls_ssl_session_copy(dst, ssl->session);
    if (ret != 0) {
        return ret;
    }

    /* Remember that we've exported the session. */
    ssl->session->exported = 1;
    return 0;
}
#endif /* MBEDTLS_SSL_CLI_C */

#if defined(MBEDTLS_SSL_PROTO_TLS1_2)

/* Serialization of TLS 1.2 sessions
 *
 * For more detail, see the description of ssl_session_save().
 */
static size_t ssl_tls12_session_save(const mbedtls_ssl_session *session,
                                     unsigned char *buf,
                                     size_t buf_len)
{
    unsigned char *p = buf;
    size_t used = 0;

#if defined(MBEDTLS_HAVE_TIME)
    uint64_t start;
#endif
#if defined(MBEDTLS_X509_CRT_PARSE_C)
#if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
    size_t cert_len;
#endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
#endif /* MBEDTLS_X509_CRT_PARSE_C */

    /*
     * Time
     */
#if defined(MBEDTLS_HAVE_TIME)
    used += 8;

    if (used <= buf_len) {
        start = (uint64_t) session->start;

        MBEDTLS_PUT_UINT64_BE(start, p, 0);
        p += 8;
    }
#endif /* MBEDTLS_HAVE_TIME */

    /*
     * Basic mandatory fields
     */
    used += 1 /* id_len */
            + sizeof(session->id)
            + sizeof(session->master)
            + 4; /* verify_result */

    if (used <= buf_len) {
        *p++ = MBEDTLS_BYTE_0(session->id_len);
        memcpy(p, session->id, 32);
        p += 32;

        memcpy(p, session->master, 48);
        p += 48;

        MBEDTLS_PUT_UINT32_BE(session->verify_result, p, 0);
        p += 4;
    }

    /*
     * Peer's end-entity certificate
     */
#if defined(MBEDTLS_X509_CRT_PARSE_C)
#if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
    if (session->peer_cert == NULL) {
        cert_len = 0;
    } else {
        cert_len = session->peer_cert->raw.len;
    }

    used += 3 + cert_len;

    if (used <= buf_len) {
        *p++ = MBEDTLS_BYTE_2(cert_len);
        *p++ = MBEDTLS_BYTE_1(cert_len);
        *p++ = MBEDTLS_BYTE_0(cert_len);

        if (session->peer_cert != NULL) {
            memcpy(p, session->peer_cert->raw.p, cert_len);
            p += cert_len;
        }
    }
#else /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
    if (session->peer_cert_digest != NULL) {
        used += 1 /* type */ + 1 /* length */ + session->peer_cert_digest_len;
        if (used <= buf_len) {
            *p++ = (unsigned char) session->peer_cert_digest_type;
            *p++ = (unsigned char) session->peer_cert_digest_len;
            memcpy(p, session->peer_cert_digest,
                   session->peer_cert_digest_len);
            p += session->peer_cert_digest_len;
        }
    } else {
        used += 2;
        if (used <= buf_len) {
            *p++ = (unsigned char) MBEDTLS_MD_NONE;
            *p++ = 0;
        }
    }
#endif /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
#endif /* MBEDTLS_X509_CRT_PARSE_C */

    /*
     * Session ticket if any, plus associated data
     */
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
#if defined(MBEDTLS_SSL_CLI_C)
    if (session->endpoint == MBEDTLS_SSL_IS_CLIENT) {
        used += 3 + session->ticket_len + 4; /* len + ticket + lifetime */

        if (used <= buf_len) {
            *p++ = MBEDTLS_BYTE_2(session->ticket_len);
            *p++ = MBEDTLS_BYTE_1(session->ticket_len);
            *p++ = MBEDTLS_BYTE_0(session->ticket_len);

            if (session->ticket != NULL) {
                memcpy(p, session->ticket, session->ticket_len);
                p += session->ticket_len;
            }

            MBEDTLS_PUT_UINT32_BE(session->ticket_lifetime, p, 0);
            p += 4;
        }
    }
#endif /* MBEDTLS_SSL_CLI_C */
#if defined(MBEDTLS_HAVE_TIME) && defined(MBEDTLS_SSL_SRV_C)
    if (session->endpoint == MBEDTLS_SSL_IS_SERVER) {
        used += 8;

        if (used <= buf_len) {
            MBEDTLS_PUT_UINT64_BE((uint64_t) session->ticket_creation_time, p, 0);
            p += 8;
        }
    }
#endif /* MBEDTLS_HAVE_TIME && MBEDTLS_SSL_SRV_C */
#endif /* MBEDTLS_SSL_SESSION_TICKETS */

    /*
     * Misc extension-related info
     */
#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
    used += 1;

    if (used <= buf_len) {
        *p++ = session->mfl_code;
    }
#endif

#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
    used += 1;

    if (used <= buf_len) {
        *p++ = MBEDTLS_BYTE_0(session->encrypt_then_mac);
    }
#endif

    return used;
}

MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls12_session_load(mbedtls_ssl_session *session,
                                  const unsigned char *buf,
                                  size_t len)
{
#if defined(MBEDTLS_HAVE_TIME)
    uint64_t start;
#endif
#if defined(MBEDTLS_X509_CRT_PARSE_C)
#if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
    size_t cert_len;
#endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
#endif /* MBEDTLS_X509_CRT_PARSE_C */

    const unsigned char *p = buf;
    const unsigned char * const end = buf + len;

    /*
     * Time
     */
#if defined(MBEDTLS_HAVE_TIME)
    if (8 > (size_t) (end - p)) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    start = MBEDTLS_GET_UINT64_BE(p, 0);
    p += 8;

    session->start = (mbedtls_time_t) start;
#endif /* MBEDTLS_HAVE_TIME */

    /*
     * Basic mandatory fields
     */
    if (1 + 32 + 48 + 4 > (size_t) (end - p)) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    session->id_len = *p++;
    memcpy(session->id, p, 32);
    p += 32;

    memcpy(session->master, p, 48);
    p += 48;

    session->verify_result = MBEDTLS_GET_UINT32_BE(p, 0);
    p += 4;

    /* Immediately clear invalid pointer values that have been read, in case
     * we exit early before we replaced them with valid ones. */
#if defined(MBEDTLS_X509_CRT_PARSE_C)
#if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
    session->peer_cert = NULL;
#else
    session->peer_cert_digest = NULL;
#endif /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
#endif /* MBEDTLS_X509_CRT_PARSE_C */
#if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C)
    session->ticket = NULL;
#endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */

    /*
     * Peer certificate
     */
#if defined(MBEDTLS_X509_CRT_PARSE_C)
#if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
    /* Deserialize CRT from the end of the ticket. */
    if (3 > (size_t) (end - p)) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    cert_len = MBEDTLS_GET_UINT24_BE(p, 0);
    p += 3;

    if (cert_len != 0) {
        int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

        if (cert_len > (size_t) (end - p)) {
            return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
        }

        session->peer_cert = mbedtls_calloc(1, sizeof(mbedtls_x509_crt));

        if (session->peer_cert == NULL) {
            return MBEDTLS_ERR_SSL_ALLOC_FAILED;
        }

        mbedtls_x509_crt_init(session->peer_cert);

        if ((ret = mbedtls_x509_crt_parse_der(session->peer_cert,
                                              p, cert_len)) != 0) {
            mbedtls_x509_crt_free(session->peer_cert);
            mbedtls_free(session->peer_cert);
            session->peer_cert = NULL;
            return ret;
        }

        p += cert_len;
    }
#else /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
    /* Deserialize CRT digest from the end of the ticket. */
    if (2 > (size_t) (end - p)) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    session->peer_cert_digest_type = (mbedtls_md_type_t) *p++;
    session->peer_cert_digest_len  = (size_t) *p++;

    if (session->peer_cert_digest_len != 0) {
        const mbedtls_md_info_t *md_info =
            mbedtls_md_info_from_type(session->peer_cert_digest_type);
        if (md_info == NULL) {
            return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
        }
        if (session->peer_cert_digest_len != mbedtls_md_get_size(md_info)) {
            return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
        }

        if (session->peer_cert_digest_len > (size_t) (end - p)) {
            return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
        }

        session->peer_cert_digest =
            mbedtls_calloc(1, session->peer_cert_digest_len);
        if (session->peer_cert_digest == NULL) {
            return MBEDTLS_ERR_SSL_ALLOC_FAILED;
        }

        memcpy(session->peer_cert_digest, p,
               session->peer_cert_digest_len);
        p += session->peer_cert_digest_len;
    }
#endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
#endif /* MBEDTLS_X509_CRT_PARSE_C */

    /*
     * Session ticket and associated data
     */
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
#if defined(MBEDTLS_SSL_CLI_C)
    if (session->endpoint == MBEDTLS_SSL_IS_CLIENT) {
        if (3 > (size_t) (end - p)) {
            return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
        }

        session->ticket_len = MBEDTLS_GET_UINT24_BE(p, 0);
        p += 3;

        if (session->ticket_len != 0) {
            if (session->ticket_len > (size_t) (end - p)) {
                return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
            }

            session->ticket = mbedtls_calloc(1, session->ticket_len);
            if (session->ticket == NULL) {
                return MBEDTLS_ERR_SSL_ALLOC_FAILED;
            }

            memcpy(session->ticket, p, session->ticket_len);
            p += session->ticket_len;
        }

        if (4 > (size_t) (end - p)) {
            return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
        }

        session->ticket_lifetime = MBEDTLS_GET_UINT32_BE(p, 0);
        p += 4;
    }
#endif /* MBEDTLS_SSL_CLI_C */
#if defined(MBEDTLS_HAVE_TIME) && defined(MBEDTLS_SSL_SRV_C)
    if (session->endpoint == MBEDTLS_SSL_IS_SERVER) {
        if (8 > (size_t) (end - p)) {
            return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
        }
        session->ticket_creation_time = MBEDTLS_GET_UINT64_BE(p, 0);
        p += 8;
    }
#endif /* MBEDTLS_HAVE_TIME && MBEDTLS_SSL_SRV_C */
#endif /* MBEDTLS_SSL_SESSION_TICKETS */

    /*
     * Misc extension-related info
     */
#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
    if (1 > (size_t) (end - p)) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    session->mfl_code = *p++;
#endif

#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
    if (1 > (size_t) (end - p)) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    session->encrypt_then_mac = *p++;
#endif

    /* Done, should have consumed entire buffer */
    if (p != end) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    return 0;
}

#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */

#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
/* Serialization of TLS 1.3 sessions:
 *
 * For more detail, see the description of ssl_session_save().
 */
#if defined(MBEDTLS_SSL_SESSION_TICKETS)
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_session_save(const mbedtls_ssl_session *session,
                                  unsigned char *buf,
                                  size_t buf_len,
                                  size_t *olen)
{
    unsigned char *p = buf;
#if defined(MBEDTLS_SSL_CLI_C) && \
    defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
    size_t hostname_len = (session->hostname == NULL) ?
                          0 : strlen(session->hostname) + 1;
#endif

#if defined(MBEDTLS_SSL_SRV_C) && \
    defined(MBEDTLS_SSL_EARLY_DATA) && defined(MBEDTLS_SSL_ALPN)
    const size_t alpn_len = (session->ticket_alpn == NULL) ?
                            0 : strlen(session->ticket_alpn) + 1;
#endif
    size_t needed =   4  /* ticket_age_add */
                    + 1  /* ticket_flags */
                    + 1; /* resumption_key length */

    *olen = 0;

    if (session->resumption_key_len > MBEDTLS_SSL_TLS1_3_TICKET_RESUMPTION_KEY_LEN) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }
    needed += session->resumption_key_len;  /* resumption_key */

#if defined(MBEDTLS_SSL_EARLY_DATA)
    needed += 4;                            /* max_early_data_size */
#endif
#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)
    needed += 2;                            /* record_size_limit */
#endif /* MBEDTLS_SSL_RECORD_SIZE_LIMIT */

#if defined(MBEDTLS_HAVE_TIME)
    needed += 8; /* ticket_creation_time or ticket_reception_time */
#endif

#if defined(MBEDTLS_SSL_SRV_C)
    if (session->endpoint == MBEDTLS_SSL_IS_SERVER) {
#if defined(MBEDTLS_SSL_EARLY_DATA) && defined(MBEDTLS_SSL_ALPN)
        needed +=   2                         /* alpn_len */
                  + alpn_len;                 /* alpn */
#endif
    }
#endif /* MBEDTLS_SSL_SRV_C */

#if defined(MBEDTLS_SSL_CLI_C)
    if (session->endpoint == MBEDTLS_SSL_IS_CLIENT) {
#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
        needed +=  2                        /* hostname_len */
                  + hostname_len;           /* hostname */
#endif

        needed +=   4                       /* ticket_lifetime */
                  + 2;                      /* ticket_len */

        /* Check size_t overflow */
        if (session->ticket_len > SIZE_MAX - needed) {
            return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
        }

        needed += session->ticket_len;      /* ticket */
    }
#endif /* MBEDTLS_SSL_CLI_C */

    *olen = needed;
    if (needed > buf_len) {
        return MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
    }

    MBEDTLS_PUT_UINT32_BE(session->ticket_age_add, p, 0);
    p[4] = session->ticket_flags;

    /* save resumption_key */
    p[5] = session->resumption_key_len;
    p += 6;
    memcpy(p, session->resumption_key, session->resumption_key_len);
    p += session->resumption_key_len;

#if defined(MBEDTLS_SSL_EARLY_DATA)
    MBEDTLS_PUT_UINT32_BE(session->max_early_data_size, p, 0);
    p += 4;
#endif
#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)
    MBEDTLS_PUT_UINT16_BE(session->record_size_limit, p, 0);
    p += 2;
#endif /* MBEDTLS_SSL_RECORD_SIZE_LIMIT */

#if defined(MBEDTLS_SSL_SRV_C)
    if (session->endpoint == MBEDTLS_SSL_IS_SERVER) {
#if defined(MBEDTLS_HAVE_TIME)
        MBEDTLS_PUT_UINT64_BE((uint64_t) session->ticket_creation_time, p, 0);
        p += 8;
#endif /* MBEDTLS_HAVE_TIME */

#if defined(MBEDTLS_SSL_EARLY_DATA) && defined(MBEDTLS_SSL_ALPN)
        MBEDTLS_PUT_UINT16_BE(alpn_len, p, 0);
        p += 2;

        if (alpn_len > 0) {
            /* save chosen alpn */
            memcpy(p, session->ticket_alpn, alpn_len);
            p += alpn_len;
        }
#endif /* MBEDTLS_SSL_EARLY_DATA && MBEDTLS_SSL_ALPN */
    }
#endif /* MBEDTLS_SSL_SRV_C */

#if defined(MBEDTLS_SSL_CLI_C)
    if (session->endpoint == MBEDTLS_SSL_IS_CLIENT) {
#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
        MBEDTLS_PUT_UINT16_BE(hostname_len, p, 0);
        p += 2;
        if (hostname_len > 0) {
            /* save host name */
            memcpy(p, session->hostname, hostname_len);
            p += hostname_len;
        }
#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */

#if defined(MBEDTLS_HAVE_TIME)
        MBEDTLS_PUT_UINT64_BE((uint64_t) session->ticket_reception_time, p, 0);
        p += 8;
#endif
        MBEDTLS_PUT_UINT32_BE(session->ticket_lifetime, p, 0);
        p += 4;

        MBEDTLS_PUT_UINT16_BE(session->ticket_len, p, 0);
        p += 2;

        if (session->ticket != NULL && session->ticket_len > 0) {
            memcpy(p, session->ticket, session->ticket_len);
            p += session->ticket_len;
        }
    }
#endif /* MBEDTLS_SSL_CLI_C */
    return 0;
}

MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_session_load(mbedtls_ssl_session *session,
                                  const unsigned char *buf,
                                  size_t len)
{
    const unsigned char *p = buf;
    const unsigned char *end = buf + len;

    if (end - p < 6) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }
    session->ticket_age_add = MBEDTLS_GET_UINT32_BE(p, 0);
    session->ticket_flags = p[4];

    /* load resumption_key */
    session->resumption_key_len = p[5];
    p += 6;

    if (end - p < session->resumption_key_len) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }

    if (sizeof(session->resumption_key) < session->resumption_key_len) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }
    memcpy(session->resumption_key, p, session->resumption_key_len);
    p += session->resumption_key_len;

#if defined(MBEDTLS_SSL_EARLY_DATA)
    if (end - p < 4) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }
    session->max_early_data_size = MBEDTLS_GET_UINT32_BE(p, 0);
    p += 4;
#endif
#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)
    if (end - p < 2) {
        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
    }
    session->record_size_limit = MBEDTLS_GET_UINT16_BE(p, 0);
    p += 2;
#endif /* MBEDTLS_SSL_RECORD_SIZE_LIMIT */

#if  defined(MBEDTLS_SSL_SRV_C)
    if (session->endpoint == MBEDTLS_SSL_IS_SERVER) {
#if defined(MBEDTLS_HAVE_TIME)
        if (end - p < 8) {
            return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
        }
        session->ticket_creation_time = MBEDTLS_GET_UINT64_BE(p, 0);
        p += 8;
#endif /* MBEDTLS_HAVE_TIME */

#if defined(MBEDTLS_SSL_EARLY_DATA) && defined(MBEDTLS_SSL_ALPN)
        size_t alpn_len;

        if (end - p < 2) {
            return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
        }

        alpn_len = MBEDTLS_GET_UINT16_BE(p, 0);
        p += 2;

        if (end - p < (long int) alpn_len) {
            return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
        }

        if (alpn_len > 0) {
            int ret = mbedtls_ssl_session_set_ticket_alpn(session, (char *) p);
            if (ret != 0) {
                return ret;
            }
            p += alpn_len;
        }
#endif /* MBEDTLS_SSL_EARLY_DATA && MBEDTLS_SSL_ALPN */
    }
#endif /* MBEDTLS_SSL_SRV_C */

#if defined(MBEDTLS_SSL_CLI_C)
    if (