Update tls state machine logic to support dtls1.3 alongside tls1.3

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22366)

4 files changed, 140 insertions, 129 deletions

diff --git a/ssl/statem/statem.c b/ssl/statem/statem.c
index 921d7cfb1e..5fd05235b4 100644
--- a/ssl/statem/statem.c
+++ b/ssl/statem/statem.c
@@ -398,7 +398,7 @@ static int state_machine(SSL_CONNECTION *s, int server)
 
         s->server = server;
         if (cb != NULL) {
-            if (SSL_IS_FIRST_HANDSHAKE(s) || !SSL_CONNECTION_IS_TLS13(s))
+            if (SSL_IS_FIRST_HANDSHAKE(s) || !(SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)))
                 cb(ssl, SSL_CB_HANDSHAKE_START, 1);
         }
 
diff --git a/ssl/statem/statem_clnt.c b/ssl/statem/statem_clnt.c
index 2233dd8f48..616cc86b12 100644
--- a/ssl/statem/statem_clnt.c
+++ b/ssl/statem/statem_clnt.c
@@ -235,7 +235,7 @@ int ossl_statem_client_read_transition(SSL_CONNECTION *s, int mt)
      * Note that after writing the first ClientHello we don't know what version
      * we are going to negotiate yet, so we don't take this branch until later.
      */
-    if (SSL_CONNECTION_IS_TLS13(s)) {
+    if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) {
         if (!ossl_statem_client13_read_transition(s, mt))
             goto err;
         return 1;
@@ -547,7 +547,7 @@ WRITE_TRAN ossl_statem_client_write_transition(SSL_CONNECTION *s)
      * version we are going to negotiate yet, so we don't take this branch until
      * later
      */
-    if (SSL_CONNECTION_IS_TLS13(s))
+    if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))
         return ossl_statem_client13_write_transition(s);
 
     switch (st->hand_state) {
@@ -573,7 +573,7 @@ WRITE_TRAN ossl_statem_client_write_transition(SSL_CONNECTION *s)
     case TLS_ST_CW_CLNT_HELLO:
         if (s->early_data_state == SSL_EARLY_DATA_CONNECTING) {
             /*
-             * We are assuming this is a TLSv1.3 connection, although we haven't
+             * We are assuming this is a (D)TLSv1.3 connection, although we haven't
              * actually selected a version yet.
              */
             if ((s->options & SSL_OP_ENABLE_MIDDLEBOX_COMPAT) != 0)
@@ -591,7 +591,7 @@ WRITE_TRAN ossl_statem_client_write_transition(SSL_CONNECTION *s)
 
     case TLS_ST_CR_SRVR_HELLO:
         /*
-         * We only get here in TLSv1.3. We just received an HRR, so issue a
+         * We only get here in (D)TLSv1.3. We just received an HRR, so issue a
          * CCS unless middlebox compat mode is off, or we already issued one
          * because we did early data.
          */
@@ -806,7 +806,7 @@ WORK_STATE ossl_statem_client_post_work(SSL_CONNECTION *s, WORK_STATE wst)
         if (s->early_data_state == SSL_EARLY_DATA_CONNECTING
                 && s->max_early_data > 0) {
             /*
-             * We haven't selected TLSv1.3 yet so we don't call the change
+             * We haven't selected (D)TLSv1.3 yet so we don't call the change
              * cipher state function associated with the SSL_METHOD. Instead
              * we call tls13_change_cipher_state() directly.
              */
@@ -836,13 +836,13 @@ WORK_STATE ossl_statem_client_post_work(SSL_CONNECTION *s, WORK_STATE wst)
         break;
 
     case TLS_ST_CW_CHANGE:
-        if (SSL_CONNECTION_IS_TLS13(s)
+        if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)
             || s->hello_retry_request == SSL_HRR_PENDING)
             break;
         if (s->early_data_state == SSL_EARLY_DATA_CONNECTING
                     && s->max_early_data > 0) {
             /*
-             * We haven't selected TLSv1.3 yet so we don't call the change
+             * We haven't selected (D)TLSv1.3 yet so we don't call the change
              * cipher state function associated with the SSL_METHOD. Instead
              * we call tls13_change_cipher_state() directly.
              */
@@ -897,7 +897,7 @@ WORK_STATE ossl_statem_client_post_work(SSL_CONNECTION *s, WORK_STATE wst)
         if (statem_flush(s) != 1)
             return WORK_MORE_B;
 
-        if (SSL_CONNECTION_IS_TLS13(s)) {
+        if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) {
             if (!tls13_save_handshake_digest_for_pha(s)) {
                 /* SSLfatal() already called */
                 return WORK_ERROR;
@@ -1058,7 +1058,7 @@ size_t ossl_statem_client_max_message_size(SSL_CONNECTION *s)
         return CCS_MAX_LENGTH;
 
     case TLS_ST_CR_SESSION_TICKET:
-        return (SSL_CONNECTION_IS_TLS13(s)) ? SESSION_TICKET_MAX_LENGTH_TLS13
+        return (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) ? SESSION_TICKET_MAX_LENGTH_TLS13
                                             : SESSION_TICKET_MAX_LENGTH_TLS12;
 
     case TLS_ST_CR_FINISHED:
@@ -1167,6 +1167,8 @@ CON_FUNC_RETURN tls_construct_client_hello(SSL_CONNECTION *s, WPACKET *pkt)
     int i, protverr;
 #ifndef OPENSSL_NO_COMP
     SSL_COMP *comp;
+    int comp_version_limit = SSL_CONNECTION_IS_DTLS(s) ? DTLS1_3_VERSION
+                                                       : TLS1_3_VERSION;
 #endif
     SSL_SESSION *sess = s->session;
     unsigned char *session_id;
@@ -1256,8 +1258,8 @@ CON_FUNC_RETURN tls_construct_client_hello(SSL_CONNECTION *s, WPACKET *pkt)
 
     /* Session ID */
     session_id = s->session->session_id;
-    if (s->new_session || s->session->ssl_version == TLS1_3_VERSION) {
-        if (s->version == TLS1_3_VERSION
+    if (s->new_session || s->session->ssl_version == TLS1_3_VERSION || s->session->ssl_version == DTLS1_3_VERSION) {
+        if ((s->version == TLS1_3_VERSION || s->version == DTLS1_3_VERSION)
                 && (s->options & SSL_OP_ENABLE_MIDDLEBOX_COMPAT) != 0) {
             sess_id_len = sizeof(s->tmp_session_id);
             s->tmp_session_id_len = sess_id_len;
@@ -1274,7 +1276,7 @@ CON_FUNC_RETURN tls_construct_client_hello(SSL_CONNECTION *s, WPACKET *pkt)
     } else {
         assert(s->session->session_id_length <= sizeof(s->session->session_id));
         sess_id_len = s->session->session_id_length;
-        if (s->version == TLS1_3_VERSION) {
+        if (s->version == TLS1_3_VERSION || s->version == DTLS1_3_VERSION) {
             s->tmp_session_id_len = sess_id_len;
             memcpy(s->tmp_session_id, s->session->session_id, sess_id_len);
         }
@@ -1321,8 +1323,7 @@ CON_FUNC_RETURN tls_construct_client_hello(SSL_CONNECTION *s, WPACKET *pkt)
 #ifndef OPENSSL_NO_COMP
     if (ssl_allow_compression(s)
             && sctx->comp_methods
-            && (SSL_CONNECTION_IS_DTLS(s)
-                || s->s3.tmp.max_ver < TLS1_3_VERSION)) {
+            && ssl_version_cmp(s, s->s3.tmp.max_ver, comp_version_limit) < 0) {
         int compnum = sk_SSL_COMP_num(sctx->comp_methods);
         for (i = 0; i < compnum; i++) {
             comp = sk_SSL_COMP_value(sctx->comp_methods, i);
@@ -1405,7 +1406,7 @@ static int set_client_ciphersuite(SSL_CONNECTION *s,
         return 0;
     }
 
-    if (SSL_CONNECTION_IS_TLS13(s) && s->s3.tmp.new_cipher != NULL
+    if ((SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) && s->s3.tmp.new_cipher != NULL
             && s->s3.tmp.new_cipher->id != c->id) {
         /* ServerHello selected a different ciphersuite to that in the HRR */
         SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_R_WRONG_CIPHER_RETURNED);
@@ -1420,7 +1421,7 @@ static int set_client_ciphersuite(SSL_CONNECTION *s,
     if (s->session->cipher != NULL)
         s->session->cipher_id = s->session->cipher->id;
     if (s->hit && (s->session->cipher_id != c->id)) {
-        if (SSL_CONNECTION_IS_TLS13(s)) {
+        if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) {
             const EVP_MD *md = ssl_md(sctx, c->algorithm2);
 
             if (!ossl_assert(s->session->cipher != NULL)) {
@@ -1473,8 +1474,8 @@ MSG_PROCESS_RETURN tls_process_server_hello(SSL_CONNECTION *s, PACKET *pkt)
     }
 
     /* load the server random */
-    if (s->version == TLS1_3_VERSION
-            && sversion == TLS1_2_VERSION
+    if (((s->version == TLS1_3_VERSION && sversion == TLS1_2_VERSION)
+         || (s->version == DTLS1_3_VERSION && sversion == DTLS1_2_VERSION))
             && PACKET_remaining(pkt) >= SSL3_RANDOM_SIZE
             && memcmp(hrrrandom, PACKET_data(pkt), SSL3_RANDOM_SIZE) == 0) {
         if (s->hello_retry_request != SSL_HRR_NONE) {
@@ -1545,7 +1546,7 @@ MSG_PROCESS_RETURN tls_process_server_hello(SSL_CONNECTION *s, PACKET *pkt)
         }
     }
 
-    if (SSL_CONNECTION_IS_TLS13(s) || hrr) {
+    if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s) || hrr) {
         if (compression != 0) {
             SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER,
                      SSL_R_INVALID_COMPRESSION_ALGORITHM);
@@ -1573,7 +1574,7 @@ MSG_PROCESS_RETURN tls_process_server_hello(SSL_CONNECTION *s, PACKET *pkt)
      * Now we have chosen the version we need to check again that the extensions
      * are appropriate for this version.
      */
-    context = SSL_CONNECTION_IS_TLS13(s) ? SSL_EXT_TLS1_3_SERVER_HELLO
+    context = (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) ? SSL_EXT_TLS1_3_SERVER_HELLO
                                          : SSL_EXT_TLS1_2_SERVER_HELLO;
     if (!tls_validate_all_contexts(s, context, extensions)) {
         SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_R_BAD_EXTENSION);
@@ -1582,7 +1583,7 @@ MSG_PROCESS_RETURN tls_process_server_hello(SSL_CONNECTION *s, PACKET *pkt)
 
     s->hit = 0;
 
-    if (SSL_CONNECTION_IS_TLS13(s)) {
+    if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) {
         /*
          * In TLSv1.3 a ServerHello message signals a key change so the end of
          * the message must be on a record boundary.
@@ -1675,7 +1676,7 @@ MSG_PROCESS_RETURN tls_process_server_hello(SSL_CONNECTION *s, PACKET *pkt)
          * echo of what we originally sent in the ClientHello and should not be
          * used for resumption.
          */
-        if (!SSL_CONNECTION_IS_TLS13(s)) {
+        if (!(SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))) {
             s->session->session_id_length = session_id_len;
             /* session_id_len could be 0 */
             if (session_id_len > 0)
@@ -1782,7 +1783,7 @@ MSG_PROCESS_RETURN tls_process_server_hello(SSL_CONNECTION *s, PACKET *pkt)
      * In TLSv1.3 we have some post-processing to change cipher state, otherwise
      * we're done with this message
      */
-    if (SSL_CONNECTION_IS_TLS13(s)) {
+    if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) {
         if (!ssl->method->ssl3_enc->setup_key_block(s)
                 || !ssl->method->ssl3_enc->change_cipher_state(s,
                     SSL3_CC_HANDSHAKE | SSL3_CHANGE_CIPHER_CLIENT_READ)) {
@@ -1818,6 +1819,7 @@ static MSG_PROCESS_RETURN tls_process_as_hello_retry_request(SSL_CONNECTION *s,
                                                              PACKET *extpkt)
 {
     RAW_EXTENSION *extensions = NULL;
+    const int isdtls = SSL_CONNECTION_IS_DTLS(s);
 
     /*
      * If we were sending early_data then any alerts should not be sent using
@@ -1825,7 +1827,7 @@ static MSG_PROCESS_RETURN tls_process_as_hello_retry_request(SSL_CONNECTION *s,
      */
     if (s->early_data_state == SSL_EARLY_DATA_FINISHED_WRITING
             && !ssl_set_new_record_layer(s,
-                                         TLS_ANY_VERSION,
+                                         isdtls ? DTLS_ANY_VERSION : TLS_ANY_VERSION,
                                          OSSL_RECORD_DIRECTION_WRITE,
                                          OSSL_RECORD_PROTECTION_LEVEL_NONE,
                                          NULL, 0, NULL, 0, NULL, 0, NULL,  0,
@@ -1834,7 +1836,7 @@ static MSG_PROCESS_RETURN tls_process_as_hello_retry_request(SSL_CONNECTION *s,
         goto err;
     }
     /* We are definitely going to be using TLSv1.3 */
-    s->rlayer.wrlmethod->set_protocol_version(s->rlayer.wrl, TLS1_3_VERSION);
+    s->rlayer.wrlmethod->set_protocol_version(s->rlayer.wrl, isdtls ? DTLS1_3_VERSION : TLS1_3_VERSION);
 
     if (!tls_collect_extensions(s, extpkt, SSL_EXT_TLS1_3_HELLO_RETRY_REQUEST,
                                 &extensions, NULL, 1)
@@ -1932,7 +1934,7 @@ static WORK_STATE tls_post_process_server_rpk(SSL_CONNECTION *sc,
      * skip check since TLS 1.3 ciphersuites can be used with any certificate
      * type.
      */
-    if (!SSL_CONNECTION_IS_TLS13(sc)) {
+    if (!(SSL_CONNECTION_IS_TLS13(sc) || SSL_CONNECTION_IS_DTLS13(sc))) {
         if ((clu->amask & sc->s3.tmp.new_cipher->algorithm_auth) == 0) {
             SSLfatal(sc, SSL_AD_ILLEGAL_PARAMETER, SSL_R_WRONG_RPK_TYPE);
             return WORK_ERROR;
@@ -1947,7 +1949,7 @@ static WORK_STATE tls_post_process_server_rpk(SSL_CONNECTION *sc,
     sc->session->verify_result = sc->verify_result;
 
     /* Save the current hash state for when we receive the CertificateVerify */
-    if (SSL_CONNECTION_IS_TLS13(sc)
+    if ((SSL_CONNECTION_IS_TLS13(sc) || SSL_CONNECTION_IS_DTLS13(sc))
             && !ssl_handshake_hash(sc, sc->cert_verify_hash,
                                    sizeof(sc->cert_verify_hash),
                                    &sc->cert_verify_hash_len)) {
@@ -1982,7 +1984,7 @@ MSG_PROCESS_RETURN tls_process_server_certificate(SSL_CONNECTION *s,
         goto err;
     }
 
-    if ((SSL_CONNECTION_IS_TLS13(s) && !PACKET_get_1(pkt, &context))
+    if (((SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) && !PACKET_get_1(pkt, &context))
             || context != 0
             || !PACKET_get_net_3(pkt, &cert_list_len)
             || PACKET_remaining(pkt) != cert_list_len
@@ -2014,7 +2016,7 @@ MSG_PROCESS_RETURN tls_process_server_certificate(SSL_CONNECTION *s,
             goto err;
         }
 
-        if (SSL_CONNECTION_IS_TLS13(s)) {
+        if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) {
             RAW_EXTENSION *rawexts = NULL;
             PACKET extensions;
 
@@ -2118,7 +2120,7 @@ WORK_STATE tls_post_process_server_certificate(SSL_CONNECTION *s,
      * skip check since TLS 1.3 ciphersuites can be used with any certificate
      * type.
      */
-    if (!SSL_CONNECTION_IS_TLS13(s)) {
+    if (!(SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))) {
         if ((clu->amask & s->s3.tmp.new_cipher->algorithm_auth) == 0) {
             SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_R_WRONG_CERTIFICATE_TYPE);
             return WORK_ERROR;
@@ -2134,7 +2136,7 @@ WORK_STATE tls_post_process_server_certificate(SSL_CONNECTION *s,
     s->session->peer_rpk = NULL;
 
     /* Save the current hash state for when we receive the CertificateVerify */
-    if (SSL_CONNECTION_IS_TLS13(s)
+    if ((SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))
             && !ssl_handshake_hash(s, s->cert_verify_hash,
                                    sizeof(s->cert_verify_hash),
                                    &s->cert_verify_hash_len)) {
@@ -2568,7 +2570,7 @@ MSG_PROCESS_RETURN tls_process_certificate_request(SSL_CONNECTION *s,
     if (s->s3.tmp.valid_flags == NULL)
         return 0;
 
-    if (SSL_CONNECTION_IS_TLS13(s)) {
+    if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) {
         PACKET reqctx, extensions;
         RAW_EXTENSION *rawexts = NULL;
 
@@ -2673,7 +2675,7 @@ MSG_PROCESS_RETURN tls_process_certificate_request(SSL_CONNECTION *s,
      * SSL_get1_peer_certificate() returns something sensible in
      * client_cert_cb.
      */
-    if (SSL_CONNECTION_IS_TLS13(s)
+    if ((SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))
         && s->post_handshake_auth != SSL_PHA_REQUESTED)
         return MSG_PROCESS_CONTINUE_READING;
 
@@ -2694,11 +2696,11 @@ MSG_PROCESS_RETURN tls_process_new_session_ticket(SSL_CONNECTION *s,
     PACKET_null_init(&nonce);
 
     if (!PACKET_get_net_4(pkt, &ticket_lifetime_hint)
-        || (SSL_CONNECTION_IS_TLS13(s)
+        || ((SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))
             && (!PACKET_get_net_4(pkt, &age_add)
                 || !PACKET_get_length_prefixed_1(pkt, &nonce)))
         || !PACKET_get_net_2(pkt, &ticklen)
-        || (SSL_CONNECTION_IS_TLS13(s) ? (ticklen == 0 
+        || ((SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) ? (ticklen == 0
                                           || PACKET_remaining(pkt) < ticklen)
                                        : PACKET_remaining(pkt) != ticklen)) {
         SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_R_LENGTH_MISMATCH);
@@ -2721,7 +2723,7 @@ MSG_PROCESS_RETURN tls_process_new_session_ticket(SSL_CONNECTION *s,
      * post-handshake and the session may have already gone into the session
      * cache.
      */
-    if (SSL_CONNECTION_IS_TLS13(s) || s->session->session_id_length > 0) {
+    if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s) || s->session->session_id_length > 0) {
         SSL_SESSION *new_sess;
 
         /*
@@ -2734,7 +2736,7 @@ MSG_PROCESS_RETURN tls_process_new_session_ticket(SSL_CONNECTION *s,
         }
 
         if ((s->session_ctx->session_cache_mode & SSL_SESS_CACHE_CLIENT) != 0
-                && !SSL_CONNECTION_IS_TLS13(s)) {
+                && !(SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))) {
             /*
              * In TLSv1.2 and below the arrival of a new tickets signals that
              * any old ticket we were using is now out of date, so we remove the
@@ -2768,7 +2770,7 @@ MSG_PROCESS_RETURN tls_process_new_session_ticket(SSL_CONNECTION *s,
     s->session->ext.tick_age_add = age_add;
     s->session->ext.ticklen = ticklen;
 
-    if (SSL_CONNECTION_IS_TLS13(s)) {
+    if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) {
         PACKET extpkt;
 
         if (!PACKET_as_length_prefixed_2(pkt, &extpkt)
@@ -2821,7 +2823,7 @@ MSG_PROCESS_RETURN tls_process_new_session_ticket(SSL_CONNECTION *s,
     s->session->not_resumable = 0;
 
     /* This is a standalone message in TLSv1.3, so there is no more to read */
-    if (SSL_CONNECTION_IS_TLS13(s)) {
+    if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) {
         const EVP_MD *md = ssl_handshake_md(s);
         int hashleni = EVP_MD_get_size(md);
         size_t hashlen;
@@ -3737,7 +3739,7 @@ WORK_STATE tls_prepare_client_certificate(SSL_CONNECTION *s, WORK_STATE wst)
             }
         }
 
-        if (!SSL_CONNECTION_IS_TLS13(s)
+        if (!(SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))
                 || (s->options & SSL_OP_NO_TX_CERTIFICATE_COMPRESSION) != 0)
             s->ext.compress_certificate_from_peer[0] = TLSEXT_comp_cert_none;
 
@@ -3757,7 +3759,7 @@ CON_FUNC_RETURN tls_construct_client_certificate(SSL_CONNECTION *s,
     CERT_PKEY *cpk = NULL;
     SSL *ssl = SSL_CONNECTION_GET_SSL(s);
 
-    if (SSL_CONNECTION_IS_TLS13(s)) {
+    if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) {
         if (s->pha_context == NULL) {
             /* no context available, add 0-length context */
             if (!WPACKET_put_bytes_u8(pkt, 0)) {
@@ -3794,7 +3796,7 @@ CON_FUNC_RETURN tls_construct_client_certificate(SSL_CONNECTION *s,
      * then we deferred changing the handshake write keys to the last possible
      * moment. We need to do it now.
      */
-    if (SSL_CONNECTION_IS_TLS13(s)
+    if ((SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))
             && SSL_IS_FIRST_HANDSHAKE(s)
             && (s->early_data_state != SSL_EARLY_DATA_NONE
                 || (s->options & SSL_OP_ENABLE_MIDDLEBOX_COMPAT) != 0)
@@ -4063,9 +4065,11 @@ int ssl_cipher_list_to_bytes(SSL_CONNECTION *s, STACK_OF(SSL_CIPHER) *sk,
 {
     int i;
     size_t totlen = 0, len, maxlen, maxverok = 0;
+    int min_proto_version_limit = SSL_CONNECTION_IS_DTLS(s)
+                                  ? DTLS1_3_VERSION : TLS1_3_VERSION;
     int empty_reneg_info_scsv = !s->renegotiate
-                                && (SSL_CONNECTION_IS_DTLS(s)
-                                    || s->min_proto_version < TLS1_3_VERSION);
+                                && (ssl_version_cmp(s, s->min_proto_version, min_proto_version_limit) < 0
+                                    || s->min_proto_version == 0);
     SSL *ssl = SSL_CONNECTION_GET_SSL(s);
 
     /* Set disabled masks for this session */
diff --git a/ssl/statem/statem_lib.c b/ssl/statem/statem_lib.c
index 7ef74b1f69..0938788384 100644
--- a/ssl/statem/statem_lib.c
+++ b/ssl/statem/statem_lib.c
@@ -261,7 +261,7 @@ static int get_cert_verify_tbs_data(SSL_CONNECTION *s, unsigned char *tls13tbs,
     static const char clientcontext[] = "\x54\x4c\x53\x20\x31\x2e\x33\x2c\x20\x63\x6c\x69"
         "\x65\x6e\x74\x20\x43\x65\x72\x74\x69\x66\x69\x63\x61\x74\x65\x56\x65\x72\x69\x66\x79";
 
-    if (SSL_CONNECTION_IS_TLS13(s)) {
+    if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) {
         size_t hashlen;
 
         /* Set the first 64 bytes of to-be-signed data to octet 32 */
@@ -580,14 +580,14 @@ MSG_PROCESS_RETURN tls_process_cert_verify(SSL_CONNECTION *s, PACKET *pkt)
     }
 
     /*
-     * In TLSv1.3 on the client side we make sure we prepare the client
+     * In (D)TLSv1.3 on the client side we make sure we prepare the client
      * certificate after the CertVerify instead of when we get the
-     * CertificateRequest. This is because in TLSv1.3 the CertificateRequest
-     * comes *before* the Certificate message. In TLSv1.2 it comes after. We
+     * CertificateRequest. This is because in (D)TLSv1.3 the CertificateRequest
+     * comes *before* the Certificate message. In (D)TLSv1.2 it comes after. We
      * want to make sure that SSL_get1_peer_certificate() will return the actual
      * server certificate from the client_cert_cb callback.
      */
-    if (!s->server && SSL_CONNECTION_IS_TLS13(s) && s->s3.tmp.cert_req == 1)
+    if (!s->server && (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) && s->s3.tmp.cert_req == 1)
         ret = MSG_PROCESS_CONTINUE_PROCESSING;
     else
         ret = MSG_PROCESS_CONTINUE_READING;
@@ -618,7 +618,7 @@ CON_FUNC_RETURN tls_construct_finished(SSL_CONNECTION *s, WPACKET *pkt)
      * moment. If we didn't already do this when we sent the client certificate
      * then we need to do it now.
      */
-    if (SSL_CONNECTION_IS_TLS13(s)
+    if ((SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))
             && !s->server
             && (s->early_data_state != SSL_EARLY_DATA_NONE
                 || (s->options & SSL_OP_ENABLE_MIDDLEBOX_COMPAT) != 0)
@@ -654,9 +654,9 @@ CON_FUNC_RETURN tls_construct_finished(SSL_CONNECTION *s, WPACKET *pkt)
 
     /*
      * Log the master secret, if logging is enabled. We don't log it for
-     * TLSv1.3: there's a different key schedule for that.
+     * (D)TLSv1.3: there's a different key schedule for that.
      */
-    if (!SSL_CONNECTION_IS_TLS13(s)
+    if (!(SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))
         && !ssl_log_secret(s, MASTER_SECRET_LABEL, s->session->master_key,
                            s->session->master_key_length)) {
         /* SSLfatal() already called */
@@ -838,13 +838,13 @@ MSG_PROCESS_RETURN tls_process_finished(SSL_CONNECTION *s, PACKET *pkt)
         /*
         * To get this far we must have read encrypted data from the client. We
         * no longer tolerate unencrypted alerts. This is ignored if less than
-        * TLSv1.3
+        * (D)TLSv1.3
         */
         if (s->rlayer.rrlmethod->set_plain_alerts != NULL)
             s->rlayer.rrlmethod->set_plain_alerts(s->rlayer.rrl, 0);
         if (s->post_handshake_auth != SSL_PHA_REQUESTED)
             s->statem.cleanuphand = 1;
-        if (SSL_CONNECTION_IS_TLS13(s)
+        if ((SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))
             && !tls13_save_handshake_digest_for_pha(s)) {
                 /* SSLfatal() already called */
                 return MSG_PROCESS_ERROR;
@@ -855,14 +855,14 @@ MSG_PROCESS_RETURN tls_process_finished(SSL_CONNECTION *s, PACKET *pkt)
      * In TLSv1.3 a Finished message signals a key change so the end of the
      * message must be on a record boundary.
      */
-    if (SSL_CONNECTION_IS_TLS13(s)
+    if ((SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))
         && RECORD_LAYER_processed_read_pending(&s->rlayer)) {
         SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_R_NOT_ON_RECORD_BOUNDARY);
         return MSG_PROCESS_ERROR;
     }
 
     /* If this occurs, we have missed a message */
-    if (!SSL_CONNECTION_IS_TLS13(s) && !s->s3.change_cipher_spec) {
+    if (!(SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) && !s->s3.change_cipher_spec) {
         SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_R_GOT_A_FIN_BEFORE_A_CCS);
         return MSG_PROCESS_ERROR;
     }
@@ -910,7 +910,7 @@ MSG_PROCESS_RETURN tls_process_finished(SSL_CONNECTION *s, PACKET *pkt)
      * In TLS1.3 we also have to change cipher state and do any final processing
      * of the initial server flight (if we are a client)
      */
-    if (SSL_CONNECTION_IS_TLS13(s)) {
+    if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) {
         if (s->server) {
             if (s->post_handshake_auth != SSL_PHA_REQUESTED &&
                     !ssl->method->ssl3_enc->change_cipher_state(s,
@@ -919,7 +919,7 @@ MSG_PROCESS_RETURN tls_process_finished(SSL_CONNECTION *s, PACKET *pkt)
                 return MSG_PROCESS_ERROR;
             }
         } else {
-            /* TLS 1.3 gets the secret size from the handshake md */
+            /* (D)TLS 1.3 gets the secret size from the handshake md */
             size_t dummy;
             if (!ssl->method->ssl3_enc->generate_master_secret(s,
                     s->master_secret, s->handshake_secret, 0,
@@ -981,7 +981,7 @@ static int ssl_add_cert_to_wpacket(SSL_CONNECTION *s, WPACKET *pkt,
         return 0;
     }
 
-    if ((SSL_CONNECTION_IS_TLS13(s) || for_comp)
+    if ((SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s) || for_comp)
             && !tls_construct_extensions(s, pkt, context, x, chain)) {
         /* SSLfatal() already called */
         return 0;
@@ -1113,7 +1113,7 @@ int tls_process_rpk(SSL_CONNECTION *sc, PACKET *pkt, EVP_PKEY **peer_rpk)
 
     /*-
      * ----------------------------
-     * TLS 1.3 Certificate message:
+     * (D)TLS 1.3 Certificate message:
      * ----------------------------
      * https://datatracker.ietf.org/doc/html/rfc8446#section-4.4.2
      *
@@ -1173,21 +1173,21 @@ int tls_process_rpk(SSL_CONNECTION *sc, PACKET *pkt, EVP_PKEY **peer_rpk)
      * -------------
      * Consequently:
      * -------------
-     * After the (TLS 1.3 only) context octet string (1 byte length + data) the
+     * After the ((D)TLS 1.3 only) context octet string (1 byte length + data) the
      * Certificate message has a 3-byte length that is zero in the client to
      * server message when the client has no RPK to send.  In that case, there
-     * are no (TLS 1.3 only) per-certificate extensions either, because the
+     * are no ((D)TLS 1.3 only) per-certificate extensions either, because the
      * [CertificateEntry] list is empty.
      *
      * In the server to client direction, or when the client had an RPK to send,
-     * the TLS 1.3 message just prepends the length of the RPK+extensions,
+     * the (D)TLS 1.3 message just prepends the length of the RPK+extensions,
      * while TLS <= 1.2 sends just the RPK (octet-string).
      *
      * The context must be zero-length in the server to client direction, and
      * must match the value recorded in the certificate request in the client
      * to server direction.
      */
-    if (SSL_CONNECTION_IS_TLS13(sc)) {
+    if (SSL_CONNECTION_IS_TLS13(sc) || SSL_CONNECTION_IS_DTLS13(sc)) {
         if (!PACKET_get_length_prefixed_1(pkt, &context)) {
             SSLfatal(sc, SSL_AD_DECODE_ERROR, SSL_R_INVALID_CONTEXT);
             goto err;
@@ -1229,7 +1229,7 @@ int tls_process_rpk(SSL_CONNECTION *sc, PACKET *pkt, EVP_PKEY **peer_rpk)
     if (cert_len == 0)
         return 1;
 
-    if (SSL_CONNECTION_IS_TLS13(sc)) {
+    if (SSL_CONNECTION_IS_TLS13(sc) || SSL_CONNECTION_IS_DTLS13(sc)) {
         /*
          * With TLS 1.3, a non-empty explicit-length RPK octet-string followed
          * by a possibly empty extension block.
@@ -1264,7 +1264,7 @@ int tls_process_rpk(SSL_CONNECTION *sc, PACKET *pkt, EVP_PKEY **peer_rpk)
     }
 
     /* Process the Extensions block */
-    if (SSL_CONNECTION_IS_TLS13(sc)) {
+    if (SSL_CONNECTION_IS_TLS13(sc) || SSL_CONNECTION_IS_DTLS13(sc)) {
         if (PACKET_remaining(pkt) != (cert_len - 3 - spki_len)) {
             SSLfatal(sc, SSL_AD_DECODE_ERROR, SSL_R_BAD_LENGTH);
             goto err;
@@ -1341,7 +1341,7 @@ unsigned long tls_output_rpk(SSL_CONNECTION *sc, WPACKET *pkt, CERT_PKEY *cpk)
      * TLSv1.2 is _just_ the raw public key
      * TLSv1.3 includes extensions, so there's a length wrapper
      */
-    if (SSL_CONNECTION_IS_TLS13(sc)) {
+    if (SSL_CONNECTION_IS_TLS13(sc)|| SSL_CONNECTION_IS_DTLS13(sc)) {
         if (!WPACKET_start_sub_packet_u24(pkt)) {
             SSLfatal(sc, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
             goto err;
@@ -1353,7 +1353,7 @@ unsigned long tls_output_rpk(SSL_CONNECTION *sc, WPACKET *pkt, CERT_PKEY *cpk)
         goto err;
     }
 
-    if (SSL_CONNECTION_IS_TLS13(sc)) {
+    if (SSL_CONNECTION_IS_TLS13(sc)|| SSL_CONNECTION_IS_DTLS13(sc)) {
         /*
          * Only send extensions relevant to raw public keys. Until such
          * extensions are defined, this will be an empty set of extensions.
@@ -1437,7 +1437,7 @@ WORK_STATE tls_finish_handshake(SSL_CONNECTION *s, ossl_unused WORK_STATE wst,
         s->init_num = 0;
     }
 
-    if (SSL_CONNECTION_IS_TLS13(s) && !s->server
+    if ((SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) && !s->server
             && s->post_handshake_auth == SSL_PHA_REQUESTED)
         s->post_handshake_auth = SSL_PHA_EXT_SENT;
 
@@ -1459,14 +1459,14 @@ WORK_STATE tls_finish_handshake(SSL_CONNECTION *s, ossl_unused WORK_STATE wst,
              * In TLSv1.3 we update the cache as part of constructing the
              * NewSessionTicket
              */
-            if (!SSL_CONNECTION_IS_TLS13(s))
+            if (!(SSL_CONNECTION_IS_TLS13(s))|| SSL_CONNECTION_IS_DTLS13(s))
                 ssl_update_cache(s, SSL_SESS_CACHE_SERVER);
 
             /* N.B. s->ctx may not equal s->session_ctx */
             ssl_tsan_counter(sctx, &sctx->stats.sess_accept_good);
             s->handshake_func = ossl_statem_accept;
         } else {
-            if (SSL_CONNECTION_IS_TLS13(s)) {
+            if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) {
                 /*
                  * We encourage applications to only use TLSv1.3 tickets once,
                  * so we remove this one from the cache.
@@ -1509,7 +1509,7 @@ WORK_STATE tls_finish_handshake(SSL_CONNECTION *s, ossl_unused WORK_STATE wst,
 
     if (cb != NULL) {
         if (cleanuphand
-                || !SSL_CONNECTION_IS_TLS13(s)
+                || !(SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))
                 || SSL_IS_FIRST_HANDSHAKE(s))
             cb(ssl, SSL_CB_HANDSHAKE_DONE, 1);
     }
@@ -1690,7 +1690,7 @@ int tls_get_message_body(SSL_CONNECTION *s, size_t *len)
          */
 #define SERVER_HELLO_RANDOM_OFFSET  (SSL3_HM_HEADER_LENGTH + 2)
         /* KeyUpdate and NewSessionTicket do not need to be added */
-        if (!SSL_CONNECTION_IS_TLS13(s)
+        if (!(SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))
             || (s->s3.tmp.message_type != SSL3_MT_NEWSESSION_TICKET
                          && s->s3.tmp.message_type != SSL3_MT_KEY_UPDATE)) {
             if (s->s3.tmp.message_type != SSL3_MT_SERVER_HELLO
@@ -1984,7 +1984,7 @@ int ssl_version_supported(const SSL_CONNECTION *s, int version,
                 && ssl_version_cmp(s, version, vent->version) == 0
                 && ssl_method_error(s, thismeth()) == 0
                 && (!s->server
-                    || version != TLS1_3_VERSION
+                    || (version != TLS1_3_VERSION && version != DTLS1_3_VERSION)
                     || is_tls13_capable(s))) {
             if (meth != NULL)
                 *meth = thismeth();
@@ -2149,12 +2149,14 @@ int ssl_choose_server_version(SSL_CONNECTION *s, CLIENTHELLO_MSG *hello,
     const version_info *table;
     int disabled = 0;
     RAW_EXTENSION *suppversions;
+    const int version1_3 = SSL_CONNECTION_IS_DTLS(s) ? DTLS1_3_VERSION
+                                                     : TLS1_3_VERSION;
 
     s->client_version = client_version;
 
     switch (server_version) {
     default:
-        if (!SSL_CONNECTION_IS_TLS13(s)) {
+        if (!(SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))) {
             if (ssl_version_cmp(s, client_version, s->version) < 0)
                 return SSL_R_WRONG_SSL_VERSION;
             *dgrd = DOWNGRADE_NONE;
@@ -2186,9 +2188,11 @@ int ssl_choose_server_version(SSL_CONNECTION *s, CLIENTHELLO_MSG *hello,
     if (!suppversions->present && s->hello_retry_request != SSL_HRR_NONE)
         return SSL_R_UNSUPPORTED_PROTOCOL;
 
-    if (suppversions->present && !SSL_CONNECTION_IS_DTLS(s)) {
+    if (suppversions->present) {
         unsigned int candidate_vers = 0;
-        unsigned int best_vers = 0;
+        const unsigned int best_vers_init = SSL_CONNECTION_IS_DTLS(s) ? UINT_MAX
+                                                                      : 0;
+        unsigned int best_vers = best_vers_init;
         const SSL_METHOD *best_method = NULL;
         PACKET versionslist;
 
@@ -2222,13 +2226,14 @@ int ssl_choose_server_version(SSL_CONNECTION *s, CLIENTHELLO_MSG *hello,
             return SSL_R_LENGTH_MISMATCH;
         }
 
-        if (best_vers > 0) {
+        /* Did best_vers change from the initial value? */
+        if (best_vers != best_vers_init) {
             if (s->hello_retry_request != SSL_HRR_NONE) {
                 /*
                  * This is after a HelloRetryRequest so we better check that we
-                 * negotiated TLSv1.3
+                 * negotiated (D)TLSv1.3
                  */
-                if (best_vers != TLS1_3_VERSION)
+                if (best_vers != TLS1_3_VERSION && best_vers != DTLS1_3_VERSION)
                     return SSL_R_UNSUPPORTED_PROTOCOL;
                 return 0;
             }
@@ -2245,10 +2250,11 @@ int ssl_choose_server_version(SSL_CONNECTION *s, CLIENTHELLO_MSG *hello,
 
     /*
      * If the supported versions extension isn't present, then the highest
-     * version we can negotiate is TLSv1.2
+     * version we can negotiate is (D)TLSv1.2
      */
-    if (ssl_version_cmp(s, client_version, TLS1_3_VERSION) >= 0)
-        client_version = TLS1_2_VERSION;
+    if (ssl_version_cmp(s, client_version, version1_3) >= 0)
+        client_version = SSL_CONNECTION_IS_DTLS(s) ? DTLS1_2_VERSION
+                                                   : TLS1_2_VERSION;
 
     /*
      * No supported versions extension, so we just use the version supplied in
@@ -2307,7 +2313,7 @@ int ssl_choose_client_version(SSL_CONNECTION *s, int version,
     }
 
     if (s->hello_retry_request != SSL_HRR_NONE
-            && s->version != TLS1_3_VERSION) {
+            && (s->version != TLS1_3_VERSION && s->version != DTLS1_3_VERSION)) {
         s->version = origv;
         SSLfatal(s, SSL_AD_PROTOCOL_VERSION, SSL_R_WRONG_SSL_VERSION);
         return 0;
diff --git a/ssl/statem/statem_srvr.c b/ssl/statem/statem_srvr.c
index 99085a4cc1..72ea84b019 100644
--- a/ssl/statem/statem_srvr.c
+++ b/ssl/statem/statem_srvr.c
@@ -180,7 +180,7 @@ int ossl_statem_server_read_transition(SSL_CONNECTION *s, int mt)
 {
     OSSL_STATEM *st = &s->statem;
 
-    if (SSL_CONNECTION_IS_TLS13(s)) {
+    if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s)) {
         if (!ossl_statem_server13_read_transition(s, mt))
             goto err;
         return 1;
@@ -415,7 +415,7 @@ int send_certificate_request(SSL_CONNECTION *s)
             * don't request if post-handshake-only unless doing
             * post-handshake in TLSv1.3:
             */
-           && (!SSL_CONNECTION_IS_TLS13(s)
+           && (!(SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))
                || !(s->verify_mode & SSL_VERIFY_POST_HANDSHAKE)
                || s->post_handshake_auth == SSL_PHA_REQUEST_PENDING)
            /*
@@ -609,7 +609,7 @@ WRITE_TRAN ossl_statem_server_write_transition(SSL_CONNECTION *s)
      * to negotiate yet, so we don't take this branch until later
      */
 
-    if (SSL_CONNECTION_IS_TLS13(s))
+    if (SSL_CONNECTION_IS_TLS13(s) || SSL_CONNECTION_IS_DTLS13(s))
         return ossl_statem_server13_write_transition(s);
 
     switch (st->hand_state) {
@@ -641,7 +641,7 @@ WRITE_TRAN ossl_statem_server_write_transition(SSL_CONNECTION *s)
         return WRITE_TRAN_CONTINUE;
 
     case TLS_ST_SR_CLNT_HELLO:
-        if (SSL_CONNECTION_IS_DTLS(s) && !s->d1->cookie_verified
+        if (SSL_CONNECTION_IS_DTLS(s) && !SSL_CONNECTION_IS_DTLS13(s) && !s->d1->cookie_verified
             && (SSL_get_options(SSL_CONNECTION_GET_SSL(s)) & SSL_OP_COOKIE_EXCHANGE)) {
             st->hand_state = DTLS_ST_SW_HELLO_VERIFY_REQUEST;
         } else if (s->renegotiate == 0 && !SSL_IS_FIRST_HANDSHAKE(s)) {
@@ -785,7 +785,7 @@ WORK_STATE ossl_statem_server_pre_work(SSL_CONNECTION *s, WORK_STATE wst)
         return WORK_FINISHED_CONTINUE;
 
     case TLS_ST_SW_SESSION_TICKET:
-        if (SSL_CONNECTION_IS_TLS13(s) && s->sent_tickets == 0
+        if ((SSL_CONNECTION_IS_TLS13(s) |