Support TLS 1.3

Fixes SIPp#693.

src/sipp.cpp

@@ -183,7 +183,7 @@ struct sipp_option options_table[] = {
     {"tls_key", "Set the name for TLS Private Key file. Default is 'cakey.pem'", SIPP_OPTION_STRING, &tls_key_name, 1},
     {"tls_ca", "Set the name for TLS CA file. If not specified, X509 verification is not activated.", SIPP_OPTION_STRING, &tls_ca_name, 1},
     {"tls_crl", "Set the name for Certificate Revocation List file. If not specified, X509 CRL is not activated.", SIPP_OPTION_STRING, &tls_crl_name, 1},
-    {"tls_version", "Set the TLS protocol version to use (1.0, 1.1, 1.2) -- default is autonegotiate", SIPP_OPTION_FLOAT, &tls_version, 1},
+    {"tls_version", "Set the TLS protocol version to use (1.0, 1.1, 1.2, 1.3) -- default is autonegotiate", SIPP_OPTION_FLOAT, &tls_version, 1},
 #else
     {"tls_cert", NULL, SIPP_OPTION_NEED_SSL, NULL, 1},
     {"tls_key", NULL, SIPP_OPTION_NEED_SSL, NULL, 1},

src/sslsocket.cpp

@@ -220,6 +220,8 @@ static SSL_CTX* instantiate_ssl_context(const char* context_name)
         max_tls_version = min_tls_version = TLS1_1_VERSION;
     } else if (tls_version == 1.2) {
         max_tls_version = min_tls_version = TLS1_2_VERSION;
+    } else if (tls_version == 1.3) {
+        max_tls_version = min_tls_version = TLS1_3_VERSION;
     } else {
         ERROR("Unrecognized TLS version for [%s] context: %1.1f", context_name, tls_version);
         return NULL;
@@ -268,6 +270,12 @@ static SSL_CTX* instantiate_ssl_context(const char* context_name)
         } else {
             ssl_ctx = SSL_CTX_new(TLSv1_2_server_method());
         }
+    } else if (tls_version == 1.3) {
+        if (!strncmp(context_name, "client", 6)) {
+            ssl_ctx = SSL_CTX_new(TLSv1_3_client_method());
+        } else {
+            ssl_ctx = SSL_CTX_new(TLSv1_3_server_method());
+        }
     } else {
         ERROR("Unrecognized TLS version for [%s] context: %1.1f", context_name, tls_version);
         ssl_ctx = NULL;