vtls: Only call add/getsession if session id is enabled

Prior to this change we called Curl_ssl_getsessionid and
Curl_ssl_addsessionid regardless of whether session ID reusing was
enabled. According to comments that is in case session ID reuse was
disabled but then later enabled.

The old way was not intuitive and probably not something users expected.
When a user disables session ID caching I'd guess they don't expect the
session ID to be cached anyway in case the caching is later enabled.

lib/vtls/axtls.c

@@ -143,8 +143,6 @@ static CURLcode connect_prep(struct connectdata *conn, int sockindex)
   int cert_types[] = {SSL_OBJ_X509_CERT, SSL_OBJ_PKCS12, 0};
   int key_types[] = {SSL_OBJ_RSA_KEY, SSL_OBJ_PKCS8, SSL_OBJ_PKCS12, 0};
   int i, ssl_fcn_return;
-  const uint8_t *ssl_sessionid;
-  size_t ssl_idsize;
 
   /* Assuming users will not compile in custom key/cert to axTLS.
   *  Also, even for blocking connects, use axTLS non-blocking feature.
@@ -258,19 +256,23 @@ static CURLcode connect_prep(struct connectdata *conn, int sockindex)
    * 2) setting up callbacks.  these seem gnutls specific
    */
 
-  /* In axTLS, handshaking happens inside ssl_client_new. */
+  if(conn->ssl_config.sessionid) {
-  Curl_ssl_sessionid_lock(conn);
+    const uint8_t *ssl_sessionid;
-  if(!Curl_ssl_getsessionid(conn, (void **) &ssl_sessionid, &ssl_idsize)) {
+    size_t ssl_idsize;
-    /* we got a session id, use it! */
+
-    infof (data, "SSL re-using session ID\n");
+    /* In axTLS, handshaking happens inside ssl_client_new. */
-    ssl = ssl_client_new(ssl_ctx, conn->sock[sockindex],
+    Curl_ssl_sessionid_lock(conn);
-                         ssl_sessionid, (uint8_t)ssl_idsize);
+    if(!Curl_ssl_getsessionid(conn, (void **) &ssl_sessionid, &ssl_idsize)) {
+      /* we got a session id, use it! */
+      infof (data, "SSL re-using session ID\n");
+      ssl = ssl_client_new(ssl_ctx, conn->sock[sockindex],
+                           ssl_sessionid, (uint8_t)ssl_idsize);
+    }
     Curl_ssl_sessionid_unlock(conn);
   }
-  else {
+
-    Curl_ssl_sessionid_unlock(conn);
+  if(!ssl)
     ssl = ssl_client_new(ssl_ctx, conn->sock[sockindex], NULL, 0);
-  }
 
   conn->ssl[sockindex].ssl = ssl;
   return CURLE_OK;
@@ -284,8 +286,6 @@ static CURLcode connect_finish(struct connectdata *conn, int sockindex)
 {
   struct SessionHandle *data = conn->data;
   SSL *ssl = conn->ssl[sockindex].ssl;
-  const uint8_t *ssl_sessionid;
-  size_t ssl_idsize;
   const char *peer_CN;
   uint32_t dns_altname_index;
   const char *dns_altname;
@@ -383,13 +383,15 @@ static CURLcode connect_finish(struct connectdata *conn, int sockindex)
   conn->send[sockindex] = axtls_send;
 
   /* Put our freshly minted SSL session in cache */
-  ssl_idsize = ssl_get_session_id_size(ssl);
+  if(conn->ssl_config.sessionid) {
-  ssl_sessionid = ssl_get_session_id(ssl);
+    const uint8_t *ssl_sessionid = ssl_get_session_id_size(ssl);
-  Curl_ssl_sessionid_lock(conn);
+    size_t ssl_idsize = ssl_get_session_id(ssl);
-  if(Curl_ssl_addsessionid(conn, (void *) ssl_sessionid, ssl_idsize)
+    Curl_ssl_sessionid_lock(conn);
-     != CURLE_OK)
+    if(Curl_ssl_addsessionid(conn, (void *) ssl_sessionid, ssl_idsize)
-    infof (data, "failed to add session to cache\n");
+       != CURLE_OK)
-  Curl_ssl_sessionid_unlock(conn);
+      infof (data, "failed to add session to cache\n");
+    Curl_ssl_sessionid_unlock(conn);
+  }
 
   return CURLE_OK;
 }

lib/vtls/cyassl.c

@@ -137,7 +137,6 @@ cyassl_connect_step1(struct connectdata *conn,
   struct SessionHandle *data = conn->data;
   struct ssl_connect_data* conssl = &conn->ssl[sockindex];
   SSL_METHOD* req_method = NULL;
-  void* ssl_sessionid = NULL;
   curl_socket_t sockfd = conn->sock[sockindex];
 #ifdef HAVE_SNI
   bool sni = FALSE;
@@ -378,19 +377,24 @@ cyassl_connect_step1(struct connectdata *conn,
 #endif /* HAVE_ALPN */
 
   /* Check if there's a cached ID we can/should use here! */
-  Curl_ssl_sessionid_lock(conn);
+  if(conn->ssl_config.sessionid) {
-  if(!Curl_ssl_getsessionid(conn, &ssl_sessionid, NULL)) {
+    void *ssl_sessionid = NULL;
-    /* we got a session id, use it! */
+
-    if(!SSL_set_session(conssl->handle, ssl_sessionid)) {
+    Curl_ssl_sessionid_lock(conn);
-      Curl_ssl_sessionid_unlock(conn);
+    if(!Curl_ssl_getsessionid(conn, &ssl_sessionid, NULL)) {
-      failf(data, "SSL: SSL_set_session failed: %s",
+      /* we got a session id, use it! */
-            ERR_error_string(SSL_get_error(conssl->handle, 0), error_buffer));
+      if(!SSL_set_session(conssl->handle, ssl_sessionid)) {
-      return CURLE_SSL_CONNECT_ERROR;
+        Curl_ssl_sessionid_unlock(conn);
+        failf(data, "SSL: SSL_set_session failed: %s",
+              ERR_error_string(SSL_get_error(conssl->handle, 0),
+              error_buffer));
+        return CURLE_SSL_CONNECT_ERROR;
+      }
+      /* Informational message */
+      infof (data, "SSL re-using session ID\n");
     }
-    /* Informational message */
+    Curl_ssl_sessionid_unlock(conn);
-    infof (data, "SSL re-using session ID\n");
   }
-  Curl_ssl_sessionid_unlock(conn);
 
   /* pass the raw socket into the SSL layer */
   if(!SSL_set_fd(conssl->handle, (int)sockfd)) {
@@ -574,36 +578,39 @@ cyassl_connect_step3(struct connectdata *conn,
                      int sockindex)
 {
   CURLcode result = CURLE_OK;
-  void *old_ssl_sessionid=NULL;
   struct SessionHandle *data = conn->data;
   struct ssl_connect_data *connssl = &conn->ssl[sockindex];
-  bool incache;
-  SSL_SESSION *our_ssl_sessionid;
 
   DEBUGASSERT(ssl_connect_3 == connssl->connecting_state);
 
-  our_ssl_sessionid = SSL_get_session(connssl->handle);
+  if(conn->ssl_config.sessionid) {
+    bool incache;
+    SSL_SESSION *our_ssl_sessionid;
+    void *old_ssl_sessionid = NULL;
 
-  Curl_ssl_sessionid_lock(conn);
+    our_ssl_sessionid = SSL_get_session(connssl->handle);
-  incache = !(Curl_ssl_getsessionid(conn, &old_ssl_sessionid, NULL));
-  if(incache) {
-    if(old_ssl_sessionid != our_ssl_sessionid) {
-      infof(data, "old SSL session ID is stale, removing\n");
-      Curl_ssl_delsessionid(conn, old_ssl_sessionid);
-      incache = FALSE;
-    }
-  }
 
-  if(!incache) {
+    Curl_ssl_sessionid_lock(conn);
-    result = Curl_ssl_addsessionid(conn, our_ssl_sessionid,
+    incache = !(Curl_ssl_getsessionid(conn, &old_ssl_sessionid, NULL));
-                                   0 /* unknown size */);
+    if(incache) {
-    if(result) {
+      if(old_ssl_sessionid != our_ssl_sessionid) {
-      Curl_ssl_sessionid_unlock(conn);
+        infof(data, "old SSL session ID is stale, removing\n");
-      failf(data, "failed to store ssl session");
+        Curl_ssl_delsessionid(conn, old_ssl_sessionid);
-      return result;
+        incache = FALSE;
+      }
     }
+
+    if(!incache) {
+      result = Curl_ssl_addsessionid(conn, our_ssl_sessionid,
+                                     0 /* unknown size */);
+      if(result) {
+        Curl_ssl_sessionid_unlock(conn);
+        failf(data, "failed to store ssl session");
+        return result;
+      }
+    }
+    Curl_ssl_sessionid_unlock(conn);
   }
-  Curl_ssl_sessionid_unlock(conn);
 
   connssl->connecting_state = ssl_connect_done;
 

lib/vtls/darwinssl.c

@@ -1009,8 +1009,6 @@ static CURLcode darwinssl_connect_step1(struct connectdata *conn,
 #endif /* ENABLE_IPV6 */
   size_t all_ciphers_count = 0UL, allowed_ciphers_count = 0UL, i;
   SSLCipherSuite *all_ciphers = NULL, *allowed_ciphers = NULL;
-  char *ssl_sessionid;
-  size_t ssl_sessionid_len;
   OSStatus err = noErr;
 #if CURL_BUILD_MAC
   int darwinver_maj = 0, darwinver_min = 0;
@@ -1474,41 +1472,46 @@ static CURLcode darwinssl_connect_step1(struct connectdata *conn,
 #endif /* CURL_BUILD_MAC_10_9 || CURL_BUILD_IOS_7 */
 
   /* Check if there's a cached ID we can/should use here! */
-  Curl_ssl_sessionid_lock(conn);
+  if(conn->ssl_config.sessionid) {
-  if(!Curl_ssl_getsessionid(conn, (void **)&ssl_sessionid,
+    char *ssl_sessionid;
-                            &ssl_sessionid_len)) {
+    size_t ssl_sessionid_len;
-    /* we got a session id, use it! */
-    err = SSLSetPeerID(connssl->ssl_ctx, ssl_sessionid, ssl_sessionid_len);
-    Curl_ssl_sessionid_unlock(conn);
-    if(err != noErr) {
-      failf(data, "SSL: SSLSetPeerID() failed: OSStatus %d", err);
-      return CURLE_SSL_CONNECT_ERROR;
-    }
-    /* Informational message */
-    infof(data, "SSL re-using session ID\n");
-  }
-  /* If there isn't one, then let's make one up! This has to be done prior
-     to starting the handshake. */
-  else {
-    CURLcode result;
-    ssl_sessionid =
-      aprintf("%s:%d:%d:%s:%hu", data->set.str[STRING_SSL_CAFILE],
-              data->set.ssl.verifypeer, data->set.ssl.verifyhost,
-              conn->host.name, conn->remote_port);
-    ssl_sessionid_len = strlen(ssl_sessionid);
 
-    err = SSLSetPeerID(connssl->ssl_ctx, ssl_sessionid, ssl_sessionid_len);
+    Curl_ssl_sessionid_lock(conn);
-    if(err != noErr) {
+    if(!Curl_ssl_getsessionid(conn, (void **)&ssl_sessionid,
+                              &ssl_sessionid_len)) {
+      /* we got a session id, use it! */
+      err = SSLSetPeerID(connssl->ssl_ctx, ssl_sessionid, ssl_sessionid_len);
       Curl_ssl_sessionid_unlock(conn);
-      failf(data, "SSL: SSLSetPeerID() failed: OSStatus %d", err);
+      if(err != noErr) {
-      return CURLE_SSL_CONNECT_ERROR;
+        failf(data, "SSL: SSLSetPeerID() failed: OSStatus %d", err);
+        return CURLE_SSL_CONNECT_ERROR;
+      }
+      /* Informational message */
+      infof(data, "SSL re-using session ID\n");
     }
+    /* If there isn't one, then let's make one up! This has to be done prior
+       to starting the handshake. */
+    else {
+      CURLcode result;
+      ssl_sessionid =
+        aprintf("%s:%d:%d:%s:%hu", data->set.str[STRING_SSL_CAFILE],
+                data->set.ssl.verifypeer, data->set.ssl.verifyhost,
+                conn->host.name, conn->remote_port);
+      ssl_sessionid_len = strlen(ssl_sessionid);
 
-    result = Curl_ssl_addsessionid(conn, ssl_sessionid, ssl_sessionid_len);
+      err = SSLSetPeerID(connssl->ssl_ctx, ssl_sessionid, ssl_sessionid_len);
-    Curl_ssl_sessionid_unlock(conn);
+      if(err != noErr) {
-    if(result) {
+        Curl_ssl_sessionid_unlock(conn);
-      failf(data, "failed to store ssl session");
+        failf(data, "SSL: SSLSetPeerID() failed: OSStatus %d", err);
-      return result;
+        return CURLE_SSL_CONNECT_ERROR;
+      }
+
+      result = Curl_ssl_addsessionid(conn, ssl_sessionid, ssl_sessionid_len);
+      Curl_ssl_sessionid_unlock(conn);
+      if(result) {
+        failf(data, "failed to store ssl session");
+        return result;
+      }
     }
   }
 

lib/vtls/gtls.c

@@ -370,8 +370,6 @@ gtls_connect_step1(struct connectdata *conn,
   struct SessionHandle *data = conn->data;
   gnutls_session_t session;
   int rc;
-  void *ssl_sessionid;
-  size_t ssl_idsize;
   bool sni = TRUE; /* default is SNI enabled */
 #ifdef ENABLE_IPV6
   struct in6_addr addr;
@@ -749,16 +747,20 @@ gtls_connect_step1(struct connectdata *conn,
 
   /* This might be a reconnect, so we check for a session ID in the cache
      to speed up things */
+  if(conn->ssl_config.sessionid) {
+    void *ssl_sessionid;
+    size_t ssl_idsize;
 
-  Curl_ssl_sessionid_lock(conn);
+    Curl_ssl_sessionid_lock(conn);
-  if(!Curl_ssl_getsessionid(conn, &ssl_sessionid, &ssl_idsize)) {
+    if(!Curl_ssl_getsessionid(conn, &ssl_sessionid, &ssl_idsize)) {
-    /* we got a session id, use it! */
+      /* we got a session id, use it! */
-    gnutls_session_set_data(session, ssl_sessionid, ssl_idsize);
+      gnutls_session_set_data(session, ssl_sessionid, ssl_idsize);
 
-    /* Informational message */
+      /* Informational message */
-    infof (data, "SSL re-using session ID\n");
+      infof (data, "SSL re-using session ID\n");
+    }
+    Curl_ssl_sessionid_unlock(conn);
   }
-  Curl_ssl_sessionid_unlock(conn);
 
   return CURLE_OK;
 }
@@ -841,8 +843,6 @@ gtls_connect_step3(struct connectdata *conn,
   struct SessionHandle *data = conn->data;
   gnutls_session_t session = conn->ssl[sockindex].session;
   int rc;
-  bool incache;
-  void *ssl_sessionid;
 #ifdef HAS_ALPN
   gnutls_datum_t proto;
 #endif
@@ -1270,11 +1270,13 @@ gtls_connect_step3(struct connectdata *conn,
   conn->recv[sockindex] = gtls_recv;
   conn->send[sockindex] = gtls_send;
 
-  {
+  if(conn->ssl_config.sessionid) {
     /* we always unconditionally get the session id here, as even if we
        already got it from the cache and asked to use it in the connection, it
        might've been rejected and then a new one is in use now and we need to
        detect that. */
+    bool incache;
+    void *ssl_sessionid;
     void *connect_sessionid;
     size_t connect_idsize = 0;
 

lib/vtls/mbedtls.c

@@ -162,7 +162,6 @@ mbed_connect_step1(struct connectdata *conn,
   struct ssl_connect_data* connssl = &conn->ssl[sockindex];
 
   int ret = -1;
-  void *old_session = NULL;
   char errorbuf[128];
   errorbuf[0]=0;
 
@@ -365,17 +364,23 @@ mbed_connect_step1(struct connectdata *conn,
 
   mbedtls_ssl_conf_ciphersuites(&connssl->config,
                                 mbedtls_ssl_list_ciphersuites());
-  Curl_ssl_sessionid_lock(conn);
+
-  if(!Curl_ssl_getsessionid(conn, &old_session, NULL)) {
+  /* Check if there's a cached ID we can/should use here! */
-    ret = mbedtls_ssl_set_session(&connssl->ssl, old_session);
+  if(conn->ssl_config.sessionid) {
-    if(ret) {
+    void *old_session = NULL;
-      Curl_ssl_sessionid_unlock(conn);
+
-      failf(data, "mbedtls_ssl_set_session returned -0x%x", -ret);
+    Curl_ssl_sessionid_lock(conn);
-      return CURLE_SSL_CONNECT_ERROR;
+    if(!Curl_ssl_getsessionid(conn, &old_session, NULL)) {
+      ret = mbedtls_ssl_set_session(&connssl->ssl, old_session);
+      if(ret) {
+        Curl_ssl_sessionid_unlock(conn);
+        failf(data, "mbedtls_ssl_set_session returned -0x%x", -ret);
+        return CURLE_SSL_CONNECT_ERROR;
+      }
+      infof(data, "mbedTLS re-using session\n");
     }
-    infof(data, "mbedTLS re-using session\n");
+    Curl_ssl_sessionid_unlock(conn);
   }
-  Curl_ssl_sessionid_unlock(conn);
 
   mbedtls_ssl_conf_ca_chain(&connssl->config,
                             &connssl->cacert,
@@ -591,35 +596,38 @@ mbed_connect_step3(struct connectdata *conn,
   CURLcode retcode = CURLE_OK;
   struct ssl_connect_data *connssl = &conn->ssl[sockindex];
   struct SessionHandle *data = conn->data;
-  void *old_ssl_sessionid = NULL;
-  mbedtls_ssl_session *our_ssl_sessionid;
-  int ret;
 
   DEBUGASSERT(ssl_connect_3 == connssl->connecting_state);
 
-  our_ssl_sessionid = malloc(sizeof(mbedtls_ssl_session));
+  if(conn->ssl_config.sessionid) {
-  if(!our_ssl_sessionid)
+    int ret;
-    return CURLE_OUT_OF_MEMORY;
+    mbedtls_ssl_session *our_ssl_sessionid;
+    void *old_ssl_sessionid = NULL;
 
-  mbedtls_ssl_session_init(our_ssl_sessionid);
+    our_ssl_sessionid = malloc(sizeof(mbedtls_ssl_session));
+    if(!our_ssl_sessionid)
+      return CURLE_OUT_OF_MEMORY;
 
-  ret = mbedtls_ssl_get_session(&connssl->ssl, our_ssl_sessionid);
+    mbedtls_ssl_session_init(our_ssl_sessionid);
-  if(ret) {
-    failf(data, "mbedtls_ssl_get_session returned -0x%x", -ret);
-    return CURLE_SSL_CONNECT_ERROR;
-  }
 
-  /* If there's already a matching session in the cache, delete it */
+    ret = mbedtls_ssl_get_session(&connssl->ssl, our_ssl_sessionid);
-  Curl_ssl_sessionid_lock(conn);
+    if(ret) {
-  if(!Curl_ssl_getsessionid(conn, &old_ssl_sessionid, NULL))
+      failf(data, "mbedtls_ssl_get_session returned -0x%x", -ret);
-    Curl_ssl_delsessionid(conn, old_ssl_sessionid);
+      return CURLE_SSL_CONNECT_ERROR;
+    }
 
-  retcode = Curl_ssl_addsessionid(conn, our_ssl_sessionid, 0);
+    /* If there's already a matching session in the cache, delete it */
-  Curl_ssl_sessionid_unlock(conn);
+    Curl_ssl_sessionid_lock(conn);
-  if(retcode) {
+    if(!Curl_ssl_getsessionid(conn, &old_ssl_sessionid, NULL))
-    free(our_ssl_sessionid);
+      Curl_ssl_delsessionid(conn, old_ssl_sessionid);
-    failf(data, "failed to store ssl session");
+
-    return retcode;
+    retcode = Curl_ssl_addsessionid(conn, our_ssl_sessionid, 0);
+    Curl_ssl_sessionid_unlock(conn);
+    if(retcode) {
+      free(our_ssl_sessionid);
+      failf(data, "failed to store ssl session");
+      return retcode;
+    }
   }
 
   connssl->connecting_state = ssl_connect_done;

lib/vtls/openssl.c

@@ -1679,7 +1679,6 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
   char *ciphers;
   struct SessionHandle *data = conn->data;
   SSL_METHOD_QUAL SSL_METHOD *req_method = NULL;
-  void *ssl_sessionid = NULL;
   X509_LOOKUP *lookup = NULL;
   curl_socket_t sockfd = conn->sock[sockindex];
   struct ssl_connect_data *connssl = &conn->ssl[sockindex];
@@ -2095,19 +2094,23 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
 #endif
 
   /* Check if there's a cached ID we can/should use here! */
-  Curl_ssl_sessionid_lock(conn);
+  if(conn->ssl_config.sessionid) {
-  if(!Curl_ssl_getsessionid(conn, &ssl_sessionid, NULL)) {
+    void *ssl_sessionid = NULL;
-    /* we got a session id, use it! */
+
-    if(!SSL_set_session(connssl->handle, ssl_sessionid)) {
+    Curl_ssl_sessionid_lock(conn);
-      Curl_ssl_sessionid_unlock(conn);
+    if(!Curl_ssl_getsessionid(conn, &ssl_sessionid, NULL)) {
-      failf(data, "SSL: SSL_set_session failed: %s",
+      /* we got a session id, use it! */
-            ERR_error_string(ERR_get_error(), NULL));
+      if(!SSL_set_session(connssl->handle, ssl_sessionid)) {
-      return CURLE_SSL_CONNECT_ERROR;
+        Curl_ssl_sessionid_unlock(conn);
+        failf(data, "SSL: SSL_set_session failed: %s",
+              ERR_error_string(ERR_get_error(), NULL));
+        return CURLE_SSL_CONNECT_ERROR;
+      }
+      /* Informational message */
+      infof (data, "SSL re-using session ID\n");
     }
-    /* Informational message */
+    Curl_ssl_sessionid_unlock(conn);
-    infof (data, "SSL re-using session ID\n");
   }
-  Curl_ssl_sessionid_unlock(conn);
 
   /* pass the raw socket into the SSL layers */
   if(!SSL_set_fd(connssl->handle, (int)sockfd)) {
@@ -2823,47 +2826,50 @@ static CURLcode servercert(struct connectdata *conn,
 static CURLcode ossl_connect_step3(struct connectdata *conn, int sockindex)
 {
   CURLcode result = CURLE_OK;
-  void *old_ssl_sessionid = NULL;
   struct SessionHandle *data = conn->data;
   struct ssl_connect_data *connssl = &conn->ssl[sockindex];
-  bool incache;
-  SSL_SESSION *our_ssl_sessionid;
 
   DEBUGASSERT(ssl_connect_3 == connssl->connecting_state);
 
-  our_ssl_sessionid = SSL_get1_session(connssl->handle);
+  if(conn->ssl_config.sessionid) {
+    bool incache;
+    SSL_SESSION *our_ssl_sessionid;
+    void *old_ssl_sessionid = NULL;
 
-  /* SSL_get1_session() will increment the reference count and the session
+    our_ssl_sessionid = SSL_get1_session(connssl->handle);
-     will stay in memory until explicitly freed with SSL_SESSION_free(3),
-     regardless of its state. */
 
-  Curl_ssl_sessionid_lock(conn);
+    /* SSL_get1_session() will increment the reference count and the session
-  incache = !(Curl_ssl_getsessionid(conn, &old_ssl_sessionid, NULL));
+        will stay in memory until explicitly freed with SSL_SESSION_free(3),
-  if(incache) {
+        regardless of its state. */
-    if(old_ssl_sessionid != our_ssl_sessionid) {
+
-      infof(data, "old SSL session ID is stale, removing\n");
+    Curl_ssl_sessionid_lock(conn);
-      Curl_ssl_delsessionid(conn, old_ssl_sessionid);
+    incache = !(Curl_ssl_getsessionid(conn, &old_ssl_sessionid, NULL));
-      incache = FALSE;
+    if(incache) {
+      if(old_ssl_sessionid != our_ssl_sessionid) {
+        infof(data, "old SSL session ID is stale, removing\n");
+        Curl_ssl_delsessionid(conn, old_ssl_sessionid);
+        incache = FALSE;
+      }
     }
-  }
 
-  if(!incache) {
+    if(!incache) {
-    result = Curl_ssl_addsessionid(conn, our_ssl_sessionid,
+      result = Curl_ssl_addsessionid(conn, our_ssl_sessionid,
-                                   0 /* unknown size */);
+                                      0 /* unknown size */);
-    if(result) {
+      if(result) {
-      Curl_ssl_sessionid_unlock(conn);
+        Curl_ssl_sessionid_unlock(conn);
-      failf(data, "failed to store ssl session");
+        failf(data, "failed to store ssl session");
-      return result;
+        return result;
+      }
     }
+    else {
+      /* Session was incache, so refcount already incremented earlier.
+        * Avoid further increments with each SSL_get1_session() call.
+        * This does not free the session as refcount remains > 0
+        */
+      SSL_SESSION_free(our_ssl_sessionid);
+    }
+    Curl_ssl_sessionid_unlock(conn);
   }
-  else {
-    /* Session was incache, so refcount already incremented earlier.
-     * Avoid further increments with each SSL_get1_session() call.
-     * This does not free the session as refcount remains > 0
-     */
-    SSL_SESSION_free(our_ssl_sessionid);
-  }
-  Curl_ssl_sessionid_unlock(conn);
 
   /*
    * We check certificates to authenticate the server; otherwise we risk

lib/vtls/polarssl.c

@@ -150,7 +150,6 @@ polarssl_connect_step1(struct connectdata *conn,
 #else
   struct in_addr addr;
 #endif
-  void *old_session = NULL;
   char errorbuf[128];
   errorbuf[0]=0;
 
@@ -337,15 +336,21 @@ polarssl_connect_step1(struct connectdata *conn,
               net_send, &conn->sock[sockindex]);
 
   ssl_set_ciphersuites(&connssl->ssl, ssl_list_ciphersuites());
-  Curl_ssl_sessionid_lock(conn);
+
-  if(!Curl_ssl_getsessionid(conn, &old_session, NULL)) {
+  /* Check if there's a cached ID we can/should use here! */
-    ret = ssl_set_session(&connssl->ssl, old_session);
+  if(conn->ssl_config.sessionid) {
-    Curl_ssl_sessionid_unlock(conn);
+    void *old_session = NULL;
-    if(ret) {
+
-      failf(data, "ssl_set_session returned -0x%x", -ret);
+    Curl_ssl_sessionid_lock(conn);
-      return CURLE_SSL_CONNECT_ERROR;
+    if(!Curl_ssl_getsessionid(conn, &old_session, NULL)) {
+      ret = ssl_set_session(&connssl->ssl, old_session);
+      Curl_ssl_sessionid_unlock(conn);
+      if(ret) {
+        failf(data, "ssl_set_session returned -0x%x", -ret);
+        return CURLE_SSL_CONNECT_ERROR;
+      }
+      infof(data, "PolarSSL re-using session\n");
     }
-    infof(data, "PolarSSL re-using session\n");
   }
 
   ssl_set_ca_chain(&connssl->ssl,
@@ -555,35 +560,38 @@ polarssl_connect_step3(struct connectdata *conn,
   CURLcode retcode = CURLE_OK;
   struct ssl_connect_data *connssl = &conn->ssl[sockindex];
   struct SessionHandle *data = conn->data;
-  void *old_ssl_sessionid = NULL;
-  ssl_session *our_ssl_sessionid;
-  int ret;
 
   DEBUGASSERT(ssl_connect_3 == connssl->connecting_state);
 
-  our_ssl_sessionid = malloc(sizeof(ssl_session));
+  if(conn->ssl_config.sessionid) {
-  if(!our_ssl_sessionid)
+    int ret;
-    return CURLE_OUT_OF_MEMORY;
+    ssl_session *our_ssl_sessionid;
+    void *old_ssl_sessionid = NULL;
 
-  ssl_session_init(our_ssl_sessionid);
+    our_ssl_sessionid = malloc(sizeof(ssl_session));
+    if(!our_ssl_sessionid)
+      return CURLE_OUT_OF_MEMORY;
 
-  ret = ssl_get_session(&connssl->ssl, our_ssl_sessionid);
+    ssl_session_init(our_ssl_sessionid);
-  if(ret) {
-    failf(data, "ssl_get_session returned -0x%x", -ret);
-    return CURLE_SSL_CONNECT_ERROR;
-  }
 
-  /* If there's already a matching session in the cache, delete it */
+    ret = ssl_get_session(&connssl->ssl, our_ssl_sessionid);
-  Curl_ssl_sessionid_lock(conn);
+    if(ret) {
-  if(!Curl_ssl_getsessionid(conn, &old_ssl_sessionid, NULL))
+      failf(data, "ssl_get_session returned -0x%x", -ret);
-    Curl_ssl_delsessionid(conn, old_ssl_sessionid);
+      return CURLE_SSL_CONNECT_ERROR;
+    }
 
-  retcode = Curl_ssl_addsessionid(conn, our_ssl_sessionid, 0);
+    /* If there's already a matching session in the cache, delete it */
-  Curl_ssl_sessionid_unlock(conn);
+    Curl_ssl_sessionid_lock(conn);
-  if(retcode) {
+    if(!Curl_ssl_getsessionid(conn, &old_ssl_sessionid, NULL))
-    free(our_ssl_sessionid);
+      Curl_ssl_delsessionid(conn, old_ssl_sessionid);
-    failf(data, "failed to store ssl session");
+
-    return retcode;
+    retcode = Curl_ssl_addsessionid(conn, our_ssl_sessionid, 0);
+    Curl_ssl_sessionid_unlock(conn);
+    if(retcode) {
+      free(our_ssl_sessionid);
+      failf(data, "failed to store ssl session");
+      return retcode;
+    }
   }
 
   connssl->connecting_state = ssl_connect_done;

lib/vtls/schannel.c

@@ -127,22 +127,24 @@ schannel_connect_step1(struct connectdata *conn, int sockindex)
   infof(data, "schannel: SSL/TLS connection with %s port %hu (step 1/3)\n",
         conn->host.name, conn->remote_port);
 
+  connssl->cred = NULL;
+
   /* check for an existing re-usable credential handle */
-  Curl_ssl_sessionid_lock(conn);
+  if(conn->ssl_config.sessionid) {
-  if(!Curl_ssl_getsessionid(conn, (void **)&old_cred, NULL)) {
+    Curl_ssl_sessionid_lock(conn);
-    connssl->cred = old_cred;
+    if(!Curl_ssl_getsessionid(conn, (void **)&old_cred, NULL)) {
-    infof(data, "schannel: re-using existing credential handle\n");
+      connssl->cred = old_cred;
-
+      infof(data, "schannel: re-using existing credential handle\n");
-    /* increment the reference counter of the credential/session handle */
-    connssl->cred->refcount++;
-    infof(data, "schannel: incremented credential handle refcount = %d\n",
-          connssl->cred->refcount);
 
+      /* increment the reference counter of the credential/session handle */
+      connssl->cred->refcount++;
+      infof(data, "schannel: incremented credential handle refcount = %d\n",
+            connssl->cred->refcount);
+    }
     Curl_ssl_sessionid_unlock(conn);
   }
-  else {
-    Curl_ssl_sessionid_unlock(conn);
 
+  if(!connssl->cred) {
     /* setup Schannel API options */
     memset(&schannel_cred, 0, sizeof(schannel_cred));
     schannel_cred.dwVersion = SCHANNEL_CRED_VERSION;
@@ -619,13 +621,11 @@ schannel_connect_step3(struct connectdata *conn, int sockindex)
   CURLcode result = CURLE_OK;
   struct SessionHandle *data = conn->data;
   struct ssl_connect_data *connssl = &conn->ssl[sockindex];
-  struct curl_schannel_cred *old_cred = NULL;
   SECURITY_STATUS sspi_status = SEC_E_OK;
   CERT_CONTEXT *ccert_context = NULL;
 #ifdef HAS_ALPN
   SecPkgContext_ApplicationProtocol alpn_result;
 #endif
-  bool incache;
 
   DEBUGASSERT(ssl_connect_3 == connssl->connecting_state);
 
@@ -689,32 +689,36 @@ schannel_connect_step3(struct connectdata *conn, int sockindex)
 #endif
 
   /* save the current session data for possible re-use */
-  Curl_ssl_sessionid_lock(conn);
+  if(conn->ssl_config.sessionid) {
-  incache = !(Curl_ssl_getsessionid(conn, (void **)&old_cred, NULL));
+    bool incache;
-  if(incache) {
+    struct curl_schannel_cred *old_cred = NULL;
-    if(old_cred != connssl->cred) {
-      infof(data, "schannel: old credential handle is stale, removing\n");
-      /* we're not taking old_cred ownership here, no refcount++ is needed */
-      Curl_ssl_delsessionid(conn, (void *)old_cred);
-      incache = FALSE;
-    }
-  }
 
-  if(!incache) {
+    Curl_ssl_sessionid_lock(conn);
-    result = Curl_ssl_addsessionid(conn, (void *)connssl->cred,
+    incache = !(Curl_ssl_getsessionid(conn, (void **)&old_cred, NULL));
-                                   sizeof(struct curl_schannel_cred));
+    if(incache) {
-    if(result) {
+      if(old_cred != connssl->cred) {
-      Curl_ssl_sessionid_unlock(conn);
+        infof(data, "schannel: old credential handle is stale, removing\n");
-      failf(data, "schannel: failed to store credential handle");
+        /* we're not taking old_cred ownership here, no refcount++ is needed */
-      return result;
+        Curl_ssl_delsessionid(conn, (void *)old_cred);
+        incache = FALSE;
+      }
     }
-    else {
+    if(!incache) {
-      /* this cred session is now also referenced by sessionid cache */
+      result = Curl_ssl_addsessionid(conn, (void *)connssl->cred,
-      connssl->cred->refcount++;
+                                     sizeof(struct curl_schannel_cred));
-      infof(data, "schannel: stored credential handle in session cache\n");
+      if(result) {
+        Curl_ssl_sessionid_unlock(conn);
+        failf(data, "schannel: failed to store credential handle");
+        return result;
+      }
+      else {
+        /* this cred session is now also referenced by sessionid cache */
+        connssl->cred->refcount++;
+        infof(data, "schannel: stored credential handle in session cache\n");
+      }
     }
+    Curl_ssl_sessionid_unlock(conn);
   }
-  Curl_ssl_sessionid_unlock(conn);
 
   if(data->set.ssl.certinfo) {
     sspi_status = s_pSecFn->QueryContextAttributes(&connssl->ctxt->ctxt_handle,

lib/vtls/vtls.c

@@ -364,6 +364,8 @@ bool Curl_ssl_getsessionid(struct connectdata *conn,
 
   *ssl_sessionid = NULL;
 
+  DEBUGASSERT(conn->ssl_config.sessionid);
+
   if(!conn->ssl_config.sessionid)
     /* session ID re-use is disabled */
     return TRUE;
@@ -460,9 +462,7 @@ CURLcode Curl_ssl_addsessionid(struct connectdata *conn,
   int conn_to_port;
   long *general_age;
 
-  /* Even though session ID re-use might be disabled, that only disables USING
+  DEBUGASSERT(conn->ssl_config.sessionid);
-     IT. We still store it here in case the re-using is again enabled for an
-     upcoming transfer */
 
   clone_host = strdup(conn->host.name);
   if(!clone_host)