connection: never reuse CONNECT_ONLY conections

and make CONNECT_ONLY conections never reuse any existing ones either.

Reported-by: Pavel Löbl
Bug: https://curl.haxx.se/mail/lib-2019-02/0064.html
Closes #3586

docs/libcurl/opts/CURLOPT_CONNECT_ONLY.3

@@ -5,7 +5,7 @@
 .\" *                            | (__| |_| |  _ <| |___
 .\" *                             \___|\___/|_| \_\_____|
 .\" *
-.\" * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
 .\" *
 .\" * This software is licensed as described in the file COPYING, which
 .\" * you should have received as part of this distribution. The terms
@@ -37,6 +37,9 @@ useful when used with the \fICURLINFO_ACTIVESOCKET(3)\fP option to
 \fIcurl_easy_getinfo(3)\fP as the library can set up the connection and then
 the application can obtain the most recently used socket for special data
 transfers.
+
+Transfers marked connect only will not reuse any existing connections and
+connections marked connect only will not be allowed to get reused.
 .SH DEFAULT
 0
 .SH PROTOCOLS

lib/url.c

@@ -1133,6 +1133,10 @@ ConnectionExists(struct Curl_easy *data,
       check = curr->ptr;
       curr = curr->next;
 
+      if(check->bits.connect_only)
+        /* connect-only connections will not be reused */
+        continue;
+
       if(extract_if_dead(check, data)) {
         /* disconnect it */
         (void)Curl_disconnect(data, check, /* dead_connection */TRUE);
@@ -1893,8 +1897,8 @@ static struct connectdata *allocate_conn(struct Curl_easy *data)
     data->set.proxy_ssl.primary.verifystatus;
   conn->proxy_ssl_config.verifypeer = data->set.proxy_ssl.primary.verifypeer;
   conn->proxy_ssl_config.verifyhost = data->set.proxy_ssl.primary.verifyhost;
-
   conn->ip_version = data->set.ipver;
+  conn->bits.connect_only = data->set.connect_only;
 
 #if !defined(CURL_DISABLE_HTTP) && defined(USE_NTLM) && \
     defined(NTLM_WB_ENABLED)
@@ -3871,8 +3875,9 @@ static CURLcode create_conn(struct Curl_easy *data,
   /* reuse_fresh is TRUE if we are told to use a new connection by force, but
      we only acknowledge this option if this is not a re-used connection
      already (which happens due to follow-location or during a HTTP
-     authentication phase). */
+     authentication phase). CONNECT_ONLY transfers also refuse reuse. */
-  if(data->set.reuse_fresh && !data->state.this_is_a_follow)
+  if((data->set.reuse_fresh && !data->state.this_is_a_follow) ||
+     data->set.connect_only)
     reuse = FALSE;
   else
     reuse = ConnectionExists(data, conn, &conn_temp, &force_reuse, &waitpipe);

lib/urldata.h

@@ -452,6 +452,7 @@ struct ConnectBits {
   bool proxy_ssl_connected[2]; /* TRUE when SSL initialization for HTTPS proxy
                                   is complete */
   bool socksproxy_connecting; /* connecting through a socks proxy */
+  bool connect_only;
 };
 
 struct hostname {

tests/data/test597

@@ -31,7 +31,6 @@ ftp://%HOSTIP:%FTPPORT
 USER anonymous
 PASS ftp@example.com
 PWD
-QUIT
 </protocol>
 </verify>
 </testcase>

tests/libtest/lib597.c

@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -32,20 +32,12 @@
 /*
  * Test case for below scenario:
  *   - Connect to an FTP server using CONNECT_ONLY option
- *   - transfer some files with re-using the connection (omitted in test case)
- *   - Disconnect from FTP server with sending QUIT command
  *
  * The test case originated for verifying CONNECT_ONLY option shall not
  * block after protocol connect is done, but it returns the message
  * with function curl_multi_info_read().
  */
 
-enum {
-  CONNECT_ONLY_PHASE = 0,
-  QUIT_PHASE,
-  LAST_PHASE
-};
-
 int test(char *URL)
 {
   CURL *easy = NULL;
@@ -53,7 +45,6 @@ int test(char *URL)
   int res = 0;
   int running;
   int msgs_left;
-  int phase;
   CURLMsg *msg;
 
   start_test_timing();
@@ -64,24 +55,14 @@ int test(char *URL)
 
   multi_init(multi);
 
-  for(phase = CONNECT_ONLY_PHASE; phase < LAST_PHASE; ++phase) {
   /* go verbose */
   easy_setopt(easy, CURLOPT_VERBOSE, 1L);
 
   /* specify target */
   easy_setopt(easy, CURLOPT_URL, URL);
 
-    /* enable 'CONNECT_ONLY' option when in connect phase */
-    if(phase == CONNECT_ONLY_PHASE)
   easy_setopt(easy, CURLOPT_CONNECT_ONLY, 1L);
 
-    /* enable 'NOBODY' option to send 'QUIT' command in quit phase */
-    if(phase == QUIT_PHASE) {
-      easy_setopt(easy, CURLOPT_CONNECT_ONLY, 0L);
-      easy_setopt(easy, CURLOPT_NOBODY, 1L);
-      easy_setopt(easy, CURLOPT_FORBID_REUSE, 1L);
-    }
-
   multi_add_handle(multi, easy);
 
   for(;;) {
@@ -132,7 +113,6 @@ int test(char *URL)
     res = msg->data.result;
 
   multi_remove_handle(multi, easy);
-  }
 
 test_cleanup: