Reorder need_bind in struct configuration_spec to save memory
[privoxy.git] / gateway.c
index 73c8a3a..135b217 100644 (file)
--- a/gateway.c
+++ b/gateway.c
@@ -1,14 +1,13 @@
-const char gateway_rcs[] = "$Id: gateway.c,v 1.46 2008/12/13 11:07:23 fabiankeil Exp $";
 /*********************************************************************
  *
  * File        :  $Source: /cvsroot/ijbswa/current/gateway.c,v $
  *
  * Purpose     :  Contains functions to connect to a server, possibly
  *                using a "forwarder" (i.e. HTTP proxy and/or a SOCKS4
- *                proxy).
+ *                or SOCKS5 proxy).
  *
- * Copyright   :  Written by and Copyright (C) 2001-2008 the SourceForge
- *                Privoxy team. http://www.privoxy.org/
+ * Copyright   :  Written by and Copyright (C) 2001-2020 the
+ *                Privoxy team. https://www.privoxy.org/
  *
  *                Based on the Internet Junkbuster originally written
  *                by and Copyright (C) 1997 Anonymous Coders and
@@ -32,209 +31,8 @@ const char gateway_rcs[] = "$Id: gateway.c,v 1.46 2008/12/13 11:07:23 fabiankeil
  *                or write to the Free Software Foundation, Inc., 59
  *                Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  *
- * Revisions   :
- *    $Log: gateway.c,v $
- *    Revision 1.46  2008/12/13 11:07:23  fabiankeil
- *    Remove duplicated debugging checks
- *    in connection_destination_matches().
- *
- *    Revision 1.45  2008/12/04 18:17:07  fabiankeil
- *    Fix some cparser warnings.
- *
- *    Revision 1.44  2008/11/22 11:54:04  fabiankeil
- *    Move log message around to include the socket number.
- *
- *    Revision 1.43  2008/11/13 09:15:51  fabiankeil
- *    Make keep_alive_timeout static.
- *
- *    Revision 1.42  2008/11/13 09:08:42  fabiankeil
- *    Add new config option: keep-alive-timeout.
- *
- *    Revision 1.41  2008/11/08 15:29:58  fabiankeil
- *    Unify two debug messages.
- *
- *    Revision 1.40  2008/11/08 15:14:05  fabiankeil
- *    Fix duplicated debugging check.
- *
- *    Revision 1.39  2008/10/25 11:33:01  fabiankeil
- *    Remove already out-commented line left over from debugging.
- *
- *    Revision 1.38  2008/10/24 17:33:00  fabiankeil
- *    - Tone the "keep-alive support is experimental" warning
- *      down a bit as hackish 0-chunk detection has been
- *      implemented recently.
- *    - Only show the "ndef HAVE_POLL" warning once on start-up.
- *
- *    Revision 1.37  2008/10/23 17:40:53  fabiankeil
- *    Fix forget_connection() and mark_connection_unused(),
- *    which would both under certain circumstances access
- *    reusable_connection[MAX_REUSABLE_CONNECTIONS]. Oops.
- *
- *    Revision 1.36  2008/10/18 19:49:15  fabiankeil
- *    - Factor close_unusable_connections() out of
- *      get_reusable_connection() to make sure we really check
- *      all the remembered connections, not just the ones before
- *      the next reusable one.
- *    - Plug two file descriptor leaks. Internally marking
- *      connections as closed doesn't cut it.
- *
- *    Revision 1.35  2008/10/17 17:12:01  fabiankeil
- *    In socket_is_still_usable(), use select()
- *    and FD_ISSET() if poll() isn't available.
- *
- *    Revision 1.34  2008/10/17 17:07:13  fabiankeil
- *    Add preliminary timeout support.
- *
- *    Revision 1.33  2008/10/16 16:34:21  fabiankeil
- *    Fix two gcc44 warnings.
- *
- *    Revision 1.32  2008/10/16 16:27:22  fabiankeil
- *    Fix compiler warning.
- *
- *    Revision 1.31  2008/10/16 07:31:11  fabiankeil
- *    - Factor socket_is_still_usable() out of get_reusable_connection().
- *    - If poll() isn't available, show a warning and assume the socket
- *      is still usable.
- *
- *    Revision 1.30  2008/10/13 17:31:03  fabiankeil
- *    If a remembered connection is no longer usable and
- *    has been marked closed, don't bother checking if the
- *    destination matches.
- *
- *    Revision 1.29  2008/10/11 16:59:41  fabiankeil
- *    Add missing dots for two log messages.
- *
- *    Revision 1.28  2008/10/09 18:21:41  fabiankeil
- *    Flush work-in-progress changes to keep outgoing connections
- *    alive where possible. Incomplete and mostly #ifdef'd out.
- *
- *    Revision 1.27  2008/09/27 15:05:51  fabiankeil
- *    Return only once in forwarded_connect().
- *
- *    Revision 1.26  2008/08/18 17:42:06  fabiankeil
- *    Fix typo in macro name.
- *
- *    Revision 1.25  2008/02/07 18:09:46  fabiankeil
- *    In socks5_connect:
- *    - make the buffers quite a bit smaller.
- *    - properly report "socks5 server unreachable" failures.
- *    - let strncpy() use the whole buffer. Using a length of 0xffu wasn't actually
- *      wrong, but requires too much thinking as it doesn't depend on the buffer size.
- *    - log a message if the socks5 server sends more data than expected.
- *    - add some assertions and comments.
- *
- *    Revision 1.24  2008/02/04 14:56:29  fabiankeil
- *    - Fix a compiler warning.
- *    - Stop assuming that htonl(INADDR_NONE) equals INADDR_NONE.
- *
- *    Revision 1.23  2008/02/04 13:11:35  fabiankeil
- *    Remember the cause of the SOCKS5 error for the CGI message.
- *
- *    Revision 1.22  2008/02/03 13:46:15  fabiankeil
- *    Add SOCKS5 support. Patch #1862863 by Eric M. Hopper with minor changes.
- *
- *    Revision 1.21  2007/07/28 12:30:03  fabiankeil
- *    Modified patch from Song Weijia (#1762559) to
- *    fix socks requests on big-endian platforms.
- *
- *    Revision 1.20  2007/05/14 10:23:48  fabiankeil
- *    - Use strlcpy() instead of strcpy().
- *    - Use the same buffer for socks requests and socks responses.
- *    - Fix bogus warning about web_server_addr being used uninitialized.
- *
- *    Revision 1.19  2007/01/25 14:09:45  fabiankeil
- *    - Save errors in socks4_connect() to csp->error_message.
- *    - Silence some gcc43 warnings, hopefully the right way.
- *
- *    Revision 1.18  2006/07/18 14:48:46  david__schmidt
- *    Reorganizing the repository: swapping out what was HEAD (the old 3.1 branch)
- *    with what was really the latest development (the v_3_0_branch branch)
- *
- *    Revision 1.16  2002/05/12 21:36:29  jongfoster
- *    Correcting function comments
- *
- *    Revision 1.15  2002/03/26 22:29:54  swa
- *    we have a new homepage!
- *
- *    Revision 1.14  2002/03/24 13:25:43  swa
- *    name change related issues
- *
- *    Revision 1.13  2002/03/13 00:29:59  jongfoster
- *    Killing warnings
- *
- *    Revision 1.12  2002/03/09 20:03:52  jongfoster
- *    - Making various functions return int rather than size_t.
- *      (Undoing a recent change).  Since size_t is unsigned on
- *      Windows, functions like read_socket that return -1 on
- *      error cannot return a size_t.
- *
- *      THIS WAS A MAJOR BUG - it caused frequent, unpredictable
- *      crashes, and also frequently caused JB to jump to 100%
- *      CPU and stay there.  (Because it thought it had just
- *      read ((unsigned)-1) == 4Gb of data...)
- *
- *    - The signature of write_socket has changed, it now simply
- *      returns success=0/failure=nonzero.
- *
- *    - Trying to get rid of a few warnings --with-debug on
- *      Windows, I've introduced a new type "jb_socket".  This is
- *      used for the socket file descriptors.  On Windows, this
- *      is SOCKET (a typedef for unsigned).  Everywhere else, it's
- *      an int.  The error value can't be -1 any more, so it's
- *      now JB_INVALID_SOCKET (which is -1 on UNIX, and in
- *      Windows it maps to the #define INVALID_SOCKET.)
- *
- *    - The signature of bind_port has changed.
- *
- *    Revision 1.11  2002/03/08 17:46:04  jongfoster
- *    Fixing int/size_t warnings
- *
- *    Revision 1.10  2002/03/07 03:50:19  oes
- *     - Improved handling of failed DNS lookups
- *     - Fixed compiler warnings
- *
- *    Revision 1.9  2001/10/25 03:40:48  david__schmidt
- *    Change in porting tactics: OS/2's EMX porting layer doesn't allow multiple
- *    threads to call select() simultaneously.  So, it's time to do a real, live,
- *    native OS/2 port.  See defines for __EMX__ (the porting layer) vs. __OS2__
- *    (native). Both versions will work, but using __OS2__ offers multi-threading.
- *
- *    Revision 1.8  2001/09/13 20:10:12  jongfoster
- *    Fixing missing #include under Windows
- *
- *    Revision 1.7  2001/09/12 17:58:26  steudten
- *
- *    add #include <string.h>
- *
- *    Revision 1.6  2001/09/10 10:41:16  oes
- *    Added #include in.h
- *
- *    Revision 1.5  2001/07/29 18:47:57  jongfoster
- *    Adding missing #include project.h
- *
- *    Revision 1.4  2001/07/24 12:47:06  oes
- *    Applied BeOS support update by Eugenia
- *
- *    Revision 1.3  2001/06/09 10:55:28  jongfoster
- *    Changing BUFSIZ ==> BUFFER_SIZE
- *
- *    Revision 1.2  2001/06/07 23:11:38  jongfoster
- *    Removing gateways[] list - no longer used.
- *    Replacing function pointer in struct gateway with a directly
- *    called function forwarded_connect(), which can do the common
- *    task of deciding whether to connect to the web server or HTTP
- *    proxy.
- *    Replacing struct gateway with struct forward_spec
- *    Fixing bug with SOCKS4A and HTTP proxy server in combination.
- *    It was a bug which led to the connection being made to the web
- *    server rather than the HTTP proxy, and also a buffer overrun.
- *
- *    Revision 1.1.1.1  2001/05/15 13:58:54  oes
- *    Initial import of version 2.9.3 source tree
- *
- *
  *********************************************************************/
-\f
+
 
 #include "config.h"
 
@@ -257,19 +55,18 @@ const char gateway_rcs[] = "$Id: gateway.c,v 1.46 2008/12/13 11:07:23 fabiankeil
 #include <netdb.h>
 #endif /* def __BEOS__ */
 
-#ifdef __OS2__
-#include <utils.h>
-#endif /* def __OS2__ */
-
 #include "project.h"
 #include "jcc.h"
 #include "errlog.h"
 #include "jbsockets.h"
 #include "gateway.h"
 #include "miscutil.h"
+#include "list.h"
+#include "parsers.h"
+
 #ifdef FEATURE_CONNECTION_KEEP_ALIVE
 #ifdef HAVE_POLL
-#ifdef __GLIBC__ 
+#ifdef __GLIBC__
 #include <sys/poll.h>
 #else
 #include <poll.h>
@@ -277,10 +74,8 @@ const char gateway_rcs[] = "$Id: gateway.c,v 1.46 2008/12/13 11:07:23 fabiankeil
 #endif /* HAVE_POLL */
 #endif /* def FEATURE_CONNECTION_KEEP_ALIVE */
 
-const char gateway_h_rcs[] = GATEWAY_H_VERSION;
-
-static jb_socket socks4_connect(const struct forward_spec * fwd,
-                                const char * target_host,
+static jb_socket socks4_connect(const struct forward_spec *fwd,
+                                const char *target_host,
                                 int target_port,
                                 struct client_state *csp);
 
@@ -289,21 +84,24 @@ static jb_socket socks5_connect(const struct forward_spec *fwd,
                                 int target_port,
                                 struct client_state *csp);
 
+enum {
+   SOCKS4_REQUEST_GRANTED        =  90,
+   SOCKS4_REQUEST_REJECT         =  91,
+   SOCKS4_REQUEST_IDENT_FAILED   =  92,
+   SOCKS4_REQUEST_IDENT_CONFLICT =  93
+};
 
-#define SOCKS_REQUEST_GRANTED          90
-#define SOCKS_REQUEST_REJECT           91
-#define SOCKS_REQUEST_IDENT_FAILED     92
-#define SOCKS_REQUEST_IDENT_CONFLICT   93
-
-#define SOCKS5_REQUEST_GRANTED             0
-#define SOCKS5_REQUEST_FAILED              1
-#define SOCKS5_REQUEST_DENIED              2
-#define SOCKS5_REQUEST_NETWORK_UNREACHABLE 3
-#define SOCKS5_REQUEST_HOST_UNREACHABLE    4
-#define SOCKS5_REQUEST_CONNECTION_REFUSED  5
-#define SOCKS5_REQUEST_TTL_EXPIRED         6
-#define SOCKS5_REQUEST_PROTOCOL_ERROR      7
-#define SOCKS5_REQUEST_BAD_ADDRESS_TYPE    8
+enum {
+   SOCKS5_REQUEST_GRANTED             = 0,
+   SOCKS5_REQUEST_FAILED              = 1,
+   SOCKS5_REQUEST_DENIED              = 2,
+   SOCKS5_REQUEST_NETWORK_UNREACHABLE = 3,
+   SOCKS5_REQUEST_HOST_UNREACHABLE    = 4,
+   SOCKS5_REQUEST_CONNECTION_REFUSED  = 5,
+   SOCKS5_REQUEST_TTL_EXPIRED         = 6,
+   SOCKS5_REQUEST_PROTOCOL_ERROR      = 7,
+   SOCKS5_REQUEST_BAD_ADDRESS_TYPE    = 8
+};
 
 /* structure of a socks client operation */
 struct socks_op {
@@ -326,32 +124,15 @@ struct socks_reply {
 
 static const char socks_userid[] = "anonymous";
 
-#ifdef FEATURE_CONNECTION_KEEP_ALIVE
+#ifdef FEATURE_CONNECTION_SHARING
+#ifndef FEATURE_CONNECTION_KEEP_ALIVE
+#error Using FEATURE_CONNECTION_SHARING without FEATURE_CONNECTION_KEEP_ALIVE is impossible
+#endif
 
 #define MAX_REUSABLE_CONNECTIONS 100
-static int keep_alive_timeout = DEFAULT_KEEP_ALIVE_TIMEOUT;
-
-struct reusable_connection
-{
-   jb_socket sfd;
-   int       in_use;
-   char      *host;
-   int       port;
-   time_t    timestamp;
-
-   int       forwarder_type;
-   char      *gateway_host;
-   int       gateway_port;
-   char      *forward_host;
-   int       forward_port;
-};
 
 static struct reusable_connection reusable_connection[MAX_REUSABLE_CONNECTIONS];
-
-static int mark_connection_unused(jb_socket sfd);
-static void mark_connection_closed(struct reusable_connection *closed_connection);
-static int socket_is_still_usable(jb_socket sfd);
-
+static int mark_connection_unused(const struct reusable_connection *connection);
 
 /*********************************************************************
  *
@@ -369,13 +150,12 @@ extern void initialize_reusable_connections(void)
 {
    unsigned int slot = 0;
 
+#if !defined(HAVE_POLL) && !defined(_WIN32)
    log_error(LOG_LEVEL_INFO,
-      "Support for 'Connection: keep-alive' is experimental."
-#ifndef HAVE_POLL
-      " Detecting already dead connections might not work"
-      " correctly on your platform."
-#endif /* ndef HAVE_POLL */
-   );
+      "Detecting already dead connections might not work "
+      "correctly on your platform. In case of problems, "
+      "unset the keep-alive-timeout option.");
+#endif
 
    for (slot = 0; slot < SZ(reusable_connection); slot++)
    {
@@ -390,25 +170,23 @@ extern void initialize_reusable_connections(void)
  *
  * Function    :  remember_connection
  *
- * Description :  Remembers a connection for reuse later on.
+ * Description :  Remembers a server connection for reuse later on.
  *
  * Parameters  :
- *          1  :  sfd  = Open socket to remember.
- *          2  :  http = The destination for the connection.
- *          3  :  fwd  = The forwarder settings used.
+ *          1  :  connection = The server connection to remember.
  *
  * Returns     : void
  *
  *********************************************************************/
-void remember_connection(jb_socket sfd, const struct http_request *http,
-                                        const struct forward_spec *fwd)
+void remember_connection(const struct reusable_connection *connection)
 {
    unsigned int slot = 0;
    int free_slot_found = FALSE;
 
-   assert(sfd != JB_INVALID_SOCKET);
+   assert(NULL != connection);
+   assert(connection->sfd != JB_INVALID_SOCKET);
 
-   if (mark_connection_unused(sfd))
+   if (mark_connection_unused(connection))
    {
       return;
    }
@@ -423,7 +201,7 @@ void remember_connection(jb_socket sfd, const struct http_request *http,
          assert(reusable_connection[slot].in_use == 0);
          log_error(LOG_LEVEL_CONNECT,
             "Remembering socket %d for %s:%d in slot %d.",
-            sfd, http->host, http->port, slot);
+            connection->sfd, connection->host, connection->port, slot);
          free_slot_found = TRUE;
          break;
       }
@@ -432,62 +210,73 @@ void remember_connection(jb_socket sfd, const struct http_request *http,
    if (!free_slot_found)
    {
       log_error(LOG_LEVEL_CONNECT,
-        "No free slots found to remembering socket for %s:%d. Last slot %d.",
-        http->host, http->port, slot);
+        "No free slots found to remember socket for %s:%d. Last slot %d.",
+        connection->host, connection->port, slot);
       privoxy_mutex_unlock(&connection_reuse_mutex);
-      close_socket(sfd);
+      close_socket(connection->sfd);
       return;
    }
 
-   assert(NULL != http->host);
-   reusable_connection[slot].host = strdup(http->host);
-   if (NULL == reusable_connection[slot].host)
-   {
-      log_error(LOG_LEVEL_FATAL, "Out of memory saving socket.");
-   }
-   reusable_connection[slot].sfd = sfd;
-   reusable_connection[slot].port = http->port;
+   assert(slot < SZ(reusable_connection));
+   assert(NULL != connection->host);
+   reusable_connection[slot].host = strdup_or_die(connection->host);
+   reusable_connection[slot].sfd = connection->sfd;
+   reusable_connection[slot].port = connection->port;
    reusable_connection[slot].in_use = 0;
-   reusable_connection[slot].timestamp = time(NULL);
+   reusable_connection[slot].timestamp = connection->timestamp;
+   reusable_connection[slot].request_sent = connection->request_sent;
+   reusable_connection[slot].response_received = connection->response_received;
+   reusable_connection[slot].keep_alive_timeout = connection->keep_alive_timeout;
+   reusable_connection[slot].requests_sent_total = connection->requests_sent_total;
 
-   assert(NULL != fwd);
    assert(reusable_connection[slot].gateway_host == NULL);
    assert(reusable_connection[slot].gateway_port == 0);
+   assert(reusable_connection[slot].auth_username == NULL);
+   assert(reusable_connection[slot].auth_password == NULL);
    assert(reusable_connection[slot].forwarder_type == SOCKS_NONE);
    assert(reusable_connection[slot].forward_host == NULL);
    assert(reusable_connection[slot].forward_port == 0);
 
-   reusable_connection[slot].forwarder_type = fwd->type;
-   if (NULL != fwd->gateway_host)
+   reusable_connection[slot].forwarder_type = connection->forwarder_type;
+   if (NULL != connection->gateway_host)
    {
-      reusable_connection[slot].gateway_host = strdup(fwd->gateway_host);
-      if (NULL == reusable_connection[slot].gateway_host)
-      {
-         log_error(LOG_LEVEL_FATAL, "Out of memory saving gateway_host.");
-      }
+      reusable_connection[slot].gateway_host = strdup_or_die(connection->gateway_host);
    }
    else
    {
       reusable_connection[slot].gateway_host = NULL;
    }
-   reusable_connection[slot].gateway_port = fwd->gateway_port;
+   reusable_connection[slot].gateway_port = connection->gateway_port;
+   if (NULL != connection->auth_username)
+   {
+      reusable_connection[slot].auth_username = strdup_or_die(connection->auth_username);
+   }
+   else
+   {
+      reusable_connection[slot].auth_username = NULL;
+   }
+   if (NULL != connection->auth_password)
+   {
+      reusable_connection[slot].auth_password = strdup_or_die(connection->auth_password);
+   }
+   else
+   {
+      reusable_connection[slot].auth_password = NULL;
+   }
 
-   if (NULL != fwd->forward_host)
+   if (NULL != connection->forward_host)
    {
-      reusable_connection[slot].forward_host = strdup(fwd->forward_host);
-      if (NULL == reusable_connection[slot].forward_host)
-      {
-         log_error(LOG_LEVEL_FATAL, "Out of memory saving forward_host.");
-      }
+      reusable_connection[slot].forward_host = strdup_or_die(connection->forward_host);
    }
    else
    {
       reusable_connection[slot].forward_host = NULL;
    }
-   reusable_connection[slot].forward_port = fwd->forward_port;
+   reusable_connection[slot].forward_port = connection->forward_port;
 
    privoxy_mutex_unlock(&connection_reuse_mutex);
 }
+#endif /* def FEATURE_CONNECTION_SHARING */
 
 
 /*********************************************************************
@@ -495,7 +284,6 @@ void remember_connection(jb_socket sfd, const struct http_request *http,
  * Function    :  mark_connection_closed
  *
  * Description : Marks a reused connection closed.
- *               Must be called with connection_reuse_mutex locked.
  *
  * Parameters  :
  *          1  :  closed_connection = The connection to mark as closed.
@@ -503,21 +291,28 @@ void remember_connection(jb_socket sfd, const struct http_request *http,
  * Returns     : void
  *
  *********************************************************************/
-static void mark_connection_closed(struct reusable_connection *closed_connection)
+void mark_connection_closed(struct reusable_connection *closed_connection)
 {
    closed_connection->in_use = FALSE;
    closed_connection->sfd = JB_INVALID_SOCKET;
    freez(closed_connection->host);
    closed_connection->port = 0;
    closed_connection->timestamp = 0;
+   closed_connection->request_sent = 0;
+   closed_connection->response_received = 0;
+   closed_connection->keep_alive_timeout = 0;
+   closed_connection->requests_sent_total = 0;
    closed_connection->forwarder_type = SOCKS_NONE;
    freez(closed_connection->gateway_host);
    closed_connection->gateway_port = 0;
+   freez(closed_connection->auth_username);
+   freez(closed_connection->auth_password);
    freez(closed_connection->forward_host);
    closed_connection->forward_port = 0;
 }
 
 
+#ifdef FEATURE_CONNECTION_SHARING
 /*********************************************************************
  *
  * Function    :  forget_connection
@@ -550,16 +345,70 @@ void forget_connection(jb_socket sfd)
             sfd, reusable_connection[slot].host,
             reusable_connection[slot].port, slot);
          mark_connection_closed(&reusable_connection[slot]);
-         privoxy_mutex_unlock(&connection_reuse_mutex);
-
-         return;
+         break;
       }
    }
 
-   log_error(LOG_LEVEL_CONNECT,
-      "Socket %d already forgotten or never remembered.", sfd);
-
    privoxy_mutex_unlock(&connection_reuse_mutex);
+
+}
+#endif /* def FEATURE_CONNECTION_SHARING */
+
+
+#ifdef FEATURE_CONNECTION_KEEP_ALIVE
+/*********************************************************************
+ *
+ * Function    :  string_or_none
+ *
+ * Description :  Returns a given string or "none" if a NULL pointer
+ *                is given.
+ *                Helper function for connection_destination_matches().
+ *
+ * Parameters  :
+ *          1  :  string = The string to check.
+ *
+ * Returns     :  The string if non-NULL, "none" otherwise.
+ *
+ *********************************************************************/
+static const char *string_or_none(const char *string)
+{
+   return(string != NULL ? string : "none");
+}
+
+
+/*********************************************************************
+ *
+ * Function    :  connection_detail_matches
+ *
+ * Description :  Helper function for connection_destination_matches().
+ *                Compares strings which can be NULL.
+ *
+ * Parameters  :
+ *          1  :  connection_detail = The connection detail to compare.
+ *          2  :  fowarder_detail = The forwarder detail to compare.
+ *
+ * Returns     :  TRUE for yes, FALSE otherwise.
+ *
+ *********************************************************************/
+static int connection_detail_matches(const char *connection_detail,
+                                     const char *forwarder_detail)
+{
+   if (connection_detail == NULL && forwarder_detail == NULL)
+   {
+      /* Both details are unset. */
+      return TRUE;
+   }
+
+   if ((connection_detail == NULL && forwarder_detail != NULL)
+    || (connection_detail != NULL && forwarder_detail == NULL))
+   {
+      /* Only one detail isn't set. */
+      return FALSE;
+   }
+
+   /* Both details are set, but do they match? */
+   return(!strcmpic(connection_detail, forwarder_detail));
+
 }
 
 
@@ -579,9 +428,9 @@ void forget_connection(jb_socket sfd)
  * Returns     :  TRUE for yes, FALSE otherwise.
  *
  *********************************************************************/
-static int connection_destination_matches(const struct reusable_connection *connection,
-                                          const struct http_request *http,
-                                          const struct forward_spec *fwd)
+int connection_destination_matches(const struct reusable_connection *connection,
+                                   const struct http_request *http,
+                                   const struct forward_spec *fwd)
 {
    if ((connection->forwarder_type != fwd->type)
     || (connection->gateway_port   != fwd->gateway_port)
@@ -591,29 +440,49 @@ static int connection_destination_matches(const struct reusable_connection *conn
       return FALSE;
    }
 
-   if ((    (NULL != connection->gateway_host)
-         && (NULL != fwd->gateway_host)
-         && strcmpic(connection->gateway_host, fwd->gateway_host))
-       && (connection->gateway_host != fwd->gateway_host))
+   if (!connection_detail_matches(connection->gateway_host, fwd->gateway_host))
+   {
+      log_error(LOG_LEVEL_CONNECT,
+         "Gateway mismatch. Previous gateway: %s. Current gateway: %s",
+         string_or_none(connection->gateway_host),
+         string_or_none(fwd->gateway_host));
+      return FALSE;
+   }
+
+   if (!connection_detail_matches(connection->auth_username, fwd->auth_username))
+   {
+      log_error(LOG_LEVEL_CONNECT, "Socks user name mismatch. "
+         "Previous user name: %s. Current user name: %s",
+         string_or_none(connection->auth_username),
+         string_or_none(fwd->auth_username));
+      return FALSE;
+   }
+
+   if (!connection_detail_matches(connection->auth_password, fwd->auth_password))
    {
-      log_error(LOG_LEVEL_CONNECT, "Gateway mismatch.");
+      log_error(LOG_LEVEL_CONNECT, "Socks user name mismatch. "
+         "Previous password: %s. Current password: %s",
+         string_or_none(connection->auth_password),
+         string_or_none(fwd->auth_password));
       return FALSE;
    }
 
-   if ((    (NULL != connection->forward_host)
-         && (NULL != fwd->forward_host)
-         && strcmpic(connection->forward_host, fwd->forward_host))
-      && (connection->forward_host != fwd->forward_host))
+   if (!connection_detail_matches(connection->forward_host, fwd->forward_host))
    {
-      log_error(LOG_LEVEL_CONNECT, "Forwarding proxy mismatch.");
+      log_error(LOG_LEVEL_CONNECT,
+         "Forwarding proxy mismatch. Previous proxy: %s. Current proxy: %s",
+         string_or_none(connection->forward_host),
+         string_or_none(fwd->forward_host));
       return FALSE;
    }
 
    return (!strcmpic(connection->host, http->host));
 
 }
+#endif /* def FEATURE_CONNECTION_KEEP_ALIVE */
 
 
+#ifdef FEATURE_CONNECTION_SHARING
 /*********************************************************************
  *
  * Function    :  close_unusable_connections
@@ -639,19 +508,23 @@ int close_unusable_connections(void)
          && (JB_INVALID_SOCKET != reusable_connection[slot].sfd))
       {
          time_t time_open = time(NULL) - reusable_connection[slot].timestamp;
+         time_t latency = (reusable_connection[slot].response_received -
+            reusable_connection[slot].request_sent) / 2;
 
-         if (keep_alive_timeout < time_open)
+         if (reusable_connection[slot].keep_alive_timeout < time_open + latency)
          {
             log_error(LOG_LEVEL_CONNECT,
                "The connection to %s:%d in slot %d timed out. "
-               "Closing socket %d. Timeout is: %d.",
+               "Closing socket %d. Timeout is: %d. Assumed latency: %ld.",
                reusable_connection[slot].host,
                reusable_connection[slot].port, slot,
-               reusable_connection[slot].sfd, keep_alive_timeout);
+               reusable_connection[slot].sfd,
+               reusable_connection[slot].keep_alive_timeout,
+               latency);
             close_socket(reusable_connection[slot].sfd);
             mark_connection_closed(&reusable_connection[slot]);
          }
-         else if (!socket_is_still_usable(reusable_connection[slot].sfd))
+         else if (!socket_is_still_alive(reusable_connection[slot].sfd))
          {
             log_error(LOG_LEVEL_CONNECT,
                "The connection to %s:%d in slot %d is no longer usable. "
@@ -675,66 +548,6 @@ int close_unusable_connections(void)
 }
 
 
-/*********************************************************************
- *
- * Function    :  socket_is_still_usable
- *
- * Description :  Decides whether or not an open socket is still usable.
- *
- * Parameters  :
- *          1  :  sfd = The socket to check.
- *
- * Returns     :  TRUE for yes, otherwise FALSE.
- *
- *********************************************************************/
-static int socket_is_still_usable(jb_socket sfd)
-{
-#ifdef HAVE_POLL
-   int poll_result;
-   struct pollfd poll_fd[1];
-
-   memset(poll_fd, 0, sizeof(poll_fd));
-   poll_fd[0].fd = sfd;
-   poll_fd[0].events = POLLIN;
-
-   poll_result = poll(poll_fd, 1, 0);
-
-   if (-1 != poll_result)
-   {
-      return !(poll_fd[0].revents & POLLIN);
-   }
-   else
-   {
-      log_error(LOG_LEVEL_CONNECT, "Polling socket %d failed.", sfd);
-      return FALSE;
-   }
-#else
-   fd_set readable_fds;
-   struct timeval timeout;
-   int ret;
-   int socket_is_alive = 0;
-
-   memset(&timeout, '\0', sizeof(timeout));
-   FD_ZERO(&readable_fds);
-   FD_SET(sfd, &readable_fds);
-
-   ret = select((int)sfd+1, &readable_fds, NULL, NULL, &timeout);
-   if (ret < 0)
-   {
-      log_error(LOG_LEVEL_ERROR, "select() failed!: %E");
-   }
-
-   /*
-    * XXX: I'm not sure why !FD_ISSET() works,
-    * but apparently it does.
-    */
-   socket_is_alive = !FD_ISSET(sfd, &readable_fds);
-
-   return socket_is_alive;
-#endif /* def HAVE_POLL */
-}
-
-
 /*********************************************************************
  *
  * Function    :  get_reusable_connection
@@ -770,8 +583,14 @@ static jb_socket get_reusable_connection(const struct http_request *http,
             reusable_connection[slot].in_use = TRUE;
             sfd = reusable_connection[slot].sfd;
             log_error(LOG_LEVEL_CONNECT,
-               "Found reusable socket %d for %s:%d in slot %d.",
-               sfd, reusable_connection[slot].host, reusable_connection[slot].port, slot);
+               "Found reusable socket %d for %s:%d in slot %d. Timestamp made %ld "
+               "seconds ago. Timeout: %d. Latency: %d. Requests served: %d",
+               sfd, reusable_connection[slot].host, reusable_connection[slot].port,
+               slot, time(NULL) - reusable_connection[slot].timestamp,
+               reusable_connection[slot].keep_alive_timeout,
+               (int)(reusable_connection[slot].response_received -
+               reusable_connection[slot].request_sent),
+               reusable_connection[slot].requests_sent_total);
             break;
          }
       }
@@ -791,33 +610,33 @@ static jb_socket get_reusable_connection(const struct http_request *http,
  * Description :  Gives a remembered connection free for reuse.
  *
  * Parameters  :
- *          1  :  sfd = The socket belonging to the connection in question.
+ *          1  :  connection = The connection in question.
  *
  * Returns     :  TRUE => Socket found and marked as unused.
  *                FALSE => Socket not found.
  *
  *********************************************************************/
-static int mark_connection_unused(jb_socket sfd)
+static int mark_connection_unused(const struct reusable_connection *connection)
 {
    unsigned int slot = 0;
    int socket_found = FALSE;
 
-   assert(sfd != JB_INVALID_SOCKET);
+   assert(connection->sfd != JB_INVALID_SOCKET);
 
    privoxy_mutex_lock(&connection_reuse_mutex);
 
    for (slot = 0; slot < SZ(reusable_connection); slot++)
    {
-      if (reusable_connection[slot].sfd == sfd)
+      if (reusable_connection[slot].sfd == connection->sfd)
       {
          assert(reusable_connection[slot].in_use);
          socket_found = TRUE;
          log_error(LOG_LEVEL_CONNECT,
             "Marking open socket %d for %s:%d in slot %d as unused.",
-            sfd, reusable_connection[slot].host,
+            connection->sfd, reusable_connection[slot].host,
             reusable_connection[slot].port, slot);
          reusable_connection[slot].in_use = 0;
-         reusable_connection[slot].timestamp = time(NULL);
+         reusable_connection[slot].timestamp = connection->timestamp;
          break;
       }
    }
@@ -827,26 +646,7 @@ static int mark_connection_unused(jb_socket sfd)
    return socket_found;
 
 }
-
-
-/*********************************************************************
- *
- * Function    :  set_keep_alive_timeout
- *
- * Description :  Sets the timeout after which open
- *                connections will no longer be reused.
- *
- * Parameters  :
- *          1  :  timeout = The timeout in seconds.
- *
- * Returns     :  void
- *
- *********************************************************************/
-void set_keep_alive_timeout(int timeout)
-{
-   keep_alive_timeout = timeout;
-}
-#endif /* def FEATURE_CONNECTION_KEEP_ALIVE */
+#endif /* def FEATURE_CONNECTION_SHARING */
 
 
 /*********************************************************************
@@ -864,21 +664,25 @@ void set_keep_alive_timeout(int timeout)
  * Returns     :  JB_INVALID_SOCKET => failure, else it is the socket file descriptor.
  *
  *********************************************************************/
-jb_socket forwarded_connect(const struct forward_spec * fwd,
+jb_socket forwarded_connect(const struct forward_spec *fwd,
                             struct http_request *http,
                             struct client_state *csp)
 {
-   const char * dest_host;
+   const char *dest_host;
    int dest_port;
    jb_socket sfd = JB_INVALID_SOCKET;
 
-#ifdef FEATURE_CONNECTION_KEEP_ALIVE
-   sfd = get_reusable_connection(http, fwd);
-   if (JB_INVALID_SOCKET != sfd)
+#ifdef FEATURE_CONNECTION_SHARING
+   if ((csp->config->feature_flags & RUNTIME_FEATURE_CONNECTION_SHARING)
+      && !(csp->flags & CSP_FLAG_SERVER_SOCKET_TAINTED))
    {
-      return sfd;
+      sfd = get_reusable_connection(http, fwd);
+      if (JB_INVALID_SOCKET != sfd)
+      {
+         return sfd;
+      }
    }
-#endif /* def FEATURE_CONNECTION_KEEP_ALIVE */
+#endif /* def FEATURE_CONNECTION_SHARING */
 
    /* Figure out if we need to connect to the web server or a HTTP proxy. */
    if (fwd->forward_host)
@@ -898,6 +702,7 @@ jb_socket forwarded_connect(const struct forward_spec * fwd,
    switch (fwd->type)
    {
       case SOCKS_NONE:
+      case FORWARD_WEBSERVER:
          sfd = connect_to(dest_host, dest_port, csp);
          break;
       case SOCKS_4:
@@ -905,12 +710,13 @@ jb_socket forwarded_connect(const struct forward_spec * fwd,
          sfd = socks4_connect(fwd, dest_host, dest_port, csp);
          break;
       case SOCKS_5:
+      case SOCKS_5T:
          sfd = socks5_connect(fwd, dest_host, dest_port, csp);
          break;
       default:
          /* Should never get here */
          log_error(LOG_LEVEL_FATAL,
-            "SOCKS4 impossible internal error - bad SOCKS type.");
+            "Internal error in forwarded_connect(). Bad proxy type: %d", fwd->type);
    }
 
    if (JB_INVALID_SOCKET != sfd)
@@ -925,6 +731,51 @@ jb_socket forwarded_connect(const struct forward_spec * fwd,
 }
 
 
+#ifdef FUZZ
+/*********************************************************************
+ *
+ * Function    :  socks_fuzz
+ *
+ * Description :  Wrapper around socks[45]_connect() used for fuzzing.
+ *
+ * Parameters  :
+ *          1  :  csp = Current client state (buffers, headers, etc...)
+ *
+ * Returns     :  JB_ERR_OK or JB_ERR_PARSE
+ *
+ *********************************************************************/
+extern jb_err socks_fuzz(struct client_state *csp)
+{
+   jb_socket socket;
+   static struct forward_spec fwd;
+   char target_host[] = "fuzz.example.org";
+   int target_port = 12345;
+
+   fwd.gateway_host = strdup_or_die("fuzz.example.org");
+   fwd.gateway_port = 12345;
+
+   fwd.type = SOCKS_4A;
+   socket = socks4_connect(&fwd, target_host, target_port, csp);
+
+   if (JB_INVALID_SOCKET != socket)
+   {
+      fwd.type = SOCKS_5;
+      socket = socks5_connect(&fwd, target_host, target_port, csp);
+   }
+
+   if (JB_INVALID_SOCKET == socket)
+   {
+      log_error(LOG_LEVEL_ERROR, "%s", csp->error_message);
+      return JB_ERR_PARSE;
+   }
+
+   log_error(LOG_LEVEL_INFO, "Input looks like an acceptable socks response");
+
+   return JB_ERR_OK;
+
+}
+#endif
+
 /*********************************************************************
  *
  * Function    :  socks4_connect
@@ -948,12 +799,12 @@ jb_socket forwarded_connect(const struct forward_spec * fwd,
  * Returns     :  JB_INVALID_SOCKET => failure, else a socket file descriptor.
  *
  *********************************************************************/
-static jb_socket socks4_connect(const struct forward_spec * fwd,
-                                const char * target_host,
+static jb_socket socks4_connect(const struct forward_spec *fwd,
+                                const char *target_host,
                                 int target_port,
                                 struct client_state *csp)
 {
-   unsigned int web_server_addr;
+   unsigned long web_server_addr;
    char buf[BUFFER_SIZE];
    struct socks_op    *c = (struct socks_op    *)buf;
    struct socks_reply *s = (struct socks_reply *)buf;
@@ -979,7 +830,7 @@ static jb_socket socks4_connect(const struct forward_spec * fwd,
    if (err)
    {
       log_error(LOG_LEVEL_CONNECT, "socks4_connect: %s", errstr);
-      csp->error_message = strdup(errstr); 
+      csp->error_message = strdup(errstr);
       errno = EINVAL;
       return(JB_INVALID_SOCKET);
    }
@@ -1048,24 +899,23 @@ static jb_socket socks4_connect(const struct forward_spec * fwd,
 
    c->vn          = 4;
    c->cd          = 1;
-   c->dstport[0]  = (unsigned char)((target_port       >> 8  ) & 0xff);
-   c->dstport[1]  = (unsigned char)((target_port             ) & 0xff);
-   c->dstip[0]    = (unsigned char)((web_server_addr   >> 24 ) & 0xff);
-   c->dstip[1]    = (unsigned char)((web_server_addr   >> 16 ) & 0xff);
-   c->dstip[2]    = (unsigned char)((web_server_addr   >>  8 ) & 0xff);
-   c->dstip[3]    = (unsigned char)((web_server_addr         ) & 0xff);
-
+   c->dstport[0]  = (unsigned char)((target_port       >> 8 ) & 0xff);
+   c->dstport[1]  = (unsigned char)((target_port            ) & 0xff);
+   c->dstip[0]    = (unsigned char)((web_server_addr   >> 24) & 0xff);
+   c->dstip[1]    = (unsigned char)((web_server_addr   >> 16) & 0xff);
+   c->dstip[2]    = (unsigned char)((web_server_addr   >>  8) & 0xff);
+   c->dstip[3]    = (unsigned char)((web_server_addr        ) & 0xff);
+
+#ifdef FUZZ
+   sfd = 0;
+#else
    /* pass the request to the socks server */
    sfd = connect_to(fwd->gateway_host, fwd->gateway_port, csp);
 
    if (sfd == JB_INVALID_SOCKET)
    {
-      /*
-       * XXX: connect_to should fill in the exact reason.
-       * Most likely resolving the IP of the forwarder failed.
-       */
-      errstr = "connect_to failed: see logfile for details";
-      err = 1;
+      /* The error an its reason have already been logged by connect_to()  */
+      return(JB_INVALID_SOCKET);
    }
    else if (write_socket(sfd, (char *)c, csiz))
    {
@@ -1074,7 +924,23 @@ static jb_socket socks4_connect(const struct forward_spec * fwd,
       err = 1;
       close_socket(sfd);
    }
-   else if (read_socket(sfd, buf, sizeof(buf)) != sizeof(*s))
+   else if (!data_is_available(sfd, csp->config->socket_timeout))
+   {
+      if (socket_is_still_alive(sfd))
+      {
+         errstr = "SOCKS4 negotiation timed out";
+      }
+      else
+      {
+         errstr = "SOCKS4 negotiation got aborted by the server";
+      }
+      log_error(LOG_LEVEL_CONNECT, "socks4_connect: %s", errstr);
+      err = 1;
+      close_socket(sfd);
+   }
+   else
+#endif
+       if (read_socket(sfd, buf, sizeof(buf)) != sizeof(*s))
    {
       errstr = "SOCKS4 negotiation read failed.";
       log_error(LOG_LEVEL_CONNECT, "socks4_connect: %s", errstr);
@@ -1084,24 +950,24 @@ static jb_socket socks4_connect(const struct forward_spec * fwd,
 
    if (err)
    {
-      csp->error_message = strdup(errstr);      
+      csp->error_message = strdup(errstr);
       return(JB_INVALID_SOCKET);
    }
 
    switch (s->cd)
    {
-      case SOCKS_REQUEST_GRANTED:
+      case SOCKS4_REQUEST_GRANTED:
          return(sfd);
-      case SOCKS_REQUEST_REJECT:
+      case SOCKS4_REQUEST_REJECT:
          errstr = "SOCKS request rejected or failed.";
          errno = EINVAL;
          break;
-      case SOCKS_REQUEST_IDENT_FAILED:
+      case SOCKS4_REQUEST_IDENT_FAILED:
          errstr = "SOCKS request rejected because "
             "SOCKS server cannot connect to identd on the client.";
          errno = EACCES;
          break;
-      case SOCKS_REQUEST_IDENT_CONFLICT:
+      case SOCKS4_REQUEST_IDENT_CONFLICT:
          errstr = "SOCKS request rejected because "
             "the client program and identd report "
             "different user-ids.";
@@ -1146,7 +1012,7 @@ static const char *translate_socks5_error(int socks_error)
       case SOCKS5_REQUEST_NETWORK_UNREACHABLE:
          return "SOCKS5 network unreachable";
       case SOCKS5_REQUEST_HOST_UNREACHABLE:
-         return "SOCKS5 host unreachable";
+         return "SOCKS5 destination host unreachable";
       case SOCKS5_REQUEST_CONNECTION_REFUSED:
          return "SOCKS5 connection refused";
       case SOCKS5_REQUEST_TTL_EXPIRED:
@@ -1162,6 +1028,7 @@ static const char *translate_socks5_error(int socks_error)
    }
 }
 
+
 /*********************************************************************
  *
  * Function    :  socks5_connect
@@ -1186,9 +1053,12 @@ static jb_socket socks5_connect(const struct forward_spec *fwd,
                                 int target_port,
                                 struct client_state *csp)
 {
+#define SIZE_SOCKS5_REPLY_IPV4 10
+#define SIZE_SOCKS5_REPLY_IPV6 22
+#define SOCKS5_REPLY_DIFFERENCE (SIZE_SOCKS5_REPLY_IPV6 - SIZE_SOCKS5_REPLY_IPV4)
    int err = 0;
    char cbuf[300];
-   char sbuf[30];
+   char sbuf[SIZE_SOCKS5_REPLY_IPV6];
    size_t client_pos = 0;
    int server_size = 0;
    size_t hostlen = 0;
@@ -1220,7 +1090,7 @@ static jb_socket socks5_connect(const struct forward_spec *fwd,
       err = 1;
    }
 
-   if (fwd->type != SOCKS_5)
+   if ((fwd->type != SOCKS_5) && (fwd->type != SOCKS_5T))
    {
       /* Should never get here */
       log_error(LOG_LEVEL_FATAL,
@@ -1237,6 +1107,10 @@ static jb_socket socks5_connect(const struct forward_spec *fwd,
       return(JB_INVALID_SOCKET);
    }
 
+#ifdef FUZZ
+   sfd = 0;
+   if (!err && read_socket(sfd, sbuf, 2) != 2)
+#else
    /* pass the request to the socks server */
    sfd = connect_to(fwd->gateway_host, fwd->gateway_port, csp);
 
@@ -1244,13 +1118,24 @@ static jb_socket socks5_connect(const struct forward_spec *fwd,
    {
       errstr = "socks5 server unreachable";
       log_error(LOG_LEVEL_CONNECT, "socks5_connect: %s", errstr);
+      /* Free the generic error message provided by connect_to() */
+      freez(csp->error_message);
       csp->error_message = strdup(errstr);
       return(JB_INVALID_SOCKET);
    }
 
    client_pos = 0;
    cbuf[client_pos++] = '\x05'; /* Version */
-   cbuf[client_pos++] = '\x01'; /* One authentication method supported */
+
+   if (fwd->auth_username && fwd->auth_password)
+   {
+      cbuf[client_pos++] = '\x02'; /* Two authentication methods supported */
+      cbuf[client_pos++] = '\x02'; /* Username/password */
+   }
+   else
+   {
+      cbuf[client_pos++] = '\x01'; /* One authentication method supported */
+   }
    cbuf[client_pos++] = '\x00'; /* The no authentication authentication method */
 
    if (write_socket(sfd, cbuf, client_pos))
@@ -1261,8 +1146,21 @@ static jb_socket socks5_connect(const struct forward_spec *fwd,
       close_socket(sfd);
       return(JB_INVALID_SOCKET);
    }
+   if (!data_is_available(sfd, csp->config->socket_timeout))
+   {
+      if (socket_is_still_alive(sfd))
+      {
+         errstr = "SOCKS5 negotiation timed out";
+      }
+      else
+      {
+         errstr = "SOCKS5 negotiation got aborted by the server";
+      }
+      err = 1;
+   }
 
-   if (read_socket(sfd, sbuf, sizeof(sbuf)) != 2)
+   if (!err && read_socket(sfd, sbuf, sizeof(sbuf)) != 2)
+#endif
    {
       errstr = "SOCKS5 negotiation read failed";
       err = 1;
@@ -1280,7 +1178,51 @@ static jb_socket socks5_connect(const struct forward_spec *fwd,
       err = 1;
    }
 
-   if (!err && (sbuf[1] != '\x00'))
+   if (!err && (sbuf[1] == '\x02'))
+   {
+      /* check cbuf overflow */
+      size_t auth_len = strlen(fwd->auth_username) + strlen(fwd->auth_password) + 3;
+      if (auth_len > sizeof(cbuf))
+      {
+         errstr = "SOCKS5 username and/or password too long";
+         err = 1;
+      }
+
+      if (!err)
+      {
+         client_pos = 0;
+         cbuf[client_pos++] = '\x01'; /* Version */
+         cbuf[client_pos++] = (char)strlen(fwd->auth_username);
+
+         memcpy(cbuf + client_pos, fwd->auth_username, strlen(fwd->auth_username));
+         client_pos += strlen(fwd->auth_username);
+         cbuf[client_pos++] = (char)strlen(fwd->auth_password);
+         memcpy(cbuf + client_pos, fwd->auth_password, strlen(fwd->auth_password));
+         client_pos += strlen(fwd->auth_password);
+
+         if (write_socket(sfd, cbuf, client_pos))
+         {
+            errstr = "SOCKS5 negotiation auth write failed";
+            csp->error_message = strdup(errstr);
+            log_error(LOG_LEVEL_CONNECT, "%s", errstr);
+            close_socket(sfd);
+            return(JB_INVALID_SOCKET);
+         }
+
+         if (read_socket(sfd, sbuf, sizeof(sbuf)) != 2)
+         {
+            errstr = "SOCKS5 negotiation auth read failed";
+            err = 1;
+         }
+      }
+
+      if (!err && (sbuf[1] != '\x00'))
+      {
+         errstr = "SOCKS5 authentication failed";
+         err = 1;
+      }
+   }
+   else if (!err && (sbuf[1] != '\x00'))
    {
       errstr = "SOCKS5 negotiation protocol error";
       err = 1;
@@ -1304,14 +1246,15 @@ static jb_socket socks5_connect(const struct forward_spec *fwd,
    cbuf[client_pos++] = (char)(hostlen & 0xffu);
    assert(sizeof(cbuf) - client_pos > (size_t)255);
    /* Using strncpy because we really want the nul byte padding. */
-   strncpy(cbuf + client_pos, target_host, sizeof(cbuf) - client_pos);
+   strncpy(cbuf + client_pos, target_host, sizeof(cbuf) - client_pos - 1);
    client_pos += (hostlen & 0xffu);
    cbuf[client_pos++] = (char)((target_port >> 8) & 0xff);
    cbuf[client_pos++] = (char)((target_port     ) & 0xff);
 
+#ifndef FUZZ
    if (write_socket(sfd, cbuf, client_pos))
    {
-      errstr = "SOCKS5 negotiation read failed";
+      errstr = "SOCKS5 negotiation write failed";
       csp->error_message = strdup(errstr);
       log_error(LOG_LEVEL_CONNECT, "%s", errstr);
       close_socket(sfd);
@@ -1319,40 +1262,102 @@ static jb_socket socks5_connect(const struct forward_spec *fwd,
       return(JB_INVALID_SOCKET);
    }
 
-   server_size = read_socket(sfd, sbuf, sizeof(sbuf));
-   if (server_size < 3)
-   {
-      errstr = "SOCKS5 negotiation read failed";
-      err = 1;
-   }
-   else if (server_size > 20)
+   /*
+    * Optimistically send the HTTP request with the initial
+    * SOCKS request if the user enabled the use of Tor extensions,
+    * the CONNECT method isn't being used (in which case the client
+    * doesn't send data until it gets our 200 response) and the
+    * client request has actually been completely read already.
+    */
+   if ((fwd->type == SOCKS_5T) && (csp->http->ssl == 0)
+      && (csp->flags & CSP_FLAG_CLIENT_REQUEST_COMPLETELY_READ))
    {
-      /* This is somewhat unexpected but doesn't realy matter. */
-      log_error(LOG_LEVEL_CONNECT, "socks5_connect: read %d bytes "
-         "from socks server. Would have accepted up to %d.",
-         server_size, sizeof(sbuf));
-   }
+      char *client_headers = list_to_text(csp->headers);
+      size_t header_length;
 
-   if (!err && (sbuf[0] != '\x05'))
-   {
-      errstr = "SOCKS5 negotiation protocol version error";
-      err = 1;
+      if (client_headers == NULL)
+      {
+         log_error(LOG_LEVEL_FATAL, "Out of memory rebuilding client headers");
+      }
+      list_remove_all(csp->headers);
+      header_length= strlen(client_headers);
+
+      log_error(LOG_LEVEL_CONNECT,
+         "Optimistically sending %lu bytes of client headers intended for %s",
+         header_length, csp->http->hostport);
+
+      if (write_socket(sfd, client_headers, header_length))
+      {
+         log_error(LOG_LEVEL_CONNECT,
+            "optimistically writing header to: %s failed: %E", csp->http->hostport);
+         freez(client_headers);
+         return(JB_INVALID_SOCKET);
+      }
+      freez(client_headers);
+      if (csp->expected_client_content_length != 0)
+      {
+         unsigned long long buffered_request_bytes =
+            (unsigned long long)(csp->client_iob->eod - csp->client_iob->cur);
+         log_error(LOG_LEVEL_CONNECT,
+            "Optimistically sending %llu bytes of client body. Expected %llu",
+            csp->expected_client_content_length, buffered_request_bytes);
+         assert(csp->expected_client_content_length == buffered_request_bytes);
+         if (write_socket(sfd, csp->client_iob->cur, buffered_request_bytes))
+         {
+            log_error(LOG_LEVEL_CONNECT,
+               "optimistically writing %llu bytes of client body to: %s failed: %E",
+               buffered_request_bytes, csp->http->hostport);
+            return(JB_INVALID_SOCKET);
+         }
+         clear_iob(csp->client_iob);
+      }
    }
+#endif
 
-   if (!err && (sbuf[2] != '\x00'))
+   server_size = read_socket(sfd, sbuf, SIZE_SOCKS5_REPLY_IPV4);
+   if (server_size != SIZE_SOCKS5_REPLY_IPV4)
    {
-      errstr = "SOCKS5 negotiation protocol error";
-      err = 1;
+      errstr = "SOCKS5 negotiation read failed";
    }
-
-   if (!err)
+   else
    {
-      if (sbuf[1] == SOCKS5_REQUEST_GRANTED)
+      if (sbuf[0] != '\x05')
       {
-         return(sfd);
+         errstr = "SOCKS5 negotiation protocol version error";
+      }
+      else if (sbuf[2] != '\x00')
+      {
+         errstr = "SOCKS5 negotiation protocol error";
+      }
+      else if (sbuf[1] != SOCKS5_REQUEST_GRANTED)
+      {
+         errstr = translate_socks5_error(sbuf[1]);
+      }
+      else
+      {
+         if (sbuf[3] == '\x04')
+         {
+            /*
+             * The address field contains an IPv6 address
+             * which means we didn't get the whole reply
+             * yet. Read and discard the rest of it to make
+             * sure it isn't treated as HTTP data later on.
+             */
+            server_size = read_socket(sfd, sbuf, SOCKS5_REPLY_DIFFERENCE);
+            if (server_size != SOCKS5_REPLY_DIFFERENCE)
+            {
+               errstr = "SOCKS5 negotiation read failed (IPv6 address)";
+            }
+         }
+         else if (sbuf[3] != '\x01')
+         {
+             errstr = "SOCKS5 reply contains unsupported address type";
+         }
+         if (errstr == NULL)
+         {
+            return(sfd);
+         }
       }
-      errstr = translate_socks5_error(sbuf[1]);
-      err = 1;
    }
 
    assert(errstr != NULL);