Richard Atterer brought a patch that added support for SOCKS4a proxies, which

is an inofficial PROXY4 variant that sends the hostname to the proxy instead
of the resolved address (which is already supported by SOCKS5).  --socks4a is
the curl command line option for it and CURLOPT_PROXYTYPE can now be set to
CURLPROXY_SOCKS4A as well.

CHANGES

@@ -6,6 +6,13 @@
 
                                   Changelog
 
+Daniel S (2 Jan 2008)
+- Richard Atterer brought a patch that added support for SOCKS4a proxies,
+  which is an inofficial PROXY4 variant that sends the hostname to the proxy
+  instead of the resolved address (which is already supported by SOCKS5).
+  --socks4a is the curl command line option for it and CURLOPT_PROXYTYPE can
+  now be set to CURLPROXY_SOCKS4A as well.
+
 Daniel S (1 Jan 2008)
 - Mohun Biswas pointed out that --libcurl generated a source code with an int
   function but without a return statement. While fixing that, I also took care

RELEASE-NOTES

@@ -1,7 +1,7 @@
 Curl and libcurl 7.17.2
 
  Public curl releases:         103
- Command line options:         123
+ Command line options:         124
  curl_easy_setopt() options:   148
  Public functions in libcurl:  55
  Public web site mirrors:      42
@@ -13,6 +13,7 @@ This release includes the following changes:
  o --data-urlencode was added
  o CURLOPT_PROXY_TRANSFER_MODE was added
  o --no-keep-alive was added
+ o --socks4a added (proxy type CURLPROXY_SOCKS4A for libcurl)
 
 This release includes the following bugfixes:
 
@@ -62,6 +63,6 @@ advice from friends like these:
  Robin Johnson, Michal Marek, Ates Goral, Andres Garcia, Rob Crittenden,
  Emil Romanus, Alessandro Vesely, Ray Pekowski, Spacen Jasset, Andrew Moise,
  Gilles Blanc, David Wright, Vikram Saxena, Mateusz Loskot, Gary Maxwell,
- Dmitry Kurochkin, Mohun Biswas
+ Dmitry Kurochkin, Mohun Biswas, Richard Atterer
  
         Thanks! (and sorry if I forgot to mention someone)

docs/curl.1

@@ -5,7 +5,7 @@
 .\" *                            | (__| |_| |  _ <| |___
 .\" *                             \___|\___/|_| \_\_____|
 .\" *
-.\" * Copyright (C) 1998 - 2007, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" * Copyright (C) 1998 - 2008, 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
@@ -1074,6 +1074,14 @@ assumed at port 1080. (Added in 7.15.2)
 This option overrides any previous use of \fI-x/--proxy\fP, as they are
 mutually exclusive.
 
+If this option is used several times, the last one will be used.
+.IP "--socks4a <host[:port]>"
+Use the specified SOCKS4a proxy. If the port number is not specified, it is
+assumed at port 1080. (Added in 7.17.2)
+
+This option overrides any previous use of \fI-x/--proxy\fP, as they are
+mutually exclusive.
+
 If this option is used several times, the last one will be used.
 .IP "--socks5 <host[:port]>"
 Use the specified SOCKS5 proxy. If the port number is not specified, it is

docs/libcurl/curl_easy_setopt.3

@@ -5,7 +5,7 @@
 .\" *                            | (__| |_| |  _ <| |___
 .\" *                             \___|\___/|_| \_\_____|
 .\" *
-.\" * Copyright (C) 1998 - 2007, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" * Copyright (C) 1998 - 2008, 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
@@ -430,8 +430,9 @@ Pass a long with this option to set the proxy port to connect to unless it is
 specified in the proxy string \fICURLOPT_PROXY\fP.
 .IP CURLOPT_PROXYTYPE
 Pass a long with this option to set type of the proxy. Available options for
-this are \fICURLPROXY_HTTP\fP, \fICURLPROXY_SOCKS4\fP (added in 7.15.2)
+this are \fICURLPROXY_HTTP\fP, \fICURLPROXY_SOCKS4\fP (added in 7.15.2),
-\fICURLPROXY_SOCKS5\fP. The HTTP type is default. (Added in 7.10)
+\fICURLPROXY_SOCKS5\fP and \fICURLPROXY_SOCKS4A\fP (added in 7.17.2). The HTTP
+type is default. (Added in 7.10)
 .IP CURLOPT_HTTPPROXYTUNNEL
 Set the parameter to non-zero to get the library to tunnel all operations
 through a given HTTP proxy. There is a big difference between using a proxy

include/curl/curl.h

@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2007, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2008, 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
@@ -510,10 +510,12 @@ typedef CURLcode (*curl_ssl_ctx_callback)(CURL *curl,    /* easy handle */
                                           void *userptr);
 
 typedef enum {
-  CURLPROXY_HTTP = 0,
+  CURLPROXY_HTTP = 0,   /* added in 7.10 */
-  CURLPROXY_SOCKS4 = 4,
+  CURLPROXY_SOCKS4 = 4, /* support added in 7.15.2, enum existed already
-  CURLPROXY_SOCKS5 = 5
+                           in 7.10 */
-} curl_proxytype;
+  CURLPROXY_SOCKS5 = 5, /* added in 7.10 */
+  CURLPROXY_SOCKS4A = 6 /* added in 7.17.2 */
+} curl_proxytype;  /* this enum was added in 7.10 */
 
 #define CURLAUTH_NONE         0       /* nothing */
 #define CURLAUTH_BASIC        (1<<0)  /* Basic (default) */
@@ -958,7 +960,7 @@ typedef enum {
   CINIT(SHARE, OBJECTPOINT, 100),
 
   /* indicates type of proxy. accepted values are CURLPROXY_HTTP (default),
-     CURLPROXY_SOCKS4 and CURLPROXY_SOCKS5. */
+     CURLPROXY_SOCKS4, CURLPROXY_SOCKS4A and CURLPROXY_SOCKS5. */
   CINIT(PROXYTYPE, LONG, 101),
 
   /* Set the Accept-Encoding string. Use this to tell a server you would like

lib/ftp.c

@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2007, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2008, 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
@@ -1726,8 +1726,9 @@ static CURLcode ftp_state_pasv_resp(struct connectdata *conn,
           newport = (unsigned short)(num & 0xffff);
 
           if(conn->bits.tunnel_proxy ||
-              data->set.proxytype == CURLPROXY_SOCKS5 ||
+             data->set.proxytype == CURLPROXY_SOCKS5 ||
-              data->set.proxytype == CURLPROXY_SOCKS4)
+             data->set.proxytype == CURLPROXY_SOCKS4 ||
+             data->set.proxytype == CURLPROXY_SOCKS4A)
             /* proxy tunnel -> use other host info because ip_addr_str is the
                proxy address not the ftp host */
             snprintf(newhost, sizeof(newhost), "%s", conn->host.name);
@@ -1781,7 +1782,8 @@ static CURLcode ftp_state_pasv_resp(struct connectdata *conn,
             conn->ip_addr_str);
       if(conn->bits.tunnel_proxy ||
           data->set.proxytype == CURLPROXY_SOCKS5 ||
-          data->set.proxytype == CURLPROXY_SOCKS4)
+          data->set.proxytype == CURLPROXY_SOCKS4 ||
+          data->set.proxytype == CURLPROXY_SOCKS4A)
         /* proxy tunnel -> use other host info because ip_addr_str is the
            proxy address not the ftp host */
         snprintf(newhost, sizeof(newhost), "%s", conn->host.name);
@@ -1886,7 +1888,11 @@ static CURLcode ftp_state_pasv_resp(struct connectdata *conn,
     break;
   case CURLPROXY_SOCKS4:
     result = Curl_SOCKS4(conn->proxyuser, newhost, newport,
-                         SECONDARYSOCKET, conn);
+                         SECONDARYSOCKET, conn, false);
+    break;
+  case CURLPROXY_SOCKS4A:
+    result = Curl_SOCKS4(conn->proxyuser, newhost, newport,
+                         SECONDARYSOCKET, conn, true);
     break;
   default:
     failf(data, "unknown proxytype option given");

lib/socks.c

@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2007, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2008, 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
@@ -118,16 +118,19 @@ static int blockread_all(struct connectdata *conn, /* connection data */
 *   http://socks.permeo.com/protocol/socks4.protocol
 *
 * Note :
-*   Nonsupport "SOCKS 4A (Simple Extension to SOCKS 4 Protocol)"
+*   Set protocol4a=true for  "SOCKS 4A (Simple Extension to SOCKS 4 Protocol)"
 *   Nonsupport "Identification Protocol (RFC1413)"
 */
 CURLcode Curl_SOCKS4(const char *proxy_name,
                      const char *hostname,
                      int remote_port,
                      int sockindex,
-                     struct connectdata *conn)
+                     struct connectdata *conn,
+                     bool protocol4a)
 {
-  unsigned char socksreq[262]; /* room for SOCKS4 request incl. user id */
+#define SOCKS4REQLEN 262
+  unsigned char socksreq[SOCKS4REQLEN]; /* room for SOCKS4 request incl. user
+                                           id */
   int result;
   CURLcode code;
   curl_socket_t sock = conn->sock[sockindex];
@@ -165,8 +168,8 @@ CURLcode Curl_SOCKS4(const char *proxy_name,
   socksreq[1] = 1; /* connect */
   *((unsigned short*)&socksreq[2]) = htons((unsigned short)remote_port);
 
-  /* DNS resolve */
+  /* DNS resolve only for SOCKS4, not SOCKS4a */
-  {
+  if (!protocol4a) {
     struct Curl_dns_entry *dns;
     Curl_addrinfo *hp=NULL;
     int rc;
@@ -225,15 +228,40 @@ CURLcode Curl_SOCKS4(const char *proxy_name,
   {
     ssize_t actualread;
     ssize_t written;
+    ssize_t hostnamelen = 0;
     int packetsize = 9 +
       (int)strlen((char*)socksreq + 8); /* size including NUL */
 
+    /* If SOCKS4a, set special invalid IP address 0.0.0.x */
+    if (protocol4a) {
+      socksreq[4] = 0;
+      socksreq[5] = 0;
+      socksreq[6] = 0;
+      socksreq[7] = 1;
+      /* If still enough room in buffer, also append hostname */
+      hostnamelen = strlen(hostname) + 1; /* length including NUL */
+      if (packetsize + hostnamelen <= SOCKS4REQLEN)
+        strcpy((char*)socksreq + packetsize, hostname);
+      else
+        hostnamelen = 0; /* Flag: hostname did not fit in buffer */
+    }
+
     /* Send request */
-    code = Curl_write(conn, sock, (char *)socksreq, packetsize, &written);
+    code = Curl_write(conn, sock, (char *)socksreq, packetsize + hostnamelen,
-    if((code != CURLE_OK) || (written != packetsize)) {
+                      &written);
+    if((code != CURLE_OK) || (written != packetsize + hostnamelen)) {
       failf(data, "Failed to send SOCKS4 connect request.");
       return CURLE_COULDNT_CONNECT;
     }
+    if (protocol4a && hostnamelen == 0) {
+      /* SOCKS4a with very long hostname - send that name separately */
+      hostnamelen = strlen(hostname) + 1;
+      code = Curl_write(conn, sock, (char *)hostname, hostnamelen, &written);
+      if((code != CURLE_OK) || (written != hostnamelen)) {
+        failf(data, "Failed to send SOCKS4 connect request.");
+        return CURLE_COULDNT_CONNECT;
+      }
+    }
 
     packetsize = 8; /* receive data size */
 
@@ -275,7 +303,10 @@ CURLcode Curl_SOCKS4(const char *proxy_name,
     switch(socksreq[1])
     {
     case 90:
-      infof(data, "SOCKS4 request granted.\n");
+      if (protocol4a)
+        infof(data, "SOCKS4a request granted.\n");
+      else
+        infof(data, "SOCKS4 request granted.\n");
       break;
     case 91:
       failf(data,

lib/socks.h

@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2007, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2008, 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
@@ -24,14 +24,15 @@
  ***************************************************************************/
 
 /*
- * This function logs in to a SOCKS4 proxy and sends the specifics to the
+ * This function logs in to a SOCKS4(a) proxy and sends the specifics to the
  * final destination server.
  */
 CURLcode Curl_SOCKS4(const char *proxy_name,
                      const char *hostname,
                      int remote_port,
                      int sockindex,
-                     struct connectdata *conn);
+                     struct connectdata *conn,
+                     bool protocol4a);
 
 /*
  * This function logs in to a SOCKS5 proxy and sends the specifics to the

lib/url.c

@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2007, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2008, 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
@@ -1868,7 +1868,7 @@ CURLcode Curl_setopt(struct SessionHandle *data, CURLoption option,
 
   case CURLOPT_PROXYTYPE:
     /*
-     * Set proxy type. HTTP/SOCKS4/SOCKS5
+     * Set proxy type. HTTP/SOCKS4/SOCKS4a/SOCKS5
      */
     data->set.proxytype = (curl_proxytype)va_arg(param, long);
     break;
@@ -2643,8 +2643,12 @@ static CURLcode ConnectPlease(struct SessionHandle *data,
         /* do nothing here. handled later. */
         break;
       case CURLPROXY_SOCKS4:
-        result = Curl_SOCKS4(conn->proxyuser, conn->host.name, conn->remote_port,
+        result = Curl_SOCKS4(conn->proxyuser, conn->host.name,
-                             FIRSTSOCKET, conn);
+                             conn->remote_port, FIRSTSOCKET, conn, false);
+        break;
+      case CURLPROXY_SOCKS4A:
+        result = Curl_SOCKS4(conn->proxyuser, conn->host.name,
+                             conn->remote_port, FIRSTSOCKET, conn, true);
         break;
       default:
         failf(data, "unknown proxytype option given");

src/main.c

@@ -712,6 +712,7 @@ static void help(void)
     " -s/--silent        Silent mode. Don't output anything",
     " -S/--show-error    Show error. With -s, make curl show errors when they occur",
     "    --socks4 <host[:port]> Use SOCKS4 proxy on given host + port",
+    "    --socks4a <host[:port]> Use SOCKS4a proxy on given host + port",
     "    --socks5 <host[:port]> Use SOCKS5 proxy on given host + port",
     "    --stderr <file> Where to redirect stderr. - means stdout",
     " -t/--telnet-option <OPT=val> Set telnet option",
@@ -1532,6 +1533,7 @@ static ParameterError getparameter(char *flag, /* f or -long-flag */
     {"$r", "ftp-method", TRUE},
     {"$s", "local-port", TRUE},
     {"$t", "socks4",     TRUE},
+    {"$T", "socks4a",    TRUE},
     {"$u", "ftp-alternative-to-user", TRUE},
     {"$v", "ftp-ssl-reqd", FALSE},
     {"$w", "no-sessionid", FALSE},
@@ -1906,6 +1908,10 @@ static ParameterError getparameter(char *flag, /* f or -long-flag */
         GetStr(&config->socksproxy, nextarg);
         config->socksver = CURLPROXY_SOCKS4;
         break;
+      case 'T': /* --socks4a specifies a socks4a proxy to use */
+        GetStr(&config->socksproxy, nextarg);
+        config->socksver = CURLPROXY_SOCKS4A;
+        break;
       case 'd': /* --tcp-nodelay option */
         config->tcp_nodelay ^= TRUE;
         break;