getinfo: added CURLINFO_ACTIVESOCKET

This patch addresses known bug #76, where on 64-bit Windows SOCKET is 64
bits wide, but long is only 32, making CURLINFO_LASTSOCKET unreliable.

Signed-off-by: Razvan Cojocaru <rcojocaru@bitdefender.com>

docs/KNOWN_BUGS

@@ -63,11 +63,6 @@ may have been fixed since this was written!
   any file at all. Like when using FTP.
   http://curl.haxx.se/bug/view.cgi?id=1063
 
-76. The SOCKET type in Win64 is 64 bits large (and thus so is curl_socket_t on
-  that platform), and long is only 32 bits. It makes it impossible for
-  curl_easy_getinfo() to return a socket properly with the CURLINFO_LASTSOCKET
-  option as for all other operating systems.
-
 75. NTLM authentication involving unicode user name or password only works
   properly if built with UNICODE defined together with the WinSSL/schannel
   backend. The original problem was mentioned in:

docs/libcurl/curl_easy_getinfo.3

@@ -205,8 +205,19 @@ libcurl close the socket and cleanup other resources associated with the
 handle. This is typically used in combination with
 \fICURLOPT_CONNECT_ONLY(3)\fP.  (Added in 7.15.2)
 
-NOTE: this API is not really working on win64, since the SOCKET type on win64
-is 64 bit large while its 'long' is only 32 bits.
+NOTE: this API is deprecated since it is not working on win64 where the SOCKET
+type is 64 bits large while its 'long' is 32 bits. Use the
+\fICURLINFO_ACTIVESOCKET\fP instead, if possible.
+.IP CURLINFO_ACTIVESOCKET
+Pass a pointer to a curl_socket_t to receive the active socket used by this
+curl session. If the socket is no longer valid, -1 is returned. When you
+finish working with the socket, you must call curl_easy_cleanup() as usual and
+let libcurl close the socket and cleanup other resources associated with the
+handle. This is typically used in combination with
+\fICURLOPT_CONNECT_ONLY(3)\fP.
+
+NOTE: this is meant as a cross-platform, safe alternative to
+\fICURLINFO_LASTSOCKET\fP, which does not work on win64.
 .IP CURLINFO_FTP_ENTRY_PATH
 Pass a pointer to a char pointer to receive a pointer to a string holding the
 path of the entry path. That is the initial path libcurl ended up in when

docs/libcurl/symbols-in-versions

@@ -199,6 +199,7 @@ CURLGSSAPI_DELEGATION_NONE      7.22.0
 CURLGSSAPI_DELEGATION_POLICY_FLAG 7.22.0
 CURLHEADER_SEPARATE             7.37.0
 CURLHEADER_UNIFIED              7.37.0
+CURLINFO_ACTIVESOCKET           7.45.0
 CURLINFO_APPCONNECT_TIME        7.19.0
 CURLINFO_CERTINFO               7.19.1
 CURLINFO_CONDITION_UNMET        7.19.4
@@ -247,6 +248,7 @@ CURLINFO_RTSP_SESSION_ID        7.20.0
 CURLINFO_SIZE_DOWNLOAD          7.4.1
 CURLINFO_SIZE_UPLOAD            7.4.1
 CURLINFO_SLIST                  7.12.3
+CURLINFO_SOCKET                 7.45.0
 CURLINFO_SPEED_DOWNLOAD         7.4.1
 CURLINFO_SPEED_UPLOAD           7.4.1
 CURLINFO_SSL_DATA_IN            7.12.1

include/curl/curl.h

@@ -2091,6 +2091,7 @@ struct curl_tlssessioninfo {
 #define CURLINFO_LONG     0x200000
 #define CURLINFO_DOUBLE   0x300000
 #define CURLINFO_SLIST    0x400000
+#define CURLINFO_SOCKET   0x500000
 #define CURLINFO_MASK     0x0fffff
 #define CURLINFO_TYPEMASK 0xf00000
 
@@ -2139,9 +2140,10 @@ typedef enum {
   CURLINFO_LOCAL_IP         = CURLINFO_STRING + 41,
   CURLINFO_LOCAL_PORT       = CURLINFO_LONG   + 42,
   CURLINFO_TLS_SESSION      = CURLINFO_SLIST  + 43,
+  CURLINFO_ACTIVESOCKET     = CURLINFO_SOCKET + 44,
   /* Fill in new entries below here! */
 
-  CURLINFO_LASTONE          = 43
+  CURLINFO_LASTONE          = 44
 } CURLINFO;
 
 /* CURLINFO_RESPONSE_CODE is the new name for the option previously known as

lib/getinfo.c

@@ -334,6 +334,31 @@ static CURLcode getinfo_slist(struct SessionHandle *data, CURLINFO info,
   return CURLE_OK;
 }
 
+static CURLcode getinfo_socket(struct SessionHandle *data, CURLINFO info,
+                               curl_socket_t *param_socketp)
+{
+  curl_socket_t sockfd;
+
+  switch(info) {
+  case CURLINFO_ACTIVESOCKET:
+    sockfd = Curl_getconnectinfo(data, NULL);
+
+    /* note: this is not a good conversion for systems with 64 bit sockets and
+       32 bit longs */
+    if(sockfd != CURL_SOCKET_BAD)
+      *param_socketp = sockfd;
+    else
+      /* this interface is documented to return -1 in case of badness, which
+         may not be the same as the CURL_SOCKET_BAD value */
+      *param_socketp = -1;
+    break;
+  default:
+    return CURLE_BAD_FUNCTION_ARGUMENT;
+  }
+
+  return CURLE_OK;
+}
+
 CURLcode Curl_getinfo(struct SessionHandle *data, CURLINFO info, ...)
 {
   va_list arg;
@@ -341,6 +366,7 @@ CURLcode Curl_getinfo(struct SessionHandle *data, CURLINFO info, ...)
   double *param_doublep = NULL;
   char **param_charp = NULL;
   struct curl_slist **param_slistp = NULL;
+  curl_socket_t *param_socketp = NULL;
   int type;
   /* default return code is to error out! */
   CURLcode result = CURLE_BAD_FUNCTION_ARGUMENT;
@@ -372,6 +398,11 @@ CURLcode Curl_getinfo(struct SessionHandle *data, CURLINFO info, ...)
     if(param_slistp)
       result = getinfo_slist(data, info, param_slistp);
     break;
+  case CURLINFO_SOCKET:
+    param_socketp = va_arg(arg, curl_socket_t *);
+    if(param_socketp)
+      result = getinfo_socket(data, info, param_socketp);
+    break;
   default:
     break;
   }