FTP: close callback fix

Keep track of which sockets that are the result of accept() calls and
refuse to call the closesocket callback for those sockets. Test case 596
now verifies that the open socket callback is called the same number of
times as the closed socket callback for active FTP connections.

Bug: http://curl.haxx.se/mail/lib-2011-12/0018.html
Reported by: Gokhan Sengun

1 files changed, 8 insertions, 4 deletions

diff --git a/lib/connect.c b/lib/connect.c
index 445261754..a560c4d3b 100644
--- a/lib/connect.c
+++ b/lib/connect.c
@@ -1110,10 +1110,14 @@ curl_socket_t Curl_getconnectinfo(struct SessionHandle *data,
 int Curl_closesocket(struct connectdata *conn,
                      curl_socket_t sock)
 {
-  if(conn && conn->fclosesocket)
-    return conn->fclosesocket(conn->closesocket_client, sock);
-  else
-    return sclose(sock);
+  if(conn && conn->fclosesocket) {
+    if((sock != conn->sock[SECONDARYSOCKET]) ||
+       !conn->sock_accepted[SECONDARYSOCKET])
+      /* if this socket matches the second socket, and that was created with
+         accept, then we MUST NOT call the callback */
+      return conn->fclosesocket(conn->closesocket_client, sock);
+  }
+  return sclose(sock);
 }
 
 /*