Added CURLOPT_LOCALPORT and CURLOPT_LOCALPORTRANGE to libcurl. Set with the

curl tool with --local-port. Plain and simply set the range of ports to bind
the local end of connections to. Implemented on to popular demand.

Not extensively tested. Please let me know how it works.

3 files changed, 106 insertions, 63 deletions

diff --git a/lib/connect.c b/lib/connect.c
index 2fb08d628..902721c80 100644
--- a/lib/connect.c
+++ b/lib/connect.c
@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2005, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2006, 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
@@ -98,6 +98,7 @@
 #include "memory.h"
 #include "select.h"
 #include "url.h" /* for Curl_safefree() */
+#include "sockaddr.h" /* required for Curl_sockaddr_storage */
 
 /* The last #include file should be: */
 #include "memdebug.h"
@@ -239,16 +240,20 @@ int waitconnect(curl_socket_t sockfd, /* socket */
 static CURLcode bindlocal(struct connectdata *conn,
                           curl_socket_t sockfd)
 {
-#ifdef HAVE_INET_NTOA
-  bool bindworked = FALSE;
   struct SessionHandle *data = conn->data;
+  struct sockaddr_in me;
+  struct sockaddr *sock = NULL;  /* bind to this address */
+  socklen_t socksize; /* size of the data sock points to */
+  unsigned short port = data->set.localport; /* use this port number, 0 for
+                                                "random" */
+  /* how many port numbers to try to bind to, increasing one at a time */
+  int portnum = data->set.localportrange;
 
   /*************************************************************
    * Select device to bind socket to
    *************************************************************/
-  if (strlen(data->set.device)<255) {
+  if (data->set.device && (strlen(data->set.device)<255) ) {
     struct Curl_dns_entry *h=NULL;
-    size_t size;
     char myhost[256] = "";
     in_addr_t in;
     int rc;
@@ -266,8 +271,10 @@ static CURLcode bindlocal(struct connectdata *conn,
       if(rc == CURLRESOLV_PENDING)
         (void)Curl_wait_for_resolv(conn, &h);
 
-      if(h)
+      if(h) {
         was_iface = TRUE;
+        Curl_resolv_unlock(data, h);
+      }
     }
 
     if(!was_iface) {
@@ -279,9 +286,11 @@ static CURLcode bindlocal(struct connectdata *conn,
       if(rc == CURLRESOLV_PENDING)
         (void)Curl_wait_for_resolv(conn, &h);
 
-      if(h)
+      if(h) {
         /* we know data->set.device is shorter than the myhost array */
         strcpy(myhost, data->set.device);
+        Curl_resolv_unlock(data, h);
+      }
     }
 
     if(! *myhost) {
@@ -295,7 +304,7 @@ static CURLcode bindlocal(struct connectdata *conn,
       return CURLE_HTTP_PORT_FAILED;
     }
 
-    infof(data, "We bind local end to %s\n", myhost);
+    infof(data, "Bind local address to %s\n", myhost);
 
 #ifdef SO_BINDTODEVICE
     /* I am not sure any other OSs than Linux that provide this feature, and
@@ -323,60 +332,79 @@ static CURLcode bindlocal(struct connectdata *conn,
 #endif
 
     in=inet_addr(myhost);
-    if (CURL_INADDR_NONE != in) {
+    if (CURL_INADDR_NONE == in) {
+      failf(data,"couldn't find my own IP address (%s)", myhost);
+      return CURLE_HTTP_PORT_FAILED;
+    } /* end of inet_addr */
 
-      if ( h ) {
-        Curl_addrinfo *addr = h->addr;
+    if ( h ) {
+      Curl_addrinfo *addr = h->addr;
+      sock = addr->ai_addr;
+      socksize = addr->ai_addrlen;
+    }
+    else
+      return CURLE_HTTP_PORT_FAILED;
 
-        Curl_resolv_unlock(data, h);
-        /* we don't need it anymore after this function has returned */
+  }
+  else if(port) {
+    /* if a local port number is requested but no local IP, extract the
+       address from the socket */
+    memset(&me, 0, sizeof(struct sockaddr));
+    me.sin_family = AF_INET;
+    me.sin_addr.s_addr = INADDR_ANY;
 
-        if( bind(sockfd, addr->ai_addr, (socklen_t)addr->ai_addrlen) >= 0) {
-          /* we succeeded to bind */
-#ifdef ENABLE_IPV6
-          struct sockaddr_in6 add;
-#else
-          struct sockaddr_in add;
-#endif
+    sock = (struct sockaddr *)&me;
+    socksize = sizeof(struct sockaddr);
 
-          bindworked = TRUE;
+  }
+  else
+    /* no local kind of binding was requested */
+    return CURLE_OK;
 
-          size = sizeof(add);
-          if(getsockname(sockfd, (struct sockaddr *) &add,
-                         (socklen_t *)&size)<0) {
-            failf(data, "getsockname() failed");
-            return CURLE_HTTP_PORT_FAILED;
-          }
-        }
+  do {
 
-        if(!bindworked) {
-          data->state.os_errno = Curl_ourerrno();
-          failf(data, "bind failure: %s",
-                Curl_strerror(conn, data->state.os_errno));
-          return CURLE_HTTP_PORT_FAILED;
-        }
+    /* Set port number to bind to, 0 makes the system pick one */
+    if(sock->sa_family == AF_INET)
+      ((struct sockaddr_in *)sock)->sin_port = htons(port);
+#ifdef ENABLE_IPV6
+    else
+      ((struct sockaddr_in6 *)sock)->sin6_port = htons(port);
+#endif
 
-      } /* end of if  h */
-      else {
-        failf(data,"couldn't find my own IP address (%s)", myhost);
+    if( bind(sockfd, sock, socksize) >= 0) {
+      /* we succeeded to bind */
+      struct Curl_sockaddr_storage add;
+      unsigned short port;
+      size_t size;
+
+      size = sizeof(add);
+      if(getsockname(sockfd, (struct sockaddr *) &add,
+                     (socklen_t *)&size)<0) {
+        failf(data, "getsockname() failed");
         return CURLE_HTTP_PORT_FAILED;
       }
-    } /* end of inet_addr */
-
-    else {
-      failf(data, "couldn't find my own IP address (%s)", myhost);
-      return CURLE_HTTP_PORT_FAILED;
+      if(((struct sockaddr *)&add)->sa_family == AF_INET)
+        port = ntohs(((struct sockaddr_in *)&add)->sin_port);
+#ifdef ENABLE_IPV6
+      else
+        port = ntohs(((struct sockaddr_in6 *)&add)->sin6_port);
+#endif
+      infof(data, "Local port: %d\n", port);
+      return CURLE_OK;
     }
+    if(--portnum > 0) {
+      infof(data, "Bind to local port %d failed, trying next\n", port);
+      port++; /* try next port */
+    }
+    else
+      break;
+  } while(1);
 
-    return CURLE_OK;
-
-  } /* end of device selection support */
-#else
-  (void)conn;
-  (void)sockfd;
-#endif /* end of HAVE_INET_NTOA */
-
+  data->state.os_errno = Curl_ourerrno();
+  failf(data, "bind failure: %s",
+        Curl_strerror(conn, data->state.os_errno));
   return CURLE_HTTP_PORT_FAILED;
+
 }
 
 /*
@@ -618,6 +646,8 @@ static void nosigpipe(struct connectdata *conn,
     infof(data, "Could not set SO_NOSIGPIPE: %s\n",
           Curl_strerror(conn, Curl_ourerrno()));
 }
+#else
+#define nosigpipe(x,y)
 #endif
 
 /* singleipconnect() connects to the given IP only, and it may return without
@@ -634,6 +664,7 @@ singleipconnect(struct connectdata *conn,
   bool isconnected;
   struct SessionHandle *data = conn->data;
   curl_socket_t sockfd;
+  CURLcode res;
 
   sockfd = socket(ai->ai_family, conn->socktype, ai->ai_protocol);
   if (sockfd == CURL_SOCKET_BAD)
@@ -647,17 +678,13 @@ singleipconnect(struct connectdata *conn,
   if(data->set.tcp_nodelay)
     tcpnodelay(conn, sockfd);
 
-#ifdef SO_NOSIGPIPE
   nosigpipe(conn, sockfd);
-#endif
-  if(conn->data->set.device) {
-    /* user selected to bind the outgoing socket to a specified "device"
-       before doing connect */
-    CURLcode res = bindlocal(conn, sockfd);
-    if(res) {
-      sclose(sockfd); /* close socket and bail out */
-      return CURL_SOCKET_BAD;
-    }
+
+  /* possibly bind the local end to an IP, interface or port */
+  res = bindlocal(conn, sockfd);
+  if(res) {
+    sclose(sockfd); /* close socket and bail out */
+    return CURL_SOCKET_BAD;
   }
 
   /* set socket non-blocking */
diff --git a/lib/url.c b/lib/url.c
index a4bd0f509..f17213f79 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -1222,13 +1222,26 @@ CURLcode Curl_setopt(struct SessionHandle *data, CURLoption option,
      */
     data->set.crlf = va_arg(param, long)?TRUE:FALSE;
     break;
+
   case CURLOPT_INTERFACE:
     /*
-     * Set what interface to bind to when performing an operation and thus
-     * what from-IP your connection will use.
+     * Set what interface or address/hostname to bind the socket to when
+     * performing an operation and thus what from-IP your connection will use.
      */
     data->set.device = va_arg(param, char *);
     break;
+  case CURLOPT_LOCALPORT:
+    /*
+     * Set what local port to bind the socket to when performing an operation.
+     */
+    data->set.localport = (unsigned short) va_arg(param, long);
+    break;
+  case CURLOPT_LOCALPORTRANGE:
+    /*
+     * Set number of local ports to try, starting with CURLOPT_LOCALPORT.
+     */
+    data->set.localportrange = (int) va_arg(param, long);
+    break;
   case CURLOPT_KRB4LEVEL:
     /*
      * A string that defines the krb4 security level.
diff --git a/lib/urldata.h b/lib/urldata.h
index c3a76b45c..96494a7ce 100644
--- a/lib/urldata.h
+++ b/lib/urldata.h
@@ -970,7 +970,10 @@ struct UserDefined {
                                of strlen(), and then the data *may* be binary
                                (contain zero bytes) */
   char *ftpport;     /* port to send with the FTP PORT command */
-  char *device;      /* network interface to use */
+  char *device;      /* local network interface/address to use */
+  unsigned short localport; /* local port number to bind to */
+  int localportrange; /* number of additional port numbers to test in case the
+                         'localport' one can't be bind()ed */
   curl_write_callback fwrite;        /* function that stores the output */
   curl_write_callback fwrite_header; /* function that stores headers */
   curl_read_callback fread;          /* function that reads the input */