xfer: bind to wildcard address when sending

When #5 was fixed, we started to always bind to the local address
connected to the irc server because the xfer.network.own_ip address
may not be able to be bound to when NATed. But this means when the
own_ip address is a different family (IPv4 vs IPv6) from the irc
server connection, we were listening for connections on the wrong
interface.

This patch lets us figure out which family is being used,
(xfer.network.own_ip's family, or the irc connection's family
otherwise) and bind() into the correct family via that family's
wildcard address.

1 files changed, 113 insertions, 69 deletions

diff --git a/src/plugins/xfer/xfer.c b/src/plugins/xfer/xfer.c
index 0839eafd9..21b5cedff 100644
--- a/src/plugins/xfer/xfer.c
+++ b/src/plugins/xfer/xfer.c
@@ -927,6 +927,60 @@ xfer_free (struct t_xfer *xfer)
         xfer_buffer_selected_line = (xfer_count == 0) ? 0 : xfer_count - 1;
 }
 
+
+/*
+ * Lookup str_address and resolve into sockaddr addr.
+ */
+static int
+xfer_resolve_addr (const char *str_address, const char *str_port,
+                   struct sockaddr *addr, socklen_t *addr_len, int ai_flags)
+{
+    struct addrinfo *ainfo, hints;
+    int rc;
+
+    memset (&hints, 0, sizeof (struct addrinfo));
+    hints.ai_flags = ai_flags;
+    hints.ai_family = AF_UNSPEC;
+    hints.ai_socktype = SOCK_STREAM;
+    hints.ai_protocol = 0;
+    hints.ai_canonname = NULL;
+    hints.ai_addr = NULL;
+    hints.ai_next = NULL;
+
+    rc = getaddrinfo (str_address, str_port, &hints, &ainfo);
+    if ((rc == 0) && ainfo && ainfo->ai_addr)
+    {
+        if (ainfo->ai_addrlen > *addr_len)
+        {
+            weechat_printf (NULL,
+                            _("%s%s: address \"%s\" resolved to a larger "
+                              "sockaddr than expected."),
+                            weechat_prefix ("error"), XFER_PLUGIN_NAME,
+                            str_address);
+
+            freeaddrinfo (ainfo);
+            return WEECHAT_RC_ERROR;
+        }
+        memcpy (addr, ainfo->ai_addr, ainfo->ai_addrlen);
+        *addr_len = ainfo->ai_addrlen;
+
+        freeaddrinfo (ainfo);
+        return WEECHAT_RC_OK;
+    }
+    else
+    {
+        weechat_printf (NULL,
+                        _("%s%s: invalid address \"%s\". error %d %s"),
+                        weechat_prefix ("error"), XFER_PLUGIN_NAME,
+                        str_address, rc, gai_strerror (rc));
+        if (rc == 0 && ainfo)
+            freeaddrinfo (ainfo);
+        return WEECHAT_RC_ERROR;
+    }
+
+    return WEECHAT_RC_ERROR;
+}
+
 /*
  * Callback for signal "xfer_add".
  */
@@ -942,10 +996,9 @@ xfer_add_cb (void *data, const char *signal, const char *type_data,
     int type, protocol, args, port_start, port_end, sock, port, rc;
     char *dir1, *dir2, *filename2, *short_filename, *pos, str_port_temp[16];
     struct stat st;
-    struct addrinfo *ainfo, hints;
-    struct sockaddr_storage addr, own_ip_addr;
+    struct sockaddr_storage addr, own_ip_addr, bind_addr;
     struct sockaddr *out_addr = (struct sockaddr*)&addr;
-    socklen_t length;
+    socklen_t length, bind_addr_len;
     unsigned long long file_size;
     struct t_xfer *ptr_xfer;
 
@@ -1095,80 +1148,71 @@ xfer_add_cb (void *data, const char *signal, const char *type_data,
     }
     port = weechat_infolist_integer (infolist, "port");
 
-    /* set address */
-    memset (&hints, 0, sizeof (struct addrinfo));
-    hints.ai_flags = AI_NUMERICHOST | AI_NUMERICSERV;
-    hints.ai_family = AF_UNSPEC;  /* allow IPv4 or IPv6 */
-    hints.ai_socktype = SOCK_STREAM;
-    hints.ai_protocol = 0;
-    hints.ai_canonname = NULL;
-    hints.ai_addr = NULL;
-    hints.ai_next = NULL;
-
+    /* resolve addresses */
     if (XFER_IS_RECV(type))
     {
         str_address = weechat_infolist_string (infolist, "remote_address");
         snprintf (str_port_temp, sizeof (str_port_temp), "%d", port);
         str_port = str_port_temp;
+        length = sizeof (addr);
+        rc = xfer_resolve_addr (str_address, str_port,
+                                (struct sockaddr*)&addr, &length,
+                                AI_NUMERICSERV | AI_NUMERICHOST);
+        if (rc == WEECHAT_RC_ERROR)
+            goto error;
     }
-    else
+    else /* XFER_IS_SEND */
     {
-        str_port = NULL;
+        memset(&bind_addr, 0, sizeof(bind_addr));
+
+        /* Determine bind_addr family from either own_ip or default */
         if (weechat_config_string (xfer_config_network_own_ip)
             && weechat_config_string (xfer_config_network_own_ip)[0])
         {
+            /* Resolve own_ip to a numeric address */
             str_address = weechat_config_string (xfer_config_network_own_ip);
-            hints.ai_flags = AI_NUMERICSERV;
+            length = sizeof (own_ip_addr);
 
-            rc = getaddrinfo (str_address, str_port, &hints, &ainfo);
-            if ((rc == 0) && ainfo && ainfo->ai_addr)
-            {
-                out_addr = (struct sockaddr*)&own_ip_addr;
-                memset (&own_ip_addr,  0, sizeof (addr));
-                memcpy (&own_ip_addr, ainfo->ai_addr, ainfo->ai_addrlen);
-                length = ainfo->ai_addrlen;
-                freeaddrinfo (ainfo);
-            }
-            else
-            {
-                weechat_printf (NULL,
-                                _("%s%s: invalid address \"%s\" (option "
-                                  "xfer.network.own_ip): error %d %s"),
-                                weechat_prefix ("error"), XFER_PLUGIN_NAME,
-                                str_address, rc, gai_strerror (rc));
-                if (rc == 0)
-                    freeaddrinfo (ainfo);
+            rc = xfer_resolve_addr (str_address, NULL,
+                                    (struct sockaddr*)&own_ip_addr, &length,
+                                    AI_NUMERICSERV);
+            if (rc == WEECHAT_RC_ERROR)
                 goto error;
-            }
-        }
 
-        str_address = weechat_infolist_string (infolist, "local_address");
-    }
+            /* set the advertised address to own_ip */
+            out_addr = (struct sockaddr*)&own_ip_addr;
 
-    rc = getaddrinfo (str_address, str_port, &hints, &ainfo);
-    if ((rc == 0) && ainfo && ainfo->ai_addr)
-    {
-        memset (&addr,  0, sizeof (addr));
-        memcpy (&addr, ainfo->ai_addr, ainfo->ai_addrlen);
-        length = ainfo->ai_addrlen;
-        freeaddrinfo (ainfo);
-    }
-    else
-    {
-        weechat_printf (NULL,
-                        _("%s%s: unable to find address for \"%s\": "
-                          "error %d %s"),
-                        weechat_prefix ("error"), XFER_PLUGIN_NAME,
-                        str_address, rc, gai_strerror (rc));
-        if (rc == 0)
-            freeaddrinfo (ainfo);
-        goto error;
-    }
+            /* bind_addr's family should be the advertised family */
+            bind_addr.ss_family = own_ip_addr.ss_family;
+        }
+        else
+        {
+            /* No own_ip, so bind_addr's family comes from irc connection  */
+            str_address = weechat_infolist_string (infolist, "local_address");
+            length = sizeof (addr);
+            rc = xfer_resolve_addr (str_address, NULL,
+                                    (struct sockaddr*)&addr, &length,
+                                    AI_NUMERICSERV | AI_NUMERICHOST);
+            if (rc == WEECHAT_RC_ERROR)
+                goto error;
+            bind_addr.ss_family = addr.ss_family;
+        }
+
+        /* Determine bind wildcard address */
+        if (bind_addr.ss_family == AF_INET)
+        {
+            ((struct sockaddr_in*)&bind_addr)->sin_addr.s_addr = INADDR_ANY;
+            bind_addr_len = sizeof (struct sockaddr_in);
+        }
+        else
+        {
+            memcpy (&((struct sockaddr_in6*)&bind_addr)->sin6_addr,
+                    &in6addr_any, sizeof (in6addr_any));
+            bind_addr_len = sizeof (struct sockaddr_in6);
+        }
 
-    if (XFER_IS_SEND(type))
-    {
         /* open socket for xfer */
-        sock = socket (addr.ss_family, SOCK_STREAM, 0);
+        sock = socket (bind_addr.ss_family, SOCK_STREAM, 0);
         if (sock < 0)
         {
             weechat_printf (NULL,
@@ -1199,11 +1243,11 @@ xfer_add_cb (void *data, const char *signal, const char *type_data,
                     if (!xfer_port_in_use (port))
                     {
                         /* attempt to bind to the free port */
-                        if (addr.ss_family == AF_INET)
-                            ((struct sockaddr_in *)&addr)->sin_port = htons (port);
+                        if (bind_addr.ss_family == AF_INET)
+                            ((struct sockaddr_in *)&bind_addr)->sin_port = htons (port);
                         else
-                            ((struct sockaddr_in6 *)&addr)->sin6_port = htons (port);
-                        if (bind (sock, (struct sockaddr *)&addr, length) == 0)
+                            ((struct sockaddr_in6 *)&bind_addr)->sin6_port = htons (port);
+                        if (bind (sock, (struct sockaddr *)&bind_addr, bind_addr_len) == 0)
                             break;
                     }
                     port++;
@@ -1217,13 +1261,13 @@ xfer_add_cb (void *data, const char *signal, const char *type_data,
         if (port == 0)
         {
             /* find port automatically */
-            if (bind (sock, (struct sockaddr *)&addr, length) == 0)
+            if (bind (sock, (struct sockaddr *)&bind_addr, bind_addr_len) == 0)
             {
-                getsockname (sock, (struct sockaddr *)&addr, &length);
-                if (addr.ss_family == AF_INET)
-                    port = ntohs (((struct sockaddr_in *)&addr)->sin_port);
+                getsockname (sock, (struct sockaddr *)&bind_addr, &bind_addr_len);
+                if (bind_addr.ss_family == AF_INET)
+                    port = ntohs (((struct sockaddr_in *)&bind_addr)->sin_port);
                 else
-                    port = ntohs (((struct sockaddr_in6 *)&addr)->sin6_port);
+                    port = ntohs (((struct sockaddr_in6 *)&bind_addr)->sin6_port);
             }
             else
                 port = -1;