From d87f5e23e2e5a5d5cc3d5671f681e374847b4842 Mon Sep 17 00:00:00 2001
From: Ralf Habacker <ralf.habacker@freenet.de>
Date: Sat, 31 Jan 2015 13:34:26 +0100
Subject: [PATCH] Detect ipv6 support and return related error message on
 creating or connection to a dbus server.

---
 dbus/dbus-sysdeps-win.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 63 insertions(+), 4 deletions(-)

diff --git a/dbus/dbus-sysdeps-win.c b/dbus/dbus-sysdeps-win.c
index 68fa72b..6539796 100644
--- a/dbus/dbus-sysdeps-win.c
+++ b/dbus/dbus-sysdeps-win.c
@@ -669,6 +669,45 @@ _dbus_connect_named_pipe (const char     *path,
 #endif
 
 /**
+ * @returns #FALSE if no ipv6 support has been found
+ */
+dbus_bool_t _dbus_has_ipv6()
+{
+    static dbus_bool_t first = TRUE;
+    static dbus_bool_t has_ipv6 = TRUE;
+
+    if(first)
+      {
+        struct addrinfo hints;
+        struct addrinfo *ai = 0;
+        int temp = INVALID_SOCKET;
+
+        _DBUS_ZERO (hints);
+
+        hints.ai_family = AF_INET6;
+        hints.ai_protocol = IPPROTO_TCP;
+        hints.ai_socktype = SOCK_STREAM;
+        hints.ai_flags = AI_PASSIVE;
+        if (getaddrinfo("::1", NULL, &hints, &ai) != 0 || !ai)
+            has_ipv6 = FALSE;
+
+        if (has_ipv6 && (temp = socket (AF_INET6, SOCK_STREAM, 0)) == INVALID_SOCKET)
+            has_ipv6 = FALSE;
+
+        if (has_ipv6 && bind (temp, ai->ai_addr, ai->ai_addrlen) == SOCKET_ERROR)
+            has_ipv6 = FALSE;
+
+        if (temp != INVALID_SOCKET)
+            closesocket(temp);
+        if (ai)
+            freeaddrinfo(ai);
+
+        first = FALSE;
+      }
+    return has_ipv6;
+}
+
+/**
  * @returns #FALSE if no memory
  */
 dbus_bool_t
@@ -1516,11 +1555,21 @@ _dbus_connect_tcp_socket_with_nonce (const char     *host,
   _DBUS_ZERO (hints);
 
   if (!family)
-    hints.ai_family = AF_UNSPEC;
+    hints.ai_family = _dbus_has_ipv6() ? AF_UNSPEC : AF_INET;
   else if (!strcmp(family, "ipv4"))
     hints.ai_family = AF_INET;
   else if (!strcmp(family, "ipv6"))
-    hints.ai_family = AF_INET6;
+    {
+      if (_dbus_has_ipv6())
+          hints.ai_family = AF_INET6;
+      else
+        {
+          dbus_set_error (error,
+                          DBUS_ERROR_INVALID_ARGS,
+                          "No ipv6 support available", "");
+          return -1;
+        }
+    }
   else
     {
       dbus_set_error (error,
@@ -1666,11 +1715,21 @@ _dbus_listen_tcp_socket (const char     *host,
   _DBUS_ZERO (hints);
 
   if (!family)
-    hints.ai_family = AF_INET;
+    hints.ai_family = _dbus_has_ipv6() ? AF_UNSPEC : AF_INET;
   else if (!strcmp(family, "ipv4"))
     hints.ai_family = AF_INET;
   else if (!strcmp(family, "ipv6"))
-    hints.ai_family = AF_INET6;
+    {
+      if (_dbus_has_ipv6())
+          hints.ai_family = AF_INET6;
+      else
+        {
+          dbus_set_error (error,
+                          DBUS_ERROR_INVALID_ARGS,
+                          "No ipv6 support available", "");
+          return -1;
+        }
+    }
   else
     {
       dbus_set_error (error,
-- 
1.8.4.5