From e50d51afe50bd8103f456dfa0dfe09a0cf9aa716 Mon Sep 17 00:00:00 2001
From: Ralf Habacker <ralf.habacker@freenet.de>
Date: Thu, 8 Mar 2018 09:20:53 +0100
Subject: [PATCH] Fix "failed to bind socket: Cannot assign requested address"
 on linux with ipv6 disabled

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=61922
---
 dbus/dbus-sysdeps-unix.c | 70 +++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 66 insertions(+), 4 deletions(-)

diff --git a/dbus/dbus-sysdeps-unix.c b/dbus/dbus-sysdeps-unix.c
index 9bd438ac..abb1d103 100644
--- a/dbus/dbus-sysdeps-unix.c
+++ b/dbus/dbus-sysdeps-unix.c
@@ -1326,6 +1326,48 @@ _dbus_listen_systemd_sockets (DBusSocket **fds,
 }
 
 /**
+ * @returns #FALSE if no ipv6 support has been found
+ */
+static dbus_bool_t
+_dbus_has_ipv6 (void)
+{
+  static DBusAtomic cached_result = { -1 };
+  struct addrinfo hints;
+  struct addrinfo *ai = 0;
+  DBusSocket temp = DBUS_SOCKET_INIT;
+  dbus_bool_t has_ipv6 = TRUE;
+
+  if(_dbus_atomic_get (&cached_result) != -1)
+    return TRUE;
+
+  _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.fd = socket (AF_INET6, SOCK_STREAM, 0)) == EINVAL)
+    has_ipv6 = FALSE;
+
+  int s;
+  if (has_ipv6 && (s = bind (temp.fd, ai->ai_addr, ai->ai_addrlen)) == -1)
+    has_ipv6 = FALSE;
+
+  if (!_dbus_socket_is_valid (temp))
+    close (temp.fd);
+  if (ai)
+    freeaddrinfo (ai);
+
+  /* Atomic version of "cached_result = has_ipv6" */
+  if (has_ipv6)
+    _dbus_atomic_inc (&cached_result);
+  return has_ipv6;
+}
+
+/**
  * Creates a socket and connects to a socket at the given host
  * and port. The connection fd is returned, and is set up as
  * nonblocking.
@@ -1365,11 +1407,21 @@ _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_BAD_ADDRESS,
+                          "No ipv6 support available", "");
+          return _dbus_socket_get_invalid ();
+        }
+    }
   else
     {
       dbus_set_error (error,
@@ -1484,11 +1536,21 @@ _dbus_listen_tcp_socket (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_BAD_ADDRESS,
+                          "No ipv6 support available");
+          return -1;
+        }
+    }
   else
     {
       dbus_set_error (error,
-- 
2.12.3