resolver: Use proper IPv6 source address when sending DNS queries

This fix is for following scenario:
 - New interface is coming up.
 - There is radvd in the connected network and it is
   advertising IPv6 addresses and DNS servers.
 - Kernel receives router advertisement and picks up the DNS
   server information which is then routed via netlink to
   rtnl.c:rtnl_newnduseropt() which then creates DNS listener.
 - Kernel activates DAD (duplicate address detection).
 - As the DAD takes some time we now have interface up
   and it only has link local IPv6 address defined.
 - The DNS listener is now using link local source addresses when
   sending queries instead of proper autoconfigured addresses.
 - When DAD is finished, the interface will have autoconfigured
   addresses assigned and corresponding netlink message will cause
   function rtnl.c:process_newaddr() to be called.
 - If all this happens, then we re-create DNS listener
   in dnsproxy.c so that listener will have a proper
   (autoconfigured) source address when sending DNS packets.

1 files changed, 14 insertions, 0 deletions

diff --git a/src/rtnl.c b/src/rtnl.c
index 39afb12b..251d9cd9 100644
--- a/src/rtnl.c
+++ b/src/rtnl.c
@@ -601,6 +601,20 @@ static void process_newaddr(unsigned char family, unsigned char prefixlen,
 
 	__connman_ipconfig_newaddr(index, family, label,
 					prefixlen, ip_string);
+
+	if (family == AF_INET6) {
+		/*
+		 * Re-create RDNSS configured servers if there are any
+		 * for this interface. This is done because we might
+		 * have now properly configured interface with proper
+		 * autoconfigured address.
+		 */
+		char *interface = connman_inet_ifname(index);
+
+		__connman_resolver_redo_servers(interface);
+
+		g_free(interface);
+	}
 }
 
 static void process_deladdr(unsigned char family, unsigned char prefixlen,