commit 3ca0302031b14c6fcb9be147e875fb794bfc583b
author Lorenzo Colitti <lorenzo@google.com> Wed Mar 27 12:39:10 2013 +0900
committer Lorenzo Colitti <lorenzo@google.com> Wed Mar 27 15:46:47 2013 +0900
tree dd895a75638c8df0b418b6ccfc7273158a13566d
parent 41e758e33e6c3b43f363591d4113dea54a4330d9

Configure the interface before bringing it up

Currently, clatd brings the clat4 interface up before assigning
its IPv4 address. This can cause a race condition, because as
soon as the interface comes up, the framework notices and reads
the interface configuration into the LinkProperties. If this
happens before the IPv4 address is configured, then the framework
ends up thinking clat4's IPv4 address is 0.0.0.0/0.

Fix this by configuring the address before the interface is
brought up.

Currently the framework does not use this address for anything,
so this is purely cosmetic, but it could make debugging more
confusing.

Bug: 8276725
Change-Id: I2bfee586a0d70050c53b10cc3f7eb9a98173e11d

clatd.c

diff --git a/clatd.c b/clatd.c
index ea8363c..edd8a2d 100644
--- a/clatd.c
+++ b/clatd.c
@@ -192,25 +192,26 @@
  * tunnel - tun device data
  */
 void configure_tun_ip(const struct tun_data *tunnel) {
-  struct in_addr default_4;
   int status;
 
-  default_4.s_addr = INADDR_ANY;
+  // Configure the interface before bringing it up. As soon as we bring the interface up, the
+  // framework will be notified and will assume the interface's configuration has been finalized.
+  status = add_address(tunnel->device4, AF_INET, &Global_Clatd_Config.ipv4_local_subnet,
+      32, &Global_Clatd_Config.ipv4_local_subnet);
+  if(status < 0) {
+    logmsg(ANDROID_LOG_FATAL,"configure_tun_ip/if_address(4) failed: %s",strerror(-status));
+    exit(1);
+  }
 
   if((status = if_up(tunnel->device6, Global_Clatd_Config.mtu)) < 0) {
     logmsg(ANDROID_LOG_FATAL,"configure_tun_ip/if_up(6) failed: %s",strerror(-status));
     exit(1);
   }
+
   if((status = if_up(tunnel->device4, Global_Clatd_Config.ipv4mtu)) < 0) {
     logmsg(ANDROID_LOG_FATAL,"configure_tun_ip/if_up(4) failed: %s",strerror(-status));
     exit(1);
   }
-  status = add_address(tunnel->device4, AF_INET, &Global_Clatd_Config.ipv4_local_subnet,
-      32, &Global_Clatd_Config.ipv4_local_subnet);
-  if(status < 0) {
-    logmsg(ANDROID_LOG_FATAL,"configure_tun_ip/if_address(4) failed: %s",strerror(-status));
-    exit(1);
-  }
 
   configure_tun_ipv6(tunnel);
 }