tunspace: re-add IPv6 address after it gets flushed

IPv6 addresses get flushed when an interface is taken down.
Now that we take the interface down for convenience reasons,
we need to re-add the address when we bring it back up.

Author: pktpls

packages/tunspace/tunspace.uc

@@ -186,21 +186,10 @@ function create_wg_interface(nsid, ifname, ifcfg, netns) {
     return false;
   }
 
-  // add ipv6 address
-  if (length(ifcfg.ipv6) > 0) {
-    rtnl_request(rtnl.const.RTM_NEWADDR,
-                 rtnl.const.NLM_F_REQUEST|rtnl.const.NLM_F_CREATE|rtnl.const.NLM_F_EXCL, {
-      "dev": ifname,
-      "family": rtnl.const.AF_INET6,
-      "address": ifcfg.ipv6,
-    });
-    if (err = rtnl.error()) {
-      log("RTM_NEWADDR with AF_INET6 failed: "+err);
-      return false;
-    }
-  }
-
   // add ipv4 address
+  // ipv4 addresses dont get flushed when the interface goes down, so we can
+  // add it once at the beginning (here) and be done with it.
+  // the ipv6 address will be added everytime we change the endpoint.
   if (length(ifcfg.ipv4) > 0) {
     rtnl_request(rtnl.const.RTM_NEWADDR,
                  rtnl.const.NLM_F_REQUEST|rtnl.const.NLM_F_CREATE|rtnl.const.NLM_F_EXCL, {
@@ -229,7 +218,8 @@ function wg_replace_endpoint(ifname, cfg, next) {
   let srvcfg = cfg.wireguard_servers[next];
   let certopt = srvcfg.insecure_cert ? "--no-check-certificate" : "";
 
-  // bring interface down to prevent OLSR and Babel from spamming syslog.
+  // bring interface down
+  // it's not technically neccessary, just for aesthetics.
   if (0 != shell_command("ip link set down "+ifname)) {
     return false;
   }
@@ -355,6 +345,22 @@ function wg_replace_endpoint(ifname, cfg, next) {
     return false;
   }
 
+  // add ipv6 address
+  // as ipv6 addresses get flushed when and interface is set down,
+  // we need to re-add it everytime we bring it up.
+  if (length(ifcfg.ipv6) > 0) {
+    rtnl_request(rtnl.const.RTM_NEWADDR,
+                 rtnl.const.NLM_F_REQUEST|rtnl.const.NLM_F_CREATE|rtnl.const.NLM_F_EXCL, {
+      "dev": ifname,
+      "family": rtnl.const.AF_INET6,
+      "address": ifcfg.ipv6,
+    });
+    if (err = rtnl.error()) {
+      log("RTM_NEWADDR with AF_INET6 failed: "+err);
+      return false;
+    }
+  }
+
   return true;
 }