From afcb84d42c8c1deb907ff9d2de33d7bede2bfd77 Mon Sep 17 00:00:00 2001
From: Bryan Boreham <bjboreham@gmail.com>
Date: Wed, 2 Dec 2015 17:47:19 +0000
Subject: [PATCH] Set up static route for multicast, with option to turn off

---
 plugin/net/driver.go | 25 +++++++++++++++++--------
 prog/plugin/main.go  | 22 ++++++++++++----------
 site/plugin.md       |  2 ++
 weave                |  2 +-
 4 files changed, 32 insertions(+), 19 deletions(-)

diff --git a/plugin/net/driver.go b/plugin/net/driver.go
index 34c5c306..12b4a62f 100644
--- a/plugin/net/driver.go
+++ b/plugin/net/driver.go
@@ -21,19 +21,21 @@ const (
 )
 
 type driver struct {
-	version    string
-	nameserver string
-	scope      string
+	version          string
+	nameserver       string
+	scope            string
+	noMulticastRoute bool
 	sync.RWMutex
 	endpoints map[string]struct{}
 }
 
-func New(client *docker.Client, version string, nameserver string, scope string) (skel.Driver, error) {
+func New(client *docker.Client, version string, nameserver string, scope string, noMulticastRoute bool) (skel.Driver, error) {
 	driver := &driver{
-		nameserver: nameserver,
-		version:    version,
-		scope:      scope,
-		endpoints:  make(map[string]struct{}),
+		nameserver:       nameserver,
+		noMulticastRoute: noMulticastRoute,
+		version:          version,
+		scope:            scope,
+		endpoints:        make(map[string]struct{}),
 	}
 
 	_, err := NewWatcher(client, driver)
@@ -162,6 +164,13 @@ func (driver *driver) JoinEndpoint(j *api.JoinRequest) (*api.JoinResponse, error
 		}
 		response.StaticRoutes = []api.StaticRoute{routeToDNS}
 	}
+	if !driver.noMulticastRoute {
+		multicastRoute := api.StaticRoute{
+			Destination: "224.0.0.0/4",
+			RouteType:   types.CONNECTED,
+		}
+		response.StaticRoutes = append(response.StaticRoutes, multicastRoute)
+	}
 	Log.Infof("Join endpoint %s:%s to %s", j.NetworkID, j.EndpointID, j.SandboxKey)
 	return response, nil
 }
diff --git a/prog/plugin/main.go b/prog/plugin/main.go
index b9a5a581..d1ffb928 100644
--- a/prog/plugin/main.go
+++ b/prog/plugin/main.go
@@ -22,12 +22,13 @@ var version = "(unreleased version)"
 
 func main() {
 	var (
-		justVersion     bool
-		address         string
-		nameserver      string
-		meshAddress     string
-		logLevel        string
-		meshNetworkName string
+		justVersion      bool
+		address          string
+		nameserver       string
+		meshAddress      string
+		logLevel         string
+		meshNetworkName  string
+		noMulticastRoute bool
 	)
 
 	flag.BoolVar(&justVersion, "version", false, "print version and exit")
@@ -36,6 +37,7 @@ func main() {
 	flag.StringVar(&nameserver, "nameserver", "", "nameserver to provide to containers")
 	flag.StringVar(&meshAddress, "meshsocket", "/run/docker/plugins/weavemesh.sock", "socket on which to listen in mesh mode")
 	flag.StringVar(&meshNetworkName, "mesh-network-name", "weave", "network name to create in mesh mode")
+	flag.BoolVar(&noMulticastRoute, "no-multicast-route", false, "do not add a multicast route to network endpoints")
 
 	flag.Parse()
 
@@ -57,14 +59,14 @@ func main() {
 	var globalListener, meshListener net.Listener
 	endChan := make(chan error, 1)
 	if address != "" {
-		globalListener, err := listenAndServe(dockerClient, address, nameserver, endChan, "global", false)
+		globalListener, err := listenAndServe(dockerClient, address, nameserver, noMulticastRoute, endChan, "global", false)
 		if err != nil {
 			Log.Fatalf("unable to create driver: %s", err)
 		}
 		defer globalListener.Close()
 	}
 	if meshAddress != "" {
-		meshListener, err := listenAndServe(dockerClient, meshAddress, nameserver, endChan, "local", true)
+		meshListener, err := listenAndServe(dockerClient, meshAddress, nameserver, noMulticastRoute, endChan, "local", true)
 		if err != nil {
 			Log.Fatalf("unable to create driver: %s", err)
 		}
@@ -94,8 +96,8 @@ func main() {
 	}
 }
 
-func listenAndServe(dockerClient *docker.Client, address, nameserver string, endChan chan<- error, scope string, withIpam bool) (net.Listener, error) {
-	d, err := netplugin.New(dockerClient, version, nameserver, scope)
+func listenAndServe(dockerClient *docker.Client, address, nameserver string, noMulticastRoute bool, endChan chan<- error, scope string, withIpam bool) (net.Listener, error) {
+	d, err := netplugin.New(dockerClient, version, nameserver, scope, noMulticastRoute)
 	if err != nil {
 		return nil, err
 	}
diff --git a/site/plugin.md b/site/plugin.md
index eb4489b1..f6497dac 100644
--- a/site/plugin.md
+++ b/site/plugin.md
@@ -68,6 +68,8 @@ The plugin command-line arguments are:
    how much information to emit for debugging.
  * `--mesh-network-name=<name>`: set it to blank to disable creation
    of a default network, or a name of your own choice.
+ * `--no-multicast-route`: stop weave adding a static IP route for
+   multicast traffic on its interface
 
 ## Restarting
 
diff --git a/weave b/weave
index 16d15feb..e2267789 100755
--- a/weave
+++ b/weave
@@ -54,7 +54,7 @@ weave launch-proxy  [-H <endpoint>] [--with-dns | --without-dns]
                       [--hostname-match <regexp>]
                       [--hostname-replacement <replacement>]
                       [--rewrite-inspect]
-weave launch-plugin
+weave launch-plugin [--no-multicast-route]
 weave env           [--restore]
 weave config
 weave dns-args