Make listenConfig replaceable

conn/controlfns.go

@@ -26,10 +26,9 @@ type controlFn func(network, address string, c syscall.RawConn) error
 // that can apply socket options.
 var controlFns = []controlFn{}
 
-// listenConfig returns a net.ListenConfig that applies the controlFns to the
-// socket prior to bind. This is used to apply socket buffer sizing and packet
-// information OOB configuration for sticky sockets.
-func listenConfig() *net.ListenConfig {
+// listenConfigFn is a function that returns a net.ListenConfig.
+// It can be replaced to use alternative network stacks.
+var listenConfigFn = func() *net.ListenConfig {
 	return &net.ListenConfig{
 		Control: func(network, address string, c syscall.RawConn) error {
 			for _, fn := range controlFns {
@@ -41,3 +40,10 @@ func listenConfig() *net.ListenConfig {
 		},
 	}
 }
+
+// listenConfig returns a net.ListenConfig that applies the controlFns to the
+// socket prior to bind. This is used to apply socket buffer sizing and packet
+// information OOB configuration for sticky sockets.
+func listenConfig() *net.ListenConfig {
+	return listenConfigFn()
+}

conn/export.go

@@ -13,6 +13,10 @@ var (
 	// export controlFns for Android to use
 	// is not thread safe and should only be modified during init.
 	ControlFns = &controlFns
+
+	// export listenConfigFn for external replacement
+	// is not thread safe and should only be modified during init.
+	ListenConfigFn = &listenConfigFn
 )
 
 type BatchReader = batchReader