From 61224ce31260c86abf379206e2131ba299e5c3bb Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Fri, 13 Mar 2015 09:37:32 -0700
Subject: [PATCH] command/server: tcp listener

---
 command/server/listener.go          | 25 ++++++++++++++++
 command/server/listener_tcp.go      | 20 +++++++++++++
 command/server/listener_tcp_test.go | 21 ++++++++++++++
 command/server/listener_test.go     | 44 +++++++++++++++++++++++++++++
 4 files changed, 110 insertions(+)
 create mode 100644 command/server/listener.go
 create mode 100644 command/server/listener_tcp.go
 create mode 100644 command/server/listener_tcp_test.go
 create mode 100644 command/server/listener_test.go

diff --git a/command/server/listener.go b/command/server/listener.go
new file mode 100644
index 000000000..28b063a0e
--- /dev/null
+++ b/command/server/listener.go
@@ -0,0 +1,25 @@
+package server
+
+import (
+	"fmt"
+	"net"
+)
+
+// ListenerFactory is the factory function to create a listener.
+type ListenerFactory func(map[string]string) (net.Listener, error)
+
+// BuiltinListeners is the list of built-in listener types.
+var BuiltinListeners = map[string]ListenerFactory{
+	"tcp": tcpListenerFactory,
+}
+
+// NewListener creates a new listener of the given type with the given
+// configuration. The type is looked up in the BuiltinListeners map.
+func NewListener(t string, config map[string]string) (net.Listener, error) {
+	f, ok := BuiltinListeners[t]
+	if !ok {
+		return nil, fmt.Errorf("unknown listener type: %s", t)
+	}
+
+	return f(config)
+}
diff --git a/command/server/listener_tcp.go b/command/server/listener_tcp.go
new file mode 100644
index 000000000..cff4d4c30
--- /dev/null
+++ b/command/server/listener_tcp.go
@@ -0,0 +1,20 @@
+package server
+
+import (
+	"fmt"
+	"net"
+)
+
+func tcpListenerFactory(config map[string]string) (net.Listener, error) {
+	addr, ok := config["address"]
+	if !ok {
+		return nil, fmt.Errorf("'address' must be set")
+	}
+
+	ln, err := net.Listen("tcp", addr)
+	if err != nil {
+		return nil, err
+	}
+
+	return ln, nil
+}
diff --git a/command/server/listener_tcp_test.go b/command/server/listener_tcp_test.go
new file mode 100644
index 000000000..61309a74a
--- /dev/null
+++ b/command/server/listener_tcp_test.go
@@ -0,0 +1,21 @@
+package server
+
+import (
+	"net"
+	"testing"
+)
+
+func TestTCPListener(t *testing.T) {
+	ln, err := tcpListenerFactory(map[string]string{
+		"address": "127.0.0.1:0",
+	})
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	connFn := func(lnReal net.Listener) (net.Conn, error) {
+		return net.Dial("tcp", ln.Addr().String())
+	}
+
+	testListenerImpl(t, ln, connFn)
+}
diff --git a/command/server/listener_test.go b/command/server/listener_test.go
new file mode 100644
index 000000000..d0894c510
--- /dev/null
+++ b/command/server/listener_test.go
@@ -0,0 +1,44 @@
+package server
+
+import (
+	"bytes"
+	"io"
+	"net"
+	"testing"
+	"time"
+)
+
+type testListenerConnFn func(net.Listener) (net.Conn, error)
+
+func testListenerImpl(t *testing.T, ln net.Listener, connFn testListenerConnFn) {
+	serverCh := make(chan net.Conn, 1)
+	go func() {
+		server, err := ln.Accept()
+		if err != nil {
+			t.Fatalf("err: %s", err)
+		}
+
+		serverCh <- server
+	}()
+
+	client, err := connFn(ln)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	server := <-serverCh
+	defer client.Close()
+	defer server.Close()
+
+	var buf bytes.Buffer
+	go io.Copy(&buf, server)
+
+	if _, err := client.Write([]byte("foo")); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	time.Sleep(100 * time.Millisecond)
+
+	if buf.String() != "foo" {
+		t.Fatalf("bad: %v", buf.String())
+	}
+}