テスト用にPHPで簡単なTCPサーバを書いた ref: http://qiita.com/uchiko/items/14b42621034ae63a69c0

echo_client.php

<?php

if (($sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP)) === false) {
    die("socket_create() failed: ".socket_strerror(socket_last_error()));
}

if (socket_connect($sock, '127.0.0.1', 5000) === false) {
    die("socket_connect() failed: ".socket_strerror(socket_last_error()));
}

$buf = "foo\n";
socket_write($sock, $buf, strlen($buf));
echo socket_read($sock, strlen($buf));

$buf = "bar\n";
socket_write($sock, $buf, strlen($buf));
echo socket_read($sock, strlen($buf));

socket_close($sock);

echo_server.php

<?php

require_once 'server.php';

$server = new TestTCPServer();
$server->run(function($remote, $line, $sock) {
    socket_write($remote, $line);
});

file2.txt

$ telnet 127.0.0.1 5000
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
test message
test message

server.php

<?php

class TestTCPServer
{
    public $sock = NULL;

    public function __construct($addr = "127.0.0.1", $port = 5000)
    {
        $sock = $this->newSocket($addr, $port);
        $this->sock = $sock;
    }

    public function newSocket($addr, $port)
    {
        if (($sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP)) === false) {
            throw new \Exception("socket_create() failed: ".socket_strerror(socket_last_error()));
        }

        if ((socket_set_option($sock, SOL_SOCKET, SO_REUSEADDR, 1)) === false) {
            throw new \Exception("socket_set_option() failed: ".socket_strerror(socket_last_error()));
        }

        if ((socket_bind($sock, $addr, $port)) === false) {
            throw new \Exception("socket_bind() failed: ".socket_strerror(socket_last_error($sock)));
        }

        if (socket_listen($sock) === false) {
            throw new \Exception("socket_listen() failed: ".socket_strerror(socket_last_error($sock)));
        }

        return $sock;
    }

    public function run(Closure $code)
    {
        while ($remote = socket_accept($this->sock)) {
            while ($line = socket_read($remote, 1024)) {
                $code($remote, $line, $this->sock);
            }
        }
    }
}