An SSH wrapper written in PHP useful when set as the GIT_SSH variable.

git-ssh-wrapper

#!/usr/bin/env php
<?php

require_once __DIR__ . '/../vendor/autoload.php';

try {
    // Get the arguments passed through the command line.
    $args = (!empty($_SERVER['argv'])) ? $_SERVER['argv'] : array();
    if (!isset($args[0])) {
        $args[0] = $_SERVER['PHP_SELF'];
    }

    // Ensure that all arguments are present.
    if (!isset($args[2])) {
        throw new \RuntimeException($args[0] . ' requires 2 parameters.');
    }
    if (!$filepath = getenv('GIT_SSH_KEY')) {
        throw new \RuntimeException($args[0] . ' expects GIT_SSH_KEY environment variable to be set.');
    }
    if (!$private_key = @file_get_contents($filepath)) {
        throw new \RuntimeException('Unable to load private key: ' . $filepath);
    }

    // Allow the setting of the Git SSH port.
    $port = getenv('GIT_SSH_PORT');
    if (!$port) {
        $port = 22;
    }

    // Parse out the userrname and host.
    $strpos = strpos($args[1], '@');
    $username = substr($args[1], 0, $strpos);
    $host = substr($args[1], $strpos + 1);

    // Load the private key.
    $key = new Crypt_RSA();
    $key->loadKey($private_key);

    // Authenticate.
    $ssh = new Net_SSH2($host, $port);
    if (!$ssh->login($username, $key)) {
        throw new \RuntimeException('Authentication failed: ' . $ssh->getLastError());
    }

    // Run the wrapper.
    print $ssh->exec($args[2]);

} catch (Exception $e) {
    // Write exception message to STDERR.
    $fh = fopen('php://stderr','a');
    fwrite(STDERR, $e->getMessage() . PHP_EOL);
    fclose($fh);
    exit(1);
}