http_server.php

<?php
/*
 * @author Ammar Faizi <ammarfaizi2@gnuweeb.org>
 *
 * A simple HTTP Server. I make this program just to do a challenge
 * from @codenoid.
 *
 * Link: https://t.me/GNUWeebTDD/7822
 * Link: https://twitter.com/imrenagi/status/1591659569637634048
 */

$g_clients_state = [];

function create_tcp_server(string $bind_addr, int $bind_port)
{
	$tcp_fd = socket_create(AF_INET, SOCK_STREAM, 0);
	if (!$tcp_fd)
		return false;

	if (!socket_bind($tcp_fd, $bind_addr, $bind_port))
		goto err;

	if (!socket_listen($tcp_fd))
		goto err;

	if (!socket_set_nonblock($tcp_fd))
		goto err;

	return $tcp_fd;

err:
	socket_close($tcp_fd);
	return false;
}

function http_get_client_state($client_fd): ?StdClass
{
	global $g_clients_state;

	$key = spl_object_hash($client_fd);
	if (isset($g_clients_state[$key]))
		return $g_clients_state[$key];

	return NULL;
}

function http_set_client_state($client_fd): StdClass
{
	global $g_clients_state;

	$obj = new StdClass;
	$obj->addr = NULL;
	$obj->port = NULL;
	$obj->buf = "";
	$obj->fd = $client_fd;
	$g_clients_state[spl_object_hash($client_fd)] = $obj;
	return $obj;
}

function http_close_client_state($client_fd)
{
	global $g_clients_state;
	unset($g_clients_state[spl_object_hash($client_fd)]);
}

function http_accept_client($tcp_fd, array &$clients): int
{
	$client_fd = socket_accept($tcp_fd);
	if ($client_fd === false)
		return 1;

	$addr = NULL;
	$port = NULL;
	if (!socket_getpeername($client_fd, $addr, $port)) {
		socket_close($client_fd);
		return 1;
	}

	printf("Accepted a new connection from %s:%d\n", $addr, $port);
	$client_obj = http_set_client_state($client_fd);
	$client_obj->addr = $addr;
	$client_obj->port = $port;
	$client_obj->fd = $client_fd;
	$clients[] = $client_fd;
	return 0;
}

function str_has_dcrlf(string $buf): bool
{
	return (count(explode("\r\n\r\n", $buf, 2)) > 1);
}

function http_parse_fhdr(StdClass $obj, string $fhdr): bool
{
	$m = [];
	if (!preg_match("/^(\S*) (\/\S*) HTTP\/.+$/", $fhdr, $m))
		return false;

	$obj->uri = $m[2];
	$obj->method = $m[1];
	return true;
}

function http_send_bad_req_response(StdClass $obj): void
{
	$txt =	"Bad Request!\n";
	$buf =	"HTTP/1.1 400 Bad Request\r\n".
		"Content-Length: ".strlen($txt)."\r\n".
		"Content-Type: text/plain\r\n\r\n".
		$txt;

	socket_send($obj->fd, $buf, strlen($buf), MSG_DONTWAIT);
}

function http_send_not_found_response(StdClass $obj): void
{
	$txt =	"Not Found!\n";
	$buf =	"HTTP/1.1 404 Not Found\r\n".
		"Content-Length: ".strlen($txt)."\r\n".
		"Content-Type: text/plain\r\n\r\n".
		$txt;

	socket_send($obj->fd, $buf, strlen($buf), MSG_DONTWAIT);
}

function http_send_ok_response(StdClass $obj, string $txt): void
{
	$buf =	"HTTP/1.1 200 OK\r\n".
		"Content-Length: ".strlen($txt)."\r\n".
		"Content-Type: text/plain\r\n\r\n".
		$txt;

	socket_send($obj->fd, $buf, strlen($buf), MSG_DONTWAIT);
}

function http_process_route(StdClass $obj): void
{
	$uri = explode("?", $obj->uri, 2);
	$qs = $uri[1] ?? NULL;
	$path = $uri[0];

	switch ($path) {
	case "/":
		$txt = "This is the index page\n";
		break;
	case "/hello":
		$txt = "Hello World!\n";
		break;
	default:
		http_send_not_found_response($obj);
		return;
	}

	http_send_ok_response($obj, $txt);
}

function http_process_client_buffer(StdClass $obj): void
{
	$buf = $obj->buf;
	$buf = explode("\r\n\r\n", $buf, 2);
	$headers = explode("\r\n", $buf[0]);
	$body = $buf[1];

	if (!http_parse_fhdr($obj, $headers[0])) {
		http_send_bad_req_response($obj);
		return;
	}

	/*
	 * Currently, we only support GET method.
	 */
	if ($obj->method !== "GET") {
		http_send_bad_req_response($obj);
		return;
	}

	http_process_route($obj);
}

function http_handle_client_packet(StdClass $obj): bool
{
	$ret = socket_recv($obj->fd, $buf, 1024, MSG_DONTWAIT);
	if ($ret === false)
		return false;

	if ($ret > 0)
		$obj->buf .= $buf;

	if (str_has_dcrlf($obj->buf)) {
		http_process_client_buffer($obj);
		return false;
	}

	return true;
}

function http_close_all_clients(array &$clients)
{
	foreach ($clients as $k => $client) {
		unset($clients[$k]);
		socket_close($client);
	}
}

function http_process_ready_sockets($tcp_fd, array &$read, array &$clients)
{
	if (in_array($tcp_fd, $read)) {
		$ret = http_accept_client($tcp_fd, $clients);
		if ($ret)
			return $ret;
	}

	foreach ($read as $client) {
		if ($client === $tcp_fd)
			continue;

		$obj = http_get_client_state($client);
		if (http_handle_client_packet($obj))
			continue;

		printf("Closing a connection from %s:%d...\n", $obj->addr,
			$obj->port);
		http_close_client_state($obj);
		socket_close($obj->fd);

		foreach ($clients as $k => $v) {
			if ($v === $client)
				unset($clients[$k]);
		}
	}
}

function http_do_event_loop($tcp_fd, array &$clients): int
{
	/*
	 * Find all sockets that are ready for a read operation.
	 */
	$read   = array_merge([$tcp_fd], $clients);
	$write  = NULL;
	$except = NULL;
	$ret = socket_select($read, $write, $except, NULL);
	if ($ret === false)
		goto err;

	$ret = http_process_ready_sockets($tcp_fd, $read, $clients);
	if ($ret)
		goto err;

	return 0;
err:
	http_close_all_clients($clients);
	return $ret;
}

function http_run_server($tcp_fd)
{
	$clients = [];
	while (true) {
		$ret = http_do_event_loop($tcp_fd, $clients);
		if ($ret)
			break;
	}

	socket_close($tcp_fd);
	return $ret;
}

function main(int $argc, array $argv)
{
	$bind_addr = "0.0.0.0";
	$bind_port = 4444;

	$tcp_fd = create_tcp_server($bind_addr, $bind_port);
	if (!$tcp_fd)
		return 1;

	printf("Listening on %s:%d...\n", $bind_addr, $bind_port);
	return http_run_server($tcp_fd);
}

exit(main($_SERVER["argc"], $_SERVER["argv"]));