[HTTP] PHP 實現 HTTP Server 原理

時間 2019-12-05

原文原文鏈接

單進程服務器簡陋版：php

<?php
/**
 * Single http server.
 *
 * Access http://127.0.0.1:8081
 *
 * @license Apache-2.0
 * @author farwish
 */

$s_socket_uri = 'tcp://0.0.0.0:8081';
$s_socket = stream_socket_server($s_socket_uri, $errno, $errstr) OR
    trigger_error("Failed to create socket: $s_socket_uri, Err($errno) $errstr", E_USER_ERROR);

while(1)
{
    while($connection = @stream_socket_accept($s_socket, 60, $peer))
    {
        echo "Connected with $peer.  Request info...\n";

        $client_request = "";
        // Read until double \r
        while( !preg_match('/\r?\n\r?\n/', $client_request) )
        {
            $client_request .= fread($connection, 1024);
        }

        if (!$client_request)
        {
            trigger_error("Client request is empty!");
        }
        $headers = "HTTP/1.1 200 OK\r\n"
            ."Server: nginx\r\n"
            ."Content-Type: text/html; charset=utf-8\r\n"
            ."\r\n";
        $body = "<h1>hello world</h1><br><br>";
        if ((int) fwrite($connection, $headers . $body) < 1) {
            trigger_error("Write to socket failed!");
        }
        fclose($connection);
    }
}

HTTP 底層基於 TCP，因此 socket 地址指定爲 tcp 協議沒有問題；stream_socket_server 功能至關於執行了 socket => bind => listen，stream_socket_accept 阻塞等待 client 鏈接，並設置了超時時間，默認的 timeout 時間使用在 php.ini 中設置。html

注意這裏的錯誤抑制符@，抑制 accept 超時狀況產生的 PHP Warning，若是用到 stream_select 也須要加錯誤抑制符 @ 來避免中斷信號引發的 PHP Warning。nginx

HTTP 響應報文格式包含響應狀態碼、響應首部、響應主體（若是有的話），響應首部每行以 \r\n 結尾，響應頭部結束單獨一行 \r\n 結尾，後面就是響應主體了，響應頭部加響應主體以 fwrite 寫入 socket 鏈接，fclose 關閉鏈接。數組

注意：上面的簡陋版既沒有設置 socket 上下文選項，也沒有使用 I/O 複用，更不是多進程的，只是做爲請求響應的演示。服務器

較爲嚴謹的HTTP協議處理版：併發

        $method             = '';
        $url                = '';
        $protocol_version   = '';

        $request_header     = [];
        $content_type       = 'text/html; charset=utf-8';
        $content_length     = 0;
        $request_body       = '';
        $end_of_header      = false;

        // @see http://php.net/manual/en/function.fread.php
        $buffer = fread($connection, 8192);

        if (false !== $buffer) {

            // Http request format check.
            if (false !== strstr($buffer, "\r\n")) {
                $list = explode("\r\n", $buffer);
            }

            if ($list) {
                foreach ($list as $line) {
                    if ($end_of_header) {
                        if (strlen($line) === $content_length) {
                            $request_body = $line;
                        } else {
                            throw new \Exception("Content-Length {$content_length} not match request body length " . strlen($line) . "\n");
                        }
                        break;
                    }

                    if ( empty($line) ) {
                        $end_of_header = true;
                    } else {
                        // Header.
                        //
                        if (false === strstr($line, ': ')) {
                            $array = explode(' ', $line);

                            // Request line.
                            if (count($array) === 3) {
                                $method           = $array[0];
                                $url              = $array[1];
                                $protocol_version = $array[2];
                            }
                        } else {
                            $array = explode(': ', $line);

                            // Request header.
                            list ($key, $value) = $array;
                            $request_header[$key] = $value;

                            if ( strtolower($key) === strtolower('Content-type') ) {
                                $content_type = $value;
                            }

                            // Have request body.
                            if ($key === 'Content-Length') {
                                $content_length = $value;
                            }
                        }
                    }
                }
            }
        }

        // No request body, show buffer from read.
        $response_body = $request_body ?: $buffer;
        $response_header = "HTTP/1.1 200 OK\r\n";
        $response_header .= "Content-type: {$content_type}\r\n";
        if (empty($content_length) && (strlen($response_body) > 0)) {
            $response_header .= "Content-Length: " . strlen($response_body) . "\r\n";
        }
        foreach ($request_header as $k => $v) {
            $response_header .= "{$k}: {$v}\r\n";
        }
        $response_header .= "\r\n";
        fwrite($connection, $response_header . $response_body);
        fclose($connection);