用c++写一个 “hello,world” 的 FastCGI程序

原文：http://chriswu.me/blog/writing-hello-world-in-fcgi-with-c-plus-plus/

上面的连接地址给出的是作者的原文地址。

另外一个作者稍微整理了一下，github 地址：https://github.com/homer6/fastcgi

下面给出我测试的截图：

这个用 C++ 写的cgi 程序哦， c++ 也可以写网站了，是不是很兴奋！！！

stackoverflow 的问题：http://stackoverflow.com/questions/2149709/c-language-fastcgi-with-nginx

俗话说：“好记性不如烂笔头”， 所以这里记录下原文地址，和稍微写一写自己的心得和一路的过程。

google 到这篇用 c++ (c)语言写的 fastCGi 程序，并能成功运行，中间实属不易。。

做 web (网站) 开发也有两三年了， 用 php 语言写的。 web server 用过 apache , nginx .  对于apache ,它会启动一个 php 的模块，来处理php脚本。 对于nginx，

则 fast-pass: 127.0.0.1:9000 , webserver (nginx)将 请求  ----cgi 协议--- 转发到 facscgi (php-fpm) 处理（当然 会传递 标准输入和一个 环境变量过去），php 解释器执行完

php 脚本后， 将标准输出  给webserver , webserver 然后将输出 通过 http response 传给 browser (client), 一个 http 的请求和响应就结束了。

cgi 程序可以用php， java， C#写，当然可以用 C， C++ 来写。

我一直也在研究一个 fastCGI 这个处理过程到底是怎么样的。 webserver 和 fastCGI 之间的交互过程是怎么样的。所以自己想写一个 C++ 的fastCGI 脚本来完成一个http 请求，于是我也找了很多资料，所以就有了这篇文章的产生。

关于 CGI 应用程序和 web server 之间的交互的过程，这里有几张图片，图片来源：(原作者：吴秦Tyler)　　https://images0.cnblogs.com/blog/92071/201412/191104473136735.png

prerequistites:

　　need some familiarity with C++;

Why fastCGI?

　　FCGI (FastCGI) is a protocol in which web applications can talk to a web server to serve web requests.

Installation:

　　We will need to install the libfcgi++ library, a web server (nignx in our case) and spawn-fcgi to run the fcgi app. We’ll also install curl to help test later on.

　　

sudo apt-get install libfcgi-dev
sudo apt-get install spawn-fcgi
sudo apt-get install nginx
sudo apt-get install curl

　　

The code:

　　a c++ source file(echo.cpp)

　　

#include <iostream>
#include "fcgio.h"

using namespace std;

int main(void) {
    // Backup the stdio streambufs
    streambuf * cin_streambuf  = cin.rdbuf();
    streambuf * cout_streambuf = cout.rdbuf();
    streambuf * cerr_streambuf = cerr.rdbuf();

    FCGX_Request request;

    FCGX_Init();
    FCGX_InitRequest(&request, 0, 0);

    while (FCGX_Accept_r(&request) == 0) {
        fcgi_streambuf cin_fcgi_streambuf(request.in);
        fcgi_streambuf cout_fcgi_streambuf(request.out);
        fcgi_streambuf cerr_fcgi_streambuf(request.err);

        cin.rdbuf(&cin_fcgi_streambuf);
        cout.rdbuf(&cout_fcgi_streambuf);
        cerr.rdbuf(&cerr_fcgi_streambuf);

        cout << "Content-type: text/html\r\n"
             << "\r\n"
             << "<html>\n"
             << "  <head>\n"
             << "    <title>Hello, World!</title>\n"
             << "  </head>\n"
             << "  <body>\n"
             << "    <h1>Hello, World!</h1>\n"
             << "  </body>\n"
             << "</html>\n";

        // Note: the fcgi_streambuf destructor will auto flush
    }

    // restore stdio streambufs
    cin.rdbuf(cin_streambuf);
    cout.rdbuf(cout_streambuf);
    cerr.rdbuf(cerr_streambuf);

    return 0;
}

　　

Nginx config:

　　

Next up we’ll setup nginx to listen on port 80 for http requests and forward those along the the fcgi process which will listen on port 8000.

The key directive is fastcgi_pass 127.0.0.1:8000 indicates that nginx should forward the fcgi request to port 8000 at localhost. You can replace the address with an upstream directive if you want to want to load balance across many processes. The rest of the fastcgi_param directives are optional and just set appropriate environment variables which get forwarded to the fcgi application.

events {
  worker_connections 1024;
}

http {
  server {
    listen 80;
    server_name localhost;

    location / {
      fastcgi_pass   127.0.0.1:8000;

      fastcgi_param  GATEWAY_INTERFACE  CGI/1.1;
      fastcgi_param  SERVER_SOFTWARE    nginx;
      fastcgi_param  QUERY_STRING       $query_string;
      fastcgi_param  REQUEST_METHOD     $request_method;
      fastcgi_param  CONTENT_TYPE       $content_type;
      fastcgi_param  CONTENT_LENGTH     $content_length;
      fastcgi_param  SCRIPT_FILENAME    $document_root$fastcgi_script_name;
      fastcgi_param  SCRIPT_NAME        $fastcgi_script_name;
      fastcgi_param  REQUEST_URI        $request_uri;
      fastcgi_param  DOCUMENT_URI       $document_uri;
      fastcgi_param  DOCUMENT_ROOT      $document_root;
      fastcgi_param  SERVER_PROTOCOL    $server_protocol;
      fastcgi_param  REMOTE_ADDR        $remote_addr;
      fastcgi_param  REMOTE_PORT        $remote_port;
      fastcgi_param  SERVER_ADDR        $server_addr;
      fastcgi_param  SERVER_PORT        $server_port;
      fastcgi_param  SERVER_NAME        $server_name;
    }
  }
}

　　

Running the code:

　　The system now comprises of three parts. One will be the executable fcgi c++ app. In order to run this we need spawn-fcgi and to listen to a port. Nginx will then forward web requests to this port, translating the http proctocol into the fast cgi protocol.

# run nginx using the provided configuration
# 下面这一行其实我没用到。
sudo nginx -c <path to nginx.conf> 

# compile hello_world
g++ main_v1.cpp -lfcgi++ -lfcgi -o hello_world

# spawn the fcgi app on port 8000 with no fork
spawn-fcgi -p 8000 -n hello_world

　　Then just head to the browser and enter http://localhost/ into the location bar and voilà! Hello, World! See the next part in this tutorial to see how to incorporate the request uri and the request content into this simple app