CGI原理解析之二------WEB服务和CGI交互数据

浏览数：14 / 时间：2015年06月09日

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
#include <stdlib.h>

#define   CGI_NAME "get_post.ums"
#define   REQUEST_METHOD "REQUEST_METHOD=POST"
#define REQUEST_PARAMETER "myname=huangzhihui"

int main(int argc, char *argv[])
{
   int fd[2];
   if (pipe(fd) < 0)
   {
       printf("create pipe fail.\n");
   }

   pid_t pid;
   if ((pid = fork()) < 0)
   {
       printf("fork fail.\n");
   }
   else if (pid > 0)
   {
       /* parent */
       //模拟先 CGI 传送数据
       ssize_t length = strlen(REQUEST_PARAMETER);
       if (write(fd[1], REQUEST_PARAMETER, length) != length)
       {
           printf("write error to pipe\n");
       }
       close(fd[1]);

       //等待CGI子进程完全把数据读取后写入,
       //实际情况应该是使用select 或者 epoll 监听
       usleep(1000);

       //模拟接收 CGI 应答的数据
       char buff[256] = { 0 };
       length = read(fd[0], buff, sizeof(buff));
       if (length <= 0)
       {
           printf("read error from pipe\n");
       }
       else
       {
           printf("pid %d read data=%u,%s\n",getpid(),length, buff);
       }
       close(fd[0]);

       if (waitpid(pid, NULL, 0) < 0)
       {
           printf("waitpid error\n");
       }
       exit(0);
   }
   else
   {
       /* child */
       //重定向标准输入到管道的输入端
       if (fd[0] != STDIN_FILENO)
       {
           if (dup2(fd[0], STDIN_FILENO) != STDIN_FILENO)
           {
               printf("dup2 error to stdin");
           }
           close(fd[0]);
       }

       //重定向标准输出到管道的输出端

       if (fd[1] != STDOUT_FILENO)
       {
           if (dup2(fd[1], STDOUT_FILENO) != STDOUT_FILENO)
           {
               printf("dup2 error to stdout");
           }
           close(fd[1]);
       }

       //覆盖进程空间,设置CGI环境变量
       char content_length[128] = { 0 };
       sprintf(content_length, "CONTENT_LENGTH=%u", strlen(REQUEST_PARAMETER));
       char *exec_argv[3] = { REQUEST_METHOD, content_length };
       if (execve(CGI_NAME,argv,exec_argv) < 0)
       {
           printf("execl error for %s", CGI_NAME);
       }
       exit(0);
   }
   exit(0);

}