CGI原理解析系列之三----CGI如何完整获取WEB服务器数据

//模拟了服务器端 httpd 进程启动 cgi的过程,
//完整展现了 get,post 方法支持
//gcc -g httpd_all.c -o httpd_all.ums;

#include
#include
#include
#include
#include

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

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

if (pipe(child) < 0)
{
close(parent[0]);
close(parent[1]);
printf("create pipe fail.\n");
}

pid_t pid;
if ((pid = fork()) < 0)
{
printf("fork fail.\n");
}
else if (pid > 0)
{
/* parent */
//关闭多余的句柄,构造单一功能读写通道
close(parent[0]);
close(child[1]);

//模拟向 CGI 传送数据
ssize_t length = strlen(REQUEST_PARAMETER);
if (write(parent[1], REQUEST_PARAMETER, length) != length)
{
printf("write error to pipe\n");
}
close(parent[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(child[0], buff, sizeof(buff));
if (length <= 0)
{
printf("read error from pipe\n");
}
else
{
printf("pid %d read data=%u\n%s",getpid(),length, buff);
}
close(child[0]);

if (waitpid(pid, NULL, 0) < 0)
{
printf("waitpid error\n");
}
exit(0);
}
else
{
/* child */

//关闭多余的句柄,构造单一功能读写通道
close(parent[1]);
close(child[0]);

//重定向管道的输入端到标准输入
if (parent[0] != STDIN_FILENO)
{
if (dup2(parent[0], STDIN_FILENO) != STDIN_FILENO)
{
printf("dup2 error to stdin");
}
close(parent[0]);
}

//重定向管道的输出端到标准输出
if (child[1] != STDOUT_FILENO)
{
if (dup2(child[1], STDOUT_FILENO) != STDOUT_FILENO)
{
printf("dup2 error to stdout");
}
close(child[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);
}