C发送http请求

C语言发送http请求和普通的socket通讯,原理是一样的.无非就三步connect()连上服务器,send()发送数据,recv()接收数据.只不过发送的数据有特定的格式.下面的是简单发送一个http请求的例子

#include <netinet/in.h>
#include <sys/socket.h>
#include <netdb.h>

#include <unistd.h>
#include <string.h>
#include <stdio.h>

int main(int argc, char **argv)
{
    /* 构造查询包 */
    const char quary[] = 
    "GET / HTTP/1.0\r\n"
    "Host: blog.youkuaiyun.com\r\n"
    "\r\n";

    const char hostname[] = "blog.youkuaiyun.com";
    struct sockaddr_in sin;
    struct hostent *h;
    const char *cp;
    int fd;
    ssize_t n_written, remaining;
    char buf[1024];

    /* 查找该域名的地址 */ 
    h = gethostbyname(hostname);
    if(h == NULL)
    {
        fprintf(stderr, "Couldn't lookup %s:%s\n", hostname, hstrerror(h_errno));
        return 1;
    }
    if (h->h_addrtype != AF_INET)
    {
        fprintf(stderr, "No ipv6 support, sorry.\n");
        return 1;
    }

    /* 创建一个套接字用来连接服务器 */
    fd = socket(AF_INET, SOCK_STREAM, 0);
    if (fd < 0)
    {
        perror("socket");
        return 1;
    }

    /* 连接到服务器 */
    sin.sin_family = AF_INET;
    sin.sin_port = htons(80);
    sin.sin_addr = *(struct in_addr*)h->h_addr;
    if (connect(fd, (struct sockaddr *)&sin, sizeof(sin)))
    {
        perror("connect");
        close(fd);
        return 1;
    }

    /* 发送请求 */
    cp = quary;
    remaining = strlen(quary);
    while(remaining)
    {
        n_written = send(fd,cp, remaining, 0);
        if (n_written <= 0)
        {
            perror("send");
            return 1;
        }
        remaining -= n_written;
        cp += n_written;
    }

    /* 获取响应 */
    while(1)
    {
        ssize_t result = recv(fd, buf, sizeof(buf), 0);
        if (result == 0)
        {
            break;
        }
        else if (result < 0)
        {
            perror("recv\n");
            close(fd);
            return 1;
        }
        fwrite(buf, 1, result, stdout);
    }
    close(fd);
    return 0;
}