用c语言实现http请求

用c语言来实现一个简单的http请求，请求 www.cnblogs.com 首页

#include<stdio.h>
#include<stdlib.h>
#include<string.h>    //strlen
#include<sys/socket.h>
#include<arpa/inet.h> //inet_addr
#include<netdb.h>
#include<errno.h>

int main(int argc, char *argv[])
{
    int socket_desc;
    struct sockaddr_in server;
    char *message;

    //Create socket
    socket_desc = socket(AF_INET, SOCK_STREAM , 0);
    if (socket_desc == -1) {
        printf("Could not create socket");
    }

    char ip[20] = {0};
    char *hostname = "www.cnblogs.com";
    struct hostent *hp;
    if ((hp = gethostbyname(hostname)) == NULL) {
        return 1;
    }
    
    strcpy(ip, inet_ntoa(*(struct in_addr *)hp->h_addr_list[0]));

    server.sin_addr.s_addr = inet_addr(ip);
    server.sin_family = AF_INET;
    server.sin_port = htons(80);


    //Connect to remote server
    if (connect(socket_desc, (struct sockaddr *)&server, sizeof(server)) < 0) {
        printf("connect error： %s", errno);
        return 1;
    }

    puts("Connected
");

    //Send some data
    //http 协议
    message = "GET / HTTP/1.1
Host: www.cnblogs.com

";

    //向服务器发送数据
    if (send(socket_desc, message, strlen(message) , 0) < 0) {
        puts("Send failed");
        return 1;
    }
    puts("Data Send
");

    struct timeval timeout = {3, 0};
    setsockopt(socket_desc, SOL_SOCKET, SO_RCVTIMEO, (char *)&timeout, sizeof(struct timeval));

    //Receive a reply from the server
    //loop
    int size_recv, total_size = 0;
    char chunk[512];
    while(1) {
        memset(chunk , 0 , 512); //clear the variable
        //获取数据
        if ((size_recv =  recv(socket_desc, chunk, 512, 0) ) == -1) {
            if (errno == EWOULDBLOCK || errno == EAGAIN) {
                printf("recv timeout ...
");
                break;
            } else if (errno == EINTR) {
                printf("interrupt by signal...
");
                continue;
            } else if (errno == ENOENT) {
                printf("recv RST segement...
");
                break;
            } else {
                printf("unknown error: %d
", errno);
                exit(1);
            }
        } else if (size_recv == 0) {
            printf("peer closed ...
");
            break;
        } else {
            total_size += size_recv;
            printf("%s" , chunk);
        }
    }

    printf("Reply received, total_size = %d bytes
", total_size);
    return 0;
}

编译： 

gcc http.c -o http

运行：

./http

就可以看到返回结果了