linux - c如何获取http响应内容?

Question

小弟初学socket，想着用socket做一个简单的翻译程序，需要通过网络请求去获取译文，现在已经能够获取到如下服务器响应的内容：

HTTP/1.1 200 OK
Date: Wed, 08 Feb 2017 06:26:12 GMT
Connection: keep-alive
Content-Length: 11

"时钟"

但是不知道如何把响应内容中的 "时钟" 取出来，最好把状态码也能取到，不知道有没有如下这种结构体：

struct response {
    int status_code;        //200
    int content_length;     //11
    char *content_data;     //时钟
    ...
}

能够把响应的字段一一对应起来。

下面是我的代码：

#include <netdb.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>

void error(const char *msg)
{
    perror(msg);
    exit(0);
}

int main(int argc, char **argv)
{
    int portno = 4000;
    char *host = "ilp64.com";
    char *message_fmt = "GET /?qs=%s&text=%s HTTP/1.1\r\nHost: %s\r\n\r\n";
    
    char *query_qs = "oj3rnfefnm,ew";
    char *query_text = "clock";
    
    struct hostent *server;
    struct sockaddr_in serv_addr;
    int sockfd;
    char message[1024], response[4096];
    
    sprintf(message, message_fmt, query_qs, query_text, host);
    printf("GET Request:\n%s\n", message);
    
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0)
        error("ERROR opening socket");
    
    server = gethostbyname(host);
    if (server == NULL)
        error("ERROR no such host");
    
    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(portno);
    memcpy(&serv_addr.sin_addr.s_addr, server->h_addr, server->h_length);
    
    if (connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
        error("ERROR connecting");
    
    if (send(sockfd, message, strlen(message), 0) < 0)
        error("ERROR sending");
    
    if (recv(sockfd, response, 4096, 0) < 0)
        error("ERROR received");

    puts(response);

    return 0;
}

Answer 1

If you do it directly through the socket, the response is a byte array to your program, and you need to disassemble it yourself according to the http protocol. Please note that content-length in the http protocol is used to tell you how big the data in the body part is. If there is no content-length, you have to look at Transfer-Encoding: chunked, which is a bit more complicated. Generally speaking, if the corresponding body is not large, content-length will be returned. content-length用来告诉你body部分的数据到底有多大。如果没有content-length，就得看Transfer-Encoding: chunked，这个复杂点了。一般来说相应体不大的话，会返回content-length。

可以考虑用libcurl

You can consider using libcurl🎜

Answer 2

Writing your own parser is very annoying. In fact, it is just a lot of string matching. Just use ready-made ones, such as the one below
http-parser

Answer 3

After receiving the data packet, the data packet is disassembled according to the http protocol.