c - 在 C 中使用套接字服务器的 HTML 头请求

Question

我正在尝试使用以下代码接收来自谷歌的回复。我正在寻找与您从 telnet www.google.com 收到的相同回复80 HEAD/HTTP/1.1 但它只是挂起。如果有人能在这里发现问题，我会非常感激

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

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

int main(int argc, char *argv[])
{
        int sockfd, portno, n;
        struct sockaddr_in serv_addr;
        struct hostent *server;

        char buffer[256];
        portno = 80;
        sockfd = socket(AF_INET, SOCK_STREAM, 0);
        if (sockfd < 0) 
        {
            error("ERROR opening socket");
        }

        server = gethostbyname("www.google.com.au");
        if (server == NULL) 
        {
            fprintf(stderr,"ERROR, no such host\n");
            exit(0);
        }

        bzero((char *) &serv_addr, sizeof(serv_addr));
        serv_addr.sin_family = AF_INET;

        bcopy((char *)server->h_addr, (char *)&serv_addr.sin_addr.s_addr,server->h_length);
        serv_addr.sin_port = htons(portno);

        if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0) 
        {
            error("ERROR connecting");
        }
        puts("Retreiving HTML Head");

        ssize_t nByte = write(sockfd,"HEAD / HTTP/1.1\r\n",strlen("HEAD / HTTP/1.1\r\n"));
        if( nByte <= 0)
        {
            perror("send");
                exit(EXIT_FAILURE);
        }

        size_t recived_len = 0;
        if ((recived_len = read(sockfd,buffer,255)) == 0)
        {
                bzero(buffer,256);
                printf("%s", buffer);
        }

        if (recived_len == -1)
        {
            perror("read");
        }

        close(sockfd);
        return 0;
}

Answer 1

这是您的代码，稍作更改，从 read 返回 HTTP 响应。

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

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

int main(int argc, char *argv[]) {
    int sockfd, portno, n;
    struct sockaddr_in serv_addr;
    struct hostent *server;

    char buffer[256];
    portno = 80;
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) {
        error("ERROR opening socket");
    }

    server = gethostbyname("www.google.com.au");
    if (server == NULL) {
        fprintf(stderr, "ERROR, no such host\n");
        exit(0);
    }

    bzero((char *) &serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;

    bcopy((char *) server->h_addr, (char *) &serv_addr.sin_addr.s_addr, server->h_length);
    serv_addr.sin_port = htons(portno);

    if (connect(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0) {
        error("ERROR connecting");
    }
    puts("Retreiving HTML Head");

    ssize_t nByte = write(sockfd, "HEAD / HTTP/1.1\r\n\r\n", strlen("HEAD / HTTP/1.1\r\n\r\n"));
    if (nByte <= 0) {
        perror("send");
        exit(EXIT_FAILURE);
    }

    size_t recived_len = 0;
    if ((recived_len = read(sockfd, buffer, 255)) > 0) {
        //bzero(buffer, 256);
        printf("%s", buffer);
    }

    if (recived_len == -1) {
        perror("read");
    }

    close(sockfd);
    return 0;
}

测试

Retreiving HTML Head
HTTP/1.1 302 Found
Cache-Control: private
Content-Type: text/html; charset=UTF-8
Location: http://www.google.se/?gfe_rd=cr&ei=GZHSV-t69OTwB4uNp5gC
Content-Length: 256
Date: Fri, 09 Sep 2016 10:38:17 GMT