Question

我正在编写一个客户端程序，它建立套接字，连接到远程服务器，并发出HTTP请求。但是，我似乎无法连接到远程服务器。

我相信我已经做好了一切，甚至为sockaddr_in设置了正确的端口＃，但我仍然无法连接。

我错过了什么？

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

int main(int argc, char *argv[])
{
    FILE *fout;

    int i, c, sk;
    char *tk, host[64], path[64], fname[64], http_msg[256], buf[1024];

    struct sockaddr_in remote;
    struct hostent *hp;
    struct servent *se;

    if(argc != 2)
    {
        printf("Invalid number of arguments. Program terminating...\n");
        exit(1);
    }

    sk = socket(AF_INET, SOCK_STREAM, 0);
    remote.sin_family = AF_INET;

    c = 0;
    tk = strtok(argv[1], "/");
    while(tk != NULL)
    {
        if(c == 0)
            strcpy(host, tk);
        else if(c == 1)
            strcpy(path, tk);
        else
            strcpy(fname, tk);
        ++c;
        tk = strtok(NULL, "/");
    }

    snprintf(http_msg, 256, "GET /%s/%s HTTP/1.1\r\nHost: %s\r\nConnection: close\r\n\n", path, fname, host);

    hp = gethostbyname(host);
    if(hp == NULL)
    {
        printf("Can't find host %s. Program terminating...\n", host);
        exit(1);
    }

    se = getservbyname("http", "tcp");
    remote.sin_port = ntohs(se->s_port);

    if(connect(sk, (struct sockaddr*)&remote, sizeof(remote)) < 0)
    {
        printf("Connection attempt failed. Program terminating...\n");
        exit(1);
    }

    send(sk, http_msg, sizeof(http_msg) + 1, 0);
    recv(sk, buf, sizeof(buf), 0);
    printf("%s\n", buf);

    return 0;
}

Answer 1

我明白了

问题在于

行

remote.sin_port = ntohs(se->s_port);

您不需要转换它。这段代码适合我：

if(argc != 2)                                                              
{                                                                          
    printf("Invalid number of arguments. Program terminating...\n");       
    exit(1);                                                               
}                                                                          

bzero(&remote, sizeof(remote));                                            
sk = socket(AF_INET, SOCK_STREAM, 0);                                      
remote.sin_family = AF_INET;                                               

c = 0;                                                                     
tk = strtok(argv[1], "/");                                                 
while(tk != NULL)                                                          
{                                                                          
    if(c == 0)                                                             
        strcpy(host, tk);                                                  
    else if(c == 1)                                                        
        strcpy(path, tk);                                                  
    else                                                                   
        strcpy(fname, tk);                                                 
    ++c;                                                                   
    tk = strtok(NULL, "/");                                                
}                                                                          

snprintf(http_msg, 256, "GET /%s/%s HTTP/1.1\r\nHost: %s\r\nConnection: close\r\n\r\n", path, fname, host); 

hp = gethostbyname(host);                                                  
if(hp == NULL)                                                             
{                                                                          
    printf("Can't find host %s. Program terminating...\n", host);          
    exit(1);                                                               
}                                                                          

se = getservbyname("http", "tcp");                                         
printf("%d port\n", ntohs(se->s_port));                                    
remote.sin_port = se->s_port;                                              
bcopy((char *)hp->h_addr, (char *)&remote.sin_addr.s_addr, hp->h_length);  

if(connect(sk, (struct sockaddr*)&remote, sizeof(remote)) < 0)             
{                                                                          
    printf("Connection attempt failed. Program terminating...\n");         
    exit(1);                                                               
}                                                                          

send(sk, http_msg, sizeof(http_msg) + 1, 0);                               
recv(sk, buf, sizeof(buf), 0);                                             
printf("%s\n", buf);                                                       

return 0;

}

Answer 2

这样做：

remote.sin_port = ntohs(se->s_port);
remote.sin_family = AF_INET;
remote.sin_addr = *((struct in_addr *) hp->h_addr);

应该这样做。连接后请参阅\ r \ n \ r \ n：关闭。

snprintf(http_msg, 256, "GET /%s/%s HTTP/1.1\r\nHost: %s\r\nConnection: close\r\n\r\n", path, fname, host);

无法通过Socket-C连接到HTTP服务

2 个答案: