c消息问题中的客户端服务器程序

Question

我最近用 c 编写了一个服务器客户端程序，但它似乎不起作用。编译它时我得到的唯一一件事是警告和客户端出现故障的事实。谁能帮我一点忙？

这是服务器代码：

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

int main()
{
    int server_socket;
    server_socket = socket(AF_INET,SOCK_STREAM,0);
    struct sockaddr_in server_address;
    int addrlen = sizeof(server_address);
    server_address.sin_family = AF_INET;
    server_address.sin_port = htons(9000);
    server_address.sin_addr.s_addr = INADDR_ANY;

    bind (server_socket, (struct sockaddr*) &server_address, sizeof(server_address));
    int client_socket;
    listen(server_socket, 3);
    client_socket=accept(server_socket, NULL, (socklen_t*)&addrlen);
    char response[256];

    recv(server_socket, &response, sizeof(response), 0);

    printf("%s",response);
    pclose (server_socket);
    return (0);
}

这是客户端代码：

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

int main()
{ 
    int network_socket; 
    network_socket = socket(AF_INET,SOCK_STREAM, 0);

    struct sockaddr_in server_address; 
    server_address.sin_family = AF_INET; 
    server_address.sin_port = htons(9000); 
    server_address.sin_addr.s_addr = INADDR_ANY; 

    int connection_status = connect(network_socket, (struct sockaddr*)&server_address, sizeof(server_address));
    if (connection_status == -1) { printf("ERROR"); } 

    char maw[256] = "this is a message"; send(network_socket, maw, sizeof(maw), 0); close(server_address); 
    return(0); 

    pclose(network_socket); 
}

Answer 1

服务器代码也有错误。

服务器代码：

当您想接收来自客户端的消息时，您必须在recv() 函数的代码中使用client_socket。不是server_socket 本身。

客户端代码：

为什么要使用pclose() 函数来关闭套接字？它用于管道并且需要一个FILE 指针。此外，该函数永远不会被调用（在 return 语句之后）。

这应该可以工作（在我的系统上测试过）：

服务器：

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

int main()
{
    int server_socket;
    server_socket = socket(AF_INET,SOCK_STREAM,0);
    struct sockaddr_in server_address;
    int addrlen = sizeof(server_address);
    server_address.sin_family = AF_INET;
    server_address.sin_port = htons(9000);
    server_address.sin_addr.s_addr = INADDR_ANY;

    bind (server_socket, (struct sockaddr*) &server_address, sizeof(server_address));
    int client_socket;
    listen(server_socket, 3);
    client_socket=accept(server_socket, NULL, (socklen_t*)&addrlen);
    char response[256];

    recv(client_socket, &response, sizeof(response), 0);

    printf("%s",response);
    shutdown (client_socket, SHUT_RDWR);
    close (client_socket);
    shutdown (server_socket, SHUT_RDWR);
    close (server_socket);
    return (0);
}

客户：

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

int main()
{ 
    int network_socket; 
    network_socket = socket(AF_INET,SOCK_STREAM, 0);

    struct sockaddr_in server_address; 
    server_address.sin_family = AF_INET; 
    server_address.sin_port = htons(9000); 
    server_address.sin_addr.s_addr = INADDR_ANY; 

    int connection_status = connect(network_socket, (struct sockaddr*)&server_address, sizeof(server_address));
    if (connection_status == -1) { printf("ERROR"); } 

    char maw[256] = "this is a message"; 
    send(network_socket, maw, sizeof(maw), 0);
    shutdown (network_socket, SHUT_RDWR);
    close(network_socket);
    return(0);
}

对于函数shutdown()，请参见answer。