Question

这些代码来自https://www.geeksforgeeks.org/udp-server-client-implementation-c/。当在同一台计算机上运行服务器和客户端时，它运行良好。但是如果在同一网络中的两台不同计算机上运行（它们可以互相ping通）。那么服务器将不会从客户端收到Hello。我注意到服务器和客户端设置地址均为INADDR_ANY。这意味着局域网中有任何机器，对吗？我尝试在客户端指定服务器的IP地址。服务器仍然不会从客户端收到消息。

请给我一些线索。谢谢。

server.c

// Server side implementation of UDP client-server model 
#include <stdio.h> 
#include <stdlib.h> 
#include <unistd.h> 
#include <string.h> 
#include <sys/types.h> 
#include <sys/socket.h> 
#include <arpa/inet.h> 
#include <netinet/in.h> 

#define PORT     8080 
#define MAXLINE 1024 

// Driver code 
int main() { 
    int sockfd; 
    char buffer[MAXLINE]; 
    char *hello = "Hello from server"; 
    struct sockaddr_in servaddr, cliaddr; 

    // Creating socket file descriptor 
    if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 ) { 
        perror("socket creation failed"); 
        exit(EXIT_FAILURE); 
    } 

    memset(&servaddr, 0, sizeof(servaddr)); 
    memset(&cliaddr, 0, sizeof(cliaddr)); 

    // Filling server information 
    servaddr.sin_family = AF_INET; // IPv4 
    servaddr.sin_addr.s_addr = INADDR_ANY; 
    servaddr.sin_port = htons(PORT); 

    // Bind the socket with the server address 
    if ( bind(sockfd, (const struct sockaddr *)&servaddr, 
            sizeof(servaddr)) < 0 ) 
    { 
        perror("bind failed"); 
        exit(EXIT_FAILURE); 
    } 

    int len, n; 
    n = recvfrom(sockfd, (char *)buffer, MAXLINE, 
                MSG_WAITALL, ( struct sockaddr *) &cliaddr, 
                &len); 
    buffer[n] = '\0'; 
    printf("Client : %s\n", buffer); 
    sendto(sockfd, (const char *)hello, strlen(hello), 
        MSG_CONFIRM, (const struct sockaddr *) &cliaddr, 
            len); 
    printf("Hello message sent.\n"); 

    return 0; 
}

client.c

// Client side implementation of UDP client-server model 
#include <stdio.h> 
#include <stdlib.h> 
#include <unistd.h> 
#include <string.h> 
#include <sys/types.h> 
#include <sys/socket.h> 
#include <arpa/inet.h> 
#include <netinet/in.h> 

#define PORT     8080 
#define MAXLINE 1024 

// Driver code 
int main() { 
    int sockfd; 
    char buffer[MAXLINE]; 
    char *hello = "Hello from client"; 
    struct sockaddr_in   servaddr; 

    // Creating socket file descriptor 
    if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 ) { 
        perror("socket creation failed"); 
        exit(EXIT_FAILURE); 
    } 

    memset(&servaddr, 0, sizeof(servaddr)); 

    // Filling server information 
    servaddr.sin_family = AF_INET; 
    servaddr.sin_port = htons(PORT); 
    servaddr.sin_addr.s_addr = INADDR_ANY; 

    int n, len; 

    sendto(sockfd, (const char *)hello, strlen(hello), 
        MSG_CONFIRM, (const struct sockaddr *) &servaddr, 
            sizeof(servaddr)); 
    printf("Hello message sent.\n"); 

    n = recvfrom(sockfd, (char *)buffer, MAXLINE, 
                MSG_WAITALL, (struct sockaddr *) &servaddr, 
                &len); 
    buffer[n] = '\0'; 
    printf("Server : %s\n", buffer); 

    close(sockfd); 
    return 0; 
}

Answer 1

在client.c中进行以下更改。（192.168.1.1）是服务器的IP地址。然后他们说话。

//servaddr.sin_addr.s_addr = INADDR_ANY; 
 servaddr.sin_addr.s_addr = inet_addr("192.168.1.1");

不同计算机上的UDP套接字服务器/客户端无法通信

1 个答案: