C Socket编程服务器向多个客户端发送相同的消息

Question

所以我对套接字编程很陌生。

我有一个基本的字链游戏，可以打印出该单词是否正确(从前一个单词的最后一个字母开始)。

我希望这个程序与多个客户端通信，并将消息(“正确”或“错误”)发送给所有客户端，而不仅仅是发送单词的客户端。

服务器代码:

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

#define PORT 4444

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

    int sockfd, ret;
     struct sockaddr_in serverAddr;

    int newSocket;
    struct sockaddr_in newAddr;
    char lastchar = 'a';
    socklen_t addr_size;

    char buffer[1024];
    pid_t childpid;

    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if(sockfd < 0){
        printf("[-]Error in connection.\n");
        exit(1);
    }
    printf("[+]Server Socket is created.\n");

    memset(&serverAddr, '\0', sizeof(serverAddr));
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(PORT);
    serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");

    ret = bind(sockfd, (struct sockaddr*)&serverAddr, sizeof(serverAddr));
    if(ret < 0){
        printf("[-]Error in binding.\n");
        exit(1);
    }
    printf("[+]Bind to port %d\n", 4444);

    if(listen(sockfd, 10) == 0){
        printf("[+]Listening....\n");
    }else{
        printf("[-]Error in binding.\n");
    }


    while(1){
        newSocket = accept(sockfd, (struct sockaddr*)&newAddr, &addr_size);
        if(newSocket < 0){
            exit(1);
        }
        printf("Connection accepted from %s:%d\n", inet_ntoa(newAddr.sin_addr), ntohs(newAddr.sin_port));

        if((childpid = fork()) == 0){
            close(sockfd);

            while(1){
                recv(newSocket, buffer, 1024, 0);

                if(strcmp(buffer, ":exit") == 0){
                    printf("Disconnected from %s:%d\n", inet_ntoa(newAddr.sin_addr), ntohs(newAddr.sin_port));
                    break;
                }else{

                    if(buffer[0]==lastchar){
                        lastchar = buffer[strlen(buffer)-1];
                        bzero(buffer, sizeof(buffer));
                        strcpy(buffer, "Correct!");
                    }else{          
                        bzero(buffer, sizeof(buffer));
                        strcpy(buffer, "Wrong!");
                    }
                    send(newSocket, buffer, strlen(buffer), 0);
                    bzero(buffer, sizeof(buffer));
                }
            }
        }

    }

    close(newSocket);


    return 0;
}

客户端代码:

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

#define PORT 4444

int main(){

    int clientSocket, ret;
    struct sockaddr_in serverAddr;
    char buffer[1024];

    clientSocket = socket(AF_INET, SOCK_STREAM, 0);
    if(clientSocket < 0){
        printf("[-]Error in connection.\n");
        exit(1);
    }
    printf("[+]Client Socket is created.\n");

    memset(&serverAddr, '\0', sizeof(serverAddr));
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(PORT);
    serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");

    ret = connect(clientSocket, (struct sockaddr*)&serverAddr, sizeof(serverAddr));
    if(ret < 0){
        printf("[-]Error in connection.\n");
        exit(1);
    }
    printf("[+]Connected to Server.\n");

    while(1){
        printf("Client: \t");
        scanf("%s", &buffer[0]);
        send(clientSocket, buffer, strlen(buffer), 0);

        if(strcmp(buffer, ":exit") == 0){
            close(clientSocket);
            printf("[-]Disconnected from server.\n");
            exit(1);
        }

        if(recv(clientSocket, buffer, 1024, 0) < 0){
            printf("[-]Error in receiving data.\n");
        }else{
            printf("Server: \t%s\n", buffer);
        }
    }

    return 0;
}

感谢您的帮助!

Answer 1

您需要与每个客户端保持连接。套接字允许双向通信。因此，首先与每个客户端建立套接字连接，然后启动游戏，然后就可以向所有客户端发送消息。