Linux C语言tcp套接字多人聊天室，可实现私聊广播，编写服务器和客户端代码

服务器端代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <pthread.h>

#define MAX_CLIENTS 10
#define BUFFER_SIZE 1024

int client_count = 0;  // 客户端数量
int client_sockets[MAX_CLIENTS];  // 客户端套接字
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;  // 互斥锁

// 发送消息给所有客户端，除了发送者
void broadcast(char *message, int sender_socket) {
    pthread_mutex_lock(&mutex);  // 加锁
    for (int i = 0; i < client_count; i++) {
        int socket_fd = client_sockets[i];
        if (socket_fd != sender_socket) {
            send(socket_fd, message, strlen(message), 0);
        }
    }
    pthread_mutex_unlock(&mutex);  // 解锁
}

// 发送消息给指定客户端
void send_to(char *message, int receiver_socket) {
    send(receiver_socket, message, strlen(message), 0);
}

// 处理客户端消息
void *handle_client(void *arg) {
    int client_socket = *(int *)arg;
    char buffer[BUFFER_SIZE];
    while (1) {
        memset(buffer, 0, BUFFER_SIZE);
        int bytes_received = recv(client_socket, buffer, BUFFER_SIZE, 0);
        if (bytes_received <= 0) {
            // 客户端断开连接
            pthread_mutex_lock(&mutex);
            for (int i = 0; i < client_count; i++) {
                if (client_sockets[i] == client_socket) {
                    client_count--;
                    for (int j = i; j < client_count; j++) {
                        client_sockets[j] = client_sockets[j+1];
                    }
                    break;
                }
            }
            pthread_mutex_unlock(&mutex);
            close(client_socket);
            break;
        }
        if (buffer[0] == '@') {
            // 私聊消息
            char *username = strtok(buffer+1, " ");
            char *message = strtok(NULL, "\n");
            int receiver_socket = -1;
            pthread_mutex_lock(&mutex);
            for (int i = 0; i < client_count; i++) {
                if (strcmp(username, inet_ntoa(((struct sockaddr_in *)&client_sockets[i])->sin_addr)) == 0) {
                    receiver_socket = client_sockets[i];
                    break;
                }
            }
            pthread_mutex_unlock(&mutex);
            if (receiver_socket != -1) {
                char response[BUFFER_SIZE];
                sprintf(response, "(私聊)%s: %s", inet_ntoa(((struct sockaddr_in *)&client_socket)->sin_addr), message);
                send_to(response, receiver_socket);
            } else {
                char response[BUFFER_SIZE];
                sprintf(response, "用户 %s 不存在或不在线", username);
                send_to(response, client_socket);
            }
        } else {
            // 广播消息
            char response[BUFFER_SIZE];
            sprintf(response, "%s: %s", inet_ntoa(((struct sockaddr_in *)&client_socket)->sin_addr), buffer);
            broadcast(response, client_socket);
        }
    }
    return NULL;
}

int main(int argc, char *argv[]) {
    if (argc != 2) {
        printf("Usage: %s <port>\n", argv[0]);
        return -1;
    }

    int server_socket = socket(AF_INET, SOCK_STREAM, 0);
    if (server_socket == -1) {
        perror("socket");
        return -1;
    }

    int port = atoi(argv[1]);
    struct sockaddr_in server_addr;
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = INADDR_ANY;
    server_addr.sin_port = htons(port);

    if (bind(server_socket, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1) {
        perror("bind");
        close(server_socket);
        return -1;
    }

    if (listen(server_socket, MAX_CLIENTS) == -1) {
        perror("listen");
        close(server_socket);
        return -1;
    }

    pthread_t tid;
    while (1) {
        struct sockaddr_in client_addr;
        socklen_t client_addr_len = sizeof(client_addr);
        int client_socket = accept(server_socket, (struct sockaddr *)&client_addr, &client_addr_len);
        if (client_socket == -1) {
            perror("accept");
            continue;
        }
        if (client_count == MAX_CLIENTS) {
            printf("已达到最大客户端数量\n");
            close(client_socket);
            continue;
        }
        client_sockets[client_count++] = client_socket;
        printf("客户端 %s:%d 连接成功\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));
        pthread_create(&tid, NULL, handle_client, &client_socket);
        pthread_detach(tid);
    }

    close(server_socket);
    return 0;
}

客户端代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <pthread.h>

#define BUFFER_SIZE 1024

int sock_fd;  // 客户端套接字
char username[20];  // 用户名

// 接收服务器消息
void *receive_message(void *arg) {
    char buffer[BUFFER_SIZE];
    while (1) {
        memset(buffer, 0, BUFFER_SIZE);
        int bytes_received = recv(sock_fd, buffer, BUFFER_SIZE, 0);
        if (bytes_received <= 0) {
            // 服务器断开连接
            printf("与服务器断开连接\n");
            close(sock_fd);
            exit(0);
        }
        printf("%s\n", buffer);
    }
    return NULL;
}

int main(int argc, char *argv[]) {
    if (argc != 3) {
        printf("Usage: %s <server_ip> <server_port>\n", argv[0]);
        return -1;
    }

    sock_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (sock_fd == -1) {
        perror("socket");
        return -1;
    }

    char *server_ip = argv[1];
    int server_port = atoi(argv[2]);
    struct sockaddr_in server_addr;
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = inet_addr(server_ip);
    server_addr.sin_port = htons(server_port);

    if (connect(sock_fd, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1) {
        perror("connect");
        close(sock_fd);
        return -1;
    }

    printf("请输入用户名: ");
    scanf("%s", username);

    pthread_t tid;
    pthread_create(&tid, NULL, receive_message, NULL);  // 创建一个线程接收服务器消息
    pthread_detach(tid);

    char buffer[BUFFER_SIZE];
    while (1) {
        memset(buffer, 0, BUFFER_SIZE);
        fgets(buffer, BUFFER_SIZE, stdin);
        if (buffer[0] == '\n') {
            continue;
        }
        if (strcmp(buffer, "exit\n") == 0) {
            break;
        }
        if (buffer[0] == '@') {
            // 私聊消息
            char *username = strtok(buffer+1, " ");
            char *message = strtok(NULL, "\n");
            if (message != NULL) {
                char request[BUFFER_SIZE];
                sprintf(request, "@%s %s\n", username, message);
                send(sock_fd, request, strlen(request), 0);
            }
        } else {
            // 广播消息
            char request[BUFFER_SIZE];
            sprintf(request, "%s\n", buffer);
            send(sock_fd, request, strlen(request), 0);
        }
    }

    close(sock_fd);
    return 0;
}