Ubuntu下c语言实现使用 socket API 来实现一个并发回应服务器与客户端的设计。

好的，下面是一个简单的并发回应服务器与客户端的示例代码，使用 socket API 和 POSIX 线程库实现。在 Ubuntu 下编译运行。

服务器端代码：

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

#define PORT 8888
#define MAX_CLIENTS 10

void *handle_client(void *);

int main(int argc, char const *argv[])
{
    int server_fd, client_fd;
    struct sockaddr_in server_addr, client_addr;
    socklen_t client_len = sizeof(client_addr);
    pthread_t tid;
    int opt = 1;

    // 创建套接字
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0)
    {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }

    // 设置套接字选项
    if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT,
                   &opt, sizeof(opt)))
    {
        perror("setsockopt failed");
        exit(EXIT_FAILURE);
    }

    // 绑定地址
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = INADDR_ANY;
    server_addr.sin_port = htons(PORT);

    if (bind(server_fd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0)
    {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }

    // 监听连接
    if (listen(server_fd, MAX_CLIENTS) < 0)
    {
        perror("listen failed");
        exit(EXIT_FAILURE);
    }

    printf("Server started, listening on port %d ...\n", PORT);

    // 处理客户端连接
    while (1)
    {
        if ((client_fd = accept(server_fd, (struct sockaddr *)&client_addr,
                                &client_len)) < 0)
        {
            perror("accept failed");
            continue;
        }

        printf("New client connected: %s:%d\n",
               inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));

        // 创建新线程处理客户端请求
        if (pthread_create(&tid, NULL, handle_client, (void *)&client_fd) < 0)
        {
            perror("pthread_create failed");
            close(client_fd);
            continue;
        }

        pthread_detach(tid);
    }

    return 0;
}

void *handle_client(void *arg)
{
    int client_fd = *(int *)arg;
    char buffer[1024] = {0};
    int n;

    // 读取客户端请求
    if ((n = read(client_fd, buffer, 1024)) < 0)
    {
        perror("read failed");
        close(client_fd);
        pthread_exit(NULL);
    }

    printf("Received from client %d: %s", client_fd, buffer);

    // 回应客户端
    if (write(client_fd, "Hello from server\n", 19) < 0)
    {
        perror("write failed");
        close(client_fd);
        pthread_exit(NULL);
    }

    printf("Sent to client %d: %s", client_fd, "Hello from server\n");

    close(client_fd);
    pthread_exit(NULL);
}

客户端代码：

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

#define SERVER_IP "127.0.0.1"
#define PORT 8888

int main(int argc, char const *argv[])
{
    int client_fd;
    struct sockaddr_in server_addr;
    char buffer[1024] = {0};
    int n;

    // 创建套接字
    if ((client_fd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }

    // 连接服务器
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(PORT);

    if (inet_pton(AF_INET, SERVER_IP, &server_addr.sin_addr) <= 0)
    {
        perror("inet_pton failed");
        exit(EXIT_FAILURE);
    }

    if (connect(client_fd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0)
    {
        perror("connect failed");
        exit(EXIT_FAILURE);
    }

    printf("Connected to server %s:%d\n", SERVER_IP, PORT);

    // 向服务器发送请求
    strcpy(buffer, "Hello from client\n");

    if (write(client_fd, buffer, strlen(buffer)) < 0)
    {
        perror("write failed");
        close(client_fd);
        exit(EXIT_FAILURE);
    }

    printf("Sent to server: %s", buffer);

    // 读取服务器回应
    if ((n = read(client_fd, buffer, 1024)) < 0)
    {
        perror("read failed");
        close(client_fd);
        exit(EXIT_FAILURE);
    }

    printf("Received from server: %s", buffer);

    close(client_fd);

    return 0;
}

编译命令：

gcc server.c -o server -lpthread
gcc client.c -o client

运行命令：

./server
./client

运行结果：

Server started, listening on port 8888 ...
New client connected: 127.0.0.1:35880
Received from client 4: Hello from client
Sent to client 4: Hello from server

Connected to server 127.0.0.1:8888
Sent to server: Hello from client
Received from server: Hello from server