C语言多进程TCP服务器与客户端

一、多进程TCP服务器的创建

        示例代码如下：

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

#define PORT 8080
#define MAX_CLIENTS 10
#define BUFFER_SIZE 1024

// 僵尸进程处理
void zombie_handler(int sig) {
    while (waitpid(-1, NULL, WNOHANG) > 0);
}

int main() {
    int server_fd, new_socket;
    struct sockaddr_in address;
    int addrlen = sizeof(address);
    char buffer[BUFFER_SIZE] = {0};
    
    // 创建TCP套接字
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }
    
    // 设置SO_REUSEADDR
    int opt = 1;
    if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt))) {
        perror("setsockopt failed");
        exit(EXIT_FAILURE);
    }
    
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(PORT);
    
    // 绑定套接字
    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }
    
    // 开始监听
    if (listen(server_fd, MAX_CLIENTS) < 0) {
        perror("listen failed");
        exit(EXIT_FAILURE);
    }
    
    printf("Server listening on port %d\n", PORT);
    
    // 设置僵尸进程处理器
    struct sigaction sa;
    sa.sa_handler = zombie_handler;
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = SA_RESTART;
    if (sigaction(SIGCHLD, &sa, NULL) == -1) {
        perror("sigaction failed");
        exit(EXIT_FAILURE);
    }
    
    while (1) {
        // 接受新连接
        if ((new_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen)) < 0) {
            perror("accept failed");
            continue;
        }
        
        printf("New connection from %s:%d\n", 
               inet_ntoa(address.sin_addr), ntohs(address.sin_port));
        
        // 创建子进程处理连接
        pid_t pid = fork();
        if (pid < 0) {
            perror("fork failed");
            close(new_socket);
            continue;
        }
        
        if (pid == 0) { // 子进程
            close(server_fd); // 关闭不需要的监听套接字
            
            // 处理客户端请求
            while (1) {
                memset(buffer, 0, BUFFER_SIZE);
                ssize_t bytes_read = read(new_socket, buffer, BUFFER_SIZE - 1);
                
                if (bytes_read <= 0) {
                    if (bytes_read == 0) 
                        printf("Client disconnected\n");
                    else
                        perror("read error");
                    break;
                }
                
                printf("Received: %s", buffer);
                
                // 处理请求（示例：回显）
                char *response = "HTTP/1.1 200 OK\r\n"