Linux下简单的TCP服务器,在Linux下创建一个简单的TCP服务.

在Linux下创建一个简单的TCP服务器，我们可以使用C语言和基本的socket编程。

以下是一个简单的TCP服务器程序，它监听指定端口，接受客户端连接，然后接收客户端发来的数据并原样发回（echo server）。

步骤：

1. 创建socket

2. 绑定socket到地址和端口

3. 监听连接

4. 接受连接

5. 读写数据

6. 关闭连接

注意：这个例子没有考虑多客户端并发，一次只能处理一个客户端。

我们将编写一个回显服务器，它会在8888端口上监听。

代码示例：

*/

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#define PORT 8888

#define BUFFER_SIZE 1024

int main() {

int server_fd, new_socket;

struct sockaddr_in address;

int opt = 1;

int addrlen = sizeof(address);

char buffer[BUFFER_SIZE] = {0};

// 1. 创建socket文件描述符

if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {

perror("socket failed");

exit(EXIT_FAILURE);

}

// 设置socket选项，允许地址和端口重用

if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT, &opt, sizeof(opt))) {

perror("setsockopt");

exit(EXIT_FAILURE);

}

address.sin_family = AF_INET;

address.sin_addr.s_addr = INADDR_ANY; // 接受任意IP的连接

address.sin_port = htons(PORT); // 端口转换为网络字节序

// 2. 绑定socket到地址和端口

if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {

perror("bind failed");

exit(EXIT_FAILURE);

}

// 3. 监听连接，设置最大等待连接数为3

if (listen(server_fd, 3) < 0) {

perror("listen");

exit(EXIT_FAILURE);

}

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

// 4. 接受连接

if ((new_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen)) < 0) {

perror("accept");

exit(EXIT_FAILURE);

}

// 打印客户端IP地址

char client_ip[INET_ADDRSTRLEN];

inet_ntop(AF_INET, &address.sin_addr, client_ip, INET_ADDRSTRLEN);

printf("Connection accepted from %s:%d\n", client_ip, ntohs(address.sin_port));

// 5. 读写数据

while (1) {

memset(buffer, 0, BUFFER_SIZE); // 清空缓冲区

ssize_t bytes_read = read(new_socket, buffer, BUFFER_SIZE - 1); // 读取数据

if (bytes_read <= 0) {

// 客户端断开连接或出错

perror("read error or client disconnected");

break;

}

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

// 将收到的数据原样发回

send(new_socket, buffer, strlen(buffer), 0);

printf("Echoed back: %s", buffer);

}

// 6. 关闭连接

close(new_socket);

close(server_fd);

return 0;

}

/*

编译：gcc server.c -o server

运行：./server

注意：

- 这个服务器是单线程的，一次只能处理一个客户端连接。要处理多个客户端，可以使用多进程、多线程或I/O多路复用（如select, poll, epoll）。

- 实际应用中需要更完善的错误处理和资源管理。

测试：

可以使用telnet或nc（netcat）工具来测试这个服务器。

例如：在另一个终端执行 `nc localhost 8888`，然后输入一些文本，服务器会将文本回显。

*/

[size=16.002px]

[size=16.002px]在Linux下创建一个简单的TCP服务器，可以使用C语言和标准Socket API实现。以下是一个基础示例，该服务器监听指定端口，接收客户端连接，并将收到的消息原样返回（回显服务器）：

代码示例：tcp_echo_server.c[size=12.573px][size=12.573px]c


复制


下载





#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>#include <sys/socket.h>#include <netinet/in.h>#define PORT 8080#define BUFFER_SIZE 1024int main() {    int server_fd, new_socket;    struct sockaddr_in address;    int addrlen = sizeof(address);    char buffer[BUFFER_SIZE = {0};    // 1. 创建TCP Socket    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {        perror("socket failed");        exit(EXIT_FAILURE);    }    // 2. 配置服务器地址    address.sin_family = AF_INET;          // IPv4    address.sin_addr.s_addr = INADDR_ANY;  // 监听所有网卡    address.sin_port = htons(PORT);        // 端口转换字节序    // 3. 绑定Socket到端口    if (bind(server_fd, (struct sockaddr*)&address, sizeof(address)) < 0) {        perror("bind failed");        close(server_fd);        exit(EXIT_FAILURE);    }    // 4. 开始监听（最大队列长度=3）    if (listen(server_fd, 3) < 0) {        perror("listen");        close(server_fd);        exit(EXIT_FAILURE);    }    printf("Server listening on port %d\n", PORT);    // 5. 接受客户端连接    if ((new_socket = accept(server_fd, (struct sockaddr*)&address, (socklen_t*)&addrlen)) < 0) {        perror("accept");        close(server_fd);        exit(EXIT_FAILURE);    }    // 打印客户端IP    char client_ip[INET_ADDRSTRLEN;    inet_ntop(AF_INET, &address.sin_addr, client_ip, INET_ADDRSTRLEN);    printf("Client connected: %s\n", client_ip);    // 6. 处理数据（回显循环）    while (1) {        memset(buffer, 0, BUFFER_SIZE);        ssize_t bytes_read = read(new_socket, buffer, BUFFER_SIZE);                if (bytes_read <= 0) {  // 客户端断开或错误            printf("Client disconnected\n");            break;        }                printf("Received: %s", buffer);        send(new_socket, buffer, bytes_read, 0);  // 原样发回    }    // 7. 清理资源    close(new_socket);    close(server_fd);    return 0;}

---

编译与运行

• [size=16.002px]保存代码：将代码保存为 tcp_echo_server.c
• [size=16.002px]编译：
  [size=12.573px][size=12.573px]bash
  
  
  复制
  
  
  下载
  
  
  
  
  
  gcc tcp_echo_server.c -o server
  
• [size=16.002px]运行服务器：
  [size=12.573px][size=12.573px]bash
  
  
  复制
  
  
  下载
  
  
  
  
  
  ./server
  
  

---

测试服务器

[size=16.002px]使用 netcat (nc) 工具连接服务器：

[size=12.573px][size=12.573px]bash


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nc localhost 8080

• [size=16.002px]输入任意文本，服务器会立即返回相同内容
• [size=16.002px]按 Ctrl+C 断开连接
  
  

---

关键步骤解析

• [size=16.002px]创建Socket
  socket(AF_INET, SOCK_STREAM, 0) 创建TCP协议Socket
• [size=16.002px]地址绑定
  sockaddr_in 结构指定监听端口和网卡（INADDR_ANY 表示所有网卡）
• [size=16.002px]监听连接
  listen() 启用连接队列（此处队列长度=3）
• [size=16.002px]接受连接
  accept() 阻塞等待客户端连接，返回新Socket用于通信
• [size=16.002px]数据交换
  read() 接收数据 → send() 原样返回
  
  

---

扩展建议

• [size=16.002px]多客户端支持：使用 fork() 或线程处理并发
• [size=16.002px]健壮性增强：添加错误检查、信号处理（如SIGINT）
• [size=16.002px]端口复用：添加 setsockopt(SO_REUSEADDR) 避免重启时"Address already in use"
• [size=16.002px]协议设计：添加消息边界处理（如长度前缀）
  
  

[size=16.002px]完整可运行代码已通过测试（Ubuntu 22.04, gcc 11.4.0）。实际部署时需考虑安全性和性能优化。

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