Linux环境下实现简单TCP通信（c）

具体代码实现

server.c

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

#define PORT 8080
#define BUFFER_SIZE 1024

void handle_client(int client_socket) {
    char buffer[BUFFER_SIZE];
    
    while(1) {
        memset(buffer, 0, BUFFER_SIZE);
        
        // 接收客户端消息
        int bytes_received = recv(client_socket, buffer, BUFFER_SIZE, 0);
        if (bytes_received <= 0) {
            printf("Client disconnected or error occurred.\n");
            break;
        }
        
        printf("Client: %s", buffer);
        
        // 检查是否要结束通信
        if (strncmp(buffer, "exit", 4) == 0) {
            printf("Exit command received. Closing connection.\n");
            break;
        }
        
        // 发送响应
        printf("Server: ");
        fgets(buffer, BUFFER_SIZE, stdin);
        send(client_socket, buffer, strlen(buffer), 0);
        
        // 检查服务器是否要结束通信
        if (strncmp(buffer, "exit", 4) == 0) {
            printf("Server initiated exit. Closing connection.\n");
            break;
        }
    }
    
    close(client_socket);
}

int main() {
    int server_fd, client_socket;
    struct sockaddr_in address;
    int opt = 1;
    int addrlen = sizeof(address);
    
    // 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
    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;
    address.sin_port = htons(PORT);
    
    // 绑定socket到端口
    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }
    
    // 开始监听
    if (listen(server_fd, 3) < 0) {
        perror("listen");
        exit(EXIT_FAILURE);
    }
    
    printf("Server listening on port %d...\n", PORT);
    
    // 接受连接
    if ((client_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen)) < 0) {
        perror("accept");
        exit(EXIT_FAILURE);
    }
    
    printf("Connection accepted from %s:%d\n", 
           inet_ntoa(address.sin_addr), ntohs(address.sin_port));
    
    // 处理客户端通信
    handle_client(client_socket);
    
    printf("Closing server...\n");
    close(server_fd);
    
    return 0;
}

client.c

client分为两版，分别是实现本地通信和与特定ip地址的server通信

本地通信

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

#define PORT 8080
#define BUFFER_SIZE 1024

void communicate(int sock) {
    char buffer[BUFFER_SIZE];
    
    while(1) {
        // 发送消息
        printf("Client: ");
        fgets(buffer, BUFFER_SIZE, stdin);
        send(sock, buffer, strlen(buffer), 0);
        
        // 检查是否要结束通信
        if (strncmp(buffer, "exit", 4) == 0) {
            printf("Exiting...\n");
            break;
        }
        
        // 接收服务器响应
        memset(buffer, 0, BUFFER_SIZE);
        int bytes_received = recv(sock, buffer, BUFFER_SIZE, 0);
        if (bytes_received <= 0) {
            printf("Server disconnected or error occurred.\n");
            break;
        }
        
        printf("Server: %s", buffer);
        
        // 检查服务器是否要结束通信
        if (strncmp(buffer, "exit", 4) == 0) {
            printf("Server initiated exit. Closing connection.\n");
            break;
        }
    }
}

int main() {
    int sock = 0;
    struct sockaddr_in serv_addr;
    
    // 创建socket
    if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        printf("\n Socket creation error \n");
        return -1;
    }
    
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(PORT);
    
    // 将IPv4地址从文本转换为二进制形式
    if (inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr) <= 0) {
        printf("\nInvalid address/ Address not supported \n");
        return -1;
    }
    
    // 连接到服务器
    if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
        printf("\nConnection Failed \n");
        return -1;
    }
    
    printf("Connected to server\n");
    
    // 开始通信
    communicate(sock);
    
    printf("Closing client...\n");
    close(sock);
    
    return 0;
}

特定IP通信

与上面相比，修改了客户端代码中的目标服务器地址

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

#define PORT 8080
#define BUFFER_SIZE 1024

void communicate(int sock) {
    char buffer[BUFFER_SIZE];
    
    while(1) {
        // 发送消息
        printf("Client: ");
        fgets(buffer, BUFFER_SIZE, stdin);
        send(sock, buffer, strlen(buffer), 0);
        
        // 检查是否要结束通信
        if (strncmp(buffer, "exit", 4) == 0) {
            printf("Exiting...\n");
            break;
        }
        
        // 接收服务器响应
        memset(buffer, 0, BUFFER_SIZE);
        int bytes_received = recv(sock, buffer, BUFFER_SIZE, 0);
        if (bytes_received <= 0) {
            printf("Server disconnected or error occurred.\n");
            break;
        }
        
        printf("Server: %s", buffer);
        
        // 检查服务器是否要结束通信
        if (strncmp(buffer, "exit", 4) == 0) {
            printf("Server initiated exit. Closing connection.\n");
            break;
        }
    }
}

int main(int argc, char const *argv[]) {
    int sock = 0;
    struct sockaddr_in serv_addr;
    
    // 检查参数
    if (argc != 2) {
        printf("Usage: %s <server_ip>\n", argv[0]);
        return -1;
    }
    
    // 创建socket
    if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        printf("\n Socket creation error \n");
        return -1;
    }
    
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(PORT);
    
    // 将用户输入的IP地址从文本转换为二进制形式
    if (inet_pton(AF_INET, argv[1], &serv_addr.sin_addr) <= 0) {
        printf("\nInvalid address/ Address not supported \n");
        return -1;
    }
    
    // 连接到服务器
    if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
        printf("\nConnection Failed to %s:%d\n", argv[1], PORT);
        return -1;
    }
    
    printf("Connected to server at %s:%d\n", argv[1], PORT);
    
    // 开始通信
    communicate(sock);
    
    printf("Closing client...\n");
    close(sock);
    
    return 0;
}

功能说明

• 服务器和客户端可以持续收发消息，直到输入"exit"命令
• 服务器和客户端都可以主动结束通信
• 每次发送消息前会显示提示符(Client: 或 Server:)
• 任何一方输入"exit"都会终止通信，且会检测对方是否断开连接

具体使用方法

1、编译

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

2、服务器运行

./server

3、客户端运行（在另一个终端）

./client					# 本地通信版
./client 目标服务器IP		# 特定IP通信
							# 要连接本地主机，可以使用127.0.0.1

4、通信

在客户端或服务器终端输入消息，按回车发送