具體代碼實現

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 1024void handle_client(int client_socket) {char buffer[BUFFER_SIZE];while(1) {memset(buffer, 0, BUFFER_SIZE);// 接收客戶端消息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);// 檢查是否要結束通信if (strncmp(buffer, "exit", 4) == 0) {printf("Exit command received. Closing connection.\n");break;}// 發送響應printf("Server: ");fgets(buffer, BUFFER_SIZE, stdin);send(client_socket, buffer, strlen(buffer), 0);// 檢查服務器是否要結束通信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);// 創建socket文件描述符if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {perror("socket failed");exit(EXIT_FAILURE);}// 設置socket選項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);// 綁定socket到端口if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {perror("bind failed");exit(EXIT_FAILURE);}// 開始監聽if (listen(server_fd, 3) < 0) {perror("listen");exit(EXIT_FAILURE);}printf("Server listening on port %d...\n", PORT);// 接受連接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));// 處理客戶端通信handle_client(client_socket);printf("Closing server...\n");close(server_fd);return 0;
}

client.c

client分為兩版，分別是實現本地通信和與特定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 1024void communicate(int sock) {char buffer[BUFFER_SIZE];while(1) {// 發送消息printf("Client: ");fgets(buffer, BUFFER_SIZE, stdin);send(sock, buffer, strlen(buffer), 0);// 檢查是否要結束通信if (strncmp(buffer, "exit", 4) == 0) {printf("Exiting...\n");break;}// 接收服務器響應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);// 檢查服務器是否要結束通信if (strncmp(buffer, "exit", 4) == 0) {printf("Server initiated exit. Closing connection.\n");break;}}
}int main() {int sock = 0;struct sockaddr_in serv_addr;// 創建socketif ((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);// 將IPv4地址從文本轉換為二進制形式if (inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr) <= 0) {printf("\nInvalid address/ Address not supported \n");return -1;}// 連接到服務器if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {printf("\nConnection Failed \n");return -1;}printf("Connected to server\n");// 開始通信communicate(sock);printf("Closing client...\n");close(sock);return 0;
}

特定IP通信

與上面相比，修改了客戶端代碼中的目標服務器地址

#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 1024void communicate(int sock) {char buffer[BUFFER_SIZE];while(1) {// 發送消息printf("Client: ");fgets(buffer, BUFFER_SIZE, stdin);send(sock, buffer, strlen(buffer), 0);// 檢查是否要結束通信if (strncmp(buffer, "exit", 4) == 0) {printf("Exiting...\n");break;}// 接收服務器響應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);// 檢查服務器是否要結束通信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;// 檢查參數if (argc != 2) {printf("Usage: %s <server_ip>\n", argv[0]);return -1;}// 創建socketif ((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);// 將用戶輸入的IP地址從文本轉換為二進制形式if (inet_pton(AF_INET, argv[1], &serv_addr.sin_addr) <= 0) {printf("\nInvalid address/ Address not supported \n");return -1;}// 連接到服務器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);// 開始通信communicate(sock);printf("Closing client...\n");close(sock);return 0;
}

功能說明

• 服務器和客戶端可以持續收發消息，直到輸入"exit"命令
• 服務器和客戶端都可以主動結束通信
• 每次發送消息前會顯示提示符(Client: 或 Server:)
• 任何一方輸入"exit"都會終止通信，且會檢測對方是否斷開連接

具體使用方法

1、編譯

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

2、服務器運行

./server

3、客戶端運行（在另一個終端）

./client					# 本地通信版
./client 目標服務器IP		# 特定IP通信# 要連接本地主機，可以使用127.0.0.1

4、通信

在客戶端或服務器終端輸入消息，按回車發送