基于UDP的网络聊天室

一.项目需求：

1. 如果有用户登录，其他用户可以收到这个人的登录信息
2. 如果有人发送信息，其他用户可以收到这个人的群聊信息
3. 如果有人下线，其他用户可以收到这个人的下线信息
4. 服务器可以发送系统信息

二.服务器端

#include <myhead.h> //服务器
#define SER_IP "192.168.125.48"
#define SER_PORT 8888
#define MAX_CLIENTS 100
#define BUFFER_SIZE 1024typedef struct Node {struct sockaddr_in addr;char username[20];struct Node *next;
} Node, *List;typedef struct Msg {char type; // 'L' 登陆模式, 'M' 消息模式, 'Q' 下线模式, 'S' 系统消息char username[20];char message[BUFFER_SIZE];
} Message;List client_list = NULL;// 添加客户端
void add_client(struct sockaddr_in *addr, const char *username) {Node *node = malloc(sizeof(Node));memcpy(&(node->addr), addr, sizeof(struct sockaddr_in));strncpy(node->username, username, 19);node->next = client_list;client_list = node;
}// 移除客户端
void remove_client(Node *node) {Node **prev = &client_list;while (*prev && *prev != node) {prev = &(*prev)->next;}if (*prev) {Node *temp = *prev;*prev = node->next;free(temp);}
}// 广播消息
void broadcast_message(int sfd, const Message *msg,struct sockaddr_in *except_addr) {Node *current = client_list;Message to_send = *msg;to_send.message[sizeof(to_send.message) - 1] ='\0'; // 确保消息字符串以null终止while (current) {if (memcmp(&(current->addr), except_addr, sizeof(struct sockaddr_in)) !=0) {sendto(sfd, (const char *)&to_send, sizeof(Message), 0,(struct sockaddr *)&(current->addr),sizeof(struct sockaddr_in));}current = current->next;}
}// 查找客户端
Node *find_client_by_addr(struct sockaddr_in *addr) {Node *current = client_list;while (current) {if (memcmp(&(current->addr), addr, sizeof(struct sockaddr_in)) == 0) {return current;}current = current->next;}return NULL;
}int main() {int sfd = socket(AF_INET, SOCK_DGRAM, 0);if (sfd < 0) {perror("socket creation failed");exit(EXIT_FAILURE);}int reuse = 1;if (setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) ==-1) {perror("setsockopt error");return -1;}struct sockaddr_in server_addr, client_addr;server_addr.sin_family = AF_INET;server_addr.sin_addr.s_addr = inet_addr(SER_IP);server_addr.sin_port = htons(SER_PORT);if (bind(sfd, (const struct sockaddr *)&server_addr, sizeof(server_addr)) <0) {perror("bind failed");exit(EXIT_FAILURE);}printf("************服务器**************\n");printf("**********等待客户端**************\n");char buffer[BUFFER_SIZE] = {0};struct timeval tv;fd_set readfds;int max_fd = sfd;tv.tv_sec = 5;tv.tv_usec = 0;while (1) {FD_ZERO(&readfds);FD_SET(sfd, &readfds);// 检查是否有新的客户端连接或消息int res = select(max_fd + 1, &readfds, NULL, NULL, &tv);if (res < 0) {perror("select error");break;} else if (res > 0) {if (FD_ISSET(sfd, &readfds)) {socklen_t client_len = sizeof(client_addr);int n = recvfrom(sfd, buffer, BUFFER_SIZE, 0,(struct sockaddr *)&client_addr, &client_len);if (n < 0) {perror("recvfrom error");continue;}buffer[n] = '\0'; // 确保字符串以null终止Message msg;memcpy(&msg, buffer,(n < sizeof(Message))? n: sizeof(Message)); // 防止缓冲区溢出switch (msg.type) {case 'L': // 客户端登录add_client(&client_addr, msg.username);printf("%s 已登录\n", msg.username);// 广播登录信息给所有客户端（除了发送者）Message login_msg;strncpy(login_msg.username, msg.username, 19);login_msg.type = 'L';login_msg.message[0] = '\0'; // 清空消息字段，因为是登录消息broadcast_message(sfd, &login_msg, &client_addr);break;case 'M': // 客户端发送消息printf("%s: %s\n", msg.username, msg.message);// 广播消息给所有客户端（除了发送者）broadcast_message(sfd, &msg, &client_addr);break;case 'Q': // 客户端退出{Node *node = find_client_by_addr(&client_addr);if (node) {printf("%s 已下线\n", node->username);Message quit_msg;strncpy(quit_msg.username, node->username, 19);quit_msg.type = 'Q';quit_msg.message[0] ='\0'; // 清空消息字段，因为是下线消息remove_client(node);broadcast_message(sfd, &quit_msg, &client_addr);}} break;case 'S': // 服务器系统消息printf("系统消息: %s\n", msg.message);// 广播系统消息给所有客户端broadcast_message(sfd, &msg, NULL);break;default:printf("未知的消息类型\n");break;}}}}close(sfd);return 0;
}

三.客户端

#include <myhead.h>
#define SER_IP "192.168.125.48"
#define SER_PORT 8888
#define BUFFER_SIZE 1024typedef struct Msg {char type; // 'L' 登陆模式, 'M' 消息模式, 'Q' 下线模式, 'S' 系统消息char username[20];char message[BUFFER_SIZE];
} Message;int main() {int sockfd = socket(AF_INET, SOCK_DGRAM, 0);if (sockfd < 0) {perror("socket creation failed");exit(EXIT_FAILURE);}struct sockaddr_in sin;memset(&sin, 0, sizeof(sin));sin.sin_family = AF_INET;sin.sin_addr.s_addr = inet_addr(SER_IP);sin.sin_port = htons(SER_PORT);char username[20];printf("输入您的名字: ");scanf("%19s", username); // 限制输入长度为19个字符，为null终止符留空间// 发送登录消息Message login_msg;login_msg.type = 'L';strncpy(login_msg.username, username, sizeof(login_msg.username) - 1);login_msg.message[0] = '\0'; // 清空消息字段，因为是登录消息sendto(sockfd, &login_msg, sizeof(login_msg), 0, (struct sockaddr *)&sin,sizeof(sin));char message[BUFFER_SIZE];char recv_buffer[BUFFER_SIZE];struct sockaddr_in from_addr;socklen_t len = sizeof(from_addr);while (1) {printf("输入消息 (or 'exit' to quit): ");if (scanf("%1023s", message) == EOF || strcmp(message, "exit") == 0) {// 发送退出消息Message quit_msg;quit_msg.type = 'Q';strncpy(quit_msg.username, username, sizeof(quit_msg.username) - 1);quit_msg.message[0] = '\0'; // 清空消息字段，因为是退出消息sendto(sockfd, &quit_msg, sizeof(quit_msg), 0,(struct sockaddr *)&sin, sizeof(sin));break;}while (getchar() != '\n'); // 清除输入缓冲区中的换行符// 发送消息到服务器Message send_msg;send_msg.type = 'M';strncpy(send_msg.username, username, sizeof(send_msg.username) - 1);strncpy(send_msg.message, message, sizeof(send_msg.message) - 1);send_msg.message[sizeof(send_msg.message) - 1] ='\0'; // 确保消息字符串以null终止sendto(sockfd, &send_msg, sizeof(send_msg), 0, (struct sockaddr *)&sin,sizeof(sin));// 接收服务器的广播消息（可能是其他客户端的消息或系统消息）int n = recvfrom(sockfd, recv_buffer, BUFFER_SIZE, 0,(struct sockaddr *)&from_addr, &len);if (n > 0) {Message *msg = (Message *)recv_buffer;recv_buffer[n] = '\0'; // 确保字符串以null终止switch (msg->type) {case 'L': // 登录通知printf("%s 已登录\n", msg->username);break;case 'M': // 群聊消息printf("%s: %s\n", msg->username, msg->message);break;case 'Q': // 下线通知printf("%s 已下线\n", msg->username);break;case 'S': // 系统消息printf("系统消息: %s\n", msg->message);break;default:printf("未知的消息类型\n");break;}}}close(sockfd);return 0;
}

不完善仅供参考