package localchat import ( "encoding/json" "fmt" "log" "net" "net/http" "os" "time" ) const ( BroadcastIP = "255.255.255.255" BroadcastPort = 20249 ) type UdpMessage struct { Type string `json:"type"` IP string `json:"ip"` Hostname string `json:"hostname"` Message interface{} `json:"message"` } var broadcastAddr = fmt.Sprintf("%s:%d", BroadcastIP, BroadcastPort) var OnlineUsers = make(map[string]UdpMessage) // SendBroadcast 发送广播消息 func init() { go InitBroadcast() go ListenForBroadcast() } func InitBroadcast() { ticker := time.NewTicker(5 * time.Second) // 每 5 秒发送一次广播消息 defer ticker.Stop() for range ticker.C { hostname, err := os.Hostname() if err != nil { log.Printf("Failed to get hostname: %v", err) continue } message := UdpMessage{ Type: "online", Hostname: hostname, Message: "", } err = SendBroadcast(message) if err != nil { log.Println("Failed to send broadcast message:", err) } } } func SendBroadcast(message UdpMessage) error { addr, err := net.ResolveUDPAddr("udp4", broadcastAddr) if err != nil { log.Printf("Failed to resolve UDP address %s: %v", broadcastAddr, err) return err } // 使用本地地址进行连接 localAddr, err := net.ResolveUDPAddr("udp4", "0.0.0.0:0") if err != nil { log.Printf("Failed to resolve local UDP address: %v", err) return err } conn, err := net.ListenUDP("udp4", localAddr) if err != nil { log.Printf("Failed to listen on UDP address %s: %v", broadcastAddr, err) return err } defer conn.Close() // 获取本地 IP 地址 localIP, err := GetLocalIP() log.Printf("本地 IP 地址: %s", localIP) if err != nil { log.Printf("Failed to get local IP address: %v", err) return err } message.IP = localIP data, err := json.Marshal(message) if err != nil { log.Printf("Failed to marshal JSON for %s: %v", broadcastAddr, err) return err } _, err = conn.WriteToUDP(data, addr) if err != nil { log.Printf("Failed to write to UDP address %s: %v", broadcastAddr, err) return err } log.Printf("发送广播消息到 %s 成功", broadcastAddr) return nil } // ListenForBroadcast 监听广播消息 func ListenForBroadcast() { // 使用本地地址监听 localAddr, err := net.ResolveUDPAddr("udp4", fmt.Sprintf(":%d", BroadcastPort)) if err != nil { log.Fatalf("Failed to resolve local UDP address: %v", err) } conn, err := net.ListenUDP("udp4", localAddr) if err != nil { log.Fatalf("Failed to listen on UDP address: %v", err) } defer conn.Close() // 获取本地 IP 地址 localIP, err := GetLocalIP() if err != nil { log.Printf("Failed to get local IP address: %v", err) } // 开始监听广播消息 buffer := make([]byte, 1024) for { n, remoteAddr, err := conn.ReadFromUDP(buffer) if err != nil { log.Printf("Error reading from UDP: %v", err) continue } var udpMsg UdpMessage err = json.Unmarshal(buffer[:n], &udpMsg) if err != nil { log.Printf("Error unmarshalling JSON: %v", err) continue } if udpMsg.IP == localIP { continue } OnlineUsers[udpMsg.IP] = udpMsg if udpMsg.Type == "file" { RecieveFile(udpMsg) } log.Printf("Received message from %s: %s", remoteAddr, udpMsg.Hostname) } } // SendToIP 向指定的 IP 地址发送 UDP 消息 func SendToIP(message UdpMessage) error { toIp := message.IP addr, err := net.ResolveUDPAddr("udp4", fmt.Sprintf("%s:%d", toIp, BroadcastPort)) if err != nil { log.Printf("Failed to resolve UDP address %s:%d: %v", toIp, BroadcastPort, err) return err } // 使用本地地址进行连接 localAddr, err := net.ResolveUDPAddr("udp4", "0.0.0.0:0") if err != nil { log.Printf("Failed to resolve local UDP address: %v", err) return err } conn, err := net.ListenUDP("udp4", localAddr) if err != nil { log.Printf("Failed to listen on UDP address %s: %v", toIp, err) return err } defer conn.Close() // 获取本地 IP 地址 localIP, err := GetLocalIP() if err != nil { log.Printf("Failed to get local IP address: %v", err) } message.IP = localIP data, err := json.Marshal(message) if err != nil { log.Printf("Failed to marshal JSON for %s: %v", toIp, err) return err } _, err = conn.WriteToUDP(data, addr) if err != nil { log.Printf("Failed to write to UDP address %s: %v", toIp, err) return err } log.Printf("发送 UDP 消息到 %s 成功", toIp) return nil } // 获取 OnlineUsers 的最新状态 func GetOnlineUsers() map[string]UdpMessage { return OnlineUsers } // HandleMessage 处理 HTTP 请求 func HandleMessage(w http.ResponseWriter, r *http.Request) { var msg UdpMessage decoder := json.NewDecoder(r.Body) if err := decoder.Decode(&msg); err != nil { http.Error(w, "Invalid request body", http.StatusBadRequest) return } defer r.Body.Close() err := SendToIP(msg) if err != nil { http.Error(w, "Failed to send message", http.StatusInternalServerError) return } w.WriteHeader(http.StatusOK) fmt.Fprintln(w, "Text message send successfully") }