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212 lines
4.4 KiB
212 lines
4.4 KiB
package localchat
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import (
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"encoding/json"
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"fmt"
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"log"
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"net"
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"net/http"
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"golang.org/x/net/ipv4"
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)
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type UdpMessage struct {
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Type string `json:"type"`
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IP string `json:"ip"`
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Hostname string `json:"hostname"`
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Message any `json:"message"`
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}
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// 多播地址列表
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var multicastAddrs = []string{"239.255.255.250:2024", "239.255.255.251:2024", "224.0.0.251:1234", "224.0.0.1:1679"}
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var OnlineUsers = make(map[string]UdpMessage) // 全局map,key为IP,value为主机名
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// SendMulticast 发送多播消息
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func init() {
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go InitMulticast()
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go ListenForMulticast()
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}
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func InitMulticast() {
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myIP, myHostname, err := GetMyIPAndHostname()
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if err != nil {
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return
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}
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message := UdpMessage{
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Type: "online",
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IP: myIP,
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Hostname: myHostname,
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Message: "online",
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}
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SendMulticast(message)
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}
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func SendMulticast(message UdpMessage) error {
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for _, addrStr := range multicastAddrs {
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addr, err := net.ResolveUDPAddr("udp4", addrStr)
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if err != nil {
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return err
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}
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conn, err := net.DialUDP("udp4", nil, addr)
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if err != nil {
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return err
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}
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defer conn.Close()
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data, err := json.Marshal(message)
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if err != nil {
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return err
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}
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_, err = conn.WriteToUDP(data, addr)
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if err != nil {
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return err
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}
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fmt.Printf("发送多播消息到 %s 成功\n", addrStr)
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}
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return nil
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}
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// ListenForMulticast 监听多播消息
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func ListenForMulticast() {
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// 选择一个可用的多播地址
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var multicastGroup *net.UDPAddr
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var err error
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for _, addrStr := range multicastAddrs {
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multicastGroup, err = net.ResolveUDPAddr("udp4", addrStr)
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if err != nil {
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fmt.Println("Error resolving UDP address:", err)
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continue
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}
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break
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}
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if multicastGroup == nil {
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fmt.Println("No available multicast address found")
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return
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}
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conn, err := net.ListenUDP("udp4", &net.UDPAddr{IP: net.IPv4zero, Port: 2024})
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if err != nil {
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fmt.Println("Error listening on UDP address:", err)
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return
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}
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defer conn.Close()
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udpConn := ipv4.NewPacketConn(conn)
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// 获取本地网络接口
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localIfaces, err := net.Interfaces()
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if err != nil {
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log.Fatalf("Failed to get local interfaces: %v", err)
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}
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// 选择一个可用的网络接口
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var localInterface *net.Interface
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for _, iface := range localIfaces {
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addrs, err := iface.Addrs()
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if err != nil {
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continue
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}
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for _, addr := range addrs {
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if ipNet, ok := addr.(*net.IPNet); ok && !ipNet.IP.IsLoopback() {
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if ipNet.IP.To4() != nil {
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localInterface = &iface
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break
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}
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}
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}
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if localInterface != nil {
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break
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}
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}
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if localInterface == nil {
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log.Fatal("No suitable network interface found")
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}
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if err := udpConn.JoinGroup(localInterface, multicastGroup); err != nil {
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log.Fatalf("Failed to join multicast group: %v", err)
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}
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buffer := make([]byte, 1024)
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for {
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n, _, src, err := udpConn.ReadFrom(buffer)
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if err != nil {
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log.Printf("Error reading from UDP: %v, addr: %v", err, src)
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continue
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}
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var udpMsg UdpMessage
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err = json.Unmarshal(buffer[:n], &udpMsg)
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if err != nil {
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fmt.Printf("Error unmarshalling JSON: %v\n", err)
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continue
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}
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OnlineUsers[udpMsg.IP] = udpMsg
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if udpMsg.Type == "file" {
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RecieveFile(udpMsg)
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}
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fmt.Printf("Received message from %s: %s\n", udpMsg.IP, udpMsg.Hostname)
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}
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}
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// SendToIP 向指定的 IP 地址发送 UDP 消息
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func SendToIP(ip string, message UdpMessage) error {
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addr, err := net.ResolveUDPAddr("udp4", fmt.Sprintf("%s:2024", ip))
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if err != nil {
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return err
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}
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conn, err := net.DialUDP("udp4", nil, addr)
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if err != nil {
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return err
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}
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defer conn.Close()
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data, err := json.Marshal(message)
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if err != nil {
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return err
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}
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_, err = conn.WriteToUDP(data, addr)
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if err != nil {
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return err
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}
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fmt.Printf("发送 UDP 消息到 %s 成功\n", ip)
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return nil
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}
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// 获取 OnlineUsers 的最新状态
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func GetOnlineUsers() map[string]UdpMessage {
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return OnlineUsers
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}
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func HandleMessage(w http.ResponseWriter, r *http.Request) {
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var msg UdpMessage
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decoder := json.NewDecoder(r.Body)
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if err := decoder.Decode(&msg); err != nil {
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http.Error(w, "Invalid request body", http.StatusBadRequest)
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return
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}
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defer r.Body.Close()
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ip := msg.IP
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preferredIP, err := GetMyIp()
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if err != nil {
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http.Error(w, "Failed to get preferred IP", http.StatusInternalServerError)
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return
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}
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msg.IP = preferredIP
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err = SendToIP(ip, msg)
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if err != nil {
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http.Error(w, "Failed to send message", http.StatusInternalServerError)
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return
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}
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w.WriteHeader(http.StatusOK)
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fmt.Fprintln(w, "Text message send successfully")
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}
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