我写了一个Java客户端,它向广播地址发送消息。
我还编写了一个Java服务器,它接受所有发送的消息并将消息发送回客户端。
现在我想尝试在 Go 中做同样的事情,只是为了获得一些经验。服务器工作正常,正在接收消息并对 Java 客户端做出响应。
但是我的 Go 客户端仅向 Go/Java 服务器发送消息,但没有收到任何返回的消息。根据wireshark,消息被发送回正确的IP和端口,但显然该端口无法访问。
我的代码如下:
去服务器:
package main
import (
"fmt"
"log"
"net"
)
func main() {
//Resolving address
udpAddr, err := net.ResolveUDPAddr("udp4", "0.0.0.0:8888")
if err != nil {
log.Println("Error: ", err)
}
// Build listining connections
conn, err := net.ListenUDP("udp", udpAddr)
defer conn.Close()
if err != nil {
log.Println("Error: ", err)
}
// Interacting with one client at a time
for {
fmt.Println(">>>Ready to receive broadcast packets!")
// Receiving a message
recvBuff := make([]byte, 15000)
_, rmAddr, err := conn.ReadFromUDP(recvBuff)
if err != nil {
panic(err)
}
fmt.Println(">>>Discovery packet received from: " + rmAddr.String())
fmt.Println(">>>Packet received; data: " + string(recvBuff))
// Sending the same message back to current client
conn.WriteToUDP(recvBuff, rmAddr)
fmt.Println(">>>Sent packet to: " + rmAddr.String())
}
}
去客户端:
package main
import (
"fmt"
"log"
"net"
"os"
)
func main() {
service := "158.129.239.255:8888"
// Resolving Address
RemoteAddr, err := net.ResolveUDPAddr("udp", service)
// Make a connection
conn, err := net.DialUDP("udp", nil, RemoteAddr)
defer conn.Close()
// Exit if some error occured
if err != nil {
log.Fatal(err)
os.Exit(1)
}
// write a message to server
message := []byte("message")
_, err = conn.Write(message)
fmt.Println(">>> Request packet sent to: 158.129.239.255 (DEFAULT)")
if err != nil {
log.Println(err)
}
// Receive response from server
buf := make([]byte, 15000)
amountByte, remAddr, err := conn.ReadFromUDP(buf)
if err != nil {
log.Println(err)
} else {
fmt.Println(amountByte, "bytes received from", remAddr)
}
}
Java客户端:
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.InterfaceAddress;
import java.net.NetworkInterface;
import java.util.Enumeration;
import java.util.logging.Level;
import java.util.logging.Logger;
public class BroadcastUDPClient {
public static void main(String[] args) {
// Find the server using UDP broadcast
try {
//Open a random port to send the package
DatagramSocket sendSD = new DatagramSocket();
sendSD.setBroadcast(true);
byte[] sendData = "message".getBytes();
//Try the 255.255.255.255 first
try {
DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, InetAddress.getByName("158.129.239.255"), 8888);
sendSD.send(sendPacket);
System.out.println(">>> Request packet sent to: 158.129.239.255 (DEFAULT)");
} catch (Exception e) {
}
//Wait for a response
byte[] recvBuf = new byte[15000];
DatagramPacket receivePacket = new DatagramPacket(recvBuf, recvBuf.length);
sendSD.receive(receivePacket);
//We have a response
System.out.println(">>> Broadcast response from server: " + receivePacket.getAddress().getHostAddress());
String message = new String(receivePacket.getData()).trim();
System.out.println(">>> Message Body: " + message);
//Close the port!
sendSD.close();
} catch (IOException ex) {
Logger.getLogger(BroadcastUDPClient.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
我的 Go 客户端做错了什么?