Examples of udp protocol and TCP communication implementation in go language

package main
import (
	"fmt"
	"net"
)
func main() {
	// Create a listener	socket, err := ("udp4", &{
		IP:   net.IPv4(0, 0, 0, 0),
		Port: 8080,
	})
	if err != nil {
		("Supervising failed!", err)
		return
	}
	defer ()
	for {
		// Read the data transmitted from the client		data := make([]byte, 4096)
		read, remoteAddr, err := (data)
		if err != nil {
			("Reading data failed!", err)
			continue
		}
		(read, remoteAddr)
		("%s\n\n", data)
		//Send data and tell the client that it has received it		senddata := []byte("hello client!")
		_, err = (senddata, remoteAddr)
		if err != nil {
			return
			("Send data failed!", err)
		}
	}
}

package main
import (
	"fmt"
	"net"
)
func main() {
	// Create a connection	socket, err := ("udp4", nil, &{
		IP:   net.IPv4(0, 0, 0, 0),
		Port: 8080,
	})
	if err != nil {
		("The connection failed!", err)
		return
	}
	defer ()
	// Send data to the server	senddata := []byte("hello server!")
	_, err = (senddata)
	if err != nil {
		("Send data failed!", err)
		return
	}
	// Receive client data	data := make([]byte, 4096)
	read, remoteAddr, err := (data)
	if err != nil {
		("Reading data failed!", err)
		return
	}
	(read, remoteAddr)
	("%s\n", data)
}

package main
import (
	"fmt"
	"net"
)
func main() {
	//monitor	listener, err := ("tcp", "127.0.0.1:8000")
	if err != nil {
		("err = ", err)
		return
	}
	defer ()
	//Blocking and waiting for user link	conn, err := ()
	if err != nil {
		("err = ", err)
		return
	}
	//Receive user request	buf := make([]byte, 1024) // 1024 size buffer	n, err1 := (buf)
	if err1 != nil {
		("err1 = ", err1)
		return
	}
	("buf = ", string(buf[:n]))
	defer () //Close the current user link}

package main
import (
	"fmt"
	"net"
)
func main() {
	//Proactively connect to the server	conn, err := ("tcp", "127.0.0.1:8000")
	if err != nil {
		("err = ", err)
		return
	}
	defer ()
	//Send data	([]byte("are u ok?"))
}

package main
import (
	"fmt"
	"net"
	"strings"
)
//Process user requestfunc HandleConn(conn ) {
	//The function call is completed, the conn will be automatically closed	defer ()
	//Get the client's network address information	addr := ().String()
	(addr, " conncet sucessful")
	buf := make([]byte, 2048)
	for {
		//Read user data		n, err := (buf)
		if err != nil {
			("err = ", err)
			return
		}
		("[%s]: %s\n", addr, string(buf[:n]))
		("len = ", len(string(buf[:n])))
		//if "exit" == string(buf[:n-1]) { //nc test		if "exit" == string(buf[:n-2]) { //The client test I wrote myself, there were 2 characters extra when sending, "\r\n"			(addr, " exit")
			return
		}
		//Convert the data to uppercase and send it to the user		([]byte((string(buf[:n]))))
	}

}
func main() {
	//monitor	listener, err := ("tcp", "127.0.0.1:8000")
	if err != nil {
		("err = ", err)
		return
	}
	defer ()
	//Receive multiple users	for {
		conn, err := ()
		if err != nil {
			("err = ", err)
			return
		}
		//Process user requests and create a new coroutine		go HandleConn(conn)
	}
}

package main
import (
	"fmt"
	"net"
	"os"
)
func main() {
	//Proactively connect to the server	conn, err := ("tcp", "127.0.0.1:8000")
	if err != nil {
		(" err = ", err)
		return
	}
	//The main call is completed, close the connection	defer ()
	go func() {
		//Enter content from the keyboard and send content to the server		str := make([]byte, 1024)
		for {
			n, err := (str) //Read content from the keyboard and place it in str			if err != nil {
				(". err = ", err)
				return
			}
			//Send the input content to the server			(str[:n])
		}
	}()
	//Receive data from the server reply	//Slice buffer	buf := make([]byte, 1024)
	for {
		n, err := (buf) //Receive server request		if err != nil {
			(" err = ", err)
			return
		}
		(string(buf[:n])) //Print the received content, convert it into a string and then print it	}
}