Implement TCP client and server with error handling; add web server for HTTP requests

Author: s1thu

tcp_server/client/client.go

@@ -0,0 +1,36 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"net"
+	"os"
+	"strings"
+)
+
+func main() {
+	// open connection:
+	conn, err := net.Dial("tcp", ":8080")
+	if err != nil {
+		// No connection could be made because the target machine actively refused it.
+		fmt.Println("Error dialing", err.Error())
+		return // terminate program
+	}
+	inputReader := bufio.NewReader(os.Stdin)
+	fmt.Println("First, what is your name?")
+	clientName, _ := inputReader.ReadString('\n')
+	// fmt.Printf("CLIENTNAME %s",clientName)
+	trimmedClient := strings.Trim(clientName, "\r\n") // "\r\n" on Windows, "\n" on Linux
+	// send info to server until Quit:
+	for {
+		fmt.Println("What to send to the server? Type Q to quit.")
+		input, _ := inputReader.ReadString('\n')
+		trimmedInput := strings.Trim(input, "\r\n")
+		// fmt.Printf("input:--%s--",input)
+		// fmt.Printf("trimmedInput:--%s--",trimmedInput)
+		if trimmedInput == "Q" {
+			return
+		}
+		_, err = conn.Write([]byte(trimmedClient + " says: " + trimmedInput + "\n"))
+	}
+}

tcp_server/polling web/main.go

@@ -0,0 +1,37 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+)
+
+var urls = []string{
+	"http://www.google.com/",
+	"http://golang.org/",
+	"http://blog.golang.org/",
+}
+
+func main() {
+	// Executes an HTTP HEAD request for all URL's
+	// and returns the HTTP status string or an error string.
+	for _, url := range urls {
+		resp, err := http.Head(url)
+		if err != nil {
+			fmt.Println("Error:", url, err)
+		}
+		fmt.Println(url, ": ", resp.Status)
+	}
+
+	res, err := http.Get("http://www.google.com/")
+	if err != nil {
+		fmt.Println("Error:", err)
+		return
+	}
+	data, err := io.ReadAll(res.Body)
+	if err != nil {
+		fmt.Println("Error reading response body:", err)
+		return
+	}
+	fmt.Println("Response body:", string(data))
+}

tcp_server/server.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"fmt"
+	"net"
+)
+
+func main() {
+	fmt.Println("Starting the TCP server...")
+
+	listener, err := net.Listen("tcp", "0.0.0.0:8080")
+	if err != nil {
+		fmt.Println("Error starting the server:", err)
+		return
+	}
+	defer listener.Close()
+
+	for {
+		conn, err := listener.Accept()
+		if err != nil {
+			fmt.Println("Error accepting connection:", err)
+			continue
+		}
+
+		go doServerStuff(conn)
+	}
+}
+
+func doServerStuff(conn net.Conn) {
+	for {
+		buf := make([]byte, 512)
+		_, err := conn.Read(buf)
+		if err != nil {
+			fmt.Println("Error reading", err.Error())
+			return // terminate program
+		}
+		fmt.Printf("Received data: %v", string(buf))
+	}
+}

tcp_server/web_server/main.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+)
+
+func HelloServer(w http.ResponseWriter, req *http.Request) {
+	fmt.Println("Inside HelloServer handler")
+	fmt.Fprint(w, "Hello, "+req.URL.Path[1:])
+}
+
+func main() {
+	http.HandleFunc("/", HelloServer)
+	err := http.ListenAndServe("0.00.0:3000", nil)
+	if err != nil {
+		log.Fatal("ListenAndServe: ", err.Error())
+	}
+}