CDE

Task/Chat-server/Go/chat-server.go

@@ -0,0 +1,148 @@
+package main
+
+import (
+	"os"
+	"fmt"
+	"net"
+	"flag"
+	"bufio"
+	"bytes"
+)
+
+// Quick and dirty error handling.
+func error_(err error, r int) {
+	fmt.Printf("Error: %v\n", err)
+
+	if r >= 0 {
+		os.Exit(r)
+	}
+}
+
+// A type for storing the connections.
+type clientMap map[string]net.Conn
+
+// A method that makes clientMap compatible with io.Writer, allowing it to be
+// used with fmt.Fprintf().
+func (cm clientMap) Write(buf []byte) (n int, err error) {
+	for _, c := range cm {
+		// Write to each client in a seperate goroutine.
+		go c.Write(buf)
+	}
+
+	n = len(buf)
+
+	return
+}
+
+// Check if a name exists; if it doesn't, add it.
+func (cm clientMap) Add(name string, c net.Conn) bool {
+	for k := range cm {
+		if name == k {
+			return false
+		}
+	}
+
+	cm[name] = c
+
+	return true
+}
+
+// A clientMap variable.
+var clients clientMap
+
+func init() {
+	// Initialize the map.
+	clients = make(clientMap)
+}
+
+func client(c net.Conn) {
+	// Close the connection when this function returns.
+	defer c.Close()
+
+	br := bufio.NewReader(c)
+
+	fmt.Fprintf(c, "Please enter your name: ")
+
+	buf, err := br.ReadBytes('\n')
+	if err != nil {
+		error_(err, -1)
+		return
+	}
+	name := string(bytes.Trim(buf, " \t\n\r\x00"))
+
+	if name == "" {
+		fmt.Fprintf(c, "!!! %v is invalid !!!\n", name)
+	}
+
+	// Try to add the connection to the map.
+	if !clients.Add(name, c) {
+		fmt.Fprintf(c, "!!! %v is not available !!!\n", name)
+		return
+	}
+
+	// Send a message telling the clients who connected.
+	fmt.Fprintf(clients, "+++ %v connected +++\n", name)
+	// Send a disconnected message when the function returns.
+	defer fmt.Fprintf(clients, "--- %v disconnected ---\n", name)
+	// Remove the client from the list.
+	defer delete(clients, name)
+
+	for {
+		buf, err = br.ReadBytes('\n')
+		if err != nil {
+			break
+		}
+		buf = bytes.Trim(buf, " \t\n\r\x00")
+
+		// Ignore empty messages.
+		if len(buf) == 0 {
+			continue
+		}
+
+		switch {
+		// Support for '/me' type messages.
+		case string(buf[0:3]) == "/me":
+			buf = append([]byte(name), buf[3:]...)
+		default:
+			// Prepend the user-name and '> '.
+			buf = append([]byte(name+"> "), buf...)
+		}
+
+		// Send the message to all the clients.
+		fmt.Fprintf(clients, "%v\n", string(buf))
+	}
+}
+
+func main() {
+	// Flags. Use -help for usage info.
+	var (
+		port int
+		help bool
+	)
+	flag.IntVar(&port, "port", 23, "Port to listen on")
+	flag.BoolVar(&help, "help", false, "Display this")
+	flag.Parse()
+
+	if help {
+		flag.Usage()
+		return
+	}
+
+	// Initialize a new listener.
+	lis, err := net.Listen("tcp", fmt.Sprintf(":%v", port))
+	if err != nil {
+		error_(err, 1)
+	}
+
+	// Begin the main loop.
+	for {
+		c, err := lis.Accept()
+		if err != nil {
+			error_(err, -1)
+			continue
+		}
+
+		// Launch a new goroutine to handle the connection.
+		go client(c)
+	}
+}