Chat server: Difference between revisions

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@@ Line 536: / Line 536: @@
 import (
-	"bufio"
+	"os"
-	"bytes"
-	"flag"
 	"fmt"
-	"log"
 	"net"
-	"os"
+	"flag"
-	"sync"
+	"bufio"
+	"bytes"
 )
+// Quick and dirty error handling.
-// A type for storing the connections.
+func error_(err error, r int) {
-type clientMap struct {
+	fmt.Printf("Error: %v\n", err)
-	// the map of names to connections
-	cl map[string]net.Conn
+	if r >= 0 {
-	// the mutex protects assoc and dissoc on cl ^
+		os.Exit(r)
-	mu sync.RWMutex
+	}
 }
+// 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 {
-	cm.mu.RLock()
-	defer cm.mu.RUnlock()
-	for _, c := range cm.cl {
 		// 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) Assoc(name string, c net.Conn) bool {
+func (cm clientMap) Add(name string, c net.Conn) bool {
+	for k := range cm {
-	cm.mu.Lock()
+		if name == k {
-	defer cm.mu.Unlock()
+			return false
-	if _, e := cm.cl[name]; e {
+		}
-		return false
 	}
 	cm[name] = c
-	return true
-}
+	return true
-func (cm clientMap) Dissoc(name string) {
-	cm.mu.Lock()
-	defer cm.mu.Unlock()
-	delete(cm.cl, name)
 }
@@ Line 589: / Line 587: @@
 func init() {
 	// Initialize the map.
-	clients = &clientMap{cl:make(map[string]net.Conn)}
+	clients = make(clientMap)
-	log.SetPrefix("!server> ")
 }
@@ Line 599: / Line 596: @@
 	br := bufio.NewReader(c)
-retry:
 	fmt.Fprintf(c, "Please enter your name: ")
 	buf, err := br.ReadBytes('\n')
 	if err != nil {
-		log.Println("Error: ", err)
+		error_(err, -1)
 		return
 	}
@@ Line 610: / Line 606: @@
 	if name == "" {
-		fmt.Fprintln(c, "!!! invalid name !!!")
+		fmt.Fprintf(c, "!!! %v is invalid !!!\n", name)
-		goto retry
 	}
 	// Try to add the connection to the map.
-	if !clients.Assoc(name, c) {
+	if !clients.Add(name, c) {
-		fmt.Fprintf(c, "!!! %s is not available !!!\n", name)
+		fmt.Fprintf(c, "!!! %v is not available !!!\n", name)
+		return
-		goto retry
 	}
 	// Send a message telling the clients who connected.
-	fmt.Fprintf(clients, "+++ %s connected +++\n", name)
+	fmt.Fprintf(clients, "+++ %v connected +++\n", name)
 	// Send a disconnected message when the function returns.
-	defer fmt.Fprintf(clients, "--- %s disconnected ---\n", name)
+	defer fmt.Fprintf(clients, "--- %v disconnected ---\n", name)
 	// Remove the client from the list.
-	defer clients.Dissoc(name)
+	defer delete(clients, name)
 	for {
@@ Line 649: / Line 644: @@
 		// Send the message to all the clients.
-		fmt.Fprintf(clients, "%s\n", buf)
+		fmt.Fprintf(clients, "%v\n", string(buf))
 	}
 }
-// Flags. Use -help for usage info.
-var (
-	port = flag.Int("port", 23, "Port to listen on")
-	help = flag.Bool("help", false, "Display this")
-)
 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 {
+	if help {
 		flag.Usage()
 		return
@@ Line 668: / Line 664: @@
 	// Initialize a new listener.
-	lis, err := net.Listen("tcp", fmt.Sprintf(":%d", *port))
+	lis, err := net.Listen("tcp", fmt.Sprintf(":%v", port))
 	if err != nil {
-		log.Fatalln("Error: ", err)
+		error_(err, 1)
 	}
@@ Line 677: / Line 673: @@
 		c, err := lis.Accept()
 		if err != nil {
-			log.Println("Error: ", err)
+			error_(err, -1)
 			continue
 		}