90 lines
1.6 KiB
Text
90 lines
1.6 KiB
Text
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// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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//!+
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// Chat is a server that lets clients chat with each other.
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package main
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import (
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"bufio"
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"fmt"
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"log"
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"net"
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)
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//!+broadcaster
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type client chan<- string // an outgoing message channel
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var (
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entering = make(chan client)
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leaving = make(chan client)
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messages = make(chan string) // all incoming client messages
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)
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func broadcaster() {
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clients := make(map[client]bool) // all connected clients
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for {
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select {
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case msg := <-messages:
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// Broadcast incoming message to all
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// clients' outgoing message channels.
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for cli := range clients {
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cli <- msg
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}
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case cli := <-entering:
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clients[cli] = true
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case cli := <-leaving:
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delete(clients, cli)
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close(cli)
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}
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}
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}
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//!-broadcaster
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//!+handleConn
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func handleConn(conn net.Conn) {
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ch := make(chan string) // outgoing client messages
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go clientWriter(conn, ch)
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who := conn.RemoteAddr().String()
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entering <- ch
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messages <- who + " has arrived"
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input := bufio.NewScanner(conn)
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for input.Scan() {
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messages <- who + ": " + input.Text()
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}
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messages <- who + " has left"
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leaving <- ch
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conn.Close()
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}
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func clientWriter(conn net.Conn, ch <-chan string) {
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for msg := range ch {
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fmt.Fprintln(conn, msg)
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}
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}
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//!-handleConn
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//!+main
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func main() {
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listener, err := net.Listen("tcp", "localhost:8000")
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if err != nil {
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log.Fatal(err)
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}
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go broadcaster()
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for {
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conn, err := listener.Accept()
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if err != nil {
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log.Print(err)
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continue
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}
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go handleConn(conn)
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}
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}
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//!-main
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