telnet.go

   1 /*
   2 midgaard_bot, a Telegram bot which sets a bridge to Midgaard Merc MUD
   3 Copyright (C) 2017 by Javier Sancho Fernandez <jsf at jsancho dot org>
   4
   5 This program is free software: you can redistribute it and/or modify
   6 it under the terms of the GNU General Public License as published by
   7 the Free Software Foundation, either version 3 of the License, or
   8 (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17 */
  18
  19 package main
  20
  21 import (
  22         "bytes"
  23         "time"
  24
  25         "github.com/reiver/go-oi"
  26         "github.com/reiver/go-telnet"
  27 )
  28
  29 type TelnetCaller struct {
  30         Input chan string
  31         Output chan string
  32 }
  33
  34 func (caller TelnetCaller) CallTELNET(ctx telnet.Context, writer telnet.Writer, reader telnet.Reader) {
  35
  36         // Send text to MUD
  37         go func() {
  38                 var buffer bytes.Buffer
  39                 var p []byte
  40
  41                 crlfBuffer := [2]byte{'\r', '\n'}
  42                 crlf := crlfBuffer[:]
  43
  44                 for {
  45                         message := <-caller.Input
  46                         buffer.Write([]byte(message))
  47                         buffer.Write(crlf)
  48
  49                         p = buffer.Bytes()
  50                         oi.LongWrite(writer, p)
  51                         buffer.Reset()
  52                 }
  53         }()
  54
  55         // Receive text from MUD
  56         chunks := make(chan string)
  57         chunk := ""
  58
  59         go func() {
  60                 var buffer [1]byte
  61                 p := buffer[:]
  62
  63                 for {
  64                         n, err := reader.Read(p)
  65                         if n <= 0 && err == nil {
  66                                 continue
  67                         } else if n <= 0 && err != nil {
  68                                 break
  69                         }
  70
  71                         chunks <- string(p)
  72                 }
  73         }()
  74
  75         for {
  76                 select {
  77                 case input := <-chunks:
  78                         chunk = input
  79                         for chunk != "" {
  80                                 select {
  81                                 case input := <-chunks:
  82                                         chunk = chunk + input
  83                                 case <-time.After(time.Millisecond * 500):
  84                                         caller.Output <- chunk
  85                                         chunk = ""
  86                                 }
  87                         }
  88                 }
  89         }
  90 }