telnetroulette/terminal_handler.go
2024-06-08 11:52:12 +02:00

109 lines
3.0 KiB
Go

package main
import (
"github.com/BRNSystems/go-telnet"
"github.com/reiver/go-oi"
"strings"
)
type InternalTerminalHandler struct {
ShellCharacter string
WelcomeMessage string
CommandRegistry *CommandRegistry
}
func NewInternalTerminalHandler(shellCharacter, welcomeMessage string, commandRegistry *CommandRegistry) *InternalTerminalHandler {
return &InternalTerminalHandler{
ShellCharacter: shellCharacter,
WelcomeMessage: welcomeMessage,
CommandRegistry: commandRegistry,
}
}
func (handler *InternalTerminalHandler) ServeTELNET(ctx telnet.Context, w telnet.Writer, r telnet.Reader) {
clientID := NewClient(ctx, w, r)
defer RemoveClient(clientID)
w.RawWrite([]byte{0xff, 0xfb, 0x03}) //send char by char
w.RawWrite([]byte{0xff, 0xfb, 0x01}) //echo from server
w.Write([]byte(strings.ReplaceAll(handler.WelcomeMessage, "\n", "\r\n") + "\r\n"))
//replace every \n with \r\n in WelcomeMessage
w.Write([]byte(handler.ShellCharacter))
var lineBuffer []byte
CSISequence := 0
for {
var bt [1]byte
n, err := r.Read(bt[:])
if err != nil {
break
}
if n > 0 {
b := bt[0]
if b == 0x03 || b == 0x04 {
return
} else if b == 0x1B { //escape
CSISequence = 1
} else if CSISequence == 1 && b == 0x5B {
CSISequence = 2
} else if CSISequence == 2 && b == 'A' {
if len(lineBuffer) == 0 && len(clients[clientID].History) > 0 {
if clients[clientID].HistoryIndex < len(clients[clientID].History)-1 {
clients[clientID].HistoryIndex++
}
lineBuffer = []byte(clients[clientID].History[clients[clientID].HistoryIndex])
w.RawWrite([]byte{0x1B, 0x5B, 0x4B}) //clear line
w.Write(lineBuffer)
}
} else if CSISequence == 2 && b == 'B' {
if len(lineBuffer) == 0 && len(clients[clientID].History) > 0 {
if clients[clientID].HistoryIndex > 0 {
clients[clientID].HistoryIndex--
}
lineBuffer = []byte(clients[clientID].History[clients[clientID].HistoryIndex])
w.RawWrite([]byte{0x1B, 0x5B, 0x4B}) //clear line
w.Write(lineBuffer)
}
} else if b == 0x7F {
if len(lineBuffer) > 0 {
w.Write([]byte{0x08, 0x20, 0x08})
lineBuffer = lineBuffer[:len(lineBuffer)-1]
}
} else if b != '\r' && b != '\n' && b != 0 {
CSISequence = 0
lineBuffer = append(lineBuffer, b)
w.RawWrite([]byte{b})
} else if b == '\r' {
w.Write([]byte("\r\n"))
command := string(lineBuffer)
args := strings.Fields(command)
var message string
if len(args) > 0 {
cmd := args[0]
if cmd == "exit" {
return
}
handlerFunc, ok, clientID := handler.CommandRegistry.GetCommandHandler(cmd, clientID)
clients[clientID].HistoryIndex = 0
if ok {
message = handlerFunc(args[1:], clientID)
clients[clientID].History = append(clients[clientID].History, command)
} else {
message = "Command not found"
}
message += "\n" + handler.ShellCharacter
} else {
message = handler.ShellCharacter
}
oi.LongWrite(w, []byte(strings.ReplaceAll(message, "\n", "\r\n")))
lineBuffer = nil
}
}
}
}