164 lines
4.3 KiB
Go
164 lines
4.3 KiB
Go
package main
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import (
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"github.com/BRNSystems/go-telnet"
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"github.com/reiver/go-oi"
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"strings"
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)
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type internalTerminalHandler struct {
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ShellCharacter string
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WelcomeMessage string
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CommandRegistry *commandRegistry
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}
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func newInternalTerminalHandler(shellCharacter, welcomeMessage string, commandRegistry *commandRegistry) *internalTerminalHandler {
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return &internalTerminalHandler{
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ShellCharacter: shellCharacter,
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WelcomeMessage: welcomeMessage,
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CommandRegistry: commandRegistry,
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}
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}
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func clearLine(w telnet.Writer) error {
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_, err := w.RawWrite([]byte{0x1B, 0x5B, 0x4B})
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return err
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}
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func (handler *internalTerminalHandler) ServeTELNET(ctx telnet.Context, w telnet.Writer, r telnet.Reader) {
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clientID := newClient(&ctx, &w, &r)
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defer removeClient(clientID)
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_, err := w.RawWrite([]byte{0xff, 0xfb, 0x03})
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if err != nil {
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return
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} //send char by char
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_, err = w.RawWrite([]byte{0xff, 0xfb, 0x01})
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if err != nil {
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return
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} //echo from server
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_, err = w.Write([]byte(strings.ReplaceAll(handler.WelcomeMessage, "\n", "\r\n") + "\r\n"))
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if err != nil {
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return
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}
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//replace every \n with \r\n in WelcomeMessage
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_, err = w.Write([]byte(handler.ShellCharacter))
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if err != nil {
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return
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}
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var lineBuffer []byte
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CSISequence := 0
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for {
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var bt [1]byte
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n, err := r.Read(bt[:])
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if err != nil {
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break
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}
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if n > 0 {
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b := bt[0]
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if b == 0x03 || b == 0x04 {
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return
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} else if b == 0x1B { //escape
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CSISequence = 1
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} else if CSISequence == 1 && b == 0x5B {
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CSISequence = 2
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} else if CSISequence == 2 && b == 'A' {
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if len(lineBuffer) == 0 && len(clients[clientID].History) > 0 {
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if clients[clientID].HistoryIndex < len(clients[clientID].History)-1 {
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clients[clientID].HistoryIndex++
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}
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lineBuffer = []byte(clients[clientID].History[clients[clientID].HistoryIndex])
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if clearLine(w) != nil {
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return
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}
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_, err := w.Write(lineBuffer)
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if err != nil {
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return
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}
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}
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} else if CSISequence == 2 && b == 'B' {
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if len(lineBuffer) == 0 && len(clients[clientID].History) > 0 {
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if clients[clientID].HistoryIndex > 0 {
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clients[clientID].HistoryIndex--
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}
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lineBuffer = []byte(clients[clientID].History[clients[clientID].HistoryIndex])
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if clearLine(w) != nil {
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return
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}
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_, err := w.Write(lineBuffer)
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if err != nil {
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return
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}
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}
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} else if b == 0x7F {
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if len(lineBuffer) > 0 {
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_, err := w.Write([]byte{0x08, 0x20, 0x08})
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if err != nil {
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return
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}
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lineBuffer = lineBuffer[:len(lineBuffer)-1]
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}
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} else if b != '\r' && b != '\n' && b != 0 {
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CSISequence = 0
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lineBuffer = append(lineBuffer, b)
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_, err := w.RawWrite([]byte{b})
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if err != nil {
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return
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}
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} else if b == '\r' {
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_, err := w.Write([]byte("\r\n"))
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if err != nil {
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return
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}
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command := string(lineBuffer)
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args := strings.Fields(command)
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var message strings.Builder
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if len(args) > 0 {
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cmd := args[0]
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internalCommand := false
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if cmd == "exit" {
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internalCommand = true
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return
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} else if cmd == "help" {
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internalCommand = true
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var commands strings.Builder
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for command, commandEntry := range handler.CommandRegistry.commands {
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commands.WriteString(command + " - " + commandEntry.description + "\r\n")
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}
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// Handle help command
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if len(clients) > 0 {
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clients[clientID].send("Just help yourself, " + clients[clientID].Username + "\r\nCommands:\r\n" + commands.String())
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} else {
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clients[clientID].send("No clients available" + "\r\nCommands:\r\n" + commands.String())
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}
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}
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handlerFunc, ok, clientID := handler.CommandRegistry.getCommandHandler(cmd, clientID)
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clients[clientID].HistoryIndex = 0
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if ok || internalCommand {
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if ok {
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message.WriteString(handlerFunc(args[1:], clientID))
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}
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clients[clientID].History = append(clients[clientID].History, command)
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} else {
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message.WriteString("Command not found")
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}
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message.WriteString("\n" + handler.ShellCharacter)
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} else {
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message.WriteString(handler.ShellCharacter)
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}
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_, err = oi.LongWrite(w, []byte(strings.ReplaceAll(message.String(), "\n", "\r\n")))
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if err != nil {
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return
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}
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lineBuffer = nil
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}
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}
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}
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}
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