actually implement telnet protocol - fixes #4164

tabby-telnet/src/profiles.ts

@@ -12,22 +12,36 @@ export class TelnetProfilesService extends ProfileProvider {
     settingsComponent = TelnetProfileSettingsComponent
 
     async getBuiltinProfiles (): Promise<TelnetProfile[]> {
-        return [{
-            id: `telnet:template`,
-            type: 'telnet',
-            name: 'Telnet/socket connection',
-            icon: 'fas fa-network-wired',
-            options: {
-                host: '',
-                port: 23,
-                inputMode: 'readline',
-                outputMode: null,
-                inputNewlines: null,
-                outputNewlines: 'crlf',
+        return [
+            {
+                id: `telnet:template`,
+                type: 'telnet',
+                name: 'Telnet session',
+                icon: 'fas fa-network-wired',
+                options: {
+                    host: '',
+                    port: 23,
+                    inputMode: 'readline',
+                    outputMode: null,
+                    inputNewlines: null,
+                    outputNewlines: 'crlf',
+                },
+                isBuiltin: true,
+                isTemplate: true,
             },
-            isBuiltin: true,
-            isTemplate: true,
-        }]
+            {
+                id: `socket:template`,
+                type: 'telnet',
+                name: 'Raw socket connection',
+                icon: 'fas fa-network-wired',
+                options: {
+                    host: '',
+                    port: 1234,
+                },
+                isBuiltin: true,
+                isTemplate: true,
+            },
+        ]
     }
 
     async getNewTabParameters (profile: Profile): Promise<NewTabParameters<TelnetTabComponent>> {

tabby-telnet/src/session.ts

@@ -16,12 +16,38 @@ export interface TelnetProfileOptions extends StreamProcessingOptions, LoginScri
     port?: number
 }
 
+enum TelnetCommands {
+    SUBOPTION_END = 240,
+    GA = 249,
+    SUBOPTION = 250,
+    WILL = 251,
+    WONT = 252,
+    DO = 253,
+    DONT = 254,
+    IAC = 255,
+}
+
+enum TelnetOptions {
+    ECHO = 0x1,
+    AUTH_OPTIONS = 0x25,
+    SUPPRESS_GO_AHEAD = 0x03,
+    TERMINAL_TYPE = 0x18,
+    NEGO_WINDOW_SIZE = 0x1f,
+    NEGO_TERMINAL_SPEED = 0x20,
+    STATUS = 0x05,
+    X_DISPLAY_LOCATION = 0x23,
+}
+
 export class TelnetSession extends BaseSession {
     get serviceMessage$ (): Observable<string> { return this.serviceMessage }
 
     private serviceMessage = new Subject<string>()
     private socket: Socket
     private streamProcessor: TerminalStreamProcessor
+    private telnetProtocol = false
+    private echoEnabled = false
+    private lastWidth = 0
+    private lastHeight = 0
 
     constructor (
         injector: Injector,
@@ -30,7 +56,7 @@ export class TelnetSession extends BaseSession {
         super(injector.get(LogService).create(`telnet-${profile.options.host}-${profile.options.port}`))
         this.streamProcessor = new TerminalStreamProcessor(profile.options)
         this.streamProcessor.outputToSession$.subscribe(data => {
-            this.socket.write(data)
+            this.socket.write(this.unescapeFF(data))
         })
         this.streamProcessor.outputToTerminal$.subscribe(data => {
             this.emitOutput(data)
@@ -38,6 +64,24 @@ export class TelnetSession extends BaseSession {
         this.setLoginScriptsOptions(profile.options)
     }
 
+    unescapeFF (data: Buffer): Buffer {
+        if (!this.telnetProtocol) {
+            return data
+        }
+        const result: Buffer[] = []
+        while (data.includes(0xff)) {
+            const pos = data.indexOf(0xff)
+
+            result.push(data.slice(0, pos))
+            result.push(Buffer.from([0xff, 0xff]))
+
+            data = data.slice(pos + 1)
+        }
+
+        result.push(data)
+        return Buffer.concat(result)
+    }
+
     async start (): Promise<void> {
         this.socket = new Socket()
         this.emitServiceMessage(`Connecting to ${this.profile.options.host}`)
@@ -52,7 +96,7 @@ export class TelnetSession extends BaseSession {
                 this.emitServiceMessage('Connection closed')
                 this.destroy()
             })
-            this.socket.on('data', data => this.streamProcessor.feedFromSession(data))
+            this.socket.on('data', data => this.onData(data))
             this.socket.connect(this.profile.options.port ?? 23, this.profile.options.host, () => {
                 this.emitServiceMessage('Connected')
                 this.open = true
@@ -68,10 +112,115 @@ export class TelnetSession extends BaseSession {
         this.logger.info(stripAnsi(msg))
     }
 
+    onData (data: Buffer): void {
+        if (!this.telnetProtocol && data[0] === TelnetCommands.IAC) {
+            this.telnetProtocol = true
+            this.emitTelnet(TelnetCommands.DO, TelnetOptions.SUPPRESS_GO_AHEAD)
+            this.emitTelnet(TelnetCommands.WILL, TelnetOptions.TERMINAL_TYPE)
+            this.emitTelnet(TelnetCommands.WILL, TelnetOptions.NEGO_WINDOW_SIZE)
+        }
+        if (this.telnetProtocol) {
+            data = this.processTelnetProtocol(data)
+        }
+        this.streamProcessor.feedFromSession(data)
+    }
+
+    emitTelnet (command: TelnetCommands, option: TelnetOptions): void {
+        this.logger.debug('>', TelnetCommands[command], TelnetOptions[option])
+        this.socket.write(Buffer.from([TelnetCommands.IAC, command, option]))
+    }
+
+    emitTelnetSuboption (option: TelnetOptions, value: Buffer): void {
+        this.logger.debug('>', 'SUBOPTION', TelnetOptions[option], value)
+        this.socket.write(Buffer.from([
+            TelnetCommands.IAC,
+            TelnetCommands.SUBOPTION,
+            option,
+            ...value,
+            TelnetCommands.IAC,
+            TelnetCommands.SUBOPTION_END,
+        ]))
+    }
+
+    processTelnetProtocol (data: Buffer): Buffer {
+        while (data.length) {
+            if (data[0] === TelnetCommands.IAC) {
+                const command = data[1]
+                const commandName = TelnetCommands[command]
+                const option = data[2]
+                const optionName = TelnetOptions[option]
+
+                if (command === TelnetCommands.IAC) {
+                    data = data.slice(1)
+                    break
+                }
+
+                data = data.slice(3)
+                this.logger.debug('<', commandName || command, optionName || option)
+                if (command === TelnetCommands.WILL) {
+                    if ([
+                        TelnetOptions.SUPPRESS_GO_AHEAD,
+                        TelnetOptions.ECHO,
+                    ].includes(option)) {
+                        this.emitTelnet(TelnetCommands.DO, option)
+                    } else {
+                        this.logger.debug('(!) Unhandled option')
+                        this.emitTelnet(TelnetCommands.DONT, option)
+                    }
+                }
+                if (command === TelnetCommands.DO) {
+                    if (option === TelnetOptions.NEGO_WINDOW_SIZE) {
+                        this.resize(0, 0)
+                    } else if (option === TelnetOptions.ECHO) {
+                        this.echoEnabled = true
+                        this.emitTelnet(TelnetCommands.WILL, option)
+                    } else if (option === TelnetOptions.TERMINAL_TYPE) {
+                        this.emitTelnetSuboption(option, Buffer.from([0, ...Buffer.from('XTERM-256COLOR')]))
+                    } else {
+                        this.logger.debug('(!) Unhandled option')
+                        this.emitTelnet(TelnetCommands.WONT, option)
+                    }
+                }
+                if (command === TelnetCommands.DONT) {
+                    if (option === TelnetOptions.ECHO) {
+                        this.echoEnabled = false
+                        this.emitTelnet(TelnetCommands.WONT, option)
+                    } else {
+                        this.logger.debug('(!) Unhandled option')
+                        this.emitTelnet(TelnetCommands.WILL, option)
+                    }
+                }
+                if (command === TelnetCommands.SUBOPTION) {
+                    const endIndex = data.indexOf(TelnetCommands.IAC)
+                    const optionValue = data.slice(0, endIndex)
+                    this.logger.debug('<', commandName || command, optionName || option, optionValue)
+                    data = data.slice(endIndex + 2)
+                }
+            } else {
+                return data
+            }
+        }
+        return data
+    }
+
     // eslint-disable-next-line @typescript-eslint/no-empty-function
-    resize (_w: number, _h: number): void { }
+    resize (w: number, h: number): void {
+        if (w && h) {
+            this.lastWidth = w
+            this.lastHeight = h
+        }
+        if (this.lastWidth && this.lastHeight && this.telnetProtocol) {
+            this.emitTelnetSuboption(TelnetOptions.NEGO_WINDOW_SIZE, Buffer.from([
+                this.lastWidth >> 8, this.lastWidth & 0xff,
+                this.lastHeight >> 8, this.lastHeight & 0xff,
+            ]))
+        }
+    }
 
     write (data: Buffer): void {
+        if (this.echoEnabled) {
+            this.emitOutput(data)
+        }
         this.streamProcessor.feedFromTerminal(data)
     }