feat(adb): group sub commands to separate objects

.vscode/settings.json

@@ -10,6 +10,7 @@
         "addrs",
         "fluentui",
         "getprop",
+        "killforward",
         "lapo",
         "lstat",
         "mitm",

packages/adb-backend-web/src/index.ts

@@ -1,6 +1,8 @@
 import { AdbBackend, decodeBase64, encodeBase64 } from '@yume-chan/adb';
 import { EventEmitter } from '@yume-chan/event';
 
+export * from './watcher';
+
 export const WebUsbDeviceFilter: USBDeviceFilter = {
     classCode: 0xFF,
     subclassCode: 0x42,
@@ -21,58 +23,15 @@ export function decodeUtf8(buffer: ArrayBuffer): string {
 }
 
 export default class AdbWebBackend implements AdbBackend {
-    public static async fromDevice(device: USBDevice): Promise<AdbWebBackend> {
+    public static async getDevices(): Promise<AdbWebBackend[]> {
-        await device.open();
+        const devices = await window.navigator.usb.getDevices();
-
+        return devices.map(device => new AdbWebBackend(device));
-        for (const configuration of device.configurations) {
-            for (const interface_ of configuration.interfaces) {
-                for (const alternate of interface_.alternates) {
-                    if (alternate.interfaceSubclass === WebUsbDeviceFilter.subclassCode &&
-                        alternate.interfaceClass === WebUsbDeviceFilter.classCode &&
-                        alternate.interfaceSubclass === WebUsbDeviceFilter.subclassCode) {
-                        if (device.configuration?.configurationValue !== configuration.configurationValue) {
-                            await device.selectConfiguration(configuration.configurationValue);
     }
 
-                        if (!interface_.claimed) {
+    public static async requestDevice(): Promise<AdbWebBackend | undefined> {
-                            await device.claimInterface(interface_.interfaceNumber);
-                        }
-
-                        if (interface_.alternate.alternateSetting !== alternate.alternateSetting) {
-                            await device.selectAlternateInterface(interface_.interfaceNumber, alternate.alternateSetting);
-                        }
-
-                        let inEndpointNumber: number | undefined;
-                        let outEndpointNumber: number | undefined;
-
-                        for (const endpoint of alternate.endpoints) {
-                            switch (endpoint.direction) {
-                                case 'in':
-                                    inEndpointNumber = endpoint.endpointNumber;
-                                    if (outEndpointNumber !== undefined) {
-                                        return new AdbWebBackend(device, inEndpointNumber, outEndpointNumber);
-                                    }
-                                    break;
-                                case 'out':
-                                    outEndpointNumber = endpoint.endpointNumber;
-                                    if (inEndpointNumber !== undefined) {
-                                        return new AdbWebBackend(device, inEndpointNumber, outEndpointNumber);
-                                    }
-                                    break;
-                            }
-                        }
-                    }
-                }
-            }
-        }
-
-        throw new Error('Unknown error');
-    }
-
-    public static async pickDevice(): Promise<AdbWebBackend | undefined> {
         try {
             const device = await navigator.usb.requestDevice({ filters: [WebUsbDeviceFilter] });
-            return AdbWebBackend.fromDevice(device);
+            return new AdbWebBackend(device);
         } catch (e) {
             switch (e.name) {
                 case 'NotFoundError':
@@ -85,18 +44,72 @@ export default class AdbWebBackend implements AdbBackend {
 
     private _device: USBDevice;
 
-    public get name() { return this._device.productName; }
+    public get serial(): string { return this._device.serialNumber!; }
 
-    private readonly onDisconnectedEvent = new EventEmitter<void>();
+    public get name(): string { return this._device.productName!; }
-    public readonly onDisconnected = this.onDisconnectedEvent.event;
+
+    private readonly disconnectEvent = new EventEmitter<void>();
+    public readonly onDisconnected = this.disconnectEvent.event;
 
     private _inEndpointNumber!: number;
     private _outEndpointNumber!: number;
 
-    private constructor(device: USBDevice, inEndPointNumber: number, outEndPointNumber: number) {
+    public constructor(device: USBDevice) {
         this._device = device;
-        this._inEndpointNumber = inEndPointNumber;
+        window.navigator.usb.addEventListener('disconnect', this.handleDisconnect);
-        this._outEndpointNumber = outEndPointNumber;
+    }
+
+    private handleDisconnect = (e: USBConnectionEvent) => {
+        if (e.device === this._device) {
+            this.disconnectEvent.fire();
+        }
+    };
+
+    public async connect(): Promise<void> {
+        if (!this._device.opened) {
+            await this._device.open();
+        }
+
+        for (const configuration of this._device.configurations) {
+            for (const interface_ of configuration.interfaces) {
+                for (const alternate of interface_.alternates) {
+                    if (alternate.interfaceSubclass === WebUsbDeviceFilter.subclassCode &&
+                        alternate.interfaceClass === WebUsbDeviceFilter.classCode &&
+                        alternate.interfaceSubclass === WebUsbDeviceFilter.subclassCode) {
+                        if (this._device.configuration?.configurationValue !== configuration.configurationValue) {
+                            await this._device.selectConfiguration(configuration.configurationValue);
+                        }
+
+                        if (!interface_.claimed) {
+                            await this._device.claimInterface(interface_.interfaceNumber);
+                        }
+
+                        if (interface_.alternate.alternateSetting !== alternate.alternateSetting) {
+                            await this._device.selectAlternateInterface(interface_.interfaceNumber, alternate.alternateSetting);
+                        }
+
+                        for (const endpoint of alternate.endpoints) {
+                            switch (endpoint.direction) {
+                                case 'in':
+                                    this._inEndpointNumber = endpoint.endpointNumber;
+                                    if (this._outEndpointNumber !== undefined) {
+                                        return;
+                                    }
+                                    break;
+                                case 'out':
+                                    this._outEndpointNumber = endpoint.endpointNumber;
+                                    if (this._inEndpointNumber !== undefined) {
+                                        return;
+                                    }
+                                    break;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        throw new Error('Unknown error');
     }
 
     public *iterateKeys(): Generator<ArrayBuffer, void, void> {
@@ -133,19 +146,10 @@ export default class AdbWebBackend implements AdbBackend {
     }
 
     public async write(buffer: ArrayBuffer): Promise<void> {
-        try {
         await this._device.transferOut(this._outEndpointNumber, buffer);
-        } catch (e) {
-            if (e instanceof Error && e.name === 'NotFoundError') {
-                this.onDisconnectedEvent.fire();
-            }
-
-            throw e;
-        }
     }
 
     public async read(length: number): Promise<ArrayBuffer> {
-        try {
         const result = await this._device.transferIn(this._inEndpointNumber, length);
 
         if (result.status === 'stall') {
@@ -154,17 +158,11 @@ export default class AdbWebBackend implements AdbBackend {
 
         const { buffer } = result.data!;
         return buffer;
-        } catch (e) {
-            if (e instanceof Error && e.name === 'NotFoundError') {
-                this.onDisconnectedEvent.fire();
-            }
-
-            throw e;
-        }
     }
 
     public async dispose() {
-        this.onDisconnectedEvent.dispose();
+        window.navigator.usb.removeEventListener('disconnect', this.handleDisconnect);
+        this.disconnectEvent.dispose();
         await this._device.close();
     }
 }

packages/adb-backend-web/src/watcher.ts

@@ -0,0 +1,15 @@
+export class AdbWebBackendWatcher {
+    private callback: () => void;
+
+    public constructor(callback: () => void) {
+        this.callback = callback;
+
+        window.navigator.usb.addEventListener('connect', callback);
+        window.navigator.usb.addEventListener('disconnect', callback);
+    }
+
+    public dispose(): void {
+        window.navigator.usb.removeEventListener('connect', this.callback);
+        window.navigator.usb.removeEventListener('disconnect', this.callback);
+    }
+}

packages/adb/src/adb.ts

@@ -2,6 +2,7 @@ import { PromiseResolver } from '@yume-chan/async-operation-manager';
 import { DisposableList } from '@yume-chan/event';
 import { AdbAuthenticationHandler, AdbDefaultAuthenticators } from './auth';
 import { AdbBackend } from './backend';
+import { AdbReverseCommand, AdbTcpIpCommand } from './commands';
 import { AdbFeatures } from './features';
 import { FrameBuffer } from './framebuffer';
 import { AdbCommand } from './packet';
@@ -16,6 +17,8 @@ export enum AdbPropKey {
 }
 
 export class Adb {
+    private packetDispatcher: AdbPacketDispatcher;
+
     private backend: AdbBackend;
     public get onDisconnected() { return this.backend.onDisconnected; }
 
@@ -36,29 +39,38 @@ export class Adb {
     private _features: AdbFeatures[] | undefined;
     public get features() { return this._features; }
 
-    private packetDispatcher: AdbPacketDispatcher;
+    public readonly tcpip: AdbTcpIpCommand;
+
+    public readonly reverse: AdbReverseCommand;
 
     public constructor(backend: AdbBackend) {
         this.backend = backend;
+
         this.packetDispatcher = new AdbPacketDispatcher(backend);
 
+        this.tcpip = new AdbTcpIpCommand(this);
+        this.reverse = new AdbReverseCommand(this.packetDispatcher);
+
         backend.onDisconnected(this.dispose, this);
     }
 
     public async connect(authenticators = AdbDefaultAuthenticators) {
+        await this.backend.connect?.();
+        this.packetDispatcher.start();
+
         const version = 0x01000001;
 
         const features = [
-            'shell_v2',
+            'shell_v2', // 9
-            'cmd',
+            'cmd', // 7
-            AdbFeatures.StatV2,
+            AdbFeatures.StatV2, // 5
             'ls_v2',
-            'fixed_push_mkdir',
+            'fixed_push_mkdir', // 4
-            'apex',
+            'apex', // 2
-            'abb',
+            'abb', // 8
-            'fixed_push_symlink_timestamp',
+            'fixed_push_symlink_timestamp', // 1
-            'abb_exec',
+            'abb_exec', // 6
-            'remount_shell',
+            'remount_shell', // 3
             'track_app',
             'sendrecv_v2',
             'sendrecv_v2_brotli',
@@ -163,33 +175,6 @@ export class Adb {
         }
     }
 
-    public async getDaemonTcpAddresses(): Promise<string[]> {
-        const propAddr = (await this.shell('getprop', 'service.adb.listen_addrs')).trim();
-        if (propAddr) {
-            return propAddr.split(',');
-        }
-
-        let port = (await this.shell('getprop', 'service.adb.tcp.port')).trim();
-        if (port) {
-            return [`0.0.0.0:${port}`];
-        }
-
-        port = (await this.shell('getprop', 'persist.adb.tcp.port')).trim();
-        if (port) {
-            return [`0.0.0.0:${port}`];
-        }
-
-        return [];
-    }
-
-    public setDaemonTcpPort(port = 5555): Promise<string> {
-        return this.createStreamAndReadAll(`tcpip:${port}`);
-    }
-
-    public disableDaemonTcp(): Promise<string> {
-        return this.createStreamAndReadAll('usb:');
-    }
-
     public async sync(): Promise<AdbSync> {
         const stream = await this.createStream('sync:');
         return new AdbSync(stream, this);
@@ -198,11 +183,7 @@ export class Adb {
     public async framebuffer(): Promise<FrameBuffer> {
         const stream = await this.createStream('framebuffer:');
         const buffered = new AdbBufferedStream(stream);
-        return await FrameBuffer.deserialize({
+        return FrameBuffer.deserialize(buffered);
-            read: buffered.read.bind(buffered),
-            encodeUtf8: this.backend.encodeUtf8.bind(this.backend),
-            decodeUtf8: this.backend.decodeUtf8.bind(this.backend),
-        });
     }
 
     public async createStream(service: string): Promise<AdbStream> {

packages/adb/src/backend.ts

@@ -3,10 +3,14 @@ import { Event } from '@yume-chan/event';
 export type AdbKeyIterator = Iterator<ArrayBuffer> | AsyncIterator<ArrayBuffer>;
 
 export interface AdbBackend {
+    readonly serial: string;
+
     readonly name: string | undefined;
 
     readonly onDisconnected: Event<void>;
 
+    connect?(): void | Promise<void>;
+
     iterateKeys(): AdbKeyIterator;
 
     generateKey(): ArrayBuffer | Promise<ArrayBuffer>;

packages/adb/src/commands/base.ts

@@ -0,0 +1,11 @@
+import { AutoDisposable } from '@yume-chan/event';
+import { Adb } from '../adb';
+
+export class AdbCommandBase extends AutoDisposable {
+    protected adb: Adb;
+
+    public constructor(adb: Adb) {
+        super();
+        this.adb = adb;
+    }
+}

packages/adb/src/commands/index.ts

@@ -0,0 +1,3 @@
+export * from './base';
+export * from './tcpip';
+export * from './reverse';

packages/adb/src/commands/reverse.ts

@@ -0,0 +1,122 @@
+import { AutoDisposable } from '@yume-chan/event';
+import { Struct } from '@yume-chan/struct';
+import { Adb } from '../adb';
+import { AdbPacket } from '../packet';
+import { AdbBufferedStream, AdbPacketDispatcher, AdbStream } from '../stream';
+import { AdbCommandBase } from './base';
+
+export interface AdbReverseHandler {
+    onStream(packet: AdbPacket, stream: AdbStream): void;
+}
+
+export interface AdbForwardListener {
+    deviceSerial: string;
+
+    localName: string;
+
+    remoteName: string;
+}
+
+const AdbReverseStringResponse =
+    new Struct({ littleEndian: true })
+        .string('length', { length: 4 })
+        .string('content', { lengthField: 'length' });
+
+const AdbReverseErrorResponse =
+    AdbReverseStringResponse
+        .afterParsed((value) => {
+            throw new Error(value.content);
+        });
+
+export class AdbReverseCommand extends AutoDisposable {
+    private portToHandlerMap = new Map<number, AdbReverseHandler>();
+
+    private devicePortToPortMap = new Map<number, number>();
+
+    private dispatcher: AdbPacketDispatcher;
+
+    private listening = false;
+
+    public constructor(dispatcher: AdbPacketDispatcher) {
+        super();
+        this.dispatcher = dispatcher;
+    }
+
+    public async list(): Promise<AdbForwardListener[]> {
+        const stream = await this.dispatcher.createStream('reverse:list-forward');
+        const buffered = new AdbBufferedStream(stream);
+
+        const response = await AdbReverseStringResponse.deserialize(buffered);
+
+        return response.content!.split('\n').map(line => {
+            const [deviceSerial, localName, remoteName] = line.split(' ');
+            return { deviceSerial, localName, remoteName };
+        });
+    }
+
+    public async add(
+        port: number,
+        handler: AdbReverseHandler,
+        devicePort: number = 0,
+    ): Promise<number> {
+        if (!this.listening) {
+            this.addDisposable(this.dispatcher.onStream(e => {
+                if (e.handled) {
+                    return;
+                }
+
+                const address = this.dispatcher.backend.decodeUtf8(e.packet.payload!);
+                const port = Number.parseInt(address.substring(4));
+                if (this.portToHandlerMap.has(port)) {
+                    this.portToHandlerMap.get(port)!.onStream(e.packet, e.stream);
+                    e.handled = true;
+                }
+            }));
+        }
+
+        const stream = await this.dispatcher.createStream(`reverse:forward:tcp:${devicePort};tcp:${port}`);
+        const buffered = new AdbBufferedStream(stream);
+
+        const success = this.dispatcher.backend.decodeUtf8(await buffered.read(4)) === 'OKAY';
+        if (success) {
+            const response = await AdbReverseStringResponse.deserialize(buffered);
+
+            devicePort = Number.parseInt(response.content!, 10);
+
+            this.portToHandlerMap.set(port, handler);
+            this.devicePortToPortMap.set(devicePort, port);
+
+            return devicePort;
+        } else {
+            return await AdbReverseErrorResponse.deserialize(buffered);
+        }
+    }
+
+    public async remove(devicePort: number): Promise<void> {
+        const stream = await this.dispatcher.createStream(`reverse:killforward:tcp:${devicePort}`);
+        const buffered = new AdbBufferedStream(stream);
+
+        const success = this.dispatcher.backend.decodeUtf8(await buffered.read(4)) === 'OKAY';
+        if (success) {
+            if (this.devicePortToPortMap.has(devicePort)) {
+                this.portToHandlerMap.delete(this.devicePortToPortMap.get(devicePort)!);
+                this.devicePortToPortMap.delete(devicePort);
+            }
+        } else {
+            await AdbReverseErrorResponse.deserialize(buffered);
+        }
+    }
+
+    public async removeAll(): Promise<void> {
+        const stream = await this.dispatcher.createStream(`reverse:killforward-all`);
+        const buffered = new AdbBufferedStream(stream);
+
+        const success = this.dispatcher.backend.decodeUtf8(await buffered.read(4)) === 'OKAY';
+        if (success) {
+            this.devicePortToPortMap.clear();
+            this.portToHandlerMap.clear();
+        } else {
+            await AdbReverseErrorResponse.deserialize(buffered);
+        }
+    }
+}

packages/adb/src/commands/tcpip.ts

@@ -0,0 +1,45 @@
+import { AdbCommandBase } from './base';
+
+export class AdbTcpIpCommand extends AdbCommandBase {
+    private async getProp(key: string): Promise<string> {
+        const output = await this.adb.shell('getprop', key);
+        return output.trim();
+    }
+
+    public async getAddresses(): Promise<string[]> {
+        const propAddr = await this.getProp('service.adb.listen_addrs');
+        if (propAddr) {
+            return propAddr.split(',');
+        }
+
+        let port = await this.getProp('service.adb.tcp.port');
+        if (port) {
+            return [`0.0.0.0:${port}`];
+        }
+
+        port = await this.getProp('persist.adb.tcp.port');
+        if (port) {
+            return [`0.0.0.0:${port}`];
+        }
+
+        return [];
+    }
+
+    public async setPort(port: number): Promise<void> {
+        if (port <= 0) {
+            throw new Error(`Invalid port ${port}`);
+        }
+
+        const output = await this.adb.createStreamAndReadAll(`tcpip:${port}`);
+        if (output !== `restarting in TCP mode port: ${port}\n`) {
+            throw new Error('Invalid response');
+        }
+    }
+
+    public async disable(): Promise<void> {
+        const output = await this.adb.createStreamAndReadAll('usb:');
+        if (output !== 'restarting in USB mode\n') {
+            throw new Error('Invalid response');
+        }
+    }
+}

packages/adb/src/stream/buffered-stream.ts

@@ -1,3 +1,4 @@
+import { StructDeserializationContext } from '@yume-chan/struct';
 import { AdbStreamBase } from './controller';
 import { AdbReadableStream } from './readable-stream';
 import { AdbStream } from './stream';
@@ -60,7 +61,9 @@ export class BufferedStream<T extends Stream> {
     }
 }
 
-export class AdbBufferedStream extends BufferedStream<AdbReadableStream> implements AdbStreamBase {
+export class AdbBufferedStream
+    extends BufferedStream<AdbReadableStream>
+    implements AdbStreamBase, StructDeserializationContext {
     public get backend() { return this.stream.backend; }
 
     public get localId() { return this.stream.localId; }
@@ -74,4 +77,12 @@ export class AdbBufferedStream extends BufferedStream<AdbReadableStream> impleme
     public write(data: ArrayBuffer): Promise<void> {
         return this.stream.write(data);
     }
+
+    public decodeUtf8(buffer: ArrayBuffer): string {
+        return this.backend.decodeUtf8(buffer);
+    }
+
+    public encodeUtf8(input: string): ArrayBuffer {
+        return this.backend.encodeUtf8(input);
+    }
 }

packages/adb/src/stream/dispatcher.ts

@@ -36,14 +36,13 @@ export class AdbPacketDispatcher extends AutoDisposable {
     private readonly errorEvent = this.addDisposable(new EventEmitter<Error>());
     public get onError() { return this.errorEvent.event; }
 
-    private _running = true;
+    private _running = false;
     public get running() { return this._running; }
 
     public constructor(backend: AdbBackend) {
         super();
 
         this.backend = backend;
-        this.receiveLoop();
     }
 
     private async receiveLoop() {
@@ -129,7 +128,8 @@ export class AdbPacketDispatcher extends AutoDisposable {
         const [localId] = this.initializers.add<number>();
         this.initializers.resolve(localId, undefined);
 
-        const controller = new AdbStreamController(localId, packet.arg0, this);
+        const remoteId = packet.arg0;
+        const controller = new AdbStreamController(localId, remoteId, this);
         const stream = new AdbStream(controller);
 
         const args: AdbStreamCreatedEventArgs = {
@@ -141,12 +141,17 @@ export class AdbPacketDispatcher extends AutoDisposable {
 
         if (args.handled) {
             this.streams.set(localId, controller);
-            await this.sendPacket(AdbCommand.OK, localId, packet.arg0);
+            await this.sendPacket(AdbCommand.OK, localId, remoteId);
         } else {
-            await this.sendPacket(AdbCommand.Close, 0, packet.arg0);
+            await this.sendPacket(AdbCommand.Close, 0, remoteId);
         }
     }
 
+    public start() {
+        this._running = true;
+        this.receiveLoop();
+    }
+
     public async createStream(service: string): Promise<AdbStream> {
         const [localId, initializer] = this.initializers.add<number>();
         await this.sendPacket(AdbCommand.Open, localId, 0, service);

packages/demo/src/connect.tsx

@@ -1,10 +1,12 @@
-import { DefaultButton, Dialog, PrimaryButton, ProgressIndicator, Stack, StackItem } from '@fluentui/react';
+import { DefaultButton, Dialog, Dropdown, IDropdownOption, PrimaryButton, ProgressIndicator, Stack, TooltipHost } from '@fluentui/react';
-import { Adb } from '@yume-chan/adb';
+import { Adb, AdbBackend } from '@yume-chan/adb';
-import AdbWebBackend from '@yume-chan/adb-backend-web';
+import AdbWebBackend, { AdbWebBackendWatcher } from '@yume-chan/adb-backend-web';
 import React, { useCallback, useContext, useEffect, useState } from 'react';
 import { ErrorDialogContext } from './error-dialog';
 import { withDisplayName } from './utils';
 
+const DropdownStyles = { dropdown: { width: 300 } };
+
 interface ConnectProps {
     device: Adb | undefined;
 
@@ -17,12 +19,66 @@ export default withDisplayName('Connect', ({
 }: ConnectProps): JSX.Element | null => {
     const { show: showErrorDialog } = useContext(ErrorDialogContext);
 
+    const [backendOptions, setBackendOptions] = useState<IDropdownOption[]>([]);
+    const [selectedBackend, setSelectedBackend] = useState<AdbBackend | undefined>();
+    useEffect(() => {
+        async function refresh() {
+            const backendList = await AdbWebBackend.getDevices();
+
+            const options = backendList.map(item => ({
+                key: item.serial,
+                text: `${item.serial} ${item.name ? `(${item.name})` : ''}`,
+                data: item,
+            }));
+            setBackendOptions(options);
+
+            setSelectedBackend(old => {
+                if (old && backendList.some(item => item.serial === old.serial)) {
+                    return old;
+                }
+                return backendList[0];
+            });
+        };
+
+        refresh();
+
+        const watcher = new AdbWebBackendWatcher(refresh);
+        return () => watcher.dispose();
+    }, []);
+
+    const handleSelectedBackendChange = (
+        _e: React.FormEvent<HTMLDivElement>,
+        option?: IDropdownOption,
+    ) => {
+        setSelectedBackend(option?.data as AdbBackend);
+    };
+
+    const requestAccess = useCallback(async () => {
+        const backend = await AdbWebBackend.requestDevice();
+        if (backend) {
+            setBackendOptions(list => {
+                for (const item of list) {
+                    if (item.key === backend.serial) {
+                        setSelectedBackend(item.data);
+                        return list;
+                    }
+                }
+
+                setSelectedBackend(backend);
+                return [...list, {
+                    key: backend.serial,
+                    text: `${backend.serial} ${backend.name ? `(${backend.name})` : ''}`,
+                    data: backend,
+                }];
+            });
+        }
+    }, []);
+
     const [connecting, setConnecting] = useState(false);
     const connect = useCallback(async () => {
         try {
-            const backend = await AdbWebBackend.pickDevice();
+            if (selectedBackend) {
-            if (backend) {
+                const device = new Adb(selectedBackend);
-                const device = new Adb(backend);
                 try {
                     setConnecting(true);
                     await device.connect();
@@ -37,7 +93,7 @@ export default withDisplayName('Connect', ({
         } finally {
             setConnecting(false);
         }
-    }, [onDeviceChange]);
+    }, [selectedBackend, onDeviceChange]);
     const disconnect = useCallback(async () => {
         try {
             await device!.dispose();
@@ -53,18 +109,42 @@ export default withDisplayName('Connect', ({
     }, [device, onDeviceChange]);
 
     return (
+        <Stack
+            horizontal
+            verticalAlign="end"
+            tokens={{ childrenGap: 8, padding: 8 }}
+        >
+            <Dropdown
+                disabled={!!device || backendOptions.length === 0}
+                label="Available devices"
+                placeholder="No available devices"
+                options={backendOptions}
+                styles={DropdownStyles}
+                selectedKey={selectedBackend?.serial}
+                onChange={handleSelectedBackendChange}
+            />
+
+            {!device ? (
                 <>
-            <Stack horizontal verticalAlign="center" tokens={{ childrenGap: 8, padding: 8 }}>
+                    <PrimaryButton
-                {!device && <StackItem>
+                        text="Connect"
-                    <PrimaryButton text="Connect" onClick={connect} />
+                        disabled={!selectedBackend}
-                </StackItem>}
+                        primary={!!selectedBackend}
-                {device && <StackItem>
+                        onClick={connect}
+                    />
+                    <TooltipHost
+                        content="WebADB can't connect to anything without your explicit permission."
+                    >
+                        <DefaultButton
+                            text="Add new device"
+                            primary={!selectedBackend}
+                            onClick={requestAccess}
+                        />
+                    </TooltipHost>
+                </>
+            ) : (
                     <DefaultButton text="Disconnect" onClick={disconnect} />
-                </StackItem>}
+                )}
-                <StackItem>
-                    {device && `Connected to ${device.name}`}
-                </StackItem>
-            </Stack>
 
             <Dialog
                 hidden={!connecting}
@@ -75,6 +155,6 @@ export default withDisplayName('Connect', ({
             >
                 <ProgressIndicator />
             </Dialog>
-        </>
+        </Stack>
     );
 });

packages/demo/src/index.tsx

@@ -12,7 +12,8 @@ import FileManager from './routes/file-manager';
 import FrameBuffer from './routes/framebuffer';
 import Intro from './routes/intro';
 import Shell from './routes/shell';
-import TcpIp from './routes/tcp-ip';
+import TcpIp from './routes/tcpip';
+import { CommonStackTokens } from './styles';
 
 initializeIcons();
 
@@ -105,7 +106,7 @@ function App(): JSX.Element | null {
                 <Separator />
             </StackItem>
             <StackItem grow styles={{ root: { minHeight: 0 } }}>
-                <Stack horizontal verticalFill tokens={{ childrenGap: 8 }}>
+                <Stack horizontal verticalFill tokens={CommonStackTokens}>
                     <StackItem>
                         <Nav
                             styles={{ root: { width: 250 } }}

packages/demo/src/routes/intro.tsx

@@ -9,6 +9,8 @@ const classNames = mergeStyleSets({
     },
 });
 
+const BoldTextStyles = { root: { fontWeight: '600' } };
+
 interface CopyLinkProps {
     href: string;
 }
@@ -56,7 +58,7 @@ export default withDisplayName('Intro', () => {
                 The latest version of Google Chrome (or Microsoft Edge) is recommended for best compatibility.
             </Text>
 
-            <Text block styles={{ root: { fontWeight: '600' } }}>
+            <Text block styles={BoldTextStyles}>
                 Windows user?
             </Text>
             <Text block>
@@ -65,7 +67,7 @@ export default withDisplayName('Intro', () => {
                 .
             </Text>
 
-            <Text block styles={{ root: { fontWeight: '600' } }}>
+            <Text block styles={BoldTextStyles}>
                 Got "Unable to claim interface" error?
             </Text>
             <Text block>
@@ -73,7 +75,7 @@ export default withDisplayName('Intro', () => {
                 1. Make sure ADB server is not running (run `adb kill-server` to stop it).<br />
                 2. Make sure no other Android management tools are running
             </Text>
-            <Text block styles={{ root: { fontWeight: '600' } }}>
+            <Text block styles={BoldTextStyles}>
                 Got "Access denied" error?
             </Text>
             <Text block>
@@ -82,7 +84,7 @@ export default withDisplayName('Intro', () => {
                     https://bugs.chromium.org/p/chromium/issues/detail?id=1127206
                 </Link>
             </Text>
-            <Text block styles={{ root: { fontWeight: '600' } }}>
+            <Text block styles={BoldTextStyles}>
                 Can I connect my device wirelessly (ADB over WiFi)?
             </Text>
             <Text block>

packages/demo/src/routes/shell.tsx

@@ -8,11 +8,14 @@ import 'xterm/css/xterm.css';
 import { ResizeObserver, withDisplayName } from '../utils';
 import { RouteProps } from './type';
 
-const containerStyle: CSSProperties = {
+const ResizeObserverStyle: CSSProperties = {
     width: '100%',
     height: '100%',
 };
 
+const UpIconProps = { iconName: 'ChevronUp' };
+const DownIconProps = { iconName: 'ChevronDown' };
+
 export default withDisplayName('Shell', ({
     device,
 }: RouteProps): JSX.Element | null => {
@@ -99,21 +102,21 @@ export default withDisplayName('Shell', ({
                     <StackItem>
                         <IconButton
                             disabled={!findKeyword}
-                            iconProps={{ iconName: 'ChevronUp' }}
+                            iconProps={UpIconProps}
                             onClick={findPrevious}
                         />
                     </StackItem>
                     <StackItem>
                         <IconButton
                             disabled={!findKeyword}
-                            iconProps={{ iconName: 'ChevronDown' }}
+                            iconProps={DownIconProps}
                             onClick={findNext}
                         />
                     </StackItem>
                 </Stack>
             </StackItem>
             <StackItem grow styles={{ root: { minHeight: 0 } }}>
-                <ResizeObserver style={containerStyle} onResize={handleResize}>
+                <ResizeObserver style={ResizeObserverStyle} onResize={handleResize}>
                     <div ref={handleContainerRef} style={{ height: '100%' }} />
                 </ResizeObserver>
             </StackItem>

packages/demo/src/routes/tcpip.tsx

@@ -1,6 +1,7 @@
 import { Label, MessageBar, PrimaryButton, Stack, StackItem, Text, TextField } from '@fluentui/react';
 import { useId } from '@uifabric/react-hooks';
 import React, { useCallback, useEffect, useState } from 'react';
+import { CommonStackTokens } from '../styles';
 import { withDisplayName } from '../utils';
 import { RouteProps } from './type';
 
@@ -19,7 +20,7 @@ export default withDisplayName('TcpIp', ({
             return;
         }
 
-        const result = await device.getDaemonTcpAddresses();
+        const result = await device.tcpip.getAddresses();
         setTcpAddresses(result);
     }, [device]);
 
@@ -30,8 +31,7 @@ export default withDisplayName('TcpIp', ({
             return;
         }
 
-        const result = await device.setDaemonTcpPort(Number.parseInt(tcpPortValue, 10));
+        await device.tcpip.setPort(Number.parseInt(tcpPortValue, 10));
-        console.log(result);
     }, [device, tcpPortValue]);
 
     const disableTcp = useCallback(async () => {
@@ -39,8 +39,7 @@ export default withDisplayName('TcpIp', ({
             return;
         }
 
-        const result = await device.disableDaemonTcp();
+        await device.tcpip.disable();
-        console.log(result);
     }, [device]);
 
     return (
@@ -55,7 +54,7 @@ export default withDisplayName('TcpIp', ({
                     <Text>Your device will disconnect after changing ADB over WiFi config.</Text>
                 </MessageBar>
             </StackItem>
-            <Stack horizontal verticalAlign="center" tokens={{ childrenGap: 8 }}>
+            <Stack horizontal verticalAlign="center" tokens={CommonStackTokens}>
                 <StackItem>
                     <PrimaryButton text="Update Status" disabled={!device} onClick={queryTcpAddress} />
                 </StackItem>
@@ -66,7 +65,7 @@ export default withDisplayName('TcpIp', ({
                             : 'Disabled')}
                 </StackItem>
             </Stack>
-            <Stack horizontal verticalAlign="center" tokens={{ childrenGap: 8 }}>
+            <Stack horizontal verticalAlign="center" tokens={CommonStackTokens}>
                 <StackItem>
                     <Label htmlFor={tcpPortInputId}>Port: </Label>
                 </StackItem>

packages/demo/src/styles.ts

@@ -0,0 +1 @@
+export const CommonStackTokens = { childrenGap: 8 };

packages/struct/src/field/variable-length-array.ts

@@ -34,7 +34,7 @@ export namespace VariableLengthArray {
 
     export interface Options<
         TInit = object,
-        TLengthField extends KeyOfType<TInit, number> = any,
+        TLengthField extends KeyOfType<TInit, number | string> = any,
         TEmptyBehavior extends EmptyBehavior = EmptyBehavior
         > extends FieldDescriptorBaseOptions {
         lengthField: TLengthField;
@@ -131,7 +131,7 @@ export interface VariableLengthArray<
     TName extends string = string,
     TType extends Array.SubType = Array.SubType,
     TInit = object,
-    TLengthField extends VariableLengthArray.KeyOfType<TInit, number> = any,
+    TLengthField extends VariableLengthArray.KeyOfType<TInit, number | string> = any,
     TEmptyBehavior extends VariableLengthArray.EmptyBehavior = VariableLengthArray.EmptyBehavior,
     TTypeScriptType = VariableLengthArray.TypeScriptType<TType, TEmptyBehavior>,
     TOptions extends VariableLengthArray.Options<TInit, TLengthField, TEmptyBehavior> = VariableLengthArray.Options<TInit, TLengthField, TEmptyBehavior>
@@ -156,7 +156,11 @@ registerFieldTypeDefinition(
         async deserialize(
             { context, field, object }
         ): Promise<{ value: string | ArrayBuffer | undefined, extra?: ArrayBuffer; }> {
-            const length = object[field.options.lengthField];
+            let length = object[field.options.lengthField];
+            if (typeof length === 'string') {
+                length = Number.parseInt(length, 10);
+            }
+
             if (length === 0) {
                 if (field.options.emptyBehavior === VariableLengthArray.EmptyBehavior.Empty) {
                     switch (field.subType) {

packages/struct/src/struct.ts

@@ -39,7 +39,7 @@ interface AddArrayFieldDescriptor<
     <
         TName extends string,
         TType extends Array.SubType,
-        TLengthField extends VariableLengthArray.KeyOfType<TInit, number>,
+        TLengthField extends VariableLengthArray.KeyOfType<TInit, number | string>,
         TEmptyBehavior extends VariableLengthArray.EmptyBehavior,
         TTypeScriptType = VariableLengthArray.TypeScriptType<TType, TEmptyBehavior>
         >(
@@ -91,7 +91,7 @@ interface AddArraySubTypeFieldDescriptor<
 
     <
         TName extends string,
-        TLengthField extends VariableLengthArray.KeyOfType<TInit, number>,
+        TLengthField extends VariableLengthArray.KeyOfType<TInit, number | string>,
         TEmptyBehavior extends VariableLengthArray.EmptyBehavior,
         TTypeScriptType = VariableLengthArray.TypeScriptType<TType, TEmptyBehavior>
         >(