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fix: CapacitorSerial Robustness & Hex Validation #4729

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fix: CapacitorSerial Robustness & Hex Validation #4729

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2774a57
fix: Gracefully handle missing native BetaflightSerial plugin
Erics1337 Dec 5, 2025
b162655
fix: Add validation to hexStringToUint8Array in CapacitorSerial
Erics1337 Dec 5, 2025
61f5c65
style: Apply lint fixes to CapacitorSerial
Erics1337 Dec 7, 2025
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59 changes: 49 additions & 10 deletions src/js/protocols/CapacitorSerial.js
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Original file line number Diff line number Diff line change
Expand Up @@ -12,9 +12,10 @@ class CapacitorSerial extends EventTarget {
constructor() {
super();

if (!BetaflightSerial) {
this.pluginAvailable = !!BetaflightSerial;

if (!this.pluginAvailable) {
console.error(`${logHead} Native BetaflightSerial plugin is not available`);
return;
}

this.connected = false;
Expand All @@ -36,15 +37,15 @@ class CapacitorSerial extends EventTarget {
this.handleDeviceAttached = this.handleDeviceAttached.bind(this);
this.handleDeviceDetached = this.handleDeviceDetached.bind(this);

// Listen for data received from native plugin
BetaflightSerial.addListener("dataReceived", this.handleDataReceived);
// Listen for data received from native plugin and load devices if plugin is available
if (this.pluginAvailable) {
BetaflightSerial.addListener("dataReceived", this.handleDataReceived);
BetaflightSerial.addListener("deviceAttached", this.handleDeviceAttached);
BetaflightSerial.addListener("deviceDetached", this.handleDeviceDetached);

// Listen for device attach/detach events
BetaflightSerial.addListener("deviceAttached", this.handleDeviceAttached);
BetaflightSerial.addListener("deviceDetached", this.handleDeviceDetached);

// Load initial device list
this.loadDevices();
// Load initial device list
this.loadDevices();
}

console.log(`${logHead} CapacitorSerial initialized`);
}
Expand Down Expand Up @@ -125,6 +126,10 @@ class CapacitorSerial extends EventTarget {
}

async loadDevices() {
if (!this.pluginAvailable) {
return;
}

try {
const result = await BetaflightSerial.getDevices();
this.ports = result.devices.map((device) => this.createPort(device));
Expand All @@ -137,6 +142,10 @@ class CapacitorSerial extends EventTarget {

async requestPermissionDevice() {
let newPermissionPort = null;
if (!this.pluginAvailable) {
return null;
}

try {
console.log(`${logHead} Requesting USB permissions...`);
const userSelectedPort = await BetaflightSerial.requestPermission();
Expand All @@ -159,6 +168,10 @@ class CapacitorSerial extends EventTarget {
}

async connect(path, options) {
if (!this.pluginAvailable) {
return false;
}

const baudRate = options?.baudRate ?? 115200;
// Prevent double connections
if (this.connected) {
Expand Down Expand Up @@ -232,6 +245,10 @@ class CapacitorSerial extends EventTarget {
}

async disconnect() {
if (!this.pluginAvailable) {
return true;
}

if (!this.connected) {
return true;
}
Expand All @@ -255,6 +272,13 @@ class CapacitorSerial extends EventTarget {
}

async send(data, callback) {
if (!this.pluginAvailable) {
if (callback) {
callback({ bytesSent: 0 });
}
return { bytesSent: 0 };
}

if (!this.connected) {
console.error(`${logHead} Failed to send data, not connected`);
if (callback) {
Expand Down Expand Up @@ -295,6 +319,21 @@ class CapacitorSerial extends EventTarget {
return new Uint8Array(0);
}

// Strip 0x prefix
if (hexString.startsWith("0x") || hexString.startsWith("0X")) {
hexString = hexString.slice(2);
}

// Validate characters
if (!/^[0-9a-fA-F]+$/.test(hexString)) {
throw new Error(`Invalid hex string: contains non-hex characters`);
}

// Validate length
if (hexString.length % 2 !== 0) {
throw new Error(`Invalid hex string: odd length (${hexString.length})`);
}

const bytes = new Uint8Array(hexString.length / 2);
for (let i = 0; i < hexString.length; i += 2) {
bytes[i / 2] = Number.parseInt(hexString.substring(i, i + 2), 16);
Expand Down