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Client Payload Validation and Automation Safety Enforcement Module #71

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ecfb075
prevent-client-side-crash
aniket866 Feb 12, 2026
34e2637
Code rabbit follow up
aniket866 Feb 12, 2026
bf52df1
Code rabbit follow up
aniket866 Feb 12, 2026
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112 changes: 94 additions & 18 deletions src/server/InputHandler.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -14,19 +14,38 @@ export interface InputMessage {
}

export class InputHandler {
// Security Constants (ADDED)
private static readonly MAX_TEXT_LENGTH = 500;
private static readonly MAX_DELTA = 2000;
private static readonly MAX_SCROLL = 500;
private static readonly MAX_ZOOM_INPUT = 1000;
private static readonly MAX_COMBO_KEYS = 5;

constructor() {
mouse.config.mouseSpeed = 1000;
}

// Utility clamp (ADDED)
private clamp(value: number, min: number, max: number): number {
if (!Number.isFinite(value)) return 0;
return Math.max(min, Math.min(max, value));
}

async handleMessage(msg: InputMessage) {
switch (msg.type) {

case 'move':
if (msg.dx !== undefined && msg.dy !== undefined) {

// Clamp dx/dy
const safeDx = this.clamp(msg.dx, -InputHandler.MAX_DELTA, InputHandler.MAX_DELTA);
const safeDy = this.clamp(msg.dy, -InputHandler.MAX_DELTA, InputHandler.MAX_DELTA);

const currentPos = await mouse.getPosition();

await mouse.setPosition(new Point(
currentPos.x + msg.dx,
currentPos.y + msg.dy
currentPos.x + safeDx,
currentPos.y + safeDy
));
}
break;
Expand All @@ -45,21 +64,30 @@ export class InputHandler {
case 'scroll':
const promises: Promise<void>[] = [];

//Clamp scroll values
const safeScrollY = typeof msg.dy === 'number'
? this.clamp(msg.dy, -InputHandler.MAX_SCROLL, InputHandler.MAX_SCROLL)
: 0;

const safeScrollX = typeof msg.dx === 'number'
? this.clamp(msg.dx, -InputHandler.MAX_SCROLL, InputHandler.MAX_SCROLL)
: 0;

// Vertical scroll
if (typeof msg.dy === 'number' && msg.dy !== 0) {
if (msg.dy > 0) {
promises.push(mouse.scrollDown(msg.dy));
if (safeScrollY !== 0) {
if (safeScrollY > 0) {
promises.push(mouse.scrollDown(safeScrollY));
} else {
promises.push(mouse.scrollUp(-msg.dy));
promises.push(mouse.scrollUp(-safeScrollY));
}
}

// Horizontal scroll
if (typeof msg.dx === 'number' && msg.dx !== 0) {
if (msg.dx > 0) {
promises.push(mouse.scrollRight(msg.dx));
if (safeScrollX !== 0) {
if (safeScrollX > 0) {
promises.push(mouse.scrollRight(safeScrollX));
} else {
promises.push(mouse.scrollLeft(-msg.dx));
promises.push(mouse.scrollLeft(-safeScrollX));
}
}

Expand All @@ -70,12 +98,20 @@ export class InputHandler {

case 'zoom':
if (msg.delta !== undefined && msg.delta !== 0) {

// Clamp incoming zoom delta
const safeDelta = this.clamp(
msg.delta,
-InputHandler.MAX_ZOOM_INPUT,
InputHandler.MAX_ZOOM_INPUT
);

const sensitivityFactor = 0.5;
const MAX_ZOOM_STEP = 5;

const scaledDelta =
Math.sign(msg.delta) *
Math.min(Math.abs(msg.delta) * sensitivityFactor, MAX_ZOOM_STEP);
Math.sign(safeDelta) *
Math.min(Math.abs(safeDelta) * sensitivityFactor, MAX_ZOOM_STEP);

const amount = -scaledDelta;

Expand All @@ -91,23 +127,56 @@ export class InputHandler {
case 'key':
if (msg.key) {
console.log(`Processing key: ${msg.key}`);
const nutKey = KEY_MAP[msg.key.toLowerCase()];
const lowerKey = msg.key.toLowerCase();

// Allowlist validation
if (!(lowerKey in KEY_MAP) && lowerKey.length !== 1) {
console.warn(`Blocked unknown key: ${msg.key}`);
return;
}

const nutKey = KEY_MAP[lowerKey];

if (nutKey !== undefined) {
await keyboard.type(nutKey);
} else if (msg.key.length === 1) {
await keyboard.type(msg.key);
} else {
console.log(`Unmapped key: ${msg.key}`);
} else if (lowerKey.length === 1) {
await keyboard.type(lowerKey);
}
}
break;

case 'combo':
if (msg.keys && msg.keys.length > 0) {
const nutKeys: (Key | string)[] = [];

// Limit combo length
if (msg.keys.length > InputHandler.MAX_COMBO_KEYS) {
console.warn('Combo too long — blocked');
return;
}

// Remove duplicate keys
const seen = new Set<string>();
const uniqueKeys: string[] = [];
for (const k of msg.keys) {
const lower = k.toLowerCase();
if (!seen.has(lower)) {
seen.add(lower);
uniqueKeys.push(k); // preserve original for single-char typing
}
}

const nutKeys: (Key | string)[] = [];

for (const k of uniqueKeys) {
const lowerKey = k.toLowerCase();

if (!(lowerKey in KEY_MAP) && lowerKey.length !== 1) {
console.warn(`Blocked unknown key in combo: ${k}`);
continue;
}

const nutKey = KEY_MAP[lowerKey];

if (nutKey !== undefined) {
nutKeys.push(nutKey);
} else if (lowerKey.length === 1) {
Expand Down Expand Up @@ -148,6 +217,13 @@ export class InputHandler {

case 'text':
if (msg.text) {

// Limit text length
if (msg.text.length > InputHandler.MAX_TEXT_LENGTH) {
console.warn('Text input too long — blocked');
return;
}

await keyboard.type(msg.text);
}
break;
Expand Down