From 9739b55b7c3bba5368156878562b38e2bfcf4d5c Mon Sep 17 00:00:00 2001
From: Chris Duncan <chris@zoso.dev>
Date: Wed, 15 Jan 2025 19:13:09 -0800
Subject: [PATCH] Fix validation in gl implementation which could return false
 positives.

---
 src/classes/gl.ts | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/src/classes/gl.ts b/src/classes/gl.ts
index 689bf99..17a3c1c 100644
--- a/src/classes/gl.ts
+++ b/src/classes/gl.ts
@@ -139,22 +139,23 @@ export class NanoPowGl {
 	* byte, converts the subsequent 3 pixels with the nonce byte values to a hex
 	* string, and returns the result.
 	*
-	* @param work - Buffer with the original random nonce value
+	* @param workBytes - Buffer with the original random nonce value
+	* @param workHex - Original nonce if provided for a validation call
 	* @returns Nonce as an 8-byte (16-char) hexadecimal string
 	*/
-	static #readResult (work: Uint8Array): string {
+	static #readResult (workBytes: Uint8Array, workHex?: string): string {
 		if (this.#gl == null) throw new Error('WebGL 2 is required to read pixels')
 		this.#gl.readPixels(0, 0, this.#gl.drawingBufferWidth, this.#gl.drawingBufferHeight, this.#gl.RGBA, this.#gl.UNSIGNED_BYTE, this.#pixels)
 		for (let i = 0; i < this.#pixels.length; i += 4) {
 			if (this.#pixels[i] !== 0) {
 				/** Return the work value with the custom bits */
-				const hex = this.#hexify(work.subarray(4, 8)) + this.#hexify([
+				const hex = this.#hexify(workBytes.subarray(4, 8)) + this.#hexify([
 					this.#pixels[i + 2],
 					this.#pixels[i + 3],
-					work[2] ^ (this.#pixels[i] - 1),
-					work[3] ^ (this.#pixels[i + 1] - 1)
+					workBytes[2] ^ (this.#pixels[i] - 1),
+					workBytes[3] ^ (this.#pixels[i + 1] - 1)
 				])
-				return hex
+				if (workHex == null || workHex == hex) return hex
 			}
 		}
 		throw new Error('Query reported result but nonce value not found')
@@ -239,9 +240,13 @@ export class NanoPowGl {
 		data.setBigUint64(0, BigInt(`0x${work}`), true)
 		const seed = new Uint8Array(data.buffer)
 		this.#draw(seed)
-		const found = await this.#checkQueryResult()
+		let found = await this.#checkQueryResult()
 		if (found) {
-			nonce = this.#readResult(seed)
+			try {
+				nonce = this.#readResult(seed, work)
+			} catch (err) {
+				found = false
+			}
 		}
 		if (found && nonce !== work) throw new Error(`Nonce found but does not match work`)
 		return found
-- 
2.34.1