fix: blockhash syncing

packages/core/jest.config.ts

@@ -6,6 +6,7 @@ export default {
     'ts-jest': {
       tsconfig: '<rootDir>/tsconfig.spec.json',
     },
+    fetch: global.fetch,
   },
   transform: {
     '^.+\\.[t]s$': 'ts-jest',

packages/core/src/lib/lit-core.spec.ts

@@ -0,0 +1,177 @@
+import { InvalidEthBlockhash } from '@lit-protocol/constants';
+
+import { LitCore } from './lit-core';
+
+describe('LitCore', () => {
+  let core: LitCore;
+
+  describe('getLatestBlockhash', () => {
+    let originalFetch: typeof fetch;
+    let originalDateNow: typeof Date.now;
+    const mockBlockhashUrl =
+      'https://block-indexer-url.com/get_most_recent_valid_block';
+
+    beforeEach(() => {
+      core = new LitCore({
+        litNetwork: 'custom',
+      });
+      core['_blockHashUrl'] = mockBlockhashUrl;
+      originalFetch = fetch;
+      originalDateNow = Date.now;
+    });
+
+    afterEach(() => {
+      global.fetch = originalFetch;
+      Date.now = originalDateNow;
+      jest.clearAllMocks();
+    });
+
+    it('should return cached blockhash if still valid', async () => {
+      // Setup
+      const mockBlockhash = '0x1234';
+      const currentTime = 1000000;
+      core.latestBlockhash = mockBlockhash;
+      core.lastBlockHashRetrieved = currentTime;
+      Date.now = jest.fn().mockReturnValue(currentTime + 15000); // 15 seconds later
+      global.fetch = jest.fn();
+
+      // Execute
+      const result = await core.getLatestBlockhash();
+
+      // Assert
+      expect(result).toBe(mockBlockhash);
+      expect(global.fetch).not.toHaveBeenCalled();
+    });
+
+    it('should fetch new blockhash when cache is expired', async () => {
+      // Setup
+      const mockBlockhash = '0x5678';
+      const currentTime = 1000000;
+      core.latestBlockhash = '0x1234';
+      core.lastBlockHashRetrieved = currentTime - 31000; // 31 seconds ago currentTime
+      const blockNumber = 12345;
+      global.fetch = jest.fn().mockResolvedValue({
+        ok: true,
+        json: () =>
+          Promise.resolve({
+            blockhash: mockBlockhash,
+            timestamp: currentTime,
+            blockNumber,
+          }),
+      });
+      Date.now = jest.fn().mockReturnValue(currentTime);
+
+      // Execute
+      const result = await core.getLatestBlockhash();
+
+      // Assert
+      expect(result).toBe(mockBlockhash);
+      expect(fetch).toHaveBeenCalledWith(mockBlockhashUrl);
+    });
+
+    it('should throw error when blockhash is not available', async () => {
+      // Setup
+      core.latestBlockhash = null;
+      core.lastBlockHashRetrieved = null;
+      global.fetch = jest.fn().mockResolvedValue({
+        ok: false,
+      });
+      core['_getProviderWithFallback'] = jest.fn(() => Promise.resolve(null));
+
+      // Execute & Assert
+      await expect(core.getLatestBlockhash()).rejects.toThrow(
+        InvalidEthBlockhash
+      );
+    });
+
+    it('should handle fetch failure and use fallback RPC', async () => {
+      // Setup
+      const mockBlockhash = '0xabc';
+      const currentTime = 1000000;
+      Date.now = jest.fn().mockReturnValue(currentTime);
+      global.fetch = jest.fn().mockRejectedValue(new Error('Fetch failed'));
+      const mockProvider = {
+        getBlockNumber: jest.fn().mockResolvedValue(12345),
+        getBlock: jest.fn().mockResolvedValue({
+          hash: mockBlockhash,
+          number: 12345,
+          timestamp: currentTime,
+        }),
+      };
+      jest.spyOn(core as any, '_getProviderWithFallback').mockResolvedValue({
+        ...mockProvider,
+      });
+
+      // Execute
+      const result = await core.getLatestBlockhash();
+
+      // Assert
+      expect(fetch).toHaveBeenCalledWith(mockBlockhashUrl);
+      expect(mockProvider.getBlock).toHaveBeenCalledWith(-1); // safety margin
+      expect(result).toBe(mockBlockhash);
+    });
+
+    it('should handle empty blockhash response with fallback RPC URLs', async () => {
+      // Setup
+      const mockBlockhash = '0xabc';
+      const currentTime = 1000000;
+      Date.now = jest.fn().mockReturnValue(currentTime);
+      global.fetch = jest.fn().mockResolvedValue({
+        ok: true,
+        json: () =>
+          Promise.resolve({
+            blockhash: null,
+            blockNumber: null,
+          }),
+      });
+      const mockProvider = {
+        getBlockNumber: jest.fn().mockResolvedValue(12345),
+        getBlock: jest.fn().mockResolvedValue({
+          hash: mockBlockhash,
+          number: 12345,
+          timestamp: currentTime,
+        }),
+      };
+      jest.spyOn(core as any, '_getProviderWithFallback').mockResolvedValue({
+        ...mockProvider,
+      });
+
+      // Execute
+      const result = await core.getLatestBlockhash();
+
+      // Assert
+      expect(fetch).toHaveBeenCalledWith(mockBlockhashUrl);
+      expect(mockProvider.getBlock).toHaveBeenCalledWith(-1); // safety margin
+      expect(result).toBe(mockBlockhash);
+    });
+
+    it('should handle network timeouts gracefully', async () => {
+      // Setup
+      const currentTime = 1000000;
+      Date.now = jest.fn().mockReturnValue(currentTime);
+
+      global.fetch = jest
+        .fn()
+        .mockImplementation(
+          () =>
+            new Promise((_, reject) =>
+              setTimeout(() => reject(new Error('Network timeout')), 1000)
+            )
+        );
+
+      const mockProvider = {
+        getBlockNumber: jest.fn().mockResolvedValue(12345),
+        getBlock: jest.fn().mockResolvedValue(null), // Provider also fails
+      };
+
+      jest.spyOn(core as any, '_getProviderWithFallback').mockResolvedValue({
+        ...mockProvider,
+      });
+
+      // Execute & Assert
+      await expect(() => core.getLatestBlockhash()).rejects.toThrow(
+        InvalidEthBlockhash
+      );
+    });
+  });
+});

packages/core/src/lib/lit-core.ts

@@ -31,6 +31,7 @@ import {
   version,
   InitError,
   InvalidParamType,
+  NetworkError,
   NodeError,
   UnknownError,
   InvalidArgumentException,
@@ -118,6 +119,8 @@ export type LitNodeClientConfigWithDefaults = Required<
 const EPOCH_PROPAGATION_DELAY = 45_000;
 // This interval is responsible for keeping latest block hash up to date
 const BLOCKHASH_SYNC_INTERVAL = 30_000;
+// When fetching the blockhash from a provider (not lit), we use a previous block to avoid a nodes not knowing about the new block yet
+const BLOCKHASH_COUNT_PROVIDER_DELAY = -1;
 
 // Intentionally not including datil-dev here per discussion with Howard
 const NETWORKS_REQUIRING_SEV: string[] = [
@@ -784,6 +787,8 @@ export class LitCore {
 
   /**
    * Fetches the latest block hash and log any errors that are returned
+   * Nodes will accept any blockhash in the last 30 days but use the latest 10 as challenges for webauthn
+   * Note: last blockhash from providers might not be propagated to the nodes yet, so we need to use a slightly older one
    * @returns void
    */
   private async _syncBlockhash() {
@@ -805,52 +810,72 @@ export class LitCore {
       this.latestBlockhash
     );
 
-    return fetch(this._blockHashUrl)
-      .then(async (resp: Response) => {
-        const blockHashBody: EthBlockhashInfo = await resp.json();
-        this.latestBlockhash = blockHashBody.blockhash;
-        this.lastBlockHashRetrieved = Date.now();
-        log('Done syncing state new blockhash: ', this.latestBlockhash);
-
-        // If the blockhash retrieval failed, throw an error to trigger fallback in catch block
-        if (!this.latestBlockhash) {
-          throw new Error(
-            `Error getting latest blockhash. Received: "${this.latestBlockhash}"`
-          );
-        }
-      })
-      .catch(async (err: BlockHashErrorResponse | Error) => {
-        logError(
-          'Error while attempting to fetch new latestBlockhash:',
-          err instanceof Error ? err.message : err.messages,
-          'Reason: ',
-          err instanceof Error ? err : err.reason
+    try {
+      // This fetches from the lit propagation service so nodes will always have it
+      const resp = await fetch(this._blockHashUrl);
+      // If the blockhash retrieval failed, throw an error to trigger fallback in catch block
+      if (!resp.ok) {
+        throw new NetworkError(
+          {
+            responseResult: resp.ok,
+            responseStatus: resp.status,
+          },
+          `Error getting latest blockhash from ${this._blockHashUrl}. Received: "${resp.status}"`
         );
+      }
 
-        log(
-          'Attempting to fetch blockhash manually using ethers with fallback RPC URLs...'
+      const blockHashBody: EthBlockhashInfo = await resp.json();
+      const { blockhash, timestamp } = blockHashBody;
+
+      // If the blockhash retrieval does not have the required fields, throw an error to trigger fallback in catch block
+      if (!blockhash || !timestamp) {
+        throw new NetworkError(
+          {
+            responseResult: resp.ok,
+            blockHashBody,
+          },
+          `Error getting latest blockhash from block indexer. Received: "${blockHashBody}"`
         );
-        const provider = await this._getProviderWithFallback();
+      }
 
-        if (!provider) {
-          logError(
-            'All fallback RPC URLs failed. Unable to retrieve blockhash.'
-          );
-          return;
-        }
+      this.latestBlockhash = blockHashBody.blockhash;
+      this.lastBlockHashRetrieved = parseInt(timestamp) * 1000;
+      log('Done syncing state new blockhash: ', this.latestBlockhash);
+    } catch (error: unknown) {
+      const err = error as BlockHashErrorResponse | Error;
+
+      logError(
+        'Error while attempting to fetch new latestBlockhash:',
+        err instanceof Error ? err.message : err.messages,
+        'Reason: ',
+        err instanceof Error ? err : err.reason
+      );
 
-        try {
-          const latestBlock = await provider.getBlock('latest');
-          this.latestBlockhash = latestBlock.hash;
-          this.lastBlockHashRetrieved = Date.now();
-          log(
-            'Successfully retrieved blockhash manually: ',
-            this.latestBlockhash
-          );
-        } catch (ethersError) {
-          logError('Failed to manually retrieve blockhash using ethers');
-        }
-      });
+      log(
+        'Attempting to fetch blockhash manually using ethers with fallback RPC URLs...'
+      );
+      const provider = await this._getProviderWithFallback();
+
+      if (!provider) {
+        logError('All fallback RPC URLs failed. Unable to retrieve blockhash.');
+        return;
+      }
+
+      try {
+        // We use a previous block to avoid nodes not having received the latest block yet
+        const priorBlock = await provider.getBlock(
+          BLOCKHASH_COUNT_PROVIDER_DELAY
+        );
+        this.latestBlockhash = priorBlock.hash;
+        this.lastBlockHashRetrieved = priorBlock.timestamp;
+        log(
+          'Successfully retrieved blockhash manually: ',
+          this.latestBlockhash
+        );
+      } catch (ethersError) {
+        logError('Failed to manually retrieve blockhash using ethers');
+      }
+    }
   }
 
   /** Currently, we perform a full sync every 30s, including handshaking with every node