feat: implement SafeRPCStrategy

For signature validations we need to make contract read calls. Safe
protocol kit expects an RPC URL to make these calls, but on Filecoin
mainnet and Filecoin Calibration they need to be JWT authenticated. This
poses a problem with the initializer of the Safe SDK so we decided to
use public RPCs on these two networks.

Author: pheuberger

src/client/evmClient.ts

@@ -107,12 +107,10 @@ export class EvmClientFactory {
 
   static getPublicRpcUrl(chainId: number): string {
     const chain = ChainFactory.getChain(chainId);
-    if (!chain.rpcUrls.public.http[0]) {
-      throw new Error(
-        `(viem) No public RPC URL available for chain ${chainId}`,
-      );
+    if (!chain.rpcUrls?.default?.http?.[0]) {
+      throw new Error(`No public RPC URL available for chain ${chainId}`);
     }
-    return chain.rpcUrls.public.http[0];
+    return chain.rpcUrls.default.http[0];
   }
 
   // Keep this for backward compatibility

src/lib/safe-signature-verification/SafeSignatureVerifier.ts

@@ -3,6 +3,8 @@ import { getAddress, hashTypedData, type HashTypedDataParameters } from "viem";
 
 import { EvmClientFactory } from "../../client/evmClient.js";
 
+import { RpcStrategyFactory } from "./safe-rpc-urls.js";
+
 export default abstract class SafeSignatureVerifier {
   protected chainId: number;
   protected safeAddress: `0x${string}`;
@@ -11,7 +13,10 @@ export default abstract class SafeSignatureVerifier {
   constructor(chainId: number, safeAddress: `0x${string}`) {
     this.chainId = chainId;
     this.safeAddress = getAddress(safeAddress);
-    this.rpcUrl = EvmClientFactory.getPublicRpcUrl(chainId);
+    this.rpcUrl = RpcStrategyFactory.getStrategy(
+      chainId,
+      EvmClientFactory,
+    ).getUrl(chainId);
   }
 
   hashTypedData() {

src/lib/safe-signature-verification/safe-rpc-urls.ts

@@ -0,0 +1,40 @@
+import { EvmClientFactory } from "../../client/evmClient.js";
+
+export interface SafeRpcStrategy {
+  getUrl(chainId: number): string;
+}
+
+export class FilecoinRpcStrategy implements SafeRpcStrategy {
+  constructor(private evmClientFactory: typeof EvmClientFactory) {}
+
+  getUrl(chainId: number): string {
+    return this.evmClientFactory.getPublicRpcUrl(chainId);
+  }
+}
+
+export class RandomRpcStrategy implements SafeRpcStrategy {
+  constructor(private evmClientFactory: typeof EvmClientFactory) {}
+
+  getUrl(chainId: number): string {
+    const urls = this.evmClientFactory.getAllAvailableUrls(chainId);
+    if (urls.length === 0) {
+      throw new Error(`No RPC URL available for chain ${chainId}`);
+    }
+    const randomIndex = Math.floor(Math.random() * urls.length);
+    return urls[randomIndex];
+  }
+}
+
+export class RpcStrategyFactory {
+  static getStrategy(
+    chainId: number,
+    evmClientFactory: typeof EvmClientFactory,
+  ): SafeRpcStrategy {
+    // Filecoin chains use public RPC
+    if (chainId === 314 || chainId === 314159) {
+      return new FilecoinRpcStrategy(evmClientFactory);
+    }
+    // All other chains use random selection from available RPCs
+    return new RandomRpcStrategy(evmClientFactory);
+  }
+}