From a63948f0df8311579584201b2aa246e4524a8a1d Mon Sep 17 00:00:00 2001
From: Benjamin Smith <bh2smith@users.noreply.github.com>
Date: Thu, 14 Nov 2024 09:37:56 +0100
Subject: [PATCH] SignRequest: Determine Broadcast Target (#110)

---
 src/decode/sign-request.ts             | 51 ++++++++++++++++-
 src/index.ts                           |  2 +
 tests/unit/decode/sign-request.spec.ts | 76 +++++++++++++++++++++++++-
 3 files changed, 127 insertions(+), 2 deletions(-)

diff --git a/src/decode/sign-request.ts b/src/decode/sign-request.ts
index 54523bd..eadf00c 100644
--- a/src/decode/sign-request.ts
+++ b/src/decode/sign-request.ts
@@ -1,10 +1,12 @@
-import { isRlpHex, isTransactionSerializable } from "near-ca";
+import { EvmMessage, isRlpHex, isTransactionSerializable } from "near-ca";
+import { parseTransaction, TransactionSerializable } from "viem";
 
 import {
   DecodedTxData,
   parseEip712TypedData,
   parseUserOperation,
   SafeEncodedSignRequest,
+  UserOperation,
 } from "../types";
 import {
   decodeRlpHex,
@@ -56,3 +58,50 @@ export function decodeTxData({
     `decodeTxData: Invalid or unsupported message format ${data}`
   );
 }
+
+/**
+ * Represents different types of broadcastable messages
+ */
+export type BroadcastTarget =
+  | { type: "evm"; transaction: TransactionSerializable }
+  | { type: "bundler"; userOp: UserOperation };
+
+/**
+ * Determines where and how an EVM message should be broadcast
+ * @param evmMessage - The message to be analyzed
+ * @returns Information about how to broadcast the message, or null if invalid
+ */
+export function determineBroadcastTarget(
+  evmMessage: EvmMessage
+): BroadcastTarget | null {
+  // Case 1: User Operation
+  if (typeof evmMessage === "string") {
+    try {
+      const parsed = parseUserOperation(evmMessage);
+      if (parsed) {
+        return {
+          type: "bundler",
+          userOp: parsed,
+        };
+      }
+    } catch (error) {
+      console.warn("Failed to parse potential UserOperation:", error);
+    }
+  }
+  // Case 2: RLP Encoded EVM transaction
+  if (isRlpHex(evmMessage)) {
+    return {
+      type: "evm",
+      transaction: parseTransaction(evmMessage),
+    };
+  }
+  // Case 3: Serializable Transaction
+  if (isTransactionSerializable(evmMessage)) {
+    return {
+      type: "evm",
+      transaction: evmMessage,
+    };
+  }
+
+  return null;
+}
diff --git a/src/index.ts b/src/index.ts
index 4cd5b1a..53e5289 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -5,6 +5,7 @@ export * from "./constants";
 export * from "./decode";
 export * from "./lib/safe-message";
 
+// TODO: Improve re-exports...
 export {
   Network,
   BaseTx,
@@ -15,4 +16,5 @@ export {
   signatureFromTxHash,
   requestRouter as mpcRequestRouter,
   EthTransactionParams,
+  isRlpHex,
 } from "near-ca";
diff --git a/tests/unit/decode/sign-request.spec.ts b/tests/unit/decode/sign-request.spec.ts
index c7f3131..ed12568 100644
--- a/tests/unit/decode/sign-request.spec.ts
+++ b/tests/unit/decode/sign-request.spec.ts
@@ -1,10 +1,15 @@
 import { EIP712TypedData } from "near-ca";
-import { TransactionSerializableEIP1559 } from "viem";
+import {
+  serializeTransaction,
+  TransactionSerializable,
+  TransactionSerializableEIP1559,
+} from "viem";
 
 import {
   SafeEncodedSignRequest,
   UserOperation,
   decodeTxData,
+  determineBroadcastTarget,
 } from "../../../src";
 import {
   decodeRlpHex,
@@ -212,3 +217,72 @@ describe("decoding functions", () => {
     });
   });
 });
+
+const validEIP1559Transaction: TransactionSerializable = {
+  to: "0x70997970C51812dc3A010C7d01b50e0d17dc79C8",
+  value: BigInt(1000000000000000000), // 1 ETH
+  chainId: 1,
+  maxFeePerGas: 1n,
+};
+describe("determineBroadcastTarget", () => {
+  it("identifies EVM transactions", () => {
+    const rlpHex = serializeTransaction(validEIP1559Transaction);
+    const result = determineBroadcastTarget(rlpHex);
+
+    expect(result).toEqual({
+      type: "evm",
+      transaction: expect.any(Object),
+    });
+  });
+
+  it("identifies EVM transactions", () => {
+    const result = determineBroadcastTarget(validEIP1559Transaction);
+
+    expect(result).toEqual({
+      type: "evm",
+      transaction: expect.any(Object),
+    });
+  });
+
+  it("identifies UserOperations", () => {
+    const userOp = {
+      nonce: "0x0",
+      sender: "0x1f87B80f909a74d8Be617f350EC20a16CfC177D7",
+      factory: "0x4e1DCf7AD4e460CfD30791CCC4F9c8a4f820ec67",
+      callData:
+        "0x7bb374280000000000000000000000008d99f8b2710e6a3b94d9bf465a98e5273069acbd0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000008000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002b00b00000000000000000000000000000000000000000000000000000000000062697474652f6e6561722d7361666500",
+      paymaster: "0x0000000000000039cd5e8aE05257CE51C473ddd1",
+      signature: "0x000000000000000000000000",
+      factoryData:
+        "0x1688f0b900000000000000000000000029fcb43b46531bca003ddc8fcb67ffe91900c76200000000000000000000000000000000000000000000000000000000000000600000000000000000000000000000000062697474652f77616c6c65740000000000000000000000000000000000000000000000000000000000000000000001e4b63e800d000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000000010000000000000000000000002dd68b007b46fbe91b9a7c3eda5a7a1063cb5b47000000000000000000000000000000000000000000000000000000000000014000000000000000000000000075cf11467937ce3f2f357ce24ffc3dbf8fd5c2260000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000000000523434f148b321a153e1c80f56e44c406c26636300000000000000000000000000000000000000000000000000000000000000648d0dc49f0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000100000000000000000000000075cf11467937ce3f2f357ce24ffc3dbf8fd5c2260000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
+      callGasLimit: "0x1f2e9",
+      maxFeePerGas: "0x6e64fe30",
+      paymasterData: "0x000000673375fe000000000000",
+      preVerificationGas: "0xe6f7",
+      maxPriorityFeePerGas: "0x139638",
+      verificationGasLimit: "0x7bb14",
+      paymasterPostOpGasLimit: "0x1",
+      paymasterVerificationGasLimit: "0x6cbb",
+    };
+
+    const result = determineBroadcastTarget(JSON.stringify(userOp));
+
+    expect(result).toEqual({
+      type: "bundler",
+      userOp,
+    });
+  });
+
+  it("returns null for invalid messages", () => {
+    const invalidCases = [
+      "not valid json",
+      "{}",
+      JSON.stringify({ invalid: "userOp" }),
+      "0xinvalidhex",
+    ];
+
+    invalidCases.forEach((testCase) => {
+      expect(determineBroadcastTarget(testCase)).toBeNull();
+    });
+  });
+});