Explain SignRequest (#108)

src/decode/explain.ts

@@ -0,0 +1,155 @@
+import { Network } from "near-ca";
+
+import { decodeTxData } from ".";
+import { DecodedTxData, SafeEncodedSignRequest } from "../types";
+
+/**
+ * Explain a Safe Signature Request.
+ * @param signRequest - The Safe Signature Request to explain.
+ * @returns The decoded transaction data as stringified JSON or null if there was an error.
+ */
+export async function explainSignRequest(
+  signRequest: SafeEncodedSignRequest
+): Promise<string> {
+  // Decode the Signature Request
+  const decodedEvmData = decodeTxData(signRequest);
+
+  // Decode the function signatures
+  const functionSignatures = await Promise.all(
+    decodedEvmData.transactions.map((tx) =>
+      safeDecodeTx(tx.data, tx.to, decodedEvmData.chainId)
+    )
+  );
+
+  // Format the decoded data
+  return formatEvmData(decodedEvmData, functionSignatures);
+}
+
+const SAFE_NETWORKS: { [chainId: number]: string } = {
+  1: "mainnet", // Ethereum Mainnet
+  10: "optimism", // Optimism Mainnet
+  56: "binance", // Binance Smart Chain Mainnet
+  97: "bsc-testnet", // Binance Smart Chain Testnet
+  100: "gnosis-chain", // Gnosis Chain (formerly xDAI)
+  137: "polygon", // Polygon Mainnet
+  250: "fantom", // Fantom Mainnet
+  288: "boba", // Boba Network Mainnet
+  1284: "moonbeam", // Moonbeam (Polkadot)
+  1285: "moonriver", // Moonriver (Kusama)
+  4002: "fantom-testnet", // Fantom Testnet
+  42161: "arbitrum", // Arbitrum One Mainnet
+  43113: "avalanche-fuji", // Avalanche Fuji Testnet
+  43114: "avalanche", // Avalanche Mainnet
+  80001: "polygon-mumbai", // Polygon Mumbai Testnet
+  8453: "base", // Base Mainnet
+  11155111: "sepolia", // Sepolia Testnet
+  1666600000: "harmony", // Harmony Mainnet
+  1666700000: "harmony-testnet", // Harmony Testnet
+  1313161554: "aurora", // Aurora Mainnet (NEAR)
+  1313161555: "aurora-testnet", // Aurora Testnet (NEAR)
+};
+
+/**
+ * Represents a parameter in a decoded contract call.
+ */
+interface DecodedParameter {
+  /** The parameter name from the contract ABI */
+  name: string;
+  /** The parameter type (e.g., 'address', 'uint256') */
+  type: string;
+  /** The actual value of the parameter */
+  value: string;
+}
+
+/**
+ * Represents a successful response from the Safe transaction decoder.
+ */
+interface FunctionSignature {
+  /** The name of the contract method that was called */
+  method: string;
+  /** Array of decoded parameters from the function call */
+  parameters: DecodedParameter[];
+}
+
+/**
+ * Represents an error response from the Safe transaction decoder.
+ */
+interface SafeDecoderErrorResponse {
+  /** Error code from the Safe API */
+  code: number;
+  /** Human-readable error message */
+  message: string;
+  /** Additional error context arguments */
+  arguments: string[];
+}
+
+/**
+ * Decode a transaction using the Safe Decoder API. According to this spec:
+ * https://safe-transaction-sepolia.safe.global/#/data-decoder/data_decoder_create
+ * @param data - The transaction data to decode.
+ * @param to - The address of the contract that was called.
+ * @param chainId - The chain ID of the transaction.
+ * @returns The decoded transaction data or null if there was an error.
+ */
+export async function safeDecodeTx(
+  data: string,
+  to: string,
+  chainId: number
+): Promise<FunctionSignature | null> {
+  try {
+    const network = SAFE_NETWORKS[chainId] || SAFE_NETWORKS[1];
+    const response = await fetch(
+      `https://safe-transaction-${network}.safe.global/api/v1/data-decoder/`,
+      {
+        method: "POST",
+        headers: {
+          "Content-Type": "application/json",
+          accept: "application/json",
+        },
+        body: JSON.stringify({ data, to }),
+      }
+    );
+
+    // Handle different response status codes
+    if (response.status === 404) {
+      console.warn("Cannot find function selector to decode data");
+      return null;
+    }
+
+    if (response.status === 422) {
+      const errorData = (await response.json()) as SafeDecoderErrorResponse;
+      console.error("Invalid data:", errorData.message, errorData.arguments);
+      return null;
+    }
+
+    if (!response.ok) {
+      console.error(`Unexpected response status: ${response.status}`);
+      return null;
+    }
+
+    return (await response.json()) as FunctionSignature;
+  } catch (error: unknown) {
+    const message = error instanceof Error ? error.message : String(error);
+    console.error("Error decoding transaction:", message);
+    return null;
+  }
+}
+
+export const formatEvmData = (
+  decodedEvmData: DecodedTxData,
+  functionSignatures: (FunctionSignature | null)[] = []
+): string => {
+  const formatted = {
+    ...decodedEvmData,
+    network: Network.fromChainId(decodedEvmData.chainId).name,
+    functionSignatures,
+  };
+
+  return JSON.stringify(formatted, bigIntReplacer, 2);
+};
+
+/**
+ * Replaces bigint values with their string representation.
+ */
+const bigIntReplacer = (_: string, value: unknown): unknown =>
+  typeof value === "bigint" ? value.toString() : value;

src/decode/index.ts

@@ -1,58 +1,2 @@
-import { isRlpHex, isTransactionSerializable } from "near-ca";
-
-import {
-  DecodedTxData,
-  parseEip712TypedData,
-  parseUserOperation,
-  SafeEncodedSignRequest,
-} from "../types";
-import {
-  decodeRlpHex,
-  decodeTransactionSerializable,
-  decodeTypedData,
-  decodeUserOperation,
-} from "./util";
-
-/**
- * Decodes transaction data for a given EVM transaction and extracts relevant details.
- *
- * @param {EvmTransactionData} data - The raw transaction data to be decoded.
- * @returns {DecodedTxData} - An object containing the chain ID, estimated cost, and a list of decoded meta-transactions.
- */
-export function decodeTxData({
-  evmMessage,
-  chainId,
-}: Omit<SafeEncodedSignRequest, "hashToSign">): DecodedTxData {
-  const data = evmMessage;
-  if (isRlpHex(evmMessage)) {
-    return decodeRlpHex(chainId, evmMessage);
-  }
-  if (isTransactionSerializable(data)) {
-    return decodeTransactionSerializable(chainId, data);
-  }
-  const parsedTypedData = parseEip712TypedData(data);
-  if (parsedTypedData) {
-    return decodeTypedData(chainId, parsedTypedData);
-  }
-  const userOp = parseUserOperation(data);
-  if (userOp) {
-    return decodeUserOperation(chainId, userOp);
-  }
-  // At this point we are certain that the data is a string.
-  // Typescript would disagree here because of the EIP712TypedData possibility that remains.
-  // However this is captured (indirectly) by parseEip712TypedData above.
-  // We check now if its a string and return a reasonable default (for the case of a raw message).
-  if (typeof data === "string") {
-    return {
-      chainId,
-      costEstimate: "0",
-      transactions: [],
-      message: data,
-    };
-  }
-  // Otherwise we have no idea what the data is and we throw.
-  console.warn("Unrecognized txData format,", chainId, data);
-  throw new Error(
-    `decodeTxData: Invalid or unsupported message format ${data}`
-  );
-}
+export * from "./explain";
+export * from "./sign-request";

src/decode/sign-request.ts

@@ -0,0 +1,58 @@
+import { isRlpHex, isTransactionSerializable } from "near-ca";
+
+import {
+  DecodedTxData,
+  parseEip712TypedData,
+  parseUserOperation,
+  SafeEncodedSignRequest,
+} from "../types";
+import {
+  decodeRlpHex,
+  decodeTransactionSerializable,
+  decodeTypedData,
+  decodeUserOperation,
+} from "./util";
+
+/**
+ * Decodes transaction data for a given EVM transaction and extracts relevant details.
+ *
+ * @param {EvmTransactionData} data - The raw transaction data to be decoded.
+ * @returns {DecodedTxData} - An object containing the chain ID, estimated cost, and a list of decoded meta-transactions.
+ */
+export function decodeTxData({
+  evmMessage,
+  chainId,
+}: Omit<SafeEncodedSignRequest, "hashToSign">): DecodedTxData {
+  const data = evmMessage;
+  if (isRlpHex(evmMessage)) {
+    return decodeRlpHex(chainId, evmMessage);
+  }
+  if (isTransactionSerializable(data)) {
+    return decodeTransactionSerializable(chainId, data);
+  }
+  const parsedTypedData = parseEip712TypedData(data);
+  if (parsedTypedData) {
+    return decodeTypedData(chainId, parsedTypedData);
+  }
+  const userOp = parseUserOperation(data);
+  if (userOp) {
+    return decodeUserOperation(chainId, userOp);
+  }
+  // At this point we are certain that the data is a string.
+  // Typescript would disagree here because of the EIP712TypedData possibility that remains.
+  // However this is captured (indirectly) by parseEip712TypedData above.
+  // We check now if its a string and return a reasonable default (for the case of a raw message).
+  if (typeof data === "string") {
+    return {
+      chainId,
+      costEstimate: "0",
+      transactions: [],
+      message: data,
+    };
+  }
+  // Otherwise we have no idea what the data is and we throw.
+  console.warn("Unrecognized txData format,", chainId, data);
+  throw new Error(
+    `decodeTxData: Invalid or unsupported message format ${data}`
+  );
+}

src/index.ts

@@ -2,7 +2,7 @@ export * from "./near-safe";
 export * from "./types";
 export * from "./util";
 export * from "./constants";
-export { decodeTxData } from "./decode";
+export * from "./decode";
 export * from "./lib/safe-message";
 
 export {

src/near-safe.ts

@@ -354,7 +354,7 @@ export class NearSafe {
   ): Promise<MetaTransaction> {
     return {
       to: this.address,
-      value: "0",
+      value: "0x00",
       data: await this.safePack.removeOwnerData(chainId, this.address, address),
     };
   }

src/types/index.ts

@@ -223,7 +223,7 @@ export interface MetaTransaction {
   /** The destination address for the meta-transaction. */
   readonly to: string;
   /** The value to be sent with the transaction (as a string to handle large numbers). */
-  readonly value: string;
+  readonly value: string; // TODO: Change to hex string! No Confusion.
   /** The encoded data for the contract call or function execution. */
   readonly data: string;
   /** Optional type of operation (call or delegate call). */

src/util.ts

@@ -57,7 +57,7 @@ export function packPaymasterData(data: PaymasterData): Hex {
 }
 
 export function containsValue(transactions: MetaTransaction[]): boolean {
-  return transactions.some((tx) => tx.value !== "0");
+  return transactions.some((tx) => BigInt(tx.value) !== 0n);
 }
 
 export async function isContract(