Bundle json decoder

flashbots · Feb 22, 2024 · 63ca911 · 63ca911
1 parent e3ae5c1
commit 63ca911
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diff --git a/src/protocols/Bundle.sol b/src/protocols/Bundle.sol
@@ -2,7 +2,9 @@
 pragma solidity ^0.8.13;
 
 import "../suavelib/Suave.sol";
+import "../utils/HexStrings.sol";
 import "solady/src/utils/LibString.sol";
+import "solady/src/utils/JSONParserLib.sol";
 
 // https://docs.flashbots.net/flashbots-auction/advanced/rpc-endpoint#eth_sendbundle
 library Bundle {
@@ -13,6 +15,9 @@ library Bundle {
         bytes[] txns;
     }
 
+    using JSONParserLib for string;
+    using JSONParserLib for JSONParserLib.Item;
+
     function sendBundle(string memory url, BundleObj memory bundle) internal returns (bytes memory) {
         Suave.HttpRequest memory request = encodeBundle(bundle);
         request.url = url;
@@ -52,4 +57,43 @@ library Bundle {
 
         return request;
     }
+
+    function _stripQuotesAndPrefix(string memory s) internal pure returns (string memory) {
+        bytes memory strBytes = bytes(s);
+        bytes memory result = new bytes(strBytes.length - 4);
+        for (uint256 i = 3; i < strBytes.length - 1; i++) {
+            result[i - 3] = strBytes[i];
+        }
+        return string(result);
+    }
+
+    function decodeBundle(string memory bundleJson) public pure returns (Bundle.BundleObj memory) {
+        JSONParserLib.Item memory root = bundleJson.parse();
+        JSONParserLib.Item memory txnsNode = root.at('"txs"');
+        Bundle.BundleObj memory bundle;
+        require(txnsNode.isArray(), "Bundle: txs is not an array");
+        uint256 txnsLength = txnsNode.size();
+        bytes[] memory txns = new bytes[](txnsLength);
+
+        for (uint256 i = 0; i < txnsLength; i++) {
+            JSONParserLib.Item memory txnNode = txnsNode.at(i);
+            bytes memory txn = HexStrings.fromHexString(_stripQuotesAndPrefix(txnNode.value()));
+            txns[i] = txn;
+        }
+        bundle.txns = txns;
+
+        require(root.at('"blockNumber"').isString(), "Bundle: blockNumber is not a string");
+        bundle.blockNumber = uint64(root.at('"blockNumber"').value().decodeString().parseUintFromHex());
+
+        if (root.at('"minTimestamp"').isNumber()) {
+            bundle.minTimestamp = uint64(root.at('"minTimestamp"').value().parseUint());
+        }
+
+        if (root.at('"maxTimestamp"').isNumber()) {
+            bundle.maxTimestamp = uint64(root.at('"maxTimestamp"').value().parseUint());
+        }
+
+        bundle.txns = txns;
+        return bundle;
+    }
 }
diff --git a/src/utils/HexStrings.sol b/src/utils/HexStrings.sol
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+// Hex string to bytes parser. Used for decoding JSON encoded data.
+library HexStrings {
+    function _fromHexChar(uint8 c) internal pure returns (uint8) {
+        if (bytes1(c) >= bytes1("0") && bytes1(c) <= bytes1("9")) {
+            return c - uint8(bytes1("0"));
+        }
+        if (bytes1(c) >= bytes1("a") && bytes1(c) <= bytes1("f")) {
+            return 10 + c - uint8(bytes1("a"));
+        }
+        if (bytes1(c) >= bytes1("A") && bytes1(c) <= bytes1("F")) {
+            return 10 + c - uint8(bytes1("A"));
+        }
+        revert("fail");
+    }
+
+    // Convert an hexadecimal string to raw bytes
+    function fromHexString(string memory s) internal pure returns (bytes memory) {
+        bytes memory ss = bytes(s);
+        require(ss.length % 2 == 0); // length must be even
+        bytes memory r = new bytes(ss.length / 2);
+        for (uint256 i = 0; i < ss.length / 2; ++i) {
+            r[i] = bytes1(_fromHexChar(uint8(ss[2 * i])) * 16 + _fromHexChar(uint8(ss[2 * i + 1])));
+        }
+        return r;
+    }
+}
diff --git a/test/protocols/Bundle.t.sol b/test/protocols/Bundle.t.sol
@@ -4,8 +4,11 @@ pragma solidity ^0.8.13;
 import "forge-std/Test.sol";
 import "src/protocols/Bundle.sol";
 import "src/suavelib/Suave.sol";
+import "solady/src/utils/LibString.sol";
 
 contract EthSendBundle is Test {
+    using LibString for *;
+
     function testEthSendBundleEncode() public {
         Bundle.BundleObj memory bundle;
         bundle.blockNumber = 1;
@@ -37,4 +40,18 @@ contract EthSendBundle is Test {
             '{"jsonrpc":"2.0","method":"eth_sendBundle","params":[{"blockNumber": "0x01", "txs": ["0x1234"], "minTimestamp": 2, "maxTimestamp": 3}],"id":1}'
         );
     }
+
+    function testBundleDecode() public {
+        string memory json = "{" '"blockNumber": "0xdead",' '"minTimestamp": 1625072400,'
+            '"maxTimestamp": 1625076000,' '"txs": [' '"0xdeadbeef",' '"0xc0ffee",' '"0x00aabb"' "]" "}";
+
+        Bundle.BundleObj memory bundle = Bundle.decodeBundle(json);
+        assertEq(bundle.blockNumber, 0xdead);
+        assertEq(bundle.minTimestamp, 1625072400);
+        assertEq(bundle.maxTimestamp, 1625076000);
+        assertEq(bundle.txns.length, 3);
+        assertEq(bundle.txns[0].toHexString(), "0xdeadbeef");
+        assertEq(bundle.txns[1].toHexString(), "0xc0ffee");
+        assertEq(bundle.txns[2].toHexString(), "0x00aabb");
+    }
 }