Merge pull request #3 from bugout-dev/annotations

Optionally generate annotations for each interface

abi.go

@@ -2,6 +2,10 @@ package main
 
 import (
 	"encoding/json"
+	"fmt"
+	"strings"
+
+	"github.com/ethereum/go-ethereum/crypto"
 )
 
 /**
@@ -53,6 +57,11 @@ type DecodedABI struct {
 	Errors    []ErrorItem
 }
 
+type Annotations struct {
+	InterfaceID       []byte
+	FunctionSelectors [][]byte
+}
+
 func Decode(rawJSON []byte) (DecodedABI, error) {
 	var typeDeclarations []TypeDeclaration
 	var rawMessages []json.RawMessage
@@ -120,6 +129,33 @@ func Decode(rawJSON []byte) (DecodedABI, error) {
 	return decodedABI, nil
 }
 
+func MethodSelector(function FunctionItem) []byte {
+	argumentTypes := make([]string, len(function.Inputs))
+	for i, input := range function.Inputs {
+		argumentTypes[i] = input.Type
+	}
+	argumentTypesString := strings.Join(argumentTypes, ",")
+	signature := fmt.Sprintf("%s(%s)", function.Name, argumentTypesString)
+	return crypto.Keccak256([]byte(signature))[:4]
+}
+
+func Annotate(decodedABI DecodedABI) (Annotations, error) {
+	var annotations Annotations
+	annotations.InterfaceID = []byte{0x0, 0x0, 0x0, 0x0}
+	annotations.FunctionSelectors = make([][]byte, len(decodedABI.Functions))
+	for i, functionItem := range decodedABI.Functions {
+		selector := MethodSelector(functionItem)
+		annotations.FunctionSelectors[i] = selector
+
+		// XOR into InterfaceID byte by byte
+		annotations.InterfaceID[0] ^= selector[0]
+		annotations.InterfaceID[1] ^= selector[1]
+		annotations.InterfaceID[2] ^= selector[2]
+		annotations.InterfaceID[3] ^= selector[3]
+	}
+	return annotations, nil
+}
+
 func (v Value) IsCompoundType() bool {
 	return len(v.Components) > 0
 }

abi_test.go

@@ -1,10 +1,44 @@
 package main
 
 import (
+	"encoding/hex"
 	"os"
 	"testing"
 )
 
+func TestMethodSelectorOnERC721SafeTransferFromWithoutCalldata(t *testing.T) {
+	functionItem := FunctionItem{Type: "function", Name: "safeTransferFrom", Inputs: []Value{
+		{Name: "from", Type: "address"},
+		{Name: "to", Type: "address"},
+		{Name: "tokenId", Type: "uint256"},
+	}}
+
+	selector := MethodSelector(functionItem)
+
+	expectedSelectorString := "42842e0e"
+	selectorString := hex.EncodeToString(selector)
+	if selectorString != expectedSelectorString {
+		t.Fatalf("Incorrect method selector for safeTransferFrom(address,address,uint256). Expected: %s, actual: %s", expectedSelectorString, selectorString)
+	}
+}
+
+func TestMethodSelectorOnERC721SafeTransferFromWithCalldata(t *testing.T) {
+	functionItem := FunctionItem{Type: "function", Name: "safeTransferFrom", Inputs: []Value{
+		{Name: "from", Type: "address"},
+		{Name: "to", Type: "address"},
+		{Name: "tokenId", Type: "uint256"},
+		{Name: "data", Type: "bytes"},
+	}}
+
+	selector := MethodSelector(functionItem)
+
+	expectedSelectorString := "b88d4fde"
+	selectorString := hex.EncodeToString(selector)
+	if selectorString != expectedSelectorString {
+		t.Fatalf("Incorrect method selector for safeTransferFrom(address,address,uint256,bytes). Expected: %s, actual: %s", expectedSelectorString, selectorString)
+	}
+}
+
 func TestDecodeOwnableERC20(t *testing.T) {
 	contents, readErr := os.ReadFile("fixtures/abis/OwnableERC20.json")
 	if readErr != nil {
@@ -214,3 +248,26 @@ func TestSingleFunction(t *testing.T) {
 		}
 	}
 }
+
+func TestERC20InterfaceID(t *testing.T) {
+	contents, readErr := os.ReadFile("fixtures/abis/ERC20.json")
+	if readErr != nil {
+		t.Fatal("Could not read file containing ABI")
+	}
+
+	decodedABI, decodeErr := Decode(contents)
+	if decodeErr != nil {
+		t.Fatalf("Could not decode ABI: %s", decodeErr.Error())
+	}
+
+	annotations, err := Annotate(decodedABI)
+	if err != nil {
+		t.Fatalf("Could not generate annotations: %s", err.Error())
+	}
+
+	expectedInterfaceID := "36372b07"
+	interfaceId := hex.EncodeToString(annotations.InterfaceID)
+	if interfaceId != expectedInterfaceID {
+		t.Fatalf("Incorrect interface ID generated: expected: %s, actual: %s", expectedInterfaceID, interfaceId)
+	}
+}

fixtures/abis/ERC20.json

@@ -0,0 +1,185 @@
+[
+  {
+    "anonymous": false,
+    "inputs": [
+      {
+        "indexed": true,
+        "internalType": "address",
+        "name": "owner",
+        "type": "address"
+      },
+      {
+        "indexed": true,
+        "internalType": "address",
+        "name": "spender",
+        "type": "address"
+      },
+      {
+        "indexed": false,
+        "internalType": "uint256",
+        "name": "value",
+        "type": "uint256"
+      }
+    ],
+    "name": "Approval",
+    "type": "event"
+  },
+  {
+    "anonymous": false,
+    "inputs": [
+      {
+        "indexed": true,
+        "internalType": "address",
+        "name": "from",
+        "type": "address"
+      },
+      {
+        "indexed": true,
+        "internalType": "address",
+        "name": "to",
+        "type": "address"
+      },
+      {
+        "indexed": false,
+        "internalType": "uint256",
+        "name": "value",
+        "type": "uint256"
+      }
+    ],
+    "name": "Transfer",
+    "type": "event"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "address",
+        "name": "owner",
+        "type": "address"
+      },
+      {
+        "internalType": "address",
+        "name": "spender",
+        "type": "address"
+      }
+    ],
+    "name": "allowance",
+    "outputs": [
+      {
+        "internalType": "uint256",
+        "name": "",
+        "type": "uint256"
+      }
+    ],
+    "stateMutability": "view",
+    "type": "function"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "address",
+        "name": "spender",
+        "type": "address"
+      },
+      {
+        "internalType": "uint256",
+        "name": "amount",
+        "type": "uint256"
+      }
+    ],
+    "name": "approve",
+    "outputs": [
+      {
+        "internalType": "bool",
+        "name": "",
+        "type": "bool"
+      }
+    ],
+    "stateMutability": "nonpayable",
+    "type": "function"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "address",
+        "name": "account",
+        "type": "address"
+      }
+    ],
+    "name": "balanceOf",
+    "outputs": [
+      {
+        "internalType": "uint256",
+        "name": "",
+        "type": "uint256"
+      }
+    ],
+    "stateMutability": "view",
+    "type": "function"
+  },
+  {
+    "inputs": [],
+    "name": "totalSupply",
+    "outputs": [
+      {
+        "internalType": "uint256",
+        "name": "",
+        "type": "uint256"
+      }
+    ],
+    "stateMutability": "view",
+    "type": "function"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "address",
+        "name": "to",
+        "type": "address"
+      },
+      {
+        "internalType": "uint256",
+        "name": "amount",
+        "type": "uint256"
+      }
+    ],
+    "name": "transfer",
+    "outputs": [
+      {
+        "internalType": "bool",
+        "name": "",
+        "type": "bool"
+      }
+    ],
+    "stateMutability": "nonpayable",
+    "type": "function"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "address",
+        "name": "from",
+        "type": "address"
+      },
+      {
+        "internalType": "address",
+        "name": "to",
+        "type": "address"
+      },
+      {
+        "internalType": "uint256",
+        "name": "amount",
+        "type": "uint256"
+      }
+    ],
+    "name": "transferFrom",
+    "outputs": [
+      {
+        "internalType": "bool",
+        "name": "",
+        "type": "bool"
+      }
+    ],
+    "stateMutability": "nonpayable",
+    "type": "function"
+  }
+]