perf: short-circuit address parsing

Author: pragmaxim

bchain/coins/eth/contract.go

@@ -2,6 +2,7 @@ package eth
 
 import (
 	"context"
+	"encoding/hex"
 	"math/big"
 	"strings"
 
@@ -30,14 +31,20 @@ const contractDecimalsSignature = "0x313ce567"
 const contractBalanceOfSignature = "0x70a08231"
 
 func addressFromPaddedHex(s string) (string, error) {
-	var t big.Int
-	var ok bool
+	// Logs/topics and calldata often include a 0x prefix; strip it so length math and decoding are consistent.
 	if has0xPrefix(s) {
-		_, ok = t.SetString(s[2:], 16)
-	} else {
-		_, ok = t.SetString(s, 16)
+		s = s[2:]
 	}
-	if !ok {
+	if len(s) >= EthereumTypeAddressDescriptorLen*2 {
+		// Fast path: padded topics/data store the address in the last 20 bytes.
+		s = s[len(s)-EthereumTypeAddressDescriptorLen*2:]
+		if b, err := hex.DecodeString(s); err == nil && len(b) == EthereumTypeAddressDescriptorLen {
+			return ethcommon.BytesToAddress(b).String(), nil
+		}
+	}
+	// Fallback: handle odd formats by parsing the full value as a number.
+	var t big.Int
+	if _, ok := t.SetString(s, 16); !ok {
 		return "", errors.New("Data is not a number")
 	}
 	a := ethcommon.BigToAddress(&t)

bchain/coins/eth/contract_test.go

@@ -3,6 +3,8 @@
 package eth
 
 import (
+	"bytes"
+	"encoding/hex"
 	"fmt"
 	"math/big"
 	"strings"
@@ -12,6 +14,80 @@ import (
 	"github.com/trezor/blockbook/tests/dbtestdata"
 )
 
+func Test_addressFromPaddedHex(t *testing.T) {
+	tests := []struct {
+		name    string
+		input   string
+		wantHex string
+		wantErr bool
+	}{
+		{
+			name:    "address_no_padding_with_prefix",
+			input:   "0x5dc6288b35e0807a3d6feb89b3a2ff4ab773168e",
+			wantHex: "5dc6288b35e0807a3d6feb89b3a2ff4ab773168e",
+		},
+		{
+			name:    "uppercase_prefix",
+			input:   "0X0000000000000000000000005dc6288b35e0807a3d6feb89b3a2ff4ab773168e",
+			wantHex: "5dc6288b35e0807a3d6feb89b3a2ff4ab773168e",
+		},
+		{
+			name:    "padded",
+			input:   "0x0000000000000000000000002aacf811ac1a60081ea39f7783c0d26c500871a8",
+			wantHex: "2aacf811ac1a60081ea39f7783c0d26c500871a8",
+		},
+		{
+			name:    "all_zero",
+			input:   "0x0000000000000000000000000000000000000000000000000000000000000000",
+			wantHex: "0000000000000000000000000000000000000000",
+		},
+		{
+			name:    "unpadded",
+			input:   "1a2b3c",
+			wantHex: "00000000000000000000000000000000001a2b3c",
+		},
+		{
+			name:    "invalid_fast_path",
+			input:   "0x0000000000000000000000002aacf811ac1a60081ea39f7783c0d26c500871zz",
+			wantErr: true,
+		},
+		{
+			name:    "invalid",
+			input:   "0xzz",
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := addressFromPaddedHex(tt.input)
+			if tt.wantErr {
+				if err == nil {
+					t.Fatalf("expected error for %q", tt.input)
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("addressFromPaddedHex(%q) error %v", tt.input, err)
+			}
+			if len(got) < 2 || !strings.HasPrefix(got, "0x") {
+				t.Fatalf("addressFromPaddedHex(%q) returned %q", tt.input, got)
+			}
+			gotBytes, err := hex.DecodeString(got[2:])
+			if err != nil {
+				t.Fatalf("decode got %q error %v", got, err)
+			}
+			wantBytes, err := hex.DecodeString(tt.wantHex)
+			if err != nil {
+				t.Fatalf("decode want %q error %v", tt.wantHex, err)
+			}
+			if !bytes.Equal(gotBytes, wantBytes) {
+				t.Fatalf("addressFromPaddedHex(%q) bytes %x want %x", tt.input, gotBytes, wantBytes)
+			}
+		})
+	}
+}
+
 func Test_contractGetTransfersFromLog(t *testing.T) {
 	tests := []struct {
 		name    string