fix: Make the length limitation configurable on bech32

types/bech32/bech32.go

@@ -11,6 +11,10 @@ import (
 	"strings"
 )
 
+// LengthLimitBIP173 is the maximum length of the bech32-encoded address
+// defined by BIP-173.
+const LengthLimitBIP173 = 90
+
 // charset is the set of characters used in the data section of bech32 strings.
 // Note that this is ordered, such that for a given charset[i], i is the binary
 // value of the character.
@@ -239,9 +243,9 @@ func DecodeNoLimit(bech string) (string, []byte, error) {
 //
 // Note that the returned data is 5-bit (base32) encoded and the human-readable
 // part will be lowercase.
-func Decode(bech string) (string, []byte, error) {
-	// The maximum allowed length for a bech32 string is 90.
-	if len(bech) > 90 {
+func Decode(bech string, limit int) (string, []byte, error) {
+	// The length of the given string should not exceed the limit.
+	if len(bech) > limit {
 		return "", nil, ErrInvalidLength(len(bech))
 	}
 
@@ -368,7 +372,7 @@ func EncodeFromBase256(hrp string, data []byte) (string, error) {
 // human-readable part (HRP) and base32-encoded data, converts that data to a
 // base256-encoded byte slice and returns it along with the lowercase HRP.
 func DecodeToBase256(bech string) (string, []byte, error) {
-	hrp, data, err := Decode(bech)
+	hrp, data, err := Decode(bech, LengthLimitBIP173)
 	if err != nil {
 		return "", nil, err
 	}

types/bech32/bech32_test.go

@@ -55,7 +55,7 @@ func TestBech32(t *testing.T) {
 
 	for i, test := range tests {
 		str := test.str
-		hrp, decoded, err := Decode(str)
+		hrp, decoded, err := Decode(str, LengthLimitBIP173)
 		if test.expectedError != err {
 			t.Errorf("%d: expected decoding error %v "+
 				"instead got %v", i, test.expectedError, err)
@@ -81,7 +81,7 @@ func TestBech32(t *testing.T) {
 		// Flip a bit in the string an make sure it is caught.
 		pos := strings.LastIndexAny(str, "1")
 		flipped := str[:pos+1] + string((str[pos+1] ^ 1)) + str[pos+2:]
-		_, _, err = Decode(flipped)
+		_, _, err = Decode(flipped, LengthLimitBIP173)
 		if err == nil {
 			t.Error("expected decoding to fail")
 		}
@@ -152,7 +152,7 @@ func TestMixedCaseEncode(t *testing.T) {
 
 		// Ensure the decoding the expected lowercase encoding converted to all
 		// uppercase produces the lowercase HRP and original data.
-		gotHRP, gotData, err := Decode(strings.ToUpper(test.encoded))
+		gotHRP, gotData, err := Decode(strings.ToUpper(test.encoded), LengthLimitBIP173)
 		if err != nil {
 			t.Errorf("%q: unexpected decode error: %v", test.name, err)
 			continue
@@ -183,7 +183,7 @@ func TestCanDecodeUnlimtedBech32(t *testing.T) {
 	input := "11qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqsqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq5kx0yd"
 
 	// Sanity check that an input of this length errors on regular Decode()
-	_, _, err := Decode(input)
+	_, _, err := Decode(input, LengthLimitBIP173)
 	if err == nil {
 		t.Fatalf("Test vector not appropriate")
 	}
@@ -403,7 +403,7 @@ func BenchmarkEncodeDecodeCycle(b *testing.B) {
 			b.Fatalf("failed to encode input: %v", err)
 		}
 
-		_, _, err = Decode(str)
+		_, _, err = Decode(str, LengthLimitBIP173)
 		if err != nil {
 			b.Fatalf("failed to decode string: %v", err)
 		}