From ac6815cb162818a9c8023d142aa53982c3a6b3cd Mon Sep 17 00:00:00 2001
From: svz-ya <sergeyzhelnin@yandex-team.ru>
Date: Mon, 10 Feb 2025 20:44:34 +0300
Subject: [PATCH] Fix DecodeLength() for long values in variable length HEX
 field

---
 prefix/hex.go      |  4 ++--
 prefix/hex_test.go | 13 +++++++++++++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/prefix/hex.go b/prefix/hex.go
index 33b282c7..b7f6a874 100644
--- a/prefix/hex.go
+++ b/prefix/hex.go
@@ -29,7 +29,7 @@ func (p *hexFixedPrefixer) EncodeLength(fixLen, dataLen int) ([]byte, error) {
 	return []byte{}, nil
 }
 
-func (p *hexFixedPrefixer) DecodeLength(fixLen int, data []byte) (int, int, error) {
+func (p *hexFixedPrefixer) DecodeLength(fixLen int, _ []byte) (int, int, error) {
 	return fixLen, 0, nil
 }
 
@@ -63,7 +63,7 @@ func (p *hexVarPrefixer) DecodeLength(maxLen int, data []byte) (int, int, error)
 		return 0, 0, fmt.Errorf(notEnoughDataToRead, length, len(data))
 	}
 
-	dataLen, err := strconv.ParseInt(string(data[:length]), 16, p.Digits*8)
+	dataLen, err := strconv.ParseUint(string(data[:length]), 16, p.Digits*8)
 	if err != nil {
 		return 0, 0, err
 	}
diff --git a/prefix/hex_test.go b/prefix/hex_test.go
index 52a2033a..c51e866c 100644
--- a/prefix/hex_test.go
+++ b/prefix/hex_test.go
@@ -113,6 +113,19 @@ func Test_hexVarPrefixer_DecodeLength(t *testing.T) {
 			wantRead:    6,
 			wantErr:     false,
 		},
+		{
+			name: "data_length_exceeds_signed_byte",
+			fields: fields{
+				Digits: 1,
+			},
+			args: args{
+				maxLen: 255,
+				data:   []byte("FFzdsadsdasdsdasasdasadadasdasdsafsdgerherhrtherherhwergewrergtertwetwegwhrwehjerjetuery4wtwegwrjerjrejereryereye4y45735u45u45ehe45yy4t34t34y4y43h34h3yh3hgey5jhrtjrjerjnerj45ki45kjtk4e5ue5u5eu545u45j45j45uj45uj45u45u45u45u45jgjgjgfjrtjtjjtrjrtjrtjtrjrthhrew"),
+			},
+			wantDataLen: 0xFF,
+			wantRead:    2,
+			wantErr:     false,
+		},
 		{
 			name: "not_enough_data",
 			fields: fields{