From 0e53833a2cb9a78601d1e5f1cfc7a9ff42dd7718 Mon Sep 17 00:00:00 2001
From: fatedier <fatedier@gmail.com>
Date: Thu, 23 Jul 2026 01:17:37 +0800
Subject: [PATCH] refactor: use standard library HKDF (#5440)

---
 pkg/util/net/conn.go      | 11 +++--------
 pkg/util/net/conn_test.go |  6 ++++++
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/pkg/util/net/conn.go b/pkg/util/net/conn.go
index 5dd605a5..fd71162e 100644
--- a/pkg/util/net/conn.go
+++ b/pkg/util/net/conn.go
@@ -16,6 +16,7 @@ package net
 
 import (
 	"context"
+	"crypto/hkdf"
 	"crypto/sha256"
 	"errors"
 	"io"
@@ -25,7 +26,6 @@ import (
 
 	libcrypto "github.com/fatedier/golib/crypto"
 	quic "github.com/quic-go/quic-go"
-	"golang.org/x/crypto/hkdf"
 
 	"github.com/fatedier/frp/pkg/util/xlog"
 )
@@ -335,11 +335,6 @@ func deriveAEADControlKeys(key []byte, algorithm string, transcriptHash []byte)
 }
 
 func deriveAEADControlKey(key []byte, algorithm string, transcriptHash []byte, direction string) ([]byte, error) {
-	info := []byte(aeadControlHKDFInfoPrefix + " " + algorithm + " " + direction)
-	reader := hkdf.New(sha256.New, key, transcriptHash, info)
-	out := make([]byte, libcrypto.AEADKeySize)
-	if _, err := io.ReadFull(reader, out); err != nil {
-		return nil, err
-	}
-	return out, nil
+	info := aeadControlHKDFInfoPrefix + " " + algorithm + " " + direction
+	return hkdf.Key(sha256.New, key, transcriptHash, info, libcrypto.AEADKeySize)
 }
diff --git a/pkg/util/net/conn_test.go b/pkg/util/net/conn_test.go
index 42d3c06b..93387384 100644
--- a/pkg/util/net/conn_test.go
+++ b/pkg/util/net/conn_test.go
@@ -114,5 +114,11 @@ func TestDeriveAEADControlKeysUsesDistinctDirections(t *testing.T) {
 		bytes.Repeat([]byte{0x44}, 32),
 	)
 	require.NoError(t, err)
+	require.Equal(t, []byte{
+		0xa0, 0x58, 0xcd, 0x02, 0x5d, 0x96, 0x98, 0x5f,
+		0xeb, 0xeb, 0xff, 0x79, 0xa1, 0x9f, 0x62, 0xb7,
+		0x15, 0xe0, 0x53, 0x91, 0x3d, 0xfc, 0x74, 0x77,
+		0x05, 0x91, 0x4c, 0x62, 0x4b, 0xf3, 0xd4, 0x95,
+	}, clientToServerKey)
 	require.NotEqual(t, clientToServerKey, serverToClientKey)
 }