p2p: use slices.Clone (#32428)

Replaces a helper method with slices.Clone

Author: cuiweixie

p2p/discover/v5wire/encoding.go

@@ -27,6 +27,7 @@ import (
 	"errors"
 	"fmt"
 	"hash"
+	"slices"
 
 	"github.com/ethereum/go-ethereum/common/mclock"
 	"github.com/ethereum/go-ethereum/p2p/enode"
@@ -222,7 +223,7 @@ func (c *Codec) Encode(id enode.ID, addr string, packet Packet, challenge *Whoar
 
 	// Store sent WHOAREYOU challenges.
 	if challenge, ok := packet.(*Whoareyou); ok {
-		challenge.ChallengeData = bytesCopy(&c.buf)
+		challenge.ChallengeData = slices.Clone(c.buf.Bytes())
 		enc, err := c.EncodeRaw(id, head, msgData)
 		if err != nil {
 			return nil, Nonce{}, err
@@ -325,7 +326,7 @@ func (c *Codec) encodeWhoareyou(toID enode.ID, packet *Whoareyou) (Header, error
 
 	// Create header.
 	head := c.makeHeader(toID, flagWhoareyou, 0)
-	head.AuthData = bytesCopy(&c.buf)
+	head.AuthData = slices.Clone(c.buf.Bytes())
 	head.Nonce = packet.Nonce
 
 	// Encode auth data.
@@ -430,7 +431,7 @@ func (c *Codec) encodeMessageHeader(toID enode.ID, s *session) (Header, error) {
 	auth := messageAuthData{SrcID: c.localnode.ID()}
 	c.buf.Reset()
 	binary.Write(&c.buf, binary.BigEndian, &auth)
-	head.AuthData = bytesCopy(&c.buf)
+	head.AuthData = slices.Clone(c.buf.Bytes())
 	head.Nonce = nonce
 	return head, err
 }
@@ -686,9 +687,3 @@ func (h *Header) mask(destID enode.ID) cipher.Stream {
 	}
 	return cipher.NewCTR(block, h.IV[:])
 }
-
-func bytesCopy(r *bytes.Buffer) []byte {
-	b := make([]byte, r.Len())
-	copy(b, r.Bytes())
-	return b
-}