From 3b3a5b7c6a9ac71cdc02d90cfee32362706f2353 Mon Sep 17 00:00:00 2001
From: Tom Thorogood <me+github@tomthorogood.co.uk>
Date: Mon, 26 Nov 2018 12:00:33 +1030
Subject: [PATCH] Replace another for loop with copy in packDomainName

This change is included as a separate commit because this loop is not as
trivial as the others.
---
 msg.go | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/msg.go b/msg.go
index 09b1a6da..16644ea4 100644
--- a/msg.go
+++ b/msg.go
@@ -251,15 +251,13 @@ func packDomainName(s string, msg []byte, off int, compression map[string]int, c
 			}
 			offset := off
 			off++
-			for j := begin; j < i; j++ {
-				if off+1 > lenmsg {
-					return lenmsg, labels, ErrBuf
-				}
-				if msg != nil {
-					msg[off] = bs[j]
-				}
-				off++
+			if off+(i-begin) > lenmsg {
+				return lenmsg, labels, ErrBuf
 			}
+			if msg != nil {
+				copy(msg[off:], bs[begin:i])
+			}
+			off += i - begin
 			if compress && !bsFresh {
 				roBs = string(bs)
 				bsFresh = true