From 6b6e08b48ca8b75ce42d9bcec4475b68edcd7c43 Mon Sep 17 00:00:00 2001
From: Tom Thorogood <me+github@tomthorogood.co.uk>
Date: Fri, 30 Nov 2018 22:50:24 +1030
Subject: [PATCH] Stop compressing names in RT records (#847)

* Stop compressing names in RT records

Although RFC 1183 allows names in the RT record to be compressed with:
 "The concrete encoding is identical to the MX RR."

RFC 3597 specifically prohibits compressing names in any record not
defined in RFC 1035.

* Add comment to RT struct regarding compression
---
 types.go  | 2 +-
 zmsg.go   | 2 +-
 ztypes.go | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/types.go b/types.go
index 26309725..c8658b34 100644
--- a/types.go
+++ b/types.go
@@ -353,7 +353,7 @@ func (rr *X25) String() string {
 type RT struct {
 	Hdr        RR_Header
 	Preference uint16
-	Host       string `dns:"cdomain-name"`
+	Host       string `dns:"domain-name"` // RFC 3597 prohibits compressing records not defined in RFC 1035.
 }
 
 func (rr *RT) String() string {
diff --git a/zmsg.go b/zmsg.go
index 057e5e6a..27887a77 100644
--- a/zmsg.go
+++ b/zmsg.go
@@ -1070,7 +1070,7 @@ func (rr *RT) pack(msg []byte, off int, compression map[string]int, compress boo
 	if err != nil {
 		return off, err
 	}
-	off, err = PackDomainName(rr.Host, msg, off, compression, compress)
+	off, err = PackDomainName(rr.Host, msg, off, compression, false)
 	if err != nil {
 		return off, err
 	}
diff --git a/ztypes.go b/ztypes.go
index a527d08a..71662b7b 100644
--- a/ztypes.go
+++ b/ztypes.go
@@ -525,7 +525,7 @@ func (rr *RRSIG) len(off int, compression map[string]struct{}) int {
 func (rr *RT) len(off int, compression map[string]struct{}) int {
 	l := rr.Hdr.len(off, compression)
 	l += 2 // Preference
-	l += domainNameLen(rr.Host, off+l, compression, true)
+	l += domainNameLen(rr.Host, off+l, compression, false)
 	return l
 }
 func (rr *SMIMEA) len(off int, compression map[string]struct{}) int {