From: Anton Lavrentiev via Cygwin-patches <cygwin-patches@cygwin.com>
Date: Tue, 18 Jan 2022 22:39:16 +0000 (-0500)
Subject: Cygwin: resolver: Targets in SRV DNS responses may not be compressed
X-Git-Tag: cygwin-3.4.0~707
X-Git-Url: https://sourceware.org/git/?a=commitdiff_plain;h=54f0590a661fc76036a524ca81b9d5375402c233;p=newlib-cygwin.git

Cygwin: resolver: Targets in SRV DNS responses may not be compressed

RFC2782 clearly says so yet it's a common misconception to perform the
compression in the violation of the standard.  This patch fixes that
---

diff --git a/winsup/cygwin/libc/minires-os-if.c b/winsup/cygwin/libc/minires-os-if.c
index 8d3178f70..5da1c0c55 100644
--- a/winsup/cygwin/libc/minires-os-if.c
+++ b/winsup/cygwin/libc/minires-os-if.c
@@ -159,6 +159,7 @@ static unsigned char * write_record(unsigned char * ptr, PDNS_RECORD rr,
       PUTSHORT(rr->Data.SRV.wWeight, ptr);
       PUTSHORT(rr->Data.SRV.wPort, ptr);
     }
+    dnptrs = 0;  /* compression not allowed */
     PUTDOMAIN(rr->Data.SRV.pNameTarget, ptr);
     break;
   default: