Resolver: explicit check for compression pointers in question. Since nginx always uses exactly one entry in the question section of a DNS query, and never uses compression pointers in this entry, parsing of a DNS response in ngx_resolver_process_response() does not expect compression pointers to appear in the question section of the DNS response. Indeed, compression pointers in the first name of a DNS response hardly make sense, do not seem to be allowed by RFC 1035 (which says "a pointer to a prior occurance of the same name", note "prior"), and were never observed in practice. Added an explicit check to ngx_resolver_process_response()'s parsing of the question section to properly report an error if compression pointers nevertheless appear in the question section.

# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


ngx_include="unistd.h";      . auto/include
ngx_include="inttypes.h";    . auto/include
ngx_include="limits.h";      . auto/include
ngx_include="sys/filio.h";   . auto/include
ngx_include="sys/param.h";   . auto/include
ngx_include="sys/mount.h";   . auto/include
ngx_include="sys/statvfs.h"; . auto/include
ngx_include="crypt.h";       . auto/include