From: bert hubert <bert.hubert@netherlabs.nl>
Date: Wed, 11 Mar 2015 10:55:39 +0000 (+0100)
Subject: Kees Monshouwer spotted a bug in our DNSName isParent() implementation and delivered... 
X-Git-Tag: dnsdist-1.0.0-alpha1~248^2~88^2~56
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3bd38afa8fb4d8a34a12952bd2016875e2d7cbc5;p=thirdparty%2Fpdns.git

Kees Monshouwer spotted a bug in our DNSName isParent() implementation and delivered a fix too. Thank you kees!
---

diff --git a/pdns/dnsname.cc b/pdns/dnsname.cc
index be9821f1a1..78df576b85 100644
--- a/pdns/dnsname.cc
+++ b/pdns/dnsname.cc
@@ -72,17 +72,24 @@ std::string DNSName::toDNSString() const
   return ret;
 }
 
-
-// true of a comparison from the end of parent terminates
+// are WE part of parent
 bool DNSName::isPartOf(const DNSName& parent) const
 {
-  auto us = d_storage.crbegin();
-  auto p = parent.d_storage.crbegin();
-  for(; us != d_storage.crend() && p != parent.d_storage.crend(); ++us, ++p) {
-    if(tolower(*p) != tolower(*us))
-      break;
+  if(parent.d_storage.size() > d_storage.size()) 
+    return false;
+
+  // this is slightly complicated since we can't start from the end, since we can't see where a label begins/ends then
+  for(auto us=d_storage.cbegin(); us<d_storage.cend() && d_storage.cend()-us >= (unsigned int)parent.d_storage.size(); us+=*us+1) {
+    if (d_storage.cend()-us == (unsigned int)parent.d_storage.size()) {
+      auto p = parent.d_storage.cbegin();
+      for(; us != d_storage.cend() && p != parent.d_storage.cend(); ++us, ++p) {
+        if(tolower(*p) != tolower(*us))
+          break;
+      }
+      return (p==parent.d_storage.end());
+    }
   }
-  return (p==parent.d_storage.crend());
+  return false;
 }
 
 void DNSName::appendRawLabel(const std::string& label)
diff --git a/pdns/test-dnsname_cc.cc b/pdns/test-dnsname_cc.cc
index 9eff64975a..f1122e0069 100644
--- a/pdns/test-dnsname_cc.cc
+++ b/pdns/test-dnsname_cc.cc
@@ -20,8 +20,10 @@ BOOST_AUTO_TEST_CASE(test_basic) {
   BOOST_CHECK_EQUAL(before, after);
 
   DNSName wwwds9anl("www.ds9a.nl.");
+  DNSName wwwds9anl1("www.ds9a\002nl.");
   DNSName nl("nl.");
   BOOST_CHECK(wwwds9anl.isPartOf(nl));
+  BOOST_CHECK(!wwwds9anl1.isPartOf(nl));
   BOOST_CHECK(wwwds9anl.isPartOf(wwwds9anl));
 
   BOOST_CHECK(!nl.isPartOf(wwwds9anl));