From: Charles-Henri Bruyand <charles-henri.bruyand@open-xchange.com>
Date: Wed, 27 Mar 2019 17:17:01 +0000 (+0100)
Subject: all: DNSName avoid copying labels while converting to string
X-Git-Tag: auth-4.2.0-rc3~19^2~21^2
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=a640c4a6344454d5ac740e427201f54b97c1a2ef;p=pdns

all: DNSName avoid copying labels while converting to string

(cherry picked from commit 19164b93abc64a56140114c0416be6fa585dfab9)
---

diff --git a/pdns/dnsname.cc b/pdns/dnsname.cc
index 58f2d3a54..2eb1d9a12 100644
--- a/pdns/dnsname.cc
+++ b/pdns/dnsname.cc
@@ -170,8 +170,16 @@ std::string DNSName::toString(const std::string& separator, const bool trailing)
 
   std::string ret;
   ret.reserve(d_storage.size());
-  for(const auto& s : getRawLabels()) {
-    ret+= escapeLabel(s) + separator;
+
+  {
+    // iterate over the raw labels
+    const char* p = d_storage.c_str();
+    const char* end = p + d_storage.size();
+
+    while (p < end && *p) {
+      ret += escapeLabel(p + 1, static_cast<size_t>(*p)) + separator;
+      p += *p + 1;
+    }
   }
   if (!trailing) {
     ret.resize(ret.size() - separator.size());
@@ -341,9 +349,9 @@ bool DNSName::slowCanonCompare(const DNSName& rhs) const
   return std::lexicographical_compare(ours.rbegin(), ours.rend(), rhsLabels.rbegin(), rhsLabels.rend(), CIStringCompare());
 }
 
-vector<string> DNSName::getRawLabels() const
+vector<std::string> DNSName::getRawLabels() const
 {
-  vector<string> ret;
+  vector<std::string> ret;
   ret.reserve(countLabels());
   // 3www4ds9a2nl0
   for(const unsigned char* p = (const unsigned char*) d_storage.c_str(); p < ((const unsigned char*) d_storage.c_str()) + d_storage.size() && *p; p+=*p+1) {
@@ -400,8 +408,13 @@ bool DNSName::isHostname() const
 unsigned int DNSName::countLabels() const
 {
   unsigned int count=0;
-  for(const unsigned char* p = (const unsigned char*) d_storage.c_str(); p < ((const unsigned char*) d_storage.c_str()) + d_storage.size() && *p; p+=*p+1)
+  const unsigned char* p = reinterpret_cast<const unsigned char*>(d_storage.c_str());
+  const unsigned char* end = reinterpret_cast<const unsigned char*>(p + d_storage.size());
+
+  while (p < end && *p) {
     ++count;
+    p += *p + 1;
+  }
   return count;
 }
 
@@ -419,9 +432,17 @@ size_t hash_value(DNSName const& d)
 
 string DNSName::escapeLabel(const std::string& label)
 {
-  string ret;
-  ret.reserve(label.size()); // saves 15% on bulk .COM load
-  for(uint8_t p : label) {
+  return escapeLabel(label.c_str(), label.size());
+}
+
+string DNSName::escapeLabel(const char* orig, size_t len)
+{
+  std::string ret;
+  size_t pos = 0;
+
+  ret.reserve(len);
+  while (pos < len) {
+    auto p = static_cast<uint8_t>(orig[pos]);
     if(p=='.')
       ret+="\\.";
     else if(p=='\\')
@@ -431,6 +452,7 @@ string DNSName::escapeLabel(const std::string& label)
     else {
       ret+="\\" + (boost::format("%03d") % (unsigned int)p).str();
     }
+    ++pos;
   }
   return ret;
 }
diff --git a/pdns/dnsname.hh b/pdns/dnsname.hh
index e5f6b11db..ea540ce47 100644
--- a/pdns/dnsname.hh
+++ b/pdns/dnsname.hh
@@ -151,6 +151,7 @@ private:
 
   void packetParser(const char* p, int len, int offset, bool uncompress, uint16_t* qtype, uint16_t* qclass, unsigned int* consumed, int depth, uint16_t minOffset);
   static std::string escapeLabel(const std::string& orig);
+  static std::string escapeLabel(const char* orig, size_t len);
   static std::string unescapeLabel(const std::string& orig);
 };