DnsClient refactoring + features (timeout, suffix search, server rotation).

net/dns/dns_response.cc

Index: net/dns/dns_response.cc
diff --git a/net/dns/dns_response.cc b/net/dns/dns_response.cc
index dabfc6ab89cd287cef90be3abc5cb8eeae0524d0..3bec0d8e2cf563f00c6930f8ba1eb159c45b9d80 100644
--- a/net/dns/dns_response.cc
+++ b/net/dns/dns_response.cc
@@ -6,6 +6,7 @@
 
 #include "base/sys_byteorder.h"
 #include "net/base/big_endian.h"
+#include "net/base/dns_util.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
 #include "net/dns/dns_protocol.h"
@@ -166,24 +167,49 @@ bool DnsResponse::InitParse(int nbytes, const DnsQuery& query) {
   return true;
 }
 
-uint8 DnsResponse::flags0() const {
-  return header()->flags[0];
+bool DnsResponse::is_valid() const {
+  return parser_.is_valid();
 }
 
-uint8 DnsResponse::flags1() const {
-  return header()->flags[1] & ~(dns_protocol::kRcodeMask);
+uint16 DnsResponse::flags() const {
+  DCHECK(parser_.is_valid());
+  return ntohs(header()->flags) & ~(dns_protocol::kRcodeMask);
 }
 
 uint8 DnsResponse::rcode() const {
-  return header()->flags[1] & dns_protocol::kRcodeMask;
+  DCHECK(parser_.is_valid());
+  return ntohs(header()->flags) & dns_protocol::kRcodeMask;
 }
 
 int DnsResponse::answer_count() const {
+  DCHECK(parser_.is_valid());
   return ntohs(header()->ancount);
 }
 
+base::StringPiece DnsResponse::qname() const {
+  DCHECK(parser_.is_valid());
+  const size_t hdr_size = sizeof(dns_protocol::Header);
+  const size_t qname_size = parser_.offset() - 2 * sizeof(uint16) - hdr_size;

[cbentzel, 2012/01/13 22:17:25]

This would benefit from an explanation - particularly why the parser_.offset is
what it is.

Another option is to reconstruct from io_buffer_->data() + hdr_size, which may
be more clear. 

Finally, you could just cache it in InitResponse from the query. 

+  return base::StringPiece(io_buffer_->data() + hdr_size,
+                           qname_size);
+}
+
+uint16 DnsResponse::qtype() const {
+  DCHECK(parser_.is_valid());
+  const size_t type_offset = parser_.offset() - 2 * sizeof(uint16);
+  uint16 type;
+  ReadBigEndian<uint16>(io_buffer_->data() + type_offset,
+                        &type);
+  return type;
+}
+
+std::string DnsResponse::GetDottedName() const {
+  return DNSDomainToString(qname());

[cbentzel, 2012/01/13 22:17:25]

[Note to self: Looks like the expansion is done by DnsResponseParser]

This doesn't handle the label compression case correctly (see 4.1.4 of RFC1035).
DNSDomainToString will return an empty string in that case.

Not sure if the expansion should be done in qname() or here.

It may not be a big issue in practice since it will typically done for response
names, but should be defensive about it.  

[szym, 2012/01/17 15:38:25]

The whole question section must be exactly as in the query, so the name in the
question cannot be compressed by the server.

+}
+
 DnsRecordParser DnsResponse::Parser() const {
-  DCHECK(parser_.IsValid());
+  DCHECK(parser_.is_valid());
+  // Return a copy of the parser.
   return parser_;
 }