Chromium Code Reviews
chromiumcodereview-hr@appspot.gserviceaccount.com (chromiumcodereview-hr) | Please choose your nickname with Settings | Help | Chromium Project | Gerrit Changes | Sign out
(27)

Unified Diff: net/dns/dns_response.cc

Issue 8762001: Isolates generic DnsClient from AsyncHostResolver. (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/src
Patch Set: applied review Created 9 years ago
Use n/p to move between diff chunks; N/P to move between comments. Draft comments are only viewable by you.
Jump to:
View side-by-side diff with in-line comments
Download patch
Index: net/dns/dns_response.cc
diff --git a/net/dns/dns_response.cc b/net/dns/dns_response.cc
index 3c5d6058f0d8a9b5e2124b9f156fd2d00bde3d76..24db67507346864c3bfa707bf3ffe06532169a24 100644
--- a/net/dns/dns_response.cc
+++ b/net/dns/dns_response.cc
@@ -4,97 +4,184 @@
#include "net/dns/dns_response.h"
-#include "net/base/dns_util.h"
+#include "net/base/big_endian.h"
#include "net/base/io_buffer.h"
#include "net/base/net_errors.h"
+#include "net/base/sys_byteorder.h"
+#include "net/dns/dns_protocol.h"
#include "net/dns/dns_query.h"
namespace net {
-// RFC 1035, section 4.2.1: Messages carried by UDP are restricted to 512
-// bytes (not counting the IP nor UDP headers).
-static const int kMaxResponseSize = 512;
+DnsRecordParser::DnsRecordParser() : packet_(NULL), length_(0), cur_(0) {
+}
+
+DnsRecordParser::DnsRecordParser(const void* packet,
+ size_t length,
+ size_t offset)
+ : packet_(reinterpret_cast<const char*>(packet)),
+ length_(length),
+ cur_(packet_ + offset) {
+ DCHECK(offset <= length);
mmenke 2011/12/06 20:43:01 nit: Use DCHECK_LE here and in ParseName, where a
szym 2011/12/06 21:06:43 Done.
+}
-DnsResponse::DnsResponse(DnsQuery* query)
- : query_(query),
- io_buffer_(new IOBufferWithSize(kMaxResponseSize + 1)) {
- DCHECK(query_);
+int DnsRecordParser::ParseName(const void* const vpos, std::string* out) const {
+ const char* const pos = reinterpret_cast<const char*>(vpos);
+ DCHECK(packet_);
+ DCHECK(packet_ <= pos);
+ DCHECK(pos <= packet_ + length_);
+
+ const char* p = pos;
+ const char* end = packet_ + length_;
+ // Count number of seen bytes to detect loops.
+ size_t seen = 0;
+ // Remember how many bytes were consumed before first jump.
+ size_t consumed = 0;
+
+ if (pos >= end)
+ return 0;
+
+ if (out) {
+ out->clear();
+ out->reserve(dns_protocol::kMaxNameLength);
+ }
+
+ for (;;) {
+ // The two couple of bits of the length give the type of the length. It's
+ // either a direct length or a pointer to the remainder of the name.
+ switch (*p & dns_protocol::kLabelMask) {
+ case dns_protocol::kLabelPointer: {
+ if (p + sizeof(uint16) > end)
+ return 0;
+ if (consumed == 0) {
+ consumed = p - pos + sizeof(uint16);
+ if (!out)
+ return consumed; // If name is not stored, that's all we need.
+ }
+ seen += sizeof(uint16);
+ // If seen the whole packet, then we must be in a loop.
+ if (seen > length_)
+ return 0;
+ uint16 offset;
+ ReadBigEndian<uint16>(p, &offset);
+ offset &= dns_protocol::kOffsetMask;
+ p = packet_ + offset;
+ if (p >= end)
+ return 0;
+ break;
+ }
+ case dns_protocol::kLabelDirect: {
+ uint8 label_len = *p;
+ ++p;
+ // Note: root domain (".") is NOT included.
+ if (label_len == 0) {
+ if (consumed == 0) {
+ consumed = p - pos;
+ } // else we set |consumed| before first jump
+ return consumed;
+ }
+ if (p + label_len >= end)
+ return 0; // Truncated or missing label.
+ if (out) {
+ if (!out->empty())
+ out->append(".");
+ out->append(p, label_len);
+ }
+ p += label_len;
+ seen += 1 + label_len;
+ break;
+ }
+ default:
+ // unhandled label type
+ return 0;
+ }
+ }
+}
+
+bool DnsRecordParser::ParseRecord(DnsResourceRecord* out) {
+ DCHECK(packet_);
+ size_t consumed = ParseName(cur_, &out->name);
+ if (!consumed)
+ return false;
+ BigEndianReader reader(cur_ + consumed,
+ packet_ + length_ - (cur_ + consumed));
+ uint16 rdlen;
+ if (reader.ReadU16(&out->type) &&
+ reader.ReadU16(&out->klass) &&
+ reader.ReadU32(&out->ttl) &&
+ reader.ReadU16(&rdlen) &&
+ reader.ReadPiece(&out->rdata, rdlen)) {
+ cur_ = reader.ptr();
+ return true;
+ }
+ return false;
+}
+
+DnsResponse::DnsResponse()
+ : io_buffer_(new IOBufferWithSize(dns_protocol::kMaxUDPSize + 1)) {
+}
+
+DnsResponse::DnsResponse(const void* data,
+ size_t length,
+ size_t answer_offset)
+ : io_buffer_(new IOBufferWithSize(length)),
+ parser_(io_buffer_->data(), length, answer_offset) {
+ memcpy(io_buffer_->data(), data, length);
}
DnsResponse::~DnsResponse() {
}
-int DnsResponse::Parse(int nbytes, IPAddressList* ip_addresses) {
+bool DnsResponse::InitParse(int nbytes, const DnsQuery& query) {
// Response includes query, it should be at least that size.
- if (nbytes < query_->io_buffer()->size() || nbytes > kMaxResponseSize)
- return ERR_DNS_MALFORMED_RESPONSE;
-
- DnsResponseBuffer response(reinterpret_cast<uint8*>(io_buffer_->data()),
- io_buffer_->size());
- uint16 id;
- if (!response.U16(&id) || id != query_->id()) // Make sure IDs match.
- return ERR_DNS_MALFORMED_RESPONSE;
-
- uint8 flags, rcode;
- if (!response.U8(&flags) || !response.U8(&rcode))
- return ERR_DNS_MALFORMED_RESPONSE;
-
- if (flags & 2) // TC is set -- server wants TCP, we don't support it (yet?).
- return ERR_DNS_SERVER_REQUIRES_TCP;
-
- rcode &= 0x0f; // 3 means NXDOMAIN, the rest means server failed.
- if (rcode && (rcode != 3))
- return ERR_DNS_SERVER_FAILED;
-
- uint16 query_count, answer_count, authority_count, additional_count;
- if (!response.U16(&query_count) ||
- !response.U16(&answer_count) ||
- !response.U16(&authority_count) ||
- !response.U16(&additional_count)) {
- return ERR_DNS_MALFORMED_RESPONSE;
- }
+ if (nbytes < query.io_buffer()->size() || nbytes > dns_protocol::kMaxUDPSize)
+ return false;
+
+ // Match the query id.
+ if (ntohs(header()->id) != query.id())
+ return false;
+
+ // Match question count.
+ if (ntohs(header()->qdcount) != 1)
+ return false;
+
+ // Match the question section.
+ const size_t hdr_size = sizeof(dns_protocol::Header);
+ const base::StringPiece question = query.question();
+ if (question != base::StringPiece(io_buffer_->data() + hdr_size,
+ question.size()))
mmenke 2011/12/06 20:43:01 nit: Add parentheses.
szym 2011/12/06 21:06:43 Done.
+ return false;
+
+ // Construct the parser.
+ parser_ = DnsRecordParser(io_buffer_->data(),
+ nbytes,
+ hdr_size + question.size());
+ return true;
+}
- if (query_count != 1) // Sent a single question, shouldn't have changed.
- return ERR_DNS_MALFORMED_RESPONSE;
+uint8 DnsResponse::flags0() const {
+ return header()->flags[0];
+}
- base::StringPiece question; // Make sure question section is echoed back.
- if (!response.Block(&question, query_->question_size()) ||
- memcmp(question.data(), query_->question_data(),
- query_->question_size())) {
- return ERR_DNS_MALFORMED_RESPONSE;
- }
+uint8 DnsResponse::flags1() const {
+ return header()->flags[1] & ~(dns_protocol::kRcodeMask);
+}
- if (answer_count < 1)
- return ERR_NAME_NOT_RESOLVED;
-
- IPAddressList rdatas;
- while (answer_count--) {
- uint32 ttl;
- uint16 rdlength, qtype, qclass;
- if (!response.DNSName(NULL) ||
- !response.U16(&qtype) ||
- !response.U16(&qclass) ||
- !response.U32(&ttl) ||
- !response.U16(&rdlength)) {
- return ERR_DNS_MALFORMED_RESPONSE;
- }
- if (qtype == query_->qtype() &&
- qclass == kClassIN &&
- (rdlength == kIPv4AddressSize || rdlength == kIPv6AddressSize)) {
- base::StringPiece rdata;
- if (!response.Block(&rdata, rdlength))
- return ERR_DNS_MALFORMED_RESPONSE;
- rdatas.push_back(IPAddressNumber(rdata.begin(), rdata.end()));
- } else if (!response.Skip(rdlength))
- return ERR_DNS_MALFORMED_RESPONSE;
- }
+uint8 DnsResponse::rcode() const {
+ return header()->flags[1] & dns_protocol::kRcodeMask;
+}
- if (rdatas.empty())
- return ERR_NAME_NOT_RESOLVED;
+int DnsResponse::answer_count() const {
+ return ntohs(header()->ancount);
+}
+
+DnsRecordParser DnsResponse::Parser() const {
+ DCHECK(parser_.IsValid());
+ return parser_;
+}
- if (ip_addresses)
- ip_addresses->swap(rdatas);
- return OK;
+const dns_protocol::Header* DnsResponse::header() const {
+ return reinterpret_cast<const dns_protocol::Header*>(io_buffer_->data());
}
} // namespace net

Powered by Google App Engine
This is Rietveld 408576698