Add simple non-response-based question parsing for mDNS passive listening

net/dns/dns_response_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/dns/dns_response.h"
 
 #include "base/time.h"
 #include "net/base/address_list.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_util.h"
@@ skipping 227 matching lines @@
 
   DnsResourceRecord record;
   DnsRecordParser parser = resp.Parser();
   EXPECT_TRUE(parser.ReadRecord(&record));
   EXPECT_FALSE(parser.AtEnd());
   EXPECT_TRUE(parser.ReadRecord(&record));
   EXPECT_TRUE(parser.AtEnd());
   EXPECT_FALSE(parser.ReadRecord(&record));
 }
 
+// TODO(noamsml): Simplify this test
+TEST(DnsResponseTest, GetResponseOffset) {
+  // Easiest way to comput size of QNAME data
+  const char qname_data[] = "\x0A""codereview""\x08""chromium""\x03""org";
+  const base::StringPiece qname(qname_data, sizeof(qname_data));
+  const size_t qsec_length = qname.size() + 4;
+
+  const uint8 response_data[] = {
+    // Header
+    0xca, 0xfe,               // ID
+    0x81, 0x80,               // Standard query response, RA, no error
+    0x00, 0x01,               // 1 question
+    0x00, 0x02,               // 2 RRs (answers)
+    0x00, 0x00,               // 0 authority RRs
+    0x00, 0x00,               // 0 additional RRs
+
+    // Question
+    // This part is echoed back from the respective query.
+    0x0a, 'c', 'o', 'd', 'e', 'r', 'e', 'v', 'i', 'e', 'w',
+    0x08, 'c', 'h', 'r', 'o', 'm', 'i', 'u', 'm',
+    0x03, 'o', 'r', 'g',
+    0x00,
+    0x00, 0x01,        // TYPE is A.
+    0x00, 0x01,        // CLASS is IN.
+
+    // Answer 1
+    0xc0, 0x0c,        // NAME is a pointer to name in Question section.
+    0x00, 0x05,        // TYPE is CNAME.
+    0x00, 0x01,        // CLASS is IN.
+    0x00, 0x01,        // TTL (4 bytes) is 20 hours, 47 minutes, 48 seconds.
+    0x24, 0x74,
+    0x00, 0x12,        // RDLENGTH is 18 bytes.
+    // ghs.l.google.com in DNS format.
+    0x03, 'g', 'h', 's',
+    0x01, 'l',
+    0x06, 'g', 'o', 'o', 'g', 'l', 'e',
+    0x03, 'c', 'o', 'm',
+    0x00,
+
+    // Answer 2
+    0xc0, 0x35,         // NAME is a pointer to name in Answer 1.
+    0x00, 0x01,         // TYPE is A.
+    0x00, 0x01,         // CLASS is IN.
+    0x00, 0x00,         // TTL (4 bytes) is 53 seconds.
+    0x00, 0x35,
+    0x00, 0x04,         // RDLENGTH is 4 bytes.
+    0x4a, 0x7d,         // RDATA is the IP: 74.125.95.121
+    0x5f, 0x79,
+  };
+
+  DnsResponse resp;
+  memcpy(resp.io_buffer()->data(), response_data, sizeof(response_data));
+
+  EXPECT_EQ(sizeof(dns_protocol::Header) + qsec_length,
+            resp.GetResponseOffset());
+}
+
+// TODO(noamsml): Simplify this test
+TEST(DnsResponseTest, GetQuestionSectionSizeNoQuestion) {
+  const uint8 response_data[] = {
+    // Header
+    0xca, 0xfe,               // ID
+    0x81, 0x80,               // Standard query response, RA, no error
+    0x00, 0x00,               // 1 question
+    0x00, 0x02,               // 2 RRs (answers)
+    0x00, 0x00,               // 0 authority RRs
+    0x00, 0x00,               // 0 additional RRs
+
+    // Answer 1
+    0xc0, 0x0c,        // NAME is a pointer to name in Question section.
+    0x00, 0x05,        // TYPE is CNAME.
+    0x00, 0x01,        // CLASS is IN.
+    0x00, 0x01,        // TTL (4 bytes) is 20 hours, 47 minutes, 48 seconds.
+    0x24, 0x74,
+    0x00, 0x12,        // RDLENGTH is 18 bytes.
+    // ghs.l.google.com in DNS format.
+    0x03, 'g', 'h', 's',
+    0x01, 'l',
+    0x06, 'g', 'o', 'o', 'g', 'l', 'e',
+    0x03, 'c', 'o', 'm',
+    0x00,
+
+    // Answer 2
+    0xc0, 0x35,         // NAME is a pointer to name in Answer 1.
+    0x00, 0x01,         // TYPE is A.
+    0x00, 0x01,         // CLASS is IN.
+    0x00, 0x00,         // TTL (4 bytes) is 53 seconds.
+    0x00, 0x35,
+    0x00, 0x04,         // RDLENGTH is 4 bytes.
+    0x4a, 0x7d,         // RDATA is the IP: 74.125.95.121
+    0x5f, 0x79,
+  };
+
+  DnsResponse resp;
+  memcpy(resp.io_buffer()->data(), response_data, sizeof(response_data));
+
+  EXPECT_EQ(sizeof(dns_protocol::Header), resp.GetResponseOffset());
+}
+
+// TODO(noamsml): Simplify this test
+TEST(DnsResponseTest, GetQuestionSectionSizeTwoQuestions) {
+  // Easiest way to compute size of QNAME data
+  const char qname_data[] = "\x0A""codereview""\x08""chromium""\x03""org";
+  const base::StringPiece qname(qname_data, sizeof(qname_data));
+  const char qname2_data[] = "\x0B""codereview2""\xc0\x18";
+  const base::StringPiece qname2(qname2_data, sizeof(qname2_data));
+  const size_t qsec_length = qname.size() + qname2.size() + 8;
+
+  const uint8 response_data[] = {
+    // Header
+    0xca, 0xfe,               // ID
+    0x81, 0x80,               // Standard query response, RA, no error
+    0x00, 0x02,               // 1 question
+    0x00, 0x02,               // 2 RRs (answers)
+    0x00, 0x00,               // 0 authority RRs
+    0x00, 0x00,               // 0 additional RRs
+
+    // Question 1
+    0x0a, 'c', 'o', 'd', 'e', 'r', 'e', 'v', 'i', 'e', 'w',
+    0x08, 'c', 'h', 'r', 'o', 'm', 'i', 'u', 'm',
+    0x03, 'o', 'r', 'g',
+    0x00,
+    0x00, 0x01,        // TYPE is A.
+    0x00, 0x01,        // CLASS is IN.
+
+    // Question 2
+    0x0b, 'c', 'o', 'd', 'e', 'r', 'e', 'v', 'i', 'e', 'w', '2',
+    0xc0, 0x18, // pointer to "chromium.org"
+    0x00,

[szym, 2013/04/17 22:11:12]

This is not a valid DNS response. The pointer is the last label. There's no
extra null-label after it.

[Noam Samuel, 2013/04/18 19:03:17]

Done.

+    0x00, 0x01,        // TYPE is A.
+    0x00, 0x01,        // CLASS is IN.
+
+    // Answer 1
+    0xc0, 0x0c,        // NAME is a pointer to name in Question section.
+    0x00, 0x05,        // TYPE is CNAME.
+    0x00, 0x01,        // CLASS is IN.
+    0x00, 0x01,        // TTL (4 bytes) is 20 hours, 47 minutes, 48 seconds.
+    0x24, 0x74,
+    0x00, 0x12,        // RDLENGTH is 18 bytes.
+    // ghs.l.google.com in DNS format.
+    0x03, 'g', 'h', 's',
+    0x01, 'l',
+    0x06, 'g', 'o', 'o', 'g', 'l', 'e',
+    0x03, 'c', 'o', 'm',
+    0x00,
+
+    // Answer 2
+    0xc0, 0x35,         // NAME is a pointer to name in Answer 1.
+    0x00, 0x01,         // TYPE is A.
+    0x00, 0x01,         // CLASS is IN.
+    0x00, 0x00,         // TTL (4 bytes) is 53 seconds.
+    0x00, 0x35,
+    0x00, 0x04,         // RDLENGTH is 4 bytes.
+    0x4a, 0x7d,         // RDATA is the IP: 74.125.95.121
+    0x5f, 0x79,
+  };
+
+  DnsResponse resp;
+  memcpy(resp.io_buffer()->data(), response_data, sizeof(response_data));
+
+  EXPECT_EQ(sizeof(dns_protocol::Header) + qsec_length,
+            resp.GetResponseOffset());
+}
+
+// TODO(noamsml): simplify test

[szym, 2013/04/17 22:11:12]

I suggest you reuse the response packets in dns_test_util.h
It makes sense to add another test for the cases of qdcount == 0 and qdcount >
1.

[Noam Samuel, 2013/04/18 19:03:17]

Done.

+TEST(DnsResponseTest, InitParseNoQuery) {
+  // This includes \0 at the end.
+  const char qname_data[] = "\x0A""codereview""\x08""chromium""\x03""org";
+  const base::StringPiece qname(qname_data, sizeof(qname_data));
+  // Compilers want to copy when binding temporary to const &, so must use heap.
+  scoped_ptr<DnsQuery> query(new DnsQuery(0xcafe, qname, dns_protocol::kTypeA));
+
+  const uint8 response_data[] = {
+    // Header
+    0xca, 0xfe,               // ID
+    0x81, 0x80,               // Standard query response, RA, no error
+    0x00, 0x01,               // 1 question
+    0x00, 0x02,               // 2 RRs (answers)
+    0x00, 0x00,               // 0 authority RRs
+    0x00, 0x00,               // 0 additional RRs
+
+    // Question
+    // This part is echoed back from the respective query.
+    0x0a, 'c', 'o', 'd', 'e', 'r', 'e', 'v', 'i', 'e', 'w',
+    0x08, 'c', 'h', 'r', 'o', 'm', 'i', 'u', 'm',
+    0x03, 'o', 'r', 'g',
+    0x00,
+    0x00, 0x01,        // TYPE is A.
+    0x00, 0x01,        // CLASS is IN.
+
+    // Answer 1
+    0xc0, 0x0c,        // NAME is a pointer to name in Question section.
+    0x00, 0x05,        // TYPE is CNAME.
+    0x00, 0x01,        // CLASS is IN.
+    0x00, 0x01,        // TTL (4 bytes) is 20 hours, 47 minutes, 48 seconds.
+    0x24, 0x74,
+    0x00, 0x12,        // RDLENGTH is 18 bytes.
+    // ghs.l.google.com in DNS format.
+    0x03, 'g', 'h', 's',
+    0x01, 'l',
+    0x06, 'g', 'o', 'o', 'g', 'l', 'e',
+    0x03, 'c', 'o', 'm',
+    0x00,
+
+    // Answer 2
+    0xc0, 0x35,         // NAME is a pointer to name in Answer 1.
+    0x00, 0x01,         // TYPE is A.
+    0x00, 0x01,         // CLASS is IN.
+    0x00, 0x00,         // TTL (4 bytes) is 53 seconds.
+    0x00, 0x35,
+    0x00, 0x04,         // RDLENGTH is 4 bytes.
+    0x4a, 0x7d,         // RDATA is the IP: 74.125.95.121
+    0x5f, 0x79,
+  };
+
+  DnsResponse resp;
+  memcpy(resp.io_buffer()->data(), response_data, sizeof(response_data));
+
+  // Accept matching question.
+  EXPECT_TRUE(resp.InitParse(sizeof(response_data)));
+  EXPECT_TRUE(resp.IsValid());
+
+  // Check header access.
+  EXPECT_EQ(0x8180, resp.flags());
+  EXPECT_EQ(0x0, resp.rcode());
+  EXPECT_EQ(2u, resp.answer_count());
+
+  // Check question access.
+  EXPECT_EQ(query->qname(), resp.qname());
+  EXPECT_EQ(query->qtype(), resp.qtype());
+  EXPECT_EQ("codereview.chromium.org", resp.GetDottedName());
+
+  DnsResourceRecord record;
+  DnsRecordParser parser = resp.Parser();
+  EXPECT_TRUE(parser.ReadRecord(&record));
+  EXPECT_FALSE(parser.AtEnd());
+  EXPECT_TRUE(parser.ReadRecord(&record));
+  EXPECT_TRUE(parser.AtEnd());
+  EXPECT_FALSE(parser.ReadRecord(&record));
+}
+
+
 void VerifyAddressList(const std::vector<const char*>& ip_addresses,
                        const AddressList& addrlist) {
   ASSERT_EQ(ip_addresses.size(), addrlist.size());
 
   for (size_t i = 0; i < addrlist.size(); ++i) {
     EXPECT_EQ(ip_addresses[i], addrlist[i].ToStringWithoutPort());
   }
 }
 
 TEST(DnsResponseTest, ParseToAddressList) {
@@ skipping 167 matching lines @@
     AddressList addr_list;
     base::TimeDelta ttl;
     EXPECT_EQ(t.expected_result,
               response.ParseToAddressList(&addr_list, &ttl));
   }
 }
 
 }  // namespace
 
 }  // namespace net