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

Added method InitParseNoQuery to begin parsing a DNS response even if there is
no matching query. This is useful in mDNS passive listening (for example, cacheing the results of unsolicited announcements as described in section 8.3 of http://www.rfc-editor.org/rfc/rfc6762.txt)

BUG=233821

Review URL: https://chromiumcodereview.appspot.com/14049018

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@195937 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 133 insertions, 0 deletions

diff --git a/net/dns/dns_response_unittest.cc b/net/dns/dns_response_unittest.cc
index 760fe47..43a1b3a 100644
--- a/net/dns/dns_response_unittest.cc
+++ b/net/dns/dns_response_unittest.cc
@@ -245,6 +245,139 @@ TEST(DnsResponseTest, InitParse) {
   EXPECT_FALSE(parser.ReadRecord(&record));
 }
 
+TEST(DnsResponseTest, InitParseWithoutQuery) {
+  DnsResponse resp;
+  memcpy(resp.io_buffer()->data(), kT0ResponseDatagram,
+         sizeof(kT0ResponseDatagram));
+
+  // Accept matching question.
+  EXPECT_TRUE(resp.InitParseWithoutQuery(sizeof(kT0ResponseDatagram)));
+  EXPECT_TRUE(resp.IsValid());
+
+  // Check header access.
+  EXPECT_EQ(0x8180, resp.flags());
+  EXPECT_EQ(0x0, resp.rcode());
+  EXPECT_EQ(kT0RecordCount, resp.answer_count());
+
+  // Check question access.
+  EXPECT_EQ(kT0Qtype, resp.qtype());
+  EXPECT_EQ(kT0HostName, resp.GetDottedName());
+
+  DnsResourceRecord record;
+  DnsRecordParser parser = resp.Parser();
+  for (unsigned i = 0; i < kT0RecordCount; i ++) {
+    EXPECT_FALSE(parser.AtEnd());
+    EXPECT_TRUE(parser.ReadRecord(&record));
+  }
+  EXPECT_TRUE(parser.AtEnd());
+  EXPECT_FALSE(parser.ReadRecord(&record));
+}
+
+TEST(DnsResponseTest, InitParseWithoutQueryNoQuestions) {
+  const uint8 response_data[] = {
+    // Header
+    0xca, 0xfe,               // ID
+    0x81, 0x80,               // Standard query response, RA, no error
+    0x00, 0x00,               // No question
+    0x00, 0x01,               // 2 RRs (answers)
+    0x00, 0x00,               // 0 authority RRs
+    0x00, 0x00,               // 0 additional RRs
+
+    // Answer 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.
+    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_TRUE(resp.InitParseWithoutQuery(sizeof(response_data)));
+
+  // Check header access.
+  EXPECT_EQ(0x8180, resp.flags());
+  EXPECT_EQ(0x0, resp.rcode());
+  EXPECT_EQ(0x1u, resp.answer_count());
+
+  DnsResourceRecord record;
+  DnsRecordParser parser = resp.Parser();
+
+  EXPECT_FALSE(parser.AtEnd());
+  EXPECT_TRUE(parser.ReadRecord(&record));
+  EXPECT_EQ("codereview.chromium.org", record.name);
+  EXPECT_EQ(0x00000035u, record.ttl);
+  EXPECT_EQ(dns_protocol::kTypeA, record.type);
+
+  EXPECT_TRUE(parser.AtEnd());
+  EXPECT_FALSE(parser.ReadRecord(&record));
+}
+
+TEST(DnsResponseTest, InitParseWithoutQueryTwoQuestions) {
+  const uint8 response_data[] = {
+    // Header
+    0xca, 0xfe,               // ID
+    0x81, 0x80,               // Standard query response, RA, no error
+    0x00, 0x02,               // 2 questions
+    0x00, 0x01,               // 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, 0x01,        // TYPE is A.
+    0x00, 0x01,        // CLASS is IN.
+
+    // Answer 1
+    0xc0, 0x0c,         // NAME is a pointer to name in Question section.
+    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_TRUE(resp.InitParseWithoutQuery(sizeof(response_data)));
+
+  // Check header access.
+  EXPECT_EQ(0x8180, resp.flags());
+  EXPECT_EQ(0x0, resp.rcode());
+  EXPECT_EQ(0x01u, resp.answer_count());
+
+  DnsResourceRecord record;
+  DnsRecordParser parser = resp.Parser();
+
+  EXPECT_FALSE(parser.AtEnd());
+  EXPECT_TRUE(parser.ReadRecord(&record));
+  EXPECT_EQ("codereview.chromium.org", record.name);
+  EXPECT_EQ(0x35u, record.ttl);
+  EXPECT_EQ(dns_protocol::kTypeA, record.type);
+
+  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());