[net/dns] Make DnsResponse::ParseToAddressList less stroct.

Obsoletes DnsResponse::DNS_ADDRESS_TTL_MISMATCH.
Ignores DNS_NAME_MISMATCH on resource records of ignored types.

BUG=164696
TEST=net_unittests --gtest_filter=DnsResponse.ParseToAddressList

Review URL: https://codereview.chromium.org/11537012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@172636 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 27 insertions, 40 deletions

diff --git a/net/dns/dns_response.cc b/net/dns/dns_response.cc
index 4ab7296..354622d 100644
--- a/net/dns/dns_response.cc
+++ b/net/dns/dns_response.cc
@@ -243,8 +243,7 @@ DnsResponse::Result DnsResponse::ParseToAddressList(
   size_t expected_size = (expected_type == dns_protocol::kTypeAAAA)
       ? kIPv6AddressSize : kIPv4AddressSize;
 
-  uint32 cname_ttl_sec = kuint32max;
-  uint32 addr_ttl_sec = kuint32max;
+  uint32 ttl_sec = kuint32max;
   IPAddressList ip_addresses;
   DnsRecordParser parser = Parser();
   DnsResourceRecord record;
@@ -253,27 +252,27 @@ DnsResponse::Result DnsResponse::ParseToAddressList(
     if (!parser.ReadRecord(&record))
       return DNS_MALFORMED_RESPONSE;
 
-    if (base::strcasecmp(record.name.c_str(), expected_name.c_str()) != 0)
-      return DNS_NAME_MISMATCH;
     if (record.type == dns_protocol::kTypeCNAME) {
       // Following the CNAME chain, only if no addresses seen.
       if (!ip_addresses.empty())
         return DNS_CNAME_AFTER_ADDRESS;
 
+      if (base::strcasecmp(record.name.c_str(), expected_name.c_str()) != 0)
+        return DNS_NAME_MISMATCH;
+
       if (record.rdata.size() !=
           parser.ReadName(record.rdata.begin(), &expected_name))
         return DNS_MALFORMED_CNAME;
 
-      cname_ttl_sec = std::min(cname_ttl_sec, record.ttl);
+      ttl_sec = std::min(ttl_sec, record.ttl);
     } else if (record.type == expected_type) {
       if (record.rdata.size() != expected_size)
         return DNS_SIZE_MISMATCH;
-      if (ip_addresses.empty()) {
-        addr_ttl_sec = record.ttl;
-      } else {
-        if (addr_ttl_sec != record.ttl)
-          return DNS_ADDRESS_TTL_MISMATCH;
-      }
+
+      if (base::strcasecmp(record.name.c_str(), expected_name.c_str()) != 0)
+        return DNS_NAME_MISMATCH;
+
+      ttl_sec = std::min(ttl_sec, record.ttl);
       ip_addresses.push_back(IPAddressNumber(record.rdata.begin(),
                                              record.rdata.end()));
     }
@@ -285,7 +284,7 @@ DnsResponse::Result DnsResponse::ParseToAddressList(
   // If the response passed all the checks so far, then |expected_name| is it.
   *addr_list = AddressList::CreateFromIPAddressList(ip_addresses,
                                                     expected_name);
-  *ttl = base::TimeDelta::FromSeconds(std::min(cname_ttl_sec, addr_ttl_sec));
+  *ttl = base::TimeDelta::FromSeconds(ttl_sec);
   return DNS_PARSE_OK;
 }
 
diff --git a/net/dns/dns_response.h b/net/dns/dns_response.h
index fe80c30..cb61e1f 100644
--- a/net/dns/dns_response.h
+++ b/net/dns/dns_response.h
@@ -89,7 +89,7 @@ class NET_EXPORT_PRIVATE DnsResponse {
                                // leads there.
     DNS_SIZE_MISMATCH,         // Got an address but size does not match.
     DNS_CNAME_AFTER_ADDRESS,   // Found CNAME after an address record.
-    DNS_ADDRESS_TTL_MISMATCH,  // TTL of all address records are not identical.
+    DNS_ADDRESS_TTL_MISMATCH,  // OBSOLETE. No longer used.
     DNS_NO_ADDRESSES,          // OBSOLETE. No longer used.
     // Only add new values here.
     DNS_PARSE_RESULT_MAX,      // Bounding value for histograms.
diff --git a/net/dns/dns_response_unittest.cc b/net/dns/dns_response_unittest.cc
index 6ed6f06..760fe47 100644
--- a/net/dns/dns_response_unittest.cc
+++ b/net/dns/dns_response_unittest.cc
@@ -379,22 +379,6 @@ const uint8 kResponseCNAMEAfterAddress[] = {
   0x00, 0x03, 0x01,  'b', 0x00,
 };
 
-const uint8 kResponseTTLMismatch[] = {
-  // Header: 1 question, 3 answer RR
-  0x00, 0x00, 0x81, 0x80, 0x00, 0x01, 0x00, 0x03, 0x00, 0x00, 0x00, 0x00,
-  // Question: name = 'a', type = A (0x1)
-  0x01,  'a', 0x00, 0x00, 0x01, 0x00, 0x01,
-  // Answer: name = 'a', type = CNAME, TTL = 0xFF, RDATA = 'b'
-  0x01,  'a', 0x00, 0x00, 0x05, 0x00, 0x01, 0x00, 0x00, 0x00, 0xFF,
-  0x00, 0x03, 0x01,  'b', 0x00,
-  // Answer: name = 'b', type = A, TTL = 0xFF, RDATA = 10.10.10.10
-  0x01,  'b', 0x00, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x00, 0xFF,
-  0x00, 0x04, 0x0A, 0x0A, 0x0A, 0x0A,
-  // Answer: name = 'b', type = A, TTL = 0xBB, RDATA = 10.10.10.11
-  0x01,  'b', 0x00, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x00, 0xBB,
-  0x00, 0x04, 0x0A, 0x0A, 0x0A, 0x0B,
-};
-
 const uint8 kResponseNoAddresses[] = {
   // Header: 1 question, 1 answer RR, 1 authority RR
   0x00, 0x00, 0x81, 0x80, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00,
@@ -427,8 +411,6 @@ TEST(DnsResponseTest, ParseToAddressListFail) {
       DnsResponse::DNS_SIZE_MISMATCH },
     { kResponseCNAMEAfterAddress, arraysize(kResponseCNAMEAfterAddress),
       DnsResponse::DNS_CNAME_AFTER_ADDRESS },
-    { kResponseTTLMismatch, arraysize(kResponseTTLMismatch),
-      DnsResponse::DNS_ADDRESS_TTL_MISMATCH },
     // Not actually a failure, just an empty result.
     { kResponseNoAddresses, arraysize(kResponseNoAddresses),
       DnsResponse::DNS_PARSE_OK },
diff --git a/net/dns/dns_test_util.h b/net/dns/dns_test_util.h
index 5c5019a..7d11920 100644
--- a/net/dns/dns_test_util.h
+++ b/net/dns/dns_test_util.h
@@ -138,7 +138,10 @@ static const uint8 kT3ResponseDatagram[] = {
   // response contains www.google.com as CNAME for www.google.az and
   // www.l.google.com as CNAME for www.google.com and the following
   // IP addresses: 74.125.226.{178,179,180,176,177}
-  0x00, 0x03, 0x81, 0x80, 0x00, 0x01, 0x00, 0x07,
+  // The TTLs on the records are: 0x00015099, 0x00025099, 0x00000415,
+  // 0x00003015, 0x00002015, 0x00000015, 0x00001015.
+  // The last record is an imaginary TXT record for t.google.com.
+  0x00, 0x03, 0x81, 0x80, 0x00, 0x01, 0x00, 0x08,
   0x00, 0x00, 0x00, 0x00, 0x03, 0x77, 0x77, 0x77,
   0x06, 0x67, 0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x02,
   0x61, 0x7a, 0x00, 0x00, 0x01, 0x00, 0x01, 0xc0,
@@ -146,18 +149,21 @@ static const uint8 kT3ResponseDatagram[] = {
   0x99, 0x00, 0x10, 0x03, 0x77, 0x77, 0x77, 0x06,
   0x67, 0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x03, 0x63,
   0x6f, 0x6d, 0x00, 0xc0, 0x2b, 0x00, 0x05, 0x00,
-  0x01, 0x00, 0x01, 0x50, 0x99, 0x00, 0x08, 0x03,
+  0x01, 0x00, 0x02, 0x50, 0x99, 0x00, 0x08, 0x03,
   0x77, 0x77, 0x77, 0x01, 0x6c, 0xc0, 0x2f, 0xc0,
-  0x47, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0x47, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x04,
   0x15, 0x00, 0x04, 0x4a, 0x7d, 0xe2, 0xb2, 0xc0,
-  0x47, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0x47, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x30,
   0x15, 0x00, 0x04, 0x4a, 0x7d, 0xe2, 0xb3, 0xc0,
-  0x47, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0x47, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x20,
   0x15, 0x00, 0x04, 0x4a, 0x7d, 0xe2, 0xb4, 0xc0,
   0x47, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x00,
   0x15, 0x00, 0x04, 0x4a, 0x7d, 0xe2, 0xb0, 0xc0,
-  0x47, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x00,
-  0x15, 0x00, 0x04, 0x4a, 0x7d, 0xe2, 0xb1
+  0x47, 0x00, 0x01, 0x00, 0x01, 0x00, 0x00, 0x10,
+  0x15, 0x00, 0x04, 0x4a, 0x7d, 0xe2, 0xb1, 0x01,
+  0x74, 0xc0, 0x2f, 0x00, 0x10, 0x00, 0x01, 0x00,
+  0x00, 0x00, 0x01, 0x00, 0x04, 0xde, 0xad, 0xfe,
+  0xed
 };
 static const char* const kT3IpAddresses[] = {
   "74.125.226.178", "74.125.226.179", "74.125.226.180",
@@ -165,8 +171,8 @@ static const char* const kT3IpAddresses[] = {
 };
 static const char kT3CanonName[] = "www.l.google.com";
 static const int kT3TTL = 0x00000015;
-// +2 for the CNAME records.
-static const unsigned kT3RecordCount = arraysize(kT3IpAddresses) + 2;
+// +2 for the CNAME records, +1 for TXT record.
+static const unsigned kT3RecordCount = arraysize(kT3IpAddresses) + 3;
 
 class DnsClient;