DNS: Don't spin on unexpected EOF reading TCP response

net/dns/dns_transaction_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_transaction.h"
 
 #include "base/bind.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "base/rand_util.h"
@@ skipping 82 matching lines @@
     scoped_ptr<DnsResponse> response(
         new DnsResponse(query_->io_buffer()->data(),
                         query_->io_buffer()->size(),
                         0));
     dns_protocol::Header* header =
         reinterpret_cast<dns_protocol::Header*>(response->io_buffer()->data());
     header->flags |= base::HostToNet16(dns_protocol::kFlagResponse | rcode);
     AddResponse(response.Pass(), mode);
   }
 
+  // Add error response.
+  void AddReadError(int error, IoMode mode) {
+    reads_.push_back(MockRead(mode, error));
+  }
+
   // Build, if needed, and return the SocketDataProvider. No new responses
   // should be added afterwards.
   SocketDataProvider* GetProvider() {
     if (provider_.get())
       return provider_.get();
     // Terminate the reads with ERR_IO_PENDING to prevent overrun and default to
     // timeout.
     reads_.push_back(MockRead(ASYNC, ERR_IO_PENDING));
     provider_.reset(new DelayedSocketData(1, &reads_[0], reads_.size(),
                                           &writes_[0], writes_.size()));
@@ skipping 782 matching lines @@
   TransactionHelper helper0(kT0HostName, kT0Qtype, ERR_DNS_SERVER_FAILED);
   EXPECT_TRUE(helper0.Run(transaction_factory_.get()));
 }
 
 TEST_F(DnsTransactionTest, TCPMalformed) {
   AddAsyncQueryAndRcode(kT0HostName, kT0Qtype,
                         dns_protocol::kRcodeNOERROR | dns_protocol::kFlagTC);
   scoped_ptr<DnsSocketData> data(
       new DnsSocketData(0 /* id */, kT0HostName, kT0Qtype, ASYNC, true));
   // Valid response but length too short.
+  // This must be truncated in the question section. The DnsResponse doesn't
+  // examine the answer section until asked to parse it, so truncating it in
+  // the answer section would result in the DnsTransaction itself succeeding.
   data->AddResponseWithLength(
       make_scoped_ptr(
           new DnsResponse(reinterpret_cast<const char*>(kT0ResponseDatagram),
                           arraysize(kT0ResponseDatagram), 0)),
       ASYNC,
       static_cast<uint16>(kT0QuerySize - 1));
   AddSocketData(data.Pass());
 
   TransactionHelper helper0(kT0HostName, kT0Qtype, ERR_DNS_MALFORMED_RESPONSE);
   EXPECT_TRUE(helper0.Run(transaction_factory_.get()));
 }
 
 TEST_F(DnsTransactionTest, TCPTimeout) {
   config_.timeout = TestTimeouts::tiny_timeout();
   ConfigureFactory();
   AddAsyncQueryAndRcode(kT0HostName, kT0Qtype,
                         dns_protocol::kRcodeNOERROR | dns_protocol::kFlagTC);
   AddSocketData(make_scoped_ptr(
       new DnsSocketData(1 /* id */, kT0HostName, kT0Qtype, ASYNC, true)));
 
   TransactionHelper helper0(kT0HostName, kT0Qtype, ERR_DNS_TIMED_OUT);
   EXPECT_TRUE(helper0.RunUntilDone(transaction_factory_.get()));
 }
 
+TEST_F(DnsTransactionTest, TCPReadReturnsZeroAsync) {
+  AddAsyncQueryAndRcode(kT0HostName, kT0Qtype,
+                        dns_protocol::kRcodeNOERROR | dns_protocol::kFlagTC);
+  scoped_ptr<DnsSocketData> data(
+      new DnsSocketData(0 /* id */, kT0HostName, kT0Qtype, ASYNC, true));
+  // Return all but the last byte of the response.
+  data->AddResponseWithLength(
+      make_scoped_ptr(
+          new DnsResponse(reinterpret_cast<const char*>(kT0ResponseDatagram),
+                          arraysize(kT0ResponseDatagram) - 1, 0)),
+      ASYNC,
+      static_cast<uint16>(arraysize(kT0ResponseDatagram)));
+  // Then return a 0-length read.
+  data->AddReadError(0, ASYNC);
+  AddSocketData(data.Pass());
+
+  TransactionHelper helper0(kT0HostName, kT0Qtype, ERR_CONNECTION_CLOSED);
+  EXPECT_TRUE(helper0.Run(transaction_factory_.get()));
+}
+
+TEST_F(DnsTransactionTest, TCPReadReturnsZeroSynchronous) {
+  AddAsyncQueryAndRcode(kT0HostName, kT0Qtype,
+                        dns_protocol::kRcodeNOERROR | dns_protocol::kFlagTC);
+  scoped_ptr<DnsSocketData> data(
+      new DnsSocketData(0 /* id */, kT0HostName, kT0Qtype, ASYNC, true));
+  // Return all but the last byte of the response.
+  data->AddResponseWithLength(
+      make_scoped_ptr(
+          new DnsResponse(reinterpret_cast<const char*>(kT0ResponseDatagram),
+                          arraysize(kT0ResponseDatagram) - 1, 0)),
+      SYNCHRONOUS,
+      static_cast<uint16>(arraysize(kT0ResponseDatagram)));
+  // Then return a 0-length read.
+  data->AddReadError(0, SYNCHRONOUS);
+  AddSocketData(data.Pass());
+
+  TransactionHelper helper0(kT0HostName, kT0Qtype, ERR_CONNECTION_CLOSED);
+  EXPECT_TRUE(helper0.Run(transaction_factory_.get()));
+}
+
+TEST_F(DnsTransactionTest, TCPConnectionClosedAsync) {
+  AddAsyncQueryAndRcode(kT0HostName, kT0Qtype,
+                        dns_protocol::kRcodeNOERROR | dns_protocol::kFlagTC);
+  scoped_ptr<DnsSocketData> data(
+      new DnsSocketData(0 /* id */, kT0HostName, kT0Qtype, ASYNC, true));
+  data->AddReadError(ERR_CONNECTION_CLOSED, ASYNC);
+  AddSocketData(data.Pass());
+
+  TransactionHelper helper0(kT0HostName, kT0Qtype, ERR_CONNECTION_CLOSED);
+  EXPECT_TRUE(helper0.Run(transaction_factory_.get()));
+}
+
+TEST_F(DnsTransactionTest, TCPConnectionClosedSynchronous) {
+  AddAsyncQueryAndRcode(kT0HostName, kT0Qtype,
+                        dns_protocol::kRcodeNOERROR | dns_protocol::kFlagTC);
+  scoped_ptr<DnsSocketData> data(
+      new DnsSocketData(0 /* id */, kT0HostName, kT0Qtype, ASYNC, true));
+  data->AddReadError(ERR_CONNECTION_CLOSED, SYNCHRONOUS);
+  AddSocketData(data.Pass());
+
+  TransactionHelper helper0(kT0HostName, kT0Qtype, ERR_CONNECTION_CLOSED);
+  EXPECT_TRUE(helper0.Run(transaction_factory_.get()));
+}
+
 TEST_F(DnsTransactionTest, InvalidQuery) {
   config_.timeout = TestTimeouts::tiny_timeout();
   ConfigureFactory();
 
   TransactionHelper helper0(".", dns_protocol::kTypeA, ERR_INVALID_ARGUMENT);
   EXPECT_TRUE(helper0.Run(transaction_factory_.get()));
 }
 
 }  // namespace
 
 }  // namespace net