Blimp: add padding for zlib framing to buffer preallocation calculations.

blimp/net/compressed_packet_unittest.cc

 // Copyright 2016 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 <stdlib.h>
+
 #include "base/memory/ptr_util.h"
 #include "base/sys_byteorder.h"
 #include "blimp/net/common.h"
 #include "blimp/net/compressed_packet_reader.h"
 #include "blimp/net/compressed_packet_writer.h"
 #include "blimp/net/test_common.h"
 #include "net/base/test_completion_callback.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 131 matching lines @@
   int size_1 = Compress("1234").size();
   int size_2 = Compress("1234").size();
   EXPECT_GT(size_1, size_2);
 }
 
 TEST_F(CompressedPacketTest, LargeInput) {
   std::string big_str(kMaxPacketPayloadSizeBytes, 'A');  // 3MB of A's.
   EXPECT_TRUE(CheckRoundTrip(big_str));
 }
 
+TEST_F(CompressedPacketTest, LowCompressionRatio) {
+  // This size (2338) was found "in the wild" to repro an issue with output
+  // buffer overflows.
+  std::vector<uint8_t> source_data(2338);
+  unsigned int rand_seed = 0;
+
+  // Write two incompressible (high entropy) blocks.

[Wez, 2016/04/13 01:11:02]

nit: Why two?

+  for (size_t i = 0; i < source_data.size(); ++i) {
+    source_data[i] = rand_r(&rand_seed);
+  }
+  EXPECT_TRUE(
+      CheckRoundTrip(std::string(source_data.begin(), source_data.end())));
+
+  for (size_t i = 0; i < source_data.size(); ++i) {
+    source_data[i] = rand_r(&rand_seed);
+  }
+  EXPECT_TRUE(
+      CheckRoundTrip(std::string(source_data.begin(), source_data.end())));
+}
+
 TEST_F(CompressedPacketTest, DecompressIllegallyLargePayload) {
   // We can't use the compressor to compress an illegally sized payload, however
   // we can concatenate the output of smaller payloads to form an uber-payload.
   std::string huge_block =
       Compress(std::string(kMaxPacketPayloadSizeBytes, 'A')) +
       Compress("1337 payl0ad 0verfl0w 'spl0it");
 
   scoped_refptr<net::StringIOBuffer> compressed_str_buf(
       new net::StringIOBuffer(huge_block));
   scoped_refptr<net::DrainableIOBuffer> compressed_buf(
@@ skipping 42 matching lines @@
           DoAll(CopyBuffer<0>(compressed_buf),
                 InvokeCompletionCallback<1>(compressed_buf->BytesRemaining())));
   net::TestCompletionCallback completion_cb_2;
   compressed_reader_->ReadPacket(make_scoped_refptr(new net::GrowableIOBuffer),
                                  completion_cb_2.callback());
   EXPECT_EQ(net::ERR_UNEXPECTED, completion_cb_2.WaitForResult());
 }
 
 }  // namespace
 }  // namespace blimp