Keep track of DTLS packet sizes to prevent partial reads.

The current use of rtc::FifoBuffer can lead to reading across DTLS packet
boundaries which could cause packets to not being processed correctly.

This CL introduces the new class rtc::BufferQueue and changes the
StreamInterfaceChannel to use it instead of the rtc::FifoBuffer.

BUG=chromium:447431
R=juberti@google.com

Review URL: https://webrtc-codereview.appspot.com/52509004

Cr-Commit-Position: refs/heads/master@{#9254}

webrtc/base/bufferqueue_unittest.cc

diff --git a/webrtc/base/bufferqueue_unittest.cc b/webrtc/base/bufferqueue_unittest.cc
new file mode 100644
index 0000000..07084c4
--- /dev/null
+++ b/webrtc/base/bufferqueue_unittest.cc
@@ -0,0 +1,86 @@
+/*
+ *  Copyright 2015 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/base/bufferqueue.h"
+#include "webrtc/base/gunit.h"
+
+namespace rtc {
+
+TEST(BufferQueueTest, TestAll) {
+  const size_t kSize = 16;
+  const char in[kSize * 2 + 1] = "0123456789ABCDEFGHIJKLMNOPQRSTUV";
+  char out[kSize * 2];
+  size_t bytes;
+  BufferQueue queue1(1, kSize);
+  BufferQueue queue2(2, kSize);
+
+  // The queue is initially empty.
+  EXPECT_EQ(0u, queue1.size());
+  EXPECT_FALSE(queue1.ReadFront(out, kSize, &bytes));
+
+  // A write should succeed.
+  EXPECT_TRUE(queue1.WriteBack(in, kSize, &bytes));
+  EXPECT_EQ(kSize, bytes);
+  EXPECT_EQ(1u, queue1.size());
+
+  // The queue is full now (only one buffer allowed).
+  EXPECT_FALSE(queue1.WriteBack(in, kSize, &bytes));
+  EXPECT_EQ(1u, queue1.size());
+
+  // Reading previously written buffer.
+  EXPECT_TRUE(queue1.ReadFront(out, kSize, &bytes));
+  EXPECT_EQ(kSize, bytes);
+  EXPECT_EQ(0, memcmp(in, out, kSize));
+
+  // The queue is empty again now.
+  EXPECT_FALSE(queue1.ReadFront(out, kSize, &bytes));
+  EXPECT_EQ(0u, queue1.size());
+
+  // Reading only returns available data.
+  EXPECT_TRUE(queue1.WriteBack(in, kSize, &bytes));
+  EXPECT_EQ(kSize, bytes);
+  EXPECT_EQ(1u, queue1.size());
+  EXPECT_TRUE(queue1.ReadFront(out, kSize * 2, &bytes));
+  EXPECT_EQ(kSize, bytes);
+  EXPECT_EQ(0, memcmp(in, out, kSize));
+  EXPECT_EQ(0u, queue1.size());
+
+  // Reading maintains buffer boundaries.
+  EXPECT_TRUE(queue2.WriteBack(in, kSize / 2, &bytes));
+  EXPECT_EQ(1u, queue2.size());
+  EXPECT_TRUE(queue2.WriteBack(in + kSize / 2, kSize / 2, &bytes));
+  EXPECT_EQ(2u, queue2.size());
+  EXPECT_TRUE(queue2.ReadFront(out, kSize, &bytes));
+  EXPECT_EQ(kSize / 2, bytes);
+  EXPECT_EQ(0, memcmp(in, out, kSize / 2));
+  EXPECT_EQ(1u, queue2.size());
+  EXPECT_TRUE(queue2.ReadFront(out, kSize, &bytes));
+  EXPECT_EQ(kSize / 2, bytes);
+  EXPECT_EQ(0, memcmp(in + kSize / 2, out, kSize / 2));
+  EXPECT_EQ(0u, queue2.size());
+
+  // Reading truncates buffers.
+  EXPECT_TRUE(queue2.WriteBack(in, kSize / 2, &bytes));
+  EXPECT_EQ(1u, queue2.size());
+  EXPECT_TRUE(queue2.WriteBack(in + kSize / 2, kSize / 2, &bytes));
+  EXPECT_EQ(2u, queue2.size());
+  // Read first packet partially in too-small buffer.
+  EXPECT_TRUE(queue2.ReadFront(out, kSize / 4, &bytes));
+  EXPECT_EQ(kSize / 4, bytes);
+  EXPECT_EQ(0, memcmp(in, out, kSize / 4));
+  EXPECT_EQ(1u, queue2.size());
+  // Remainder of first packet is truncated, reading starts with next packet.
+  EXPECT_TRUE(queue2.ReadFront(out, kSize, &bytes));
+  EXPECT_EQ(kSize / 2, bytes);
+  EXPECT_EQ(0, memcmp(in + kSize / 2, out, kSize / 2));
+  EXPECT_EQ(0u, queue2.size());
+}
+
+}  // namespace rtc