Add new HTTP/2 and HPACK decoder in net/http2/.

net/http2/decoder/http2_structure_decoder.cc

Index: net/http2/decoder/http2_structure_decoder.cc
diff --git a/net/http2/decoder/http2_structure_decoder.cc b/net/http2/decoder/http2_structure_decoder.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a7b1dca47a346594ff9e7776a7d3aeddc5c407be
--- /dev/null
+++ b/net/http2/decoder/http2_structure_decoder.cc
@@ -0,0 +1,90 @@
+// 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 "net/http2/decoder/http2_structure_decoder.h"
+
+#include <algorithm>
+
+#include "net/http2/tools/http2_bug_tracker.h"
+
+namespace net {
+
+// Below we have some defensive coding: if we somehow run off the end, don't
+// overwrite lots of memory. Note that most of this decoder is not defensive
+// against bugs in the decoder, only against malicious encoders, but since
+// we're copying memory into a buffer here, let's make sure we don't allow a
+// small mistake to grow larger. The decoder will get stuck if we hit the
+// HTTP2_BUG conditions, but shouldn't corrupt memory.
+
+uint32_t Http2StructureDecoder::IncompleteStart(DecodeBuffer* db,
+                                                uint32_t target_size) {
+  if (target_size > sizeof buffer_) {
+    HTTP2_BUG << "target_size too large for buffer: " << target_size;
+    return 0;
+  }
+  const uint32_t num_to_copy = db->MinLengthRemaining(target_size);
+  memcpy(buffer_, db->cursor(), num_to_copy);
+  offset_ = num_to_copy;
+  db->AdvanceCursor(num_to_copy);
+  return num_to_copy;
+}
+
+DecodeStatus Http2StructureDecoder::IncompleteStart(DecodeBuffer* db,
+                                                    uint32_t* remaining_payload,
+                                                    uint32_t target_size) {
+  DVLOG(1) << "IncompleteStart@" << this
+           << ": *remaining_payload=" << *remaining_payload
+           << "; target_size=" << target_size
+           << "; db->Remaining=" << db->Remaining();
+  *remaining_payload -=
+      IncompleteStart(db, std::min(target_size, *remaining_payload));
+  if (*remaining_payload > 0 && db->Empty()) {
+    return DecodeStatus::kDecodeInProgress;
+  }
+  DVLOG(1) << "IncompleteStart: kDecodeError";
+  return DecodeStatus::kDecodeError;
+}
+
+bool Http2StructureDecoder::ResumeFillingBuffer(DecodeBuffer* db,
+                                                uint32_t target_size) {
+  DVLOG(2) << "ResumeFillingBuffer@" << this << ": target_size=" << target_size
+           << "; offset_=" << offset_ << "; db->Remaining=" << db->Remaining();
+  if (target_size < offset_) {
+    HTTP2_BUG << "Already filled buffer_! target_size=" << target_size
+              << "    offset_=" << offset_;
+    return false;
+  }
+  const uint32_t needed = target_size - offset_;
+  const uint32_t num_to_copy = db->MinLengthRemaining(needed);
+  DVLOG(2) << "ResumeFillingBuffer num_to_copy=" << num_to_copy;
+  memcpy(&buffer_[offset_], db->cursor(), num_to_copy);
+  db->AdvanceCursor(num_to_copy);
+  offset_ += num_to_copy;
+  return needed == num_to_copy;
+}
+
+bool Http2StructureDecoder::ResumeFillingBuffer(DecodeBuffer* db,
+                                                uint32_t* remaining_payload,
+                                                uint32_t target_size) {
+  DVLOG(2) << "ResumeFillingBuffer@" << this << ": target_size=" << target_size
+           << "; offset_=" << offset_
+           << "; *remaining_payload=" << *remaining_payload
+           << "; db->Remaining=" << db->Remaining();
+  if (target_size < offset_) {
+    HTTP2_BUG << "Already filled buffer_! target_size=" << target_size
+              << "    offset_=" << offset_;
+    return false;
+  }
+  const uint32_t needed = target_size - offset_;
+  const uint32_t num_to_copy =
+      db->MinLengthRemaining(std::min(needed, *remaining_payload));
+  DVLOG(2) << "ResumeFillingBuffer num_to_copy=" << num_to_copy;
+  memcpy(&buffer_[offset_], db->cursor(), num_to_copy);
+  db->AdvanceCursor(num_to_copy);
+  offset_ += num_to_copy;
+  *remaining_payload -= num_to_copy;
+  return needed == num_to_copy;
+}
+
+}  // namespace net