1 files changed, 117 insertions, 0 deletions
diff --git a/net/spdy/hpack_input_stream.cc b/net/spdy/hpack_input_stream.cc
new file mode 100644
index 0000000..8dc30e1
--- /dev/null
+++ b/net/spdy/hpack_input_stream.cc
@@ -0,0 +1,117 @@
+// Copyright 2014 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/spdy/hpack_input_stream.h"
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+
+namespace net {
+
+using base::StringPiece;
+
+HpackInputStream::HpackInputStream(uint32 max_string_literal_size,
+                                   StringPiece buffer)
+    : max_string_literal_size_(max_string_literal_size),
+      buffer_(buffer),
+      bit_offset_(0) {}
+
+HpackInputStream::~HpackInputStream() {}
+
+bool HpackInputStream::HasMoreData() const {
+  return !buffer_.empty();
+}
+
+bool HpackInputStream::MatchPrefixAndConsume(HpackPrefix prefix) {
+  DCHECK_GT(prefix.bit_size, 0u);
+  DCHECK_LE(prefix.bit_size, 8u);
+
+  uint8 next_octet = 0;
+  if (!PeekNextOctet(&next_octet))
+    return false;
+
+  if ((next_octet >> (8 - prefix.bit_size)) == prefix.bits) {
+    bit_offset_ = prefix.bit_size;
+    return true;
+  }
+
+  return false;
+}
+
+bool HpackInputStream::PeekNextOctet(uint8* next_octet) {
+  if ((bit_offset_ > 0) || buffer_.empty())
+    return false;
+
+  *next_octet = buffer_[0];
+  return true;
+}
+
+bool HpackInputStream::DecodeNextOctet(uint8* next_octet) {
+  if (!PeekNextOctet(next_octet))
+    return false;
+
+  buffer_.remove_prefix(1);
+  return true;
+}
+
+bool HpackInputStream::DecodeNextUint32(uint32* I) {
+  size_t N = 8 - bit_offset_;
+  DCHECK_GT(N, 0u);
+  DCHECK_LE(N, 8u);
+
+  bit_offset_ = 0;
+
+  *I = 0;
+
+  uint8 next_marker = (1 << N) - 1;
+  uint8 next_octet = 0;
+  if (!DecodeNextOctet(&next_octet))
+    return false;
+  *I = next_octet & next_marker;
+
+  bool has_more = (*I == next_marker);
+  size_t shift = 0;
+  while (has_more && (shift < 32)) {
+    uint8 next_octet = 0;
+    if (!DecodeNextOctet(&next_octet))
+      return false;
+    has_more = (next_octet & 0x80) != 0;
+    next_octet &= 0x7f;
+    uint32 addend = next_octet << shift;
+    // Check for overflow.
+    if ((addend >> shift) != next_octet) {
+      return false;
+    }
+    *I += addend;
+    shift += 7;
+  }
+
+  return !has_more;
+}
+
+// TODO(akalin): Figure out how to handle the storage for
+// Huffman-encoded sequences.
+bool HpackInputStream::DecodeNextStringLiteral(StringPiece* str) {
+  if (MatchPrefixAndConsume(kStringLiteralIdentityEncoded)) {
+    uint32 size = 0;
+    if (!DecodeNextUint32(&size))
+      return false;
+
+    if (size > max_string_literal_size_)
+      return false;
+
+    if (size > buffer_.size())
+      return false;
+
+    *str = StringPiece(buffer_.data(), size);
+    buffer_.remove_prefix(size);
+    return true;
+  }
+
+  // TODO(akalin): Handle Huffman-encoded sequences.
+
+  return false;
+}
+
+}  // namespace net