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| 1 // Copyright 2016 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #include "net/http2/hpack/tools/hpack_block_builder.h" |
| 6 |
| 7 #include "testing/gtest/include/gtest/gtest.h" |
| 8 |
| 9 namespace net { |
| 10 namespace test { |
| 11 |
| 12 void HpackBlockBuilder::AppendHighBitsAndVarint(uint8_t high_bits, |
| 13 uint8_t prefix_length, |
| 14 uint64_t varint) { |
| 15 EXPECT_LE(4, prefix_length); |
| 16 EXPECT_LE(prefix_length, 7); |
| 17 |
| 18 // prefix_mask defines the sequence of low-order bits of the first byte |
| 19 // that encode the prefix of the value. It is also the marker in those bits |
| 20 // of the first byte indicating that at least one extension byte is needed. |
| 21 uint8_t prefix_mask = (1 << prefix_length) - 1; |
| 22 EXPECT_EQ(0, high_bits & prefix_mask); |
| 23 |
| 24 if (varint < prefix_mask) { |
| 25 uint8_t b = high_bits | static_cast<uint8_t>(varint); |
| 26 buffer_.push_back(static_cast<char>(b)); |
| 27 return; |
| 28 } |
| 29 |
| 30 // We need extension bytes. |
| 31 buffer_.push_back(static_cast<char>(high_bits | prefix_mask)); |
| 32 varint -= prefix_mask; |
| 33 while (varint >= 128) { |
| 34 uint8_t b = static_cast<uint8_t>((varint % 128) + 128); |
| 35 buffer_.push_back(static_cast<char>(b)); |
| 36 varint = varint / 128; |
| 37 } |
| 38 char c = static_cast<char>(varint); |
| 39 buffer_.push_back(c); |
| 40 } |
| 41 |
| 42 void HpackBlockBuilder::AppendEntryTypeAndVarint(HpackEntryType entry_type, |
| 43 uint64_t varint) { |
| 44 uint8_t high_bits; |
| 45 uint8_t prefix_length; // Bits of the varint prefix in the first byte. |
| 46 switch (entry_type) { |
| 47 case HpackEntryType::kIndexedHeader: |
| 48 high_bits = 0x80; |
| 49 prefix_length = 7; |
| 50 break; |
| 51 case HpackEntryType::kDynamicTableSizeUpdate: |
| 52 high_bits = 0x20; |
| 53 prefix_length = 5; |
| 54 break; |
| 55 case HpackEntryType::kIndexedLiteralHeader: |
| 56 high_bits = 0x40; |
| 57 prefix_length = 6; |
| 58 break; |
| 59 case HpackEntryType::kUnindexedLiteralHeader: |
| 60 high_bits = 0x00; |
| 61 prefix_length = 4; |
| 62 break; |
| 63 case HpackEntryType::kNeverIndexedLiteralHeader: |
| 64 high_bits = 0x10; |
| 65 prefix_length = 4; |
| 66 break; |
| 67 default: |
| 68 NOTREACHED(); |
| 69 high_bits = 0; |
| 70 prefix_length = 0; |
| 71 } |
| 72 AppendHighBitsAndVarint(high_bits, prefix_length, varint); |
| 73 } |
| 74 |
| 75 void HpackBlockBuilder::AppendString(bool is_huffman_encoded, |
| 76 base::StringPiece str) { |
| 77 uint8_t high_bits = is_huffman_encoded ? 0x80 : 0; |
| 78 uint8_t prefix_length = 7; |
| 79 AppendHighBitsAndVarint(high_bits, prefix_length, str.size()); |
| 80 str.AppendToString(&buffer_); |
| 81 } |
| 82 |
| 83 } // namespace test |
| 84 } // namespace net |
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