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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 "blimp/net/compressed_packet_writer.h" | |
6 | |
7 #include <vector> | |
8 | |
9 #include "base/logging.h" | |
10 #include "base/numerics/safe_conversions.h" | |
11 #include "base/sys_byteorder.h" | |
12 #include "blimp/net/common.h" | |
13 #include "net/base/io_buffer.h" | |
14 #include "third_party/zlib/zlib.h" | |
15 | |
16 namespace blimp { | |
17 namespace { | |
18 | |
19 // Allocate the maxmimum amount of memory to deflate (512KB) for higher | |
20 // compression. (See zconf.h for details on memLevel semantics.) | |
21 const int kZlibMemoryLevel = 9; | |
22 | |
23 // Byte count of the zlib end-of-block marker (0x00, 0x00, 0xFF, 0xFF). | |
24 // Used for buffer preallocation. | |
25 const size_t kZlibBlockMarkerSize = 4; | |
26 | |
27 } // namespace | |
28 | |
29 CompressedPacketWriter::CompressedPacketWriter( | |
30 std::unique_ptr<PacketWriter> sink) | |
31 : sink_(std::move(sink)), compressed_buf_(new net::GrowableIOBuffer) { | |
32 DCHECK(sink_); | |
33 | |
34 memset(&zlib_stream_, 0, sizeof(z_stream)); | |
35 | |
36 // MAX_WBITS means we are using the maximal window size for decompression; | |
37 // negating it means that we are ignoring headers and CRC checks. | |
38 int init_error = | |
39 deflateInit2(&zlib_stream_, Z_BEST_COMPRESSION, Z_DEFLATED, | |
40 -MAX_WBITS, // Negative value = no headers or CRC. | |
41 kZlibMemoryLevel, Z_DEFAULT_STRATEGY); | |
42 CHECK_EQ(Z_OK, init_error); | |
43 } | |
44 | |
45 CompressedPacketWriter::~CompressedPacketWriter() { | |
46 deflateEnd(&zlib_stream_); | |
47 } | |
48 | |
49 void CompressedPacketWriter::WritePacket( | |
50 const scoped_refptr<net::DrainableIOBuffer>& write_buffer, | |
51 const net::CompletionCallback& callback) { | |
52 DCHECK(write_buffer); | |
53 DCHECK(!callback.is_null()); | |
54 size_t uncompressed_size = | |
55 base::checked_cast<size_t>(write_buffer->BytesRemaining()); | |
56 | |
57 // Zero-length input => zero-length output. | |
58 if (uncompressed_size == 0) { | |
59 sink_->WritePacket(write_buffer, callback); | |
60 return; | |
61 } | |
62 | |
63 // Don't compress anything that's bigger than the maximum allowable payload | |
64 // size. | |
65 if (uncompressed_size > kMaxPacketPayloadSizeBytes) { | |
66 callback.Run(net::ERR_FILE_TOO_BIG); | |
67 return; | |
68 } | |
69 | |
70 int compress_result = Compress(write_buffer, compressed_buf_); | |
71 if (compress_result < 0) { | |
72 callback.Run(compress_result); | |
73 return; | |
74 } | |
75 | |
76 #if !defined(NDEBUG) | |
77 uncompressed_size_total_ += uncompressed_size; | |
78 compressed_size_total_ += compress_result; | |
79 #endif // !defined(NDEBUG) | |
80 | |
81 scoped_refptr<net::DrainableIOBuffer> compressed_outbuf( | |
82 new net::DrainableIOBuffer(compressed_buf_.get(), compress_result)); | |
83 sink_->WritePacket(compressed_outbuf, callback); | |
84 DVLOG(4) << "deflate packet: " << uncompressed_size << " in, " | |
85 << compress_result << " out."; | |
86 DVLOG(3) << "deflate total: " << uncompressed_size_total_ << " in, " | |
87 << compressed_size_total_ << " out."; | |
88 } | |
89 | |
90 int CompressedPacketWriter::Compress( | |
91 const scoped_refptr<net::DrainableIOBuffer>& src_buf, | |
92 const scoped_refptr<net::GrowableIOBuffer>& dest_buf) { | |
93 DCHECK_EQ(0, dest_buf->offset()); | |
94 | |
95 // Preallocate a buffer that's large enough to fit the compressed contents of | |
96 // src_buf, plus some overhead for zlib. | |
97 const int zlib_output_ubound = | |
98 deflateBound(&zlib_stream_, src_buf->BytesRemaining()) + | |
99 kZlibBlockMarkerSize; | |
100 if (dest_buf->capacity() < zlib_output_ubound) { | |
101 dest_buf->SetCapacity(zlib_output_ubound); | |
102 } | |
103 | |
104 zlib_stream_.next_in = reinterpret_cast<uint8_t*>(src_buf->data()); | |
105 zlib_stream_.avail_in = static_cast<unsigned>(src_buf->BytesRemaining()); | |
106 zlib_stream_.next_out = reinterpret_cast<uint8_t*>(dest_buf->data()); | |
107 zlib_stream_.avail_out = static_cast<unsigned>(zlib_output_ubound); | |
108 int deflate_error = deflate(&zlib_stream_, Z_SYNC_FLUSH); | |
109 | |
110 if (deflate_error != Z_OK) { | |
111 DLOG(FATAL) << "Unexpected deflate() return value: " << deflate_error; | |
112 return net::ERR_UNEXPECTED; | |
113 } | |
114 if (zlib_stream_.avail_in > 0) { | |
115 DLOG(ERROR) << "deflate() did not consume all data, remainder: " | |
116 << zlib_stream_.avail_in << " bytes."; | |
117 return net::ERR_UNEXPECTED; | |
118 } | |
119 | |
120 return zlib_output_ubound - zlib_stream_.avail_out; | |
121 } | |
122 | |
123 } // namespace blimp | |
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