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1 // Copyright (c) 2013 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/websockets/websocket_deflater.h" | |
6 | |
7 #include <string.h> | |
8 #include <vector> | |
9 | |
10 #include "base/logging.h" | |
11 #include "net/base/io_buffer.h" | |
12 #include "third_party/zlib/zlib.h" | |
13 | |
14 namespace net { | |
15 | |
16 WebSocketDeflater::WebSocketDeflater(int window_bits, | |
17 ContextTakeOverMode mode) | |
18 : stream_(new z_stream), | |
19 mode_(mode), | |
20 are_bytes_added_(false) { | |
21 DCHECK_LE(8, window_bits); | |
22 DCHECK_GE(15, window_bits); | |
23 memset(stream_.get(), 0, sizeof(*stream_)); | |
24 int result = deflateInit2(stream_.get(), | |
25 Z_DEFAULT_COMPRESSION, | |
26 Z_DEFLATED, | |
27 -window_bits, | |
28 8, // default mem level | |
29 Z_DEFAULT_STRATEGY); | |
30 DCHECK_EQ(Z_OK, result); | |
31 } | |
32 | |
33 WebSocketDeflater::~WebSocketDeflater() { | |
34 if (stream_) { | |
35 deflateEnd(stream_.get()); | |
36 stream_.reset(NULL); | |
37 } | |
38 } | |
39 | |
40 bool WebSocketDeflater::AddBytes(const char* data, size_t size) { | |
41 if (!size) | |
42 return true; | |
43 | |
44 stream_->next_in = reinterpret_cast<Bytef*>(const_cast<char*>(data)); | |
45 stream_->avail_in = size; | |
46 | |
47 // The estimation by deflateBound is not accurate if the zlib has some | |
48 // remaining input of the last compression. | |
49 size_t estimation = deflateBound(stream_.get(), size); | |
50 DCHECK_GT(estimation, 0u); | |
51 do { | |
52 size_t current = buffer_.size(); | |
53 // TODO(yhirano): std::vector initializes the expanded area, | |
54 // but the initialization is actually not necessary. | |
55 buffer_.resize(buffer_.size() + estimation); | |
56 stream_->next_out = reinterpret_cast<Bytef*>(&buffer_[current]); | |
57 stream_->avail_out = buffer_.size() - current; | |
58 | |
59 int result = deflate(stream_.get(), Z_NO_FLUSH); | |
60 if (result != Z_OK) { | |
Adam Rice
2013/08/30 07:16:11
Probably these { } need to be removed too.
yhirano
2013/08/30 09:42:11
Done.
| |
61 return false; | |
62 } | |
63 buffer_.resize(buffer_.size() - stream_->avail_out); | |
64 estimation *= 2; | |
65 } while (!stream_->avail_out); | |
66 are_bytes_added_ = true; | |
67 | |
68 return true; | |
69 } | |
70 | |
71 scoped_refptr<IOBufferWithSize> WebSocketDeflater::Finish() { | |
72 scoped_refptr<IOBufferWithSize> result; | |
73 if (!are_bytes_added_) { | |
74 // Since consecutive calls of deflate with Z_SYNC_FLUSH and no input | |
75 // lead to an error, we create and return the output for the empty input | |
76 // manually. | |
77 DCHECK(buffer_.empty()); | |
78 result = new IOBufferWithSize(2); | |
79 memcpy(result->data(), "\x02\x00", result->size()); | |
80 Reset(); | |
81 return result; | |
82 } | |
83 stream_->next_in = NULL; | |
84 stream_->avail_in = 0; | |
85 | |
86 const size_t available_size = 4096; | |
Adam Rice
2013/08/30 07:16:11
Where did the number 4096 come from?
yhirano
2013/08/30 07:26:34
The deflater works for arbitrary value if it is no
| |
87 do { | |
Adam Rice
2013/08/30 07:16:11
I just realised that this loop is almost the same
yhirano
2013/08/30 09:42:11
Done.
yhirano
2013/08/30 10:56:31
I'm sorry, I was wrong.
Loop condition in AddBytes
| |
88 size_t current = buffer_.size(); | |
89 buffer_.resize(buffer_.size() + available_size); | |
90 stream_->next_out = reinterpret_cast<Bytef*>(&buffer_[current]); | |
91 stream_->avail_out = buffer_.size() - current; | |
92 | |
93 int result = deflate(stream_.get(), Z_SYNC_FLUSH); | |
94 buffer_.resize(buffer_.size() - stream_->avail_out); | |
95 if (result != Z_OK && result != Z_BUF_ERROR) { | |
96 Reset(); | |
97 return NULL; | |
98 } | |
99 } while (!stream_->avail_out); | |
100 // Remove 4 octets from the tail as the specification requires. | |
101 if (buffer_.size() < 4) { | |
102 Reset(); | |
103 return NULL; | |
104 } | |
105 result = new IOBufferWithSize(buffer_.size() - 4); | |
106 memcpy(result->data(), buffer_.data(), result->size()); | |
107 Reset(); | |
108 return result; | |
109 } | |
110 | |
111 void WebSocketDeflater::Reset() { | |
112 buffer_.clear(); | |
113 if (mode_ == DO_NOT_TAKE_OVER_CONTEXT) | |
114 deflateReset(stream_.get()); | |
115 are_bytes_added_ = false; | |
116 } | |
117 | |
118 } // namespace net | |
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