1 // Copyright 2013 The Chromium Authors
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_inflater.h"
6
7 #include <algorithm>
8 #include <vector>
9 #include <zlib.h>
10
11 #include "base/check_op.h"
12 #include "net/base/io_buffer.h"
13
14 namespace net {
15
16 namespace {
17
18 class ShrinkableIOBufferWithSize : public IOBufferWithSize {
19 public:
ShrinkableIOBufferWithSize(size_t size)20 explicit ShrinkableIOBufferWithSize(size_t size) : IOBufferWithSize(size) {}
21
Shrink(int new_size)22 void Shrink(int new_size) {
23 CHECK_GE(new_size, 0);
24 CHECK_LE(new_size, size_);
25 size_ = new_size;
26 }
27
28 private:
29 ~ShrinkableIOBufferWithSize() override = default;
30 };
31
32 } // namespace
33
WebSocketInflater()34 WebSocketInflater::WebSocketInflater()
35 : input_queue_(kDefaultInputIOBufferCapacity),
36 output_buffer_(kDefaultBufferCapacity) {}
37
WebSocketInflater(size_t input_queue_capacity,size_t output_buffer_capacity)38 WebSocketInflater::WebSocketInflater(size_t input_queue_capacity,
39 size_t output_buffer_capacity)
40 : input_queue_(input_queue_capacity),
41 output_buffer_(output_buffer_capacity) {
42 DCHECK_GT(input_queue_capacity, 0u);
43 DCHECK_GT(output_buffer_capacity, 0u);
44 }
45
Initialize(int window_bits)46 bool WebSocketInflater::Initialize(int window_bits) {
47 DCHECK_LE(8, window_bits);
48 DCHECK_GE(15, window_bits);
49 stream_ = std::make_unique<z_stream>();
50 memset(stream_.get(), 0, sizeof(*stream_));
51 int result = inflateInit2(stream_.get(), -window_bits);
52 if (result != Z_OK) {
53 inflateEnd(stream_.get());
54 stream_.reset();
55 return false;
56 }
57 return true;
58 }
59
~WebSocketInflater()60 WebSocketInflater::~WebSocketInflater() {
61 if (stream_) {
62 inflateEnd(stream_.get());
63 stream_.reset();
64 }
65 }
66
AddBytes(const char * data,size_t size)67 bool WebSocketInflater::AddBytes(const char* data, size_t size) {
68 if (!size)
69 return true;
70
71 if (!input_queue_.IsEmpty()) {
72 // choked
73 input_queue_.Push(data, size);
74 return true;
75 }
76
77 int result = InflateWithFlush(data, size);
78 if (stream_->avail_in > 0)
79 input_queue_.Push(&data[size - stream_->avail_in], stream_->avail_in);
80
81 return result == Z_OK || result == Z_BUF_ERROR;
82 }
83
Finish()84 bool WebSocketInflater::Finish() {
85 return AddBytes("\x00\x00\xff\xff", 4);
86 }
87
GetOutput(size_t size)88 scoped_refptr<IOBufferWithSize> WebSocketInflater::GetOutput(size_t size) {
89 auto buffer = base::MakeRefCounted<ShrinkableIOBufferWithSize>(size);
90 size_t num_bytes_copied = 0;
91
92 while (num_bytes_copied < size && output_buffer_.Size() > 0) {
93 size_t num_bytes_to_copy =
94 std::min(output_buffer_.Size(), size - num_bytes_copied);
95 output_buffer_.Read(&buffer->data()[num_bytes_copied], num_bytes_to_copy);
96 num_bytes_copied += num_bytes_to_copy;
97 int result = InflateChokedInput();
98 if (result != Z_OK && result != Z_BUF_ERROR)
99 return nullptr;
100 }
101 buffer->Shrink(num_bytes_copied);
102 return buffer;
103 }
104
InflateWithFlush(const char * next_in,size_t avail_in)105 int WebSocketInflater::InflateWithFlush(const char* next_in, size_t avail_in) {
106 int result = Inflate(next_in, avail_in, Z_NO_FLUSH);
107 if (result != Z_OK && result != Z_BUF_ERROR)
108 return result;
109
110 if (CurrentOutputSize() > 0)
111 return result;
112 // CurrentOutputSize() == 0 means there is no data to be output,
113 // so we should make sure it by using Z_SYNC_FLUSH.
114 return Inflate(reinterpret_cast<const char*>(stream_->next_in),
115 stream_->avail_in,
116 Z_SYNC_FLUSH);
117 }
118
Inflate(const char * next_in,size_t avail_in,int flush)119 int WebSocketInflater::Inflate(const char* next_in,
120 size_t avail_in,
121 int flush) {
122 stream_->next_in = reinterpret_cast<Bytef*>(const_cast<char*>(next_in));
123 stream_->avail_in = avail_in;
124
125 int result = Z_BUF_ERROR;
126 do {
127 std::pair<char*, size_t> tail = output_buffer_.GetTail();
128 if (!tail.second)
129 break;
130
131 stream_->next_out = reinterpret_cast<Bytef*>(tail.first);
132 stream_->avail_out = tail.second;
133 result = inflate(stream_.get(), flush);
134 output_buffer_.AdvanceTail(tail.second - stream_->avail_out);
135 if (result == Z_STREAM_END) {
136 // Received a block with BFINAL set to 1. Reset the decompression state.
137 result = inflateReset(stream_.get());
138 } else if (tail.second == stream_->avail_out) {
139 break;
140 }
141 } while (result == Z_OK || result == Z_BUF_ERROR);
142 return result;
143 }
144
InflateChokedInput()145 int WebSocketInflater::InflateChokedInput() {
146 if (input_queue_.IsEmpty())
147 return InflateWithFlush(nullptr, 0);
148
149 int result = Z_BUF_ERROR;
150 while (!input_queue_.IsEmpty()) {
151 std::pair<char*, size_t> top = input_queue_.Top();
152
153 result = InflateWithFlush(top.first, top.second);
154 input_queue_.Consume(top.second - stream_->avail_in);
155
156 if (result != Z_OK && result != Z_BUF_ERROR)
157 return result;
158
159 if (stream_->avail_in > 0) {
160 // There are some data which are not consumed.
161 break;
162 }
163 }
164 return result;
165 }
166
OutputBuffer(size_t capacity)167 WebSocketInflater::OutputBuffer::OutputBuffer(size_t capacity)
168 : capacity_(capacity),
169 buffer_(capacity_ + 1) // 1 for sentinel
170 {}
171
172 WebSocketInflater::OutputBuffer::~OutputBuffer() = default;
173
Size() const174 size_t WebSocketInflater::OutputBuffer::Size() const {
175 return (tail_ + buffer_.size() - head_) % buffer_.size();
176 }
177
GetTail()178 std::pair<char*, size_t> WebSocketInflater::OutputBuffer::GetTail() {
179 DCHECK_LT(tail_, buffer_.size());
180 return std::make_pair(&buffer_[tail_],
181 std::min(capacity_ - Size(), buffer_.size() - tail_));
182 }
183
Read(char * dest,size_t size)184 void WebSocketInflater::OutputBuffer::Read(char* dest, size_t size) {
185 DCHECK_LE(size, Size());
186
187 size_t num_bytes_copied = 0;
188 if (tail_ < head_) {
189 size_t num_bytes_to_copy = std::min(size, buffer_.size() - head_);
190 DCHECK_LT(head_, buffer_.size());
191 memcpy(&dest[num_bytes_copied], &buffer_[head_], num_bytes_to_copy);
192 AdvanceHead(num_bytes_to_copy);
193 num_bytes_copied += num_bytes_to_copy;
194 }
195
196 if (num_bytes_copied == size)
197 return;
198 DCHECK_LE(head_, tail_);
199 size_t num_bytes_to_copy = size - num_bytes_copied;
200 DCHECK_LE(num_bytes_to_copy, tail_ - head_);
201 DCHECK_LT(head_, buffer_.size());
202 memcpy(&dest[num_bytes_copied], &buffer_[head_], num_bytes_to_copy);
203 AdvanceHead(num_bytes_to_copy);
204 num_bytes_copied += num_bytes_to_copy;
205 DCHECK_EQ(size, num_bytes_copied);
206 return;
207 }
208
AdvanceHead(size_t advance)209 void WebSocketInflater::OutputBuffer::AdvanceHead(size_t advance) {
210 DCHECK_LE(advance, Size());
211 head_ = (head_ + advance) % buffer_.size();
212 }
213
AdvanceTail(size_t advance)214 void WebSocketInflater::OutputBuffer::AdvanceTail(size_t advance) {
215 DCHECK_LE(advance + Size(), capacity_);
216 tail_ = (tail_ + advance) % buffer_.size();
217 }
218
InputQueue(size_t capacity)219 WebSocketInflater::InputQueue::InputQueue(size_t capacity)
220 : capacity_(capacity) {}
221
222 WebSocketInflater::InputQueue::~InputQueue() = default;
223
Top()224 std::pair<char*, size_t> WebSocketInflater::InputQueue::Top() {
225 DCHECK(!IsEmpty());
226 if (buffers_.size() == 1) {
227 return std::make_pair(&buffers_.front()->data()[head_of_first_buffer_],
228 tail_of_last_buffer_ - head_of_first_buffer_);
229 }
230 return std::make_pair(&buffers_.front()->data()[head_of_first_buffer_],
231 capacity_ - head_of_first_buffer_);
232 }
233
Push(const char * data,size_t size)234 void WebSocketInflater::InputQueue::Push(const char* data, size_t size) {
235 if (!size)
236 return;
237
238 size_t num_copied_bytes = 0;
239 if (!IsEmpty())
240 num_copied_bytes += PushToLastBuffer(data, size);
241
242 while (num_copied_bytes < size) {
243 DCHECK(IsEmpty() || tail_of_last_buffer_ == capacity_);
244
245 buffers_.push_back(base::MakeRefCounted<IOBufferWithSize>(capacity_));
246 tail_of_last_buffer_ = 0;
247 num_copied_bytes +=
248 PushToLastBuffer(&data[num_copied_bytes], size - num_copied_bytes);
249 }
250 }
251
Consume(size_t size)252 void WebSocketInflater::InputQueue::Consume(size_t size) {
253 DCHECK(!IsEmpty());
254 DCHECK_LE(size + head_of_first_buffer_, capacity_);
255
256 head_of_first_buffer_ += size;
257 if (head_of_first_buffer_ == capacity_) {
258 buffers_.pop_front();
259 head_of_first_buffer_ = 0;
260 }
261 if (buffers_.size() == 1 && head_of_first_buffer_ == tail_of_last_buffer_) {
262 buffers_.pop_front();
263 head_of_first_buffer_ = 0;
264 tail_of_last_buffer_ = 0;
265 }
266 }
267
PushToLastBuffer(const char * data,size_t size)268 size_t WebSocketInflater::InputQueue::PushToLastBuffer(const char* data,
269 size_t size) {
270 DCHECK(!IsEmpty());
271 size_t num_bytes_to_copy = std::min(size, capacity_ - tail_of_last_buffer_);
272 if (!num_bytes_to_copy)
273 return 0;
274 IOBufferWithSize* buffer = buffers_.back().get();
275 memcpy(&buffer->data()[tail_of_last_buffer_], data, num_bytes_to_copy);
276 tail_of_last_buffer_ += num_bytes_to_copy;
277 return num_bytes_to_copy;
278 }
279
280 } // namespace net
281