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1 // Copyright (c) 2012 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_frame_parser.h" | |
6 | |
7 #include <algorithm> | |
8 #include <limits> | |
9 | |
10 #include "base/basictypes.h" | |
11 #include "base/big_endian.h" | |
12 #include "base/logging.h" | |
13 #include "base/memory/ref_counted.h" | |
14 #include "base/memory/scoped_ptr.h" | |
15 #include "base/memory/scoped_vector.h" | |
16 #include "net/base/io_buffer.h" | |
17 #include "net/websockets/websocket_frame.h" | |
18 | |
19 namespace { | |
20 | |
21 const uint8 kFinalBit = 0x80; | |
22 const uint8 kReserved1Bit = 0x40; | |
23 const uint8 kReserved2Bit = 0x20; | |
24 const uint8 kReserved3Bit = 0x10; | |
25 const uint8 kOpCodeMask = 0xF; | |
26 const uint8 kMaskBit = 0x80; | |
27 const uint8 kPayloadLengthMask = 0x7F; | |
28 const uint64 kMaxPayloadLengthWithoutExtendedLengthField = 125; | |
29 const uint64 kPayloadLengthWithTwoByteExtendedLengthField = 126; | |
30 const uint64 kPayloadLengthWithEightByteExtendedLengthField = 127; | |
31 | |
32 } // Unnamed namespace. | |
33 | |
34 namespace net { | |
35 | |
36 WebSocketFrameParser::WebSocketFrameParser() | |
37 : current_read_pos_(0), | |
38 frame_offset_(0), | |
39 websocket_error_(kWebSocketNormalClosure) { | |
40 std::fill(masking_key_.key, | |
41 masking_key_.key + WebSocketFrameHeader::kMaskingKeyLength, | |
42 '\0'); | |
43 } | |
44 | |
45 WebSocketFrameParser::~WebSocketFrameParser() {} | |
46 | |
47 bool WebSocketFrameParser::Decode( | |
48 const char* data, | |
49 size_t length, | |
50 ScopedVector<WebSocketFrameChunk>* frame_chunks) { | |
51 if (websocket_error_ != kWebSocketNormalClosure) | |
52 return false; | |
53 if (!length) | |
54 return true; | |
55 | |
56 // TODO(yutak): Remove copy. | |
57 buffer_.insert(buffer_.end(), data, data + length); | |
58 | |
59 while (current_read_pos_ < buffer_.size()) { | |
60 bool first_chunk = false; | |
61 if (!current_frame_header_.get()) { | |
62 DecodeFrameHeader(); | |
63 if (websocket_error_ != kWebSocketNormalClosure) | |
64 return false; | |
65 // If frame header is incomplete, then carry over the remaining | |
66 // data to the next round of Decode(). | |
67 if (!current_frame_header_.get()) | |
68 break; | |
69 first_chunk = true; | |
70 } | |
71 | |
72 scoped_ptr<WebSocketFrameChunk> frame_chunk = | |
73 DecodeFramePayload(first_chunk); | |
74 DCHECK(frame_chunk.get()); | |
75 frame_chunks->push_back(frame_chunk.release()); | |
76 | |
77 if (current_frame_header_.get()) { | |
78 DCHECK(current_read_pos_ == buffer_.size()); | |
79 break; | |
80 } | |
81 } | |
82 | |
83 // Drain unnecessary data. TODO(yutak): Remove copy. (but how?) | |
84 buffer_.erase(buffer_.begin(), buffer_.begin() + current_read_pos_); | |
85 current_read_pos_ = 0; | |
86 | |
87 // Sanity check: the size of carried-over data should not exceed | |
88 // the maximum possible length of a frame header. | |
89 static const size_t kMaximumFrameHeaderSize = | |
90 WebSocketFrameHeader::kBaseHeaderSize + | |
91 WebSocketFrameHeader::kMaximumExtendedLengthSize + | |
92 WebSocketFrameHeader::kMaskingKeyLength; | |
93 DCHECK_LT(buffer_.size(), kMaximumFrameHeaderSize); | |
94 | |
95 return true; | |
96 } | |
97 | |
98 void WebSocketFrameParser::DecodeFrameHeader() { | |
99 typedef WebSocketFrameHeader::OpCode OpCode; | |
100 static const int kMaskingKeyLength = WebSocketFrameHeader::kMaskingKeyLength; | |
101 | |
102 DCHECK(!current_frame_header_.get()); | |
103 | |
104 const char* start = &buffer_.front() + current_read_pos_; | |
105 const char* current = start; | |
106 const char* end = &buffer_.front() + buffer_.size(); | |
107 | |
108 // Header needs 2 bytes at minimum. | |
109 if (end - current < 2) | |
110 return; | |
111 | |
112 uint8 first_byte = *current++; | |
113 uint8 second_byte = *current++; | |
114 | |
115 bool final = (first_byte & kFinalBit) != 0; | |
116 bool reserved1 = (first_byte & kReserved1Bit) != 0; | |
117 bool reserved2 = (first_byte & kReserved2Bit) != 0; | |
118 bool reserved3 = (first_byte & kReserved3Bit) != 0; | |
119 OpCode opcode = first_byte & kOpCodeMask; | |
120 | |
121 bool masked = (second_byte & kMaskBit) != 0; | |
122 uint64 payload_length = second_byte & kPayloadLengthMask; | |
123 if (payload_length == kPayloadLengthWithTwoByteExtendedLengthField) { | |
124 if (end - current < 2) | |
125 return; | |
126 uint16 payload_length_16; | |
127 base::ReadBigEndian(current, &payload_length_16); | |
128 current += 2; | |
129 payload_length = payload_length_16; | |
130 if (payload_length <= kMaxPayloadLengthWithoutExtendedLengthField) | |
131 websocket_error_ = kWebSocketErrorProtocolError; | |
132 } else if (payload_length == kPayloadLengthWithEightByteExtendedLengthField) { | |
133 if (end - current < 8) | |
134 return; | |
135 base::ReadBigEndian(current, &payload_length); | |
136 current += 8; | |
137 if (payload_length <= kuint16max || | |
138 payload_length > static_cast<uint64>(kint64max)) { | |
139 websocket_error_ = kWebSocketErrorProtocolError; | |
140 } else if (payload_length > static_cast<uint64>(kint32max)) { | |
141 websocket_error_ = kWebSocketErrorMessageTooBig; | |
142 } | |
143 } | |
144 if (websocket_error_ != kWebSocketNormalClosure) { | |
145 buffer_.clear(); | |
146 current_read_pos_ = 0; | |
147 current_frame_header_.reset(); | |
148 frame_offset_ = 0; | |
149 return; | |
150 } | |
151 | |
152 if (masked) { | |
153 if (end - current < kMaskingKeyLength) | |
154 return; | |
155 std::copy(current, current + kMaskingKeyLength, masking_key_.key); | |
156 current += kMaskingKeyLength; | |
157 } else { | |
158 std::fill(masking_key_.key, masking_key_.key + kMaskingKeyLength, '\0'); | |
159 } | |
160 | |
161 current_frame_header_.reset(new WebSocketFrameHeader(opcode)); | |
162 current_frame_header_->final = final; | |
163 current_frame_header_->reserved1 = reserved1; | |
164 current_frame_header_->reserved2 = reserved2; | |
165 current_frame_header_->reserved3 = reserved3; | |
166 current_frame_header_->masked = masked; | |
167 current_frame_header_->payload_length = payload_length; | |
168 current_read_pos_ += current - start; | |
169 DCHECK_EQ(0u, frame_offset_); | |
170 } | |
171 | |
172 scoped_ptr<WebSocketFrameChunk> WebSocketFrameParser::DecodeFramePayload( | |
173 bool first_chunk) { | |
174 // The cast here is safe because |payload_length| is already checked to be | |
175 // less than std::numeric_limits<int>::max() when the header is parsed. | |
176 int next_size = static_cast<int>(std::min( | |
177 static_cast<uint64>(buffer_.size() - current_read_pos_), | |
178 current_frame_header_->payload_length - frame_offset_)); | |
179 | |
180 scoped_ptr<WebSocketFrameChunk> frame_chunk(new WebSocketFrameChunk); | |
181 if (first_chunk) { | |
182 frame_chunk->header = current_frame_header_->Clone(); | |
183 } | |
184 frame_chunk->final_chunk = false; | |
185 if (next_size) { | |
186 frame_chunk->data = new IOBufferWithSize(static_cast<int>(next_size)); | |
187 char* io_data = frame_chunk->data->data(); | |
188 memcpy(io_data, &buffer_.front() + current_read_pos_, next_size); | |
189 if (current_frame_header_->masked) { | |
190 // The masking function is its own inverse, so we use the same function to | |
191 // unmask as to mask. | |
192 MaskWebSocketFramePayload( | |
193 masking_key_, frame_offset_, io_data, next_size); | |
194 } | |
195 | |
196 current_read_pos_ += next_size; | |
197 frame_offset_ += next_size; | |
198 } | |
199 | |
200 DCHECK_LE(frame_offset_, current_frame_header_->payload_length); | |
201 if (frame_offset_ == current_frame_header_->payload_length) { | |
202 frame_chunk->final_chunk = true; | |
203 current_frame_header_.reset(); | |
204 frame_offset_ = 0; | |
205 } | |
206 | |
207 return frame_chunk.Pass(); | |
208 } | |
209 | |
210 } // namespace net | |
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