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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 #ifndef NET_HTTP2_DECODER_HTTP2_FRAME_DECODER_H_ | |
6 #define NET_HTTP2_DECODER_HTTP2_FRAME_DECODER_H_ | |
7 | |
8 // Http2FrameDecoder decodes the available input until it reaches the end of | |
9 // the input or it reaches the end of the first frame in the input. | |
10 // Note that Http2FrameDecoder does only minimal validation; for example, | |
11 // stream ids are not checked, nor is the sequence of frames such as | |
12 // CONTINUATION frame placement. | |
13 // | |
14 // Http2FrameDecoder enters state kError once it has called the listener's | |
15 // OnFrameSizeError or OnPaddingTooLong methods, and at this time has no | |
16 // provision for leaving that state. While the HTTP/2 spec (RFC7540) allows | |
17 // for some such errors to be considered as just stream errors in some cases, | |
18 // this implementation treats them all as connection errors. | |
19 | |
20 #include <stddef.h> | |
21 | |
22 #include "base/logging.h" | |
23 #include "base/macros.h" | |
24 #include "net/base/net_export.h" | |
25 #include "net/http2/decoder/decode_buffer.h" | |
26 #include "net/http2/decoder/decode_status.h" | |
27 #include "net/http2/decoder/frame_decoder_state.h" | |
28 #include "net/http2/decoder/http2_frame_decoder_listener.h" | |
29 #include "net/http2/decoder/payload_decoders/altsvc_payload_decoder.h" | |
30 #include "net/http2/decoder/payload_decoders/continuation_payload_decoder.h" | |
31 #include "net/http2/decoder/payload_decoders/data_payload_decoder.h" | |
32 #include "net/http2/decoder/payload_decoders/goaway_payload_decoder.h" | |
33 #include "net/http2/decoder/payload_decoders/headers_payload_decoder.h" | |
34 #include "net/http2/decoder/payload_decoders/ping_payload_decoder.h" | |
35 #include "net/http2/decoder/payload_decoders/priority_payload_decoder.h" | |
36 #include "net/http2/decoder/payload_decoders/push_promise_payload_decoder.h" | |
37 #include "net/http2/decoder/payload_decoders/rst_stream_payload_decoder.h" | |
38 #include "net/http2/decoder/payload_decoders/settings_payload_decoder.h" | |
39 #include "net/http2/decoder/payload_decoders/unknown_payload_decoder.h" | |
40 #include "net/http2/decoder/payload_decoders/window_update_payload_decoder.h" | |
41 #include "net/http2/http2_structures.h" | |
42 | |
43 namespace net { | |
44 namespace test { | |
45 class Http2FrameDecoderPeer; | |
46 } // namespace test | |
47 | |
48 class NET_EXPORT_PRIVATE Http2FrameDecoder { | |
49 public: | |
50 explicit Http2FrameDecoder(Http2FrameDecoderListener* listener); | |
51 Http2FrameDecoder() : Http2FrameDecoder(nullptr) {} | |
52 | |
53 // The decoder will call the listener's methods as it decodes a frame. | |
54 void set_listener(Http2FrameDecoderListener* listener); | |
55 Http2FrameDecoderListener* listener() const; | |
56 | |
57 // The decoder will reject frame's whose payload | |
58 // length field exceeds the maximum payload size. | |
59 void set_maximum_payload_size(size_t v) { maximum_payload_size_ = v; } | |
60 size_t maximum_payload_size() const { return maximum_payload_size_; } | |
61 | |
62 // Decodes the input up to the next frame boundary (i.e. at most one frame). | |
63 // | |
64 // Returns kDecodeDone if it decodes the final byte of a frame, OR if there | |
65 // is no input and it is awaiting the start of a new frame (e.g. if this | |
66 // is the first call to DecodeFrame, or if the previous call returned | |
67 // kDecodeDone). | |
68 // | |
69 // Returns kDecodeInProgress if it decodes all of the decode buffer, but has | |
70 // not reached the end of the frame. | |
71 // | |
72 // Returns kDecodeError if the frame's padding or length wasn't valid (i.e. if | |
73 // the decoder called either the listener's OnPaddingTooLong or | |
74 // OnFrameSizeError method). | |
75 DecodeStatus DecodeFrame(DecodeBuffer* db); | |
76 | |
77 ////////////////////////////////////////////////////////////////////////////// | |
78 // Methods that support Http2FrameDecoderAdapter. | |
79 | |
80 // Is the remainder of the frame's payload being discarded? | |
81 bool IsDiscardingPayload() const { return state_ == State::kDiscardPayload; } | |
82 | |
83 // Returns the number of bytes of the frame's payload that remain to be | |
84 // decoded, excluding any trailing padding. This method must only be called | |
85 // after the frame header has been decoded AND DecodeFrame has returned | |
86 // kDecodeInProgress. | |
87 size_t remaining_payload() const; | |
88 | |
89 // Returns the number of bytes of trailing padding after the payload that | |
90 // remain to be decoded. This method must only be called if the frame type | |
91 // allows padding, and after the frame header has been decoded AND | |
92 // DecodeFrame has returned. Will return 0 if the Pad Length field has not | |
93 // yet been decoded. | |
94 uint32_t remaining_padding() const; | |
95 | |
96 private: | |
97 enum class State { | |
98 // Ready to start decoding a new frame's header. | |
99 kStartDecodingHeader, | |
100 // Was in state kStartDecodingHeader, but unable to read the entire frame | |
101 // header, so needs more input to complete decoding the header. | |
102 kResumeDecodingHeader, | |
103 | |
104 // Have decoded the frame header, and started decoding the available bytes | |
105 // of the frame's payload, but need more bytes to finish the job. | |
106 kResumeDecodingPayload, | |
107 | |
108 // Decoding of the most recently started frame resulted in an error: | |
109 // OnPaddingTooLong or OnFrameSizeError was called to indicate that the | |
110 // decoder detected a problem, or OnFrameHeader returned false, indicating | |
111 // that the listener detected a problem. Regardless of which, the decoder | |
112 // will stay in state kDiscardPayload until it has been passed the rest | |
113 // of the bytes of the frame's payload that it hasn't yet seen, after | |
114 // which it will be ready to decode another frame. | |
115 kDiscardPayload, | |
116 }; | |
117 | |
118 friend class test::Http2FrameDecoderPeer; | |
119 friend std::ostream& operator<<(std::ostream& out, State v); | |
120 | |
121 DecodeStatus StartDecodingPayload(DecodeBuffer* db); | |
122 DecodeStatus ResumeDecodingPayload(DecodeBuffer* db); | |
123 DecodeStatus DiscardPayload(DecodeBuffer* db); | |
124 | |
125 const Http2FrameHeader& frame_header() const { | |
126 return frame_decoder_state_.frame_header(); | |
127 } | |
128 | |
129 // Clear any of the flags in the frame header that aren't set in valid_flags. | |
130 void RetainFlags(uint8_t valid_flags); | |
131 | |
132 // Clear all of the flags in the frame header; for use with frame types that | |
133 // don't define any flags, such as WINDOW_UPDATE. | |
134 void ClearFlags(); | |
135 | |
136 // These methods call the StartDecodingPayload() method of the frame type's | |
137 // payload decoder, after first clearing invalid flags in the header. The | |
138 // caller must ensure that the decode buffer does not extend beyond the | |
139 // end of the payload (handled by Http2FrameDecoder::StartDecodingPayload). | |
140 DecodeStatus StartDecodingAltSvcPayload(DecodeBuffer* db); | |
141 DecodeStatus StartDecodingContinuationPayload(DecodeBuffer* db); | |
142 DecodeStatus StartDecodingDataPayload(DecodeBuffer* db); | |
143 DecodeStatus StartDecodingGoAwayPayload(DecodeBuffer* db); | |
144 DecodeStatus StartDecodingHeadersPayload(DecodeBuffer* db); | |
145 DecodeStatus StartDecodingPingPayload(DecodeBuffer* db); | |
146 DecodeStatus StartDecodingPriorityPayload(DecodeBuffer* db); | |
147 DecodeStatus StartDecodingPushPromisePayload(DecodeBuffer* db); | |
148 DecodeStatus StartDecodingRstStreamPayload(DecodeBuffer* db); | |
149 DecodeStatus StartDecodingSettingsPayload(DecodeBuffer* db); | |
150 DecodeStatus StartDecodingUnknownPayload(DecodeBuffer* db); | |
151 DecodeStatus StartDecodingWindowUpdatePayload(DecodeBuffer* db); | |
152 | |
153 // These methods call the ResumeDecodingPayload() method of the frame type's | |
154 // payload decoder; they are called only if the preceding call to the | |
155 // corresponding Start method (above) returned kDecodeInProgress, as did any | |
156 // subsequent calls to the resume method. | |
157 // Unlike the Start methods, the decode buffer may extend beyond the | |
158 // end of the payload, so the method will create a DecodeBufferSubset | |
159 // before calling the ResumeDecodingPayload method of the frame type's | |
160 // payload decoder. | |
161 DecodeStatus ResumeDecodingAltSvcPayload(DecodeBuffer* db); | |
162 DecodeStatus ResumeDecodingContinuationPayload(DecodeBuffer* db); | |
163 DecodeStatus ResumeDecodingDataPayload(DecodeBuffer* db); | |
164 DecodeStatus ResumeDecodingGoAwayPayload(DecodeBuffer* db); | |
165 DecodeStatus ResumeDecodingHeadersPayload(DecodeBuffer* db); | |
166 DecodeStatus ResumeDecodingPingPayload(DecodeBuffer* db); | |
167 DecodeStatus ResumeDecodingPriorityPayload(DecodeBuffer* db); | |
168 DecodeStatus ResumeDecodingPushPromisePayload(DecodeBuffer* db); | |
169 DecodeStatus ResumeDecodingRstStreamPayload(DecodeBuffer* db); | |
170 DecodeStatus ResumeDecodingSettingsPayload(DecodeBuffer* db); | |
171 DecodeStatus ResumeDecodingUnknownPayload(DecodeBuffer* db); | |
172 DecodeStatus ResumeDecodingWindowUpdatePayload(DecodeBuffer* db); | |
173 | |
174 FrameDecoderState frame_decoder_state_; | |
175 | |
176 // We only need one payload decoder at a time, so they share the same storage. | |
177 union { | |
178 AltSvcPayloadDecoder altsvc_payload_decoder_; | |
179 ContinuationPayloadDecoder continuation_payload_decoder_; | |
180 DataPayloadDecoder data_payload_decoder_; | |
181 GoAwayPayloadDecoder goaway_payload_decoder_; | |
182 HeadersPayloadDecoder headers_payload_decoder_; | |
183 PingPayloadDecoder ping_payload_decoder_; | |
184 PriorityPayloadDecoder priority_payload_decoder_; | |
185 PushPromisePayloadDecoder push_promise_payload_decoder_; | |
186 RstStreamPayloadDecoder rst_stream_payload_decoder_; | |
187 SettingsPayloadDecoder settings_payload_decoder_; | |
188 UnknownPayloadDecoder unknown_payload_decoder_; | |
189 WindowUpdatePayloadDecoder window_update_payload_decoder_; | |
190 }; | |
191 | |
192 State state_; | |
193 size_t maximum_payload_size_; | |
194 | |
195 // Listener used whenever caller passes nullptr to set_listener. | |
196 Http2FrameDecoderNoOpListener no_op_listener_; | |
197 | |
198 DISALLOW_COPY_AND_ASSIGN(Http2FrameDecoder); | |
199 }; | |
200 | |
201 } // namespace net | |
202 | |
203 #endif // NET_HTTP2_DECODER_HTTP2_FRAME_DECODER_H_ | |
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