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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_STRUCTURE_DECODER_H_ | |
| 6 #define NET_HTTP2_DECODER_HTTP2_STRUCTURE_DECODER_H_ | |
| 7 | |
| 8 // Http2StructureDecoder is a class for decoding the fixed size structures in | |
| 9 // the HTTP/2 spec, defined in net/http2/http2_structures.h. This class | |
| 10 // is in aid of deciding whether to keep the SlowDecode methods which I | |
| 11 // (jamessynge) now think may not be worth their complexity. In particular, | |
| 12 // if most transport buffers are large, so it is rare that a structure is | |
| 13 // split across buffer boundaries, than the cost of buffering upon | |
| 14 // those rare occurrences is small, which then simplifies the callers. | |
| 15 | |
| 16 #include "base/logging.h" | |
| 17 #include "net/base/net_export.h" | |
| 18 #include "net/http2/decoder/decode_buffer.h" | |
| 19 #include "net/http2/decoder/decode_http2_structures.h" | |
| 20 #include "net/http2/decoder/decode_status.h" | |
| 21 #include "net/http2/http2_structures.h" | |
| 22 | |
| 23 namespace net { | |
| 24 namespace test { | |
| 25 class Http2StructureDecoderPeer; | |
| 26 } // namespace test | |
| 27 | |
| 28 class NET_EXPORT_PRIVATE Http2StructureDecoder { | |
| 29 public: | |
| 30 // The caller needs to keep track of whether to call Start or Resume. | |
| 31 // | |
| 32 // Start has an optimization for the case where the DecodeBuffer holds the | |
| 33 // entire encoded structure; in that case it decodes into *out and returns | |
| 34 // true, and does NOT touch the data members of the Http2StructureDecoder | |
| 35 // instance because the caller won't be calling Resume later. | |
| 36 // | |
| 37 // However, if the DecodeBuffer is too small to hold the entire encoded | |
| 38 // structure, Start copies the available bytes into the Http2StructureDecoder | |
| 39 // instance, and returns false to indicate that it has not been able to | |
| 40 // complete the decoding. | |
| 41 // | |
| 42 template <class S> | |
| 43 bool Start(S* out, DecodeBuffer* db) { | |
| 44 static_assert(S::EncodedSize() <= sizeof buffer_, "buffer_ is too small"); | |
| 45 DVLOG(2) << __func__ << "@" << this << ": db->Remaining=" << db->Remaining() | |
| 46 << "; EncodedSize=" << S::EncodedSize(); | |
| 47 if (db->Remaining() >= S::EncodedSize()) { | |
| 48 DoDecode(out, db); | |
| 49 return true; | |
| 50 } | |
| 51 IncompleteStart(db, S::EncodedSize()); | |
| 52 return false; | |
| 53 } | |
| 54 | |
| 55 template <class S> | |
| 56 bool Resume(S* out, DecodeBuffer* db) { | |
| 57 DVLOG(2) << __func__ << "@" << this << ": offset_=" << offset_ | |
| 58 << "; db->Remaining=" << db->Remaining(); | |
| 59 if (ResumeFillingBuffer(db, S::EncodedSize())) { | |
| 60 // We have the whole thing now. | |
| 61 DVLOG(2) << __func__ << "@" << this << " offset_=" << offset_ | |
| 62 << " Ready to decode from buffer_."; | |
| 63 DecodeBuffer buffer_db(buffer_, S::EncodedSize()); | |
| 64 DoDecode(out, &buffer_db); | |
| 65 return true; | |
| 66 } | |
| 67 DCHECK_LT(offset_, S::EncodedSize()); | |
| 68 return false; | |
| 69 } | |
| 70 | |
| 71 // A second pair of Start and Resume, where the caller has a variable, | |
| 72 // |remaining_payload| that is both tested for sufficiency and updated | |
| 73 // during decoding. Note that the decode buffer may extend beyond the | |
| 74 // remaining payload because the buffer may include padding. | |
| 75 template <class S> | |
| 76 DecodeStatus Start(S* out, DecodeBuffer* db, uint32_t* remaining_payload) { | |
| 77 static_assert(S::EncodedSize() <= sizeof buffer_, "buffer_ is too small"); | |
| 78 DVLOG(2) << __func__ << "@" << this | |
| 79 << ": *remaining_payload=" << *remaining_payload | |
| 80 << "; db->Remaining=" << db->Remaining() | |
| 81 << "; EncodedSize=" << S::EncodedSize(); | |
| 82 if (db->MinLengthRemaining(*remaining_payload) >= S::EncodedSize()) { | |
| 83 DoDecode(out, db); | |
| 84 *remaining_payload -= S::EncodedSize(); | |
| 85 return DecodeStatus::kDecodeDone; | |
| 86 } | |
| 87 return IncompleteStart(db, remaining_payload, S::EncodedSize()); | |
| 88 } | |
| 89 | |
| 90 template <class S> | |
| 91 bool Resume(S* out, DecodeBuffer* db, uint32_t* remaining_payload) { | |
| 92 DVLOG(3) << __func__ << "@" << this << ": offset_=" << offset_ | |
| 93 << "; *remaining_payload=" << *remaining_payload | |
| 94 << "; db->Remaining=" << db->Remaining() | |
| 95 << "; EncodedSize=" << S::EncodedSize(); | |
| 96 if (ResumeFillingBuffer(db, remaining_payload, S::EncodedSize())) { | |
| 97 // We have the whole thing now. | |
| 98 DVLOG(2) << __func__ << "@" << this << ": offset_=" << offset_ | |
| 99 << "; Ready to decode from buffer_."; | |
| 100 DecodeBuffer buffer_db(buffer_, S::EncodedSize()); | |
| 101 DoDecode(out, &buffer_db); | |
| 102 return true; | |
| 103 } | |
| 104 DCHECK_LT(offset_, S::EncodedSize()); | |
| 105 return false; | |
| 106 } | |
| 107 | |
| 108 uint32_t offset() const { return offset_; } | |
| 109 | |
| 110 private: | |
| 111 friend class test::Http2StructureDecoderPeer; | |
| 112 | |
| 113 uint32_t IncompleteStart(DecodeBuffer* db, uint32_t target_size); | |
| 114 DecodeStatus IncompleteStart(DecodeBuffer* db, | |
| 115 uint32_t* remaining_payload, | |
| 116 uint32_t target_size); | |
| 117 | |
| 118 bool ResumeFillingBuffer(DecodeBuffer* db, uint32_t target_size); | |
| 119 bool ResumeFillingBuffer(DecodeBuffer* db, | |
| 120 uint32_t* remaining_payload, | |
| 121 uint32_t target_size); | |
| 122 | |
| 123 uint32_t offset_; | |
| 124 char buffer_[Http2FrameHeader::EncodedSize()]; | |
| 125 }; | |
| 126 | |
| 127 } // namespace net | |
| 128 | |
| 129 #endif // NET_HTTP2_DECODER_HTTP2_STRUCTURE_DECODER_H_ | |
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Chromium Code Reviews
Issue 2554683003:
Revert of Add new HTTP/2 and HPACK decoder in net/http2/. (Closed)
