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 #ifndef NET_SPDY_SPDY_FRAME_BUILDER_H_ 6 #define NET_SPDY_SPDY_FRAME_BUILDER_H_ 7 8 #include <string> 9 10 #include "base/basictypes.h" 11 #include "base/memory/scoped_ptr.h" 12 #include "base/strings/string_piece.h" 13 #include "base/sys_byteorder.h" 14 #include "net/base/net_export.h" 15 #include "net/spdy/spdy_protocol.h" 16 17 namespace net { 18 19 class SpdyFramer; 20 21 // This class provides facilities for basic binary value packing 22 // into Spdy frames. 23 // 24 // The SpdyFrameBuilder supports appending primitive values (int, string, etc) 25 // to a frame instance. The SpdyFrameBuilder grows its internal memory buffer 26 // dynamically to hold the sequence of primitive values. The internal memory 27 // buffer is exposed as the "data" of the SpdyFrameBuilder. 28 class NET_EXPORT_PRIVATE SpdyFrameBuilder { 29 public: 30 // Initializes a SpdyFrameBuilder with a buffer of given size 31 SpdyFrameBuilder(size_t size, SpdyMajorVersion version); 32 33 ~SpdyFrameBuilder(); 34 35 // Returns the total size of the SpdyFrameBuilder's data, which may include 36 // multiple frames. 37 size_t length() const { return offset_ + length_; } 38 39 // Returns a writeable buffer of given size in bytes, to be appended to the 40 // currently written frame. Does bounds checking on length but does not 41 // increment the underlying iterator. To do so, consumers should subsequently 42 // call Seek(). 43 // In general, consumers should use Write*() calls instead of this. 44 // Returns NULL on failure. 45 char* GetWritableBuffer(size_t length); 46 47 // Seeks forward by the given number of bytes. Useful in conjunction with 48 // GetWriteableBuffer() above. 49 bool Seek(size_t length); 50 51 // Populates this frame with a SPDY control frame header using 52 // version-specific information from the |framer| and length information from 53 // capacity_. The given type must be a control frame type. 54 // Used only for SPDY versions <4. 55 bool WriteControlFrameHeader(const SpdyFramer& framer, 56 SpdyFrameType type, 57 uint8 flags); 58 59 // Populates this frame with a SPDY data frame header using version-specific 60 // information from the |framer| and length information from capacity_. 61 bool WriteDataFrameHeader(const SpdyFramer& framer, 62 SpdyStreamId stream_id, 63 uint8 flags); 64 65 // Populates this frame with a SPDY4/HTTP2 frame prefix using 66 // version-specific information from the |framer| and length information from 67 // capacity_. The given type must be a control frame type. 68 // Used only for SPDY versions >=4. 69 bool BeginNewFrame(const SpdyFramer& framer, 70 SpdyFrameType type, 71 uint8 flags, 72 SpdyStreamId stream_id); 73 74 // Takes the buffer from the SpdyFrameBuilder. 75 SpdyFrame* take() { 76 if (version_ > SPDY3) { 77 DLOG_IF(DFATAL, SpdyConstants::GetFrameMaximumSize(version_) < length_) 78 << "Frame length " << length_ 79 << " is longer than the maximum allowed length."; 80 } 81 SpdyFrame* rv = new SpdyFrame(buffer_.release(), length(), true); 82 capacity_ = 0; 83 length_ = 0; 84 offset_ = 0; 85 return rv; 86 } 87 88 // Methods for adding to the payload. These values are appended to the end 89 // of the SpdyFrameBuilder payload. Note - binary integers are converted from 90 // host to network form. 91 bool WriteUInt8(uint8 value) { 92 return WriteBytes(&value, sizeof(value)); 93 } 94 bool WriteUInt16(uint16 value) { 95 value = htons(value); 96 return WriteBytes(&value, sizeof(value)); 97 } 98 bool WriteUInt24(uint32 value) { 99 value = htonl(value); 100 return WriteBytes(reinterpret_cast<char*>(&value) + 1, 101 sizeof(value) - 1); 102 } 103 bool WriteUInt32(uint32 value) { 104 value = htonl(value); 105 return WriteBytes(&value, sizeof(value)); 106 } 107 bool WriteUInt64(uint64 value) { 108 uint32 upper = htonl(value >> 32); 109 uint32 lower = htonl(value); 110 return (WriteBytes(&upper, sizeof(upper)) && 111 WriteBytes(&lower, sizeof(lower))); 112 } 113 // TODO(hkhalil) Rename to WriteStringPiece16(). 114 bool WriteString(const std::string& value); 115 bool WriteStringPiece32(const base::StringPiece& value); 116 bool WriteBytes(const void* data, uint32 data_len); 117 118 // Update (in-place) the length field in the frame being built to reflect the 119 // current actual length of bytes written to said frame through this builder. 120 // The framer parameter is used to determine version-specific location and 121 // size information of the length field to be written, and must be initialized 122 // with the correct version for the frame being written. 123 bool RewriteLength(const SpdyFramer& framer); 124 125 // Update (in-place) the length field in the frame being built to reflect the 126 // given length. 127 // The framer parameter is used to determine version-specific location and 128 // size information of the length field to be written, and must be initialized 129 // with the correct version for the frame being written. 130 bool OverwriteLength(const SpdyFramer& framer, size_t length); 131 132 // Update (in-place) the flags field in the frame being built to reflect the 133 // given flags value. 134 // Used only for SPDY versions >=4. 135 bool OverwriteFlags(const SpdyFramer& framer, uint8 flags); 136 137 private: 138 // Checks to make sure that there is an appropriate amount of space for a 139 // write of given size, in bytes. 140 bool CanWrite(size_t length) const; 141 142 scoped_ptr<char[]> buffer_; 143 size_t capacity_; // Allocation size of payload, set by constructor. 144 size_t length_; // Length of the latest frame in the buffer. 145 size_t offset_; // Position at which the latest frame begins. 146 147 const SpdyMajorVersion version_; 148 }; 149 150 } // namespace net 151 152 #endif // NET_SPDY_SPDY_FRAME_BUILDER_H_ 153
