| // Copyright 2018 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef INSPECTOR_PROTOCOL_ENCODING_CBOR_H_ |
| #define INSPECTOR_PROTOCOL_ENCODING_CBOR_H_ |
| |
| #include <cstdint> |
| #include <memory> |
| #include <vector> |
| #include "cbor_internals.h" |
| #include "json_parser_handler.h" |
| #include "span.h" |
| #include "status.h" |
| |
| namespace inspector_protocol { |
| |
| namespace cbor { |
| |
| // The major types from RFC 7049 Section 2.1. |
| enum class MajorType { |
| UNSIGNED = 0, |
| NEGATIVE = 1, |
| BYTE_STRING = 2, |
| STRING = 3, |
| ARRAY = 4, |
| MAP = 5, |
| TAG = 6, |
| SIMPLE_VALUE = 7 |
| }; |
| |
| // Indicates the number of bits the "initial byte" needs to be shifted to the |
| // right after applying |kMajorTypeMask| to produce the major type in the |
| // lowermost bits. |
| static constexpr uint8_t kMajorTypeBitShift = 5u; |
| // Mask selecting the low-order 5 bits of the "initial byte", which is where |
| // the additional information is encoded. |
| static constexpr uint8_t kAdditionalInformationMask = 0x1f; |
| // Mask selecting the high-order 3 bits of the "initial byte", which indicates |
| // the major type of the encoded value. |
| static constexpr uint8_t kMajorTypeMask = 0xe0; |
| // Indicates the integer is in the following byte. |
| static constexpr uint8_t kAdditionalInformation1Byte = 24u; |
| // Indicates the integer is in the next 2 bytes. |
| static constexpr uint8_t kAdditionalInformation2Bytes = 25u; |
| // Indicates the integer is in the next 4 bytes. |
| static constexpr uint8_t kAdditionalInformation4Bytes = 26u; |
| // Indicates the integer is in the next 8 bytes. |
| static constexpr uint8_t kAdditionalInformation8Bytes = 27u; |
| |
| // Encodes the initial byte, consisting of the |type| in the first 3 bits |
| // followed by 5 bits of |additional_info|. |
| constexpr uint8_t EncodeInitialByte(MajorType type, uint8_t additional_info) { |
| return (static_cast<uint8_t>(type) << kMajorTypeBitShift) | |
| (additional_info & kAdditionalInformationMask); |
| } |
| |
| // TAG 24 indicates that what follows is a byte string which is |
| // encoded in CBOR format. We use this as a wrapper for |
| // maps and arrays, allowing us to skip them, because the |
| // byte string carries its size (byte length). |
| // https://tools.ietf.org/html/rfc7049#section-2.4.4.1 |
| static constexpr uint8_t kInitialByteForEnvelope = |
| EncodeInitialByte(MajorType::TAG, 24); |
| // The initial byte for a byte string with at most 2^32 bytes |
| // of payload. This is used for envelope encoding, even if |
| // the byte string is shorter. |
| static constexpr uint8_t kInitialByteFor32BitLengthByteString = |
| EncodeInitialByte(MajorType::BYTE_STRING, 26); |
| |
| // See RFC 7049 Section 2.2.1, indefinite length arrays / maps have additional |
| // info = 31. |
| static constexpr uint8_t kInitialByteIndefiniteLengthArray = |
| EncodeInitialByte(MajorType::ARRAY, 31); |
| static constexpr uint8_t kInitialByteIndefiniteLengthMap = |
| EncodeInitialByte(MajorType::MAP, 31); |
| // See RFC 7049 Section 2.3, Table 1; this is used for finishing indefinite |
| // length maps / arrays. |
| static constexpr uint8_t kStopByte = |
| EncodeInitialByte(MajorType::SIMPLE_VALUE, 31); |
| |
| } // namespace cbor |
| |
| // The binary encoding for the inspector protocol follows the CBOR specification |
| // (RFC 7049). Additional constraints: |
| // - Only indefinite length maps and arrays are supported. |
| // - Maps and arrays are wrapped with an envelope, that is, a |
| // CBOR tag with value 24 followed by a byte string specifying |
| // the byte length of the enclosed map / array. The byte string |
| // must use a 32 bit wide length. |
| // - At the top level, a message must be an indefinite length map |
| // wrapped by an envelope. |
| // - Maximal size for messages is 2^32 (4 GB). |
| // - For scalars, we support only the int32_t range, encoded as |
| // UNSIGNED/NEGATIVE (major types 0 / 1). |
| // - UTF16 strings, including with unbalanced surrogate pairs, are encoded |
| // as CBOR BYTE_STRING (major type 2). For such strings, the number of |
| // bytes encoded must be even. |
| // - UTF8 strings (major type 3) are supported. |
| // - 7 bit US-ASCII strings must always be encoded as UTF8 strings, not |
| // as UTF16 strings. |
| // - Arbitrary byte arrays, in the inspector protocol called 'binary', |
| // are encoded as BYTE_STRING (major type 2), prefixed with a byte |
| // indicating base64 when rendered as JSON. |
| |
| // Encodes |value| as |UNSIGNED| (major type 0) iff >= 0, or |NEGATIVE| |
| // (major type 1) iff < 0. |
| void EncodeInt32(int32_t value, std::vector<uint8_t>* out); |
| |
| // Encodes a UTF16 string as a BYTE_STRING (major type 2). Each utf16 |
| // character in |in| is emitted with most significant byte first, |
| // appending to |out|. |
| void EncodeString16(span<uint16_t> in, std::vector<uint8_t>* out); |
| |
| // Encodes a UTF8 string |in| as STRING (major type 3). |
| void EncodeString8(span<uint8_t> in, std::vector<uint8_t>* out); |
| |
| // Encodes the given |latin1| string as STRING8. |
| // If any non-ASCII character is present, it will be represented |
| // as a 2 byte UTF8 sequence. |
| void EncodeFromLatin1(span<uint8_t> latin1, std::vector<uint8_t>* out); |
| |
| // Encodes the given |utf16| string as STRING8 if it's entirely US-ASCII. |
| // Otherwise, encodes as STRING16. |
| void EncodeFromUTF16(span<uint16_t> utf16, std::vector<uint8_t>* out); |
| |
| // Encodes arbitrary binary data in |in| as a BYTE_STRING (major type 2) with |
| // definitive length, prefixed with tag 22 indicating expected conversion to |
| // base64 (see RFC 7049, Table 3 and Section 2.4.4.2). |
| void EncodeBinary(span<uint8_t> in, std::vector<uint8_t>* out); |
| |
| // Encodes / decodes a double as Major type 7 (SIMPLE_VALUE), |
| // with additional info = 27, followed by 8 bytes in big endian. |
| void EncodeDouble(double value, std::vector<uint8_t>* out); |
| |
| // Some constants for CBOR tokens that only take a single byte on the wire. |
| uint8_t EncodeTrue(); |
| uint8_t EncodeFalse(); |
| uint8_t EncodeNull(); |
| uint8_t EncodeIndefiniteLengthArrayStart(); |
| uint8_t EncodeIndefiniteLengthMapStart(); |
| uint8_t EncodeStop(); |
| |
| // An envelope indicates the byte length of a wrapped item. |
| // We use this for maps and array, which allows the decoder |
| // to skip such (nested) values whole sale. |
| // It's implemented as a CBOR tag (major type 6) with additional |
| // info = 24, followed by a byte string with a 32 bit length value; |
| // so the maximal structure that we can wrap is 2^32 bits long. |
| // See also: https://tools.ietf.org/html/rfc7049#section-2.4.4.1 |
| class EnvelopeEncoder { |
| public: |
| // Emits the envelope start bytes and records the position for the |
| // byte size in |byte_size_pos_|. Also emits empty bytes for the |
| // byte sisze so that encoding can continue. |
| void EncodeStart(std::vector<uint8_t>* out); |
| // This records the current size in |out| at position byte_size_pos_. |
| // Returns true iff successful. |
| bool EncodeStop(std::vector<uint8_t>* out); |
| |
| private: |
| std::size_t byte_size_pos_ = 0; |
| }; |
| |
| // This can be used to convert from JSON to CBOR, by passing the |
| // return value to the routines in json_parser.h. The handler will encode into |
| // |out|, and iff an error occurs it will set |status| to an error and clear |
| // |out|. Otherwise, |status.ok()| will be |true|. |
| std::unique_ptr<JSONParserHandler> NewJSONToCBOREncoder( |
| std::vector<uint8_t>* out, Status* status); |
| |
| // Parses a CBOR encoded message from |bytes|, sending JSON events to |
| // |json_out|. If an error occurs, sends |out->HandleError|, and parsing stops. |
| // The client is responsible for discarding the already received information in |
| // that case. |
| void ParseCBOR(span<uint8_t> bytes, JSONParserHandler* json_out); |
| |
| // Tags for the tokens within a CBOR message that CBORStream understands. |
| // Note that this is not the same terminology as the CBOR spec (RFC 7049), |
| // but rather, our adaptation. For instance, we lump unsigned and signed |
| // major type into INT32 here (and disallow values outside the int32_t range). |
| enum class CBORTokenTag { |
| // Encountered an error in the structure of the message. Consult |
| // status() for details. |
| ERROR_VALUE, |
| // Booleans and NULL. |
| TRUE_VALUE, |
| FALSE_VALUE, |
| NULL_VALUE, |
| // An int32_t (signed 32 bit integer). |
| INT32, |
| // A double (64 bit floating point). |
| DOUBLE, |
| // A UTF8 string. |
| STRING8, |
| // A UTF16 string. |
| STRING16, |
| // A binary string. |
| BINARY, |
| // Starts an indefinite length map; after the map start we expect |
| // alternating keys and values, followed by STOP. |
| MAP_START, |
| // Starts an indefinite length array; after the array start we |
| // expect values, followed by STOP. |
| ARRAY_START, |
| // Ends a map or an array. |
| STOP, |
| // An envelope indicator, wrapping a map or array. |
| // Internally this carries the byte length of the wrapped |
| // map or array. While CBORTokenizer::Next() will read / skip the entire |
| // envelope, CBORTokenizer::EnterEnvelope() reads the tokens |
| // inside of it. |
| ENVELOPE, |
| // We've reached the end there is nothing else to read. |
| DONE, |
| }; |
| |
| // CBORTokenizer segments a CBOR message, presenting the tokens therein as |
| // numbers, strings, etc. This is not a complete CBOR parser, but makes it much |
| // easier to implement one (e.g. ParseCBOR, above). It can also be used to parse |
| // messages partially. |
| class CBORTokenizer { |
| public: |
| explicit CBORTokenizer(span<uint8_t> bytes); |
| ~CBORTokenizer(); |
| |
| // Identifies the current token that we're looking at, |
| // or ERROR_VALUE (in which ase ::Status() has details) |
| // or DONE (if we're past the last token). |
| CBORTokenTag TokenTag() const; |
| |
| // Advances to the next token. |
| void Next(); |
| // Can only be called if TokenTag() == CBORTokenTag::ENVELOPE. |
| // While Next() would skip past the entire envelope / what it's |
| // wrapping, EnterEnvelope positions the cursor inside of the envelope, |
| // letting the client explore the nested structure. |
| void EnterEnvelope(); |
| |
| // If TokenTag() is CBORTokenTag::ERROR_VALUE, then Status().error describes |
| // the error more precisely; otherwise it'll be set to Error::OK. |
| // In either case, Status().pos is the current position. |
| struct Status Status() const; |
| |
| // The following methods retrieve the token values. They can only |
| // be called if TokenTag() matches. |
| |
| // To be called only if ::TokenTag() == CBORTokenTag::INT32. |
| int32_t GetInt32() const; |
| |
| // To be called only if ::TokenTag() == CBORTokenTag::DOUBLE. |
| double GetDouble() const; |
| |
| // To be called only if ::TokenTag() == CBORTokenTag::STRING8. |
| span<uint8_t> GetString8() const; |
| |
| // Wire representation for STRING16 is low byte first (little endian). |
| // To be called only if ::TokenTag() == CBORTokenTag::STRING16. |
| span<uint8_t> GetString16WireRep() const; |
| |
| // To be called only if ::TokenTag() == CBORTokenTag::BINARY. |
| span<uint8_t> GetBinary() const; |
| |
| private: |
| void ReadNextToken(bool enter_envelope); |
| void SetToken(CBORTokenTag token, std::ptrdiff_t token_byte_length); |
| void SetError(Error error); |
| |
| span<uint8_t> bytes_; |
| CBORTokenTag token_tag_; |
| struct Status status_; |
| std::ptrdiff_t token_byte_length_; |
| cbor::MajorType token_start_type_; |
| uint64_t token_start_internal_value_; |
| }; |
| |
| void DumpCBOR(span<uint8_t> cbor); |
| |
| } // namespace inspector_protocol |
| #endif // INSPECTOR_PROTOCOL_ENCODING_CBOR_H_ |