mirror of
https://github.com/klzgrad/naiveproxy.git
synced 2024-11-24 14:26:09 +03:00
208 lines
8.9 KiB
C++
208 lines
8.9 KiB
C++
// Copyright 2015 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 NET_DER_PARSER_H_
|
|
#define NET_DER_PARSER_H_
|
|
|
|
#include <stdint.h>
|
|
|
|
#include "base/compiler_specific.h"
|
|
#include "base/macros.h"
|
|
#include "net/base/net_export.h"
|
|
#include "net/der/input.h"
|
|
#include "net/der/tag.h"
|
|
#include "third_party/boringssl/src/include/openssl/bytestring.h"
|
|
|
|
namespace net {
|
|
|
|
namespace der {
|
|
|
|
class BitString;
|
|
struct GeneralizedTime;
|
|
|
|
// Parses a DER-encoded ASN.1 structure. DER (distinguished encoding rules)
|
|
// encodes each data value with a tag, length, and value (TLV). The tag
|
|
// indicates the type of the ASN.1 value. Depending on the type of the value,
|
|
// it could contain arbitrary bytes, so the length of the value is encoded
|
|
// after the tag and before the value to indicate how many bytes of value
|
|
// follow. DER also defines how the values are encoded for particular types.
|
|
//
|
|
// This Parser places a few restrictions on the DER encoding it can parse. The
|
|
// largest restriction is that it only supports tags which have a tag number
|
|
// no greater than 30 - these are the tags that fit in a single octet. The
|
|
// second restriction is that the maximum length for a value that can be parsed
|
|
// is 4GB. Both of these restrictions should be fine for any reasonable input.
|
|
//
|
|
// The Parser class is mainly focused on parsing the TLV structure of DER
|
|
// encoding, and does not directly handle parsing primitive values (other
|
|
// functions in the net::der namespace are provided for this.) When a Parser
|
|
// is created, it is passed in a reference to the encoded data. Because the
|
|
// encoded data is not owned by the Parser, the data cannot change during the
|
|
// lifespan of the Parser. The Parser functions by keeping a pointer to the
|
|
// current TLV which starts at the beginning of the input and advancing through
|
|
// the input as each TLV is read. As such, a Parser instance is thread-unsafe.
|
|
//
|
|
// Most methods for using the Parser write the current tag and/or value to
|
|
// the output parameters provided and then advance the input to the next TLV.
|
|
// None of the methods explicitly expose the length because it is part of the
|
|
// value. All methods return a boolean indicating whether there was a parsing
|
|
// error with the current TLV.
|
|
//
|
|
// Some methods are provided in the Parser class as convenience to both read
|
|
// the current TLV from the input and also parse the DER encoded value,
|
|
// converting it to a corresponding C++ type. These methods simply combine
|
|
// ReadTag() with the appropriate ParseType() free function.
|
|
//
|
|
// The design of DER encoding allows for nested data structures with
|
|
// constructed values, where the value is a series of TLVs. The Parser class
|
|
// is not designed to traverse through a nested encoding from a single object,
|
|
// but it does facilitate parsing nested data structures through the
|
|
// convenience methods ReadSequence() and the more general ReadConstructed(),
|
|
// which provide the user with another Parser object to traverse the next
|
|
// level of TLVs.
|
|
//
|
|
// For a brief example of how to use the Parser, suppose we have the following
|
|
// ASN.1 type definition:
|
|
//
|
|
// Foo ::= SEQUENCE {
|
|
// bar OCTET STRING OPTIONAL,
|
|
// quux OCTET STRING }
|
|
//
|
|
// If we have a DER-encoded Foo in an Input |encoded_value|, the
|
|
// following code shows an example of how to parse the quux field from the
|
|
// encoded data.
|
|
//
|
|
// bool ReadQuux(const Input& encoded_value, Input* quux_out) {
|
|
// Parser parser(encoded_value);
|
|
// Parser foo_parser;
|
|
// if (!parser.ReadSequence(&foo_parser))
|
|
// return false;
|
|
// if (!foo_parser->SkipOptionalTag(kOctetString))
|
|
// return false;
|
|
// if (!foo_parser->ReadTag(kOctetString, quux_out))
|
|
// return false;
|
|
// return true;
|
|
// }
|
|
class NET_EXPORT Parser {
|
|
public:
|
|
// Default constructor; equivalent to calling Parser(Input()). This only
|
|
// exists so that a Parser can be stack allocated and passed in to
|
|
// ReadConstructed() and similar methods.
|
|
Parser();
|
|
|
|
// Creates a parser to parse over the data represented by input. This class
|
|
// assumes that the underlying data will not change over the lifetime of
|
|
// the Parser object.
|
|
explicit Parser(const Input& input);
|
|
|
|
// Returns whether there is any more data left in the input to parse. This
|
|
// does not guarantee that the data is parseable.
|
|
bool HasMore();
|
|
|
|
// Reads the current TLV from the input and advances. If the tag or length
|
|
// encoding for the current value is invalid, this method returns false and
|
|
// does not advance the input. Otherwise, it returns true, putting the
|
|
// read tag in |tag| and the value in |out|.
|
|
bool ReadTagAndValue(Tag* tag, Input* out) WARN_UNUSED_RESULT;
|
|
|
|
// Reads the current TLV from the input and advances. Unlike ReadTagAndValue
|
|
// where only the value is put in |out|, this puts the raw bytes from the
|
|
// tag, length, and value in |out|.
|
|
bool ReadRawTLV(Input* out) WARN_UNUSED_RESULT;
|
|
|
|
// Basic methods for reading or skipping the current TLV, with an
|
|
// expectation of what the current tag should be. It should be possible
|
|
// to parse any structure with these 4 methods; convenience methods are also
|
|
// provided to make some cases easier.
|
|
|
|
// If the current tag in the input is |tag|, it puts the corresponding value
|
|
// in |out|, sets |was_present| to true, and advances the input to the next
|
|
// TLV. If the current tag is something else, then |was_present| is set to
|
|
// false and the input is not advanced. Like ReadTagAndValue, it returns
|
|
// false if the encoding is invalid and does not advance the input.
|
|
bool ReadOptionalTag(Tag tag,
|
|
Input* out,
|
|
bool* was_present) WARN_UNUSED_RESULT;
|
|
|
|
// Like ReadOptionalTag, but the value is discarded.
|
|
bool SkipOptionalTag(Tag tag, bool* was_present) WARN_UNUSED_RESULT;
|
|
|
|
// If the current tag matches |tag|, it puts the current value in |out|,
|
|
// advances the input, and returns true. Otherwise, it returns false.
|
|
bool ReadTag(Tag tag, Input* out) WARN_UNUSED_RESULT;
|
|
|
|
// Advances the input and returns true if the current tag matches |tag|;
|
|
// otherwise it returns false.
|
|
bool SkipTag(Tag tag) WARN_UNUSED_RESULT;
|
|
|
|
// Convenience methods to combine parsing the TLV with parsing the DER
|
|
// encoding for a specific type.
|
|
|
|
// Reads the current TLV from the input, checks that the tag matches |tag|
|
|
// and is a constructed tag, and creates a new Parser from the value.
|
|
bool ReadConstructed(Tag tag, Parser* out) WARN_UNUSED_RESULT;
|
|
|
|
// A more specific form of ReadConstructed that expects the current tag
|
|
// to be 0x30 (SEQUENCE).
|
|
bool ReadSequence(Parser* out) WARN_UNUSED_RESULT;
|
|
|
|
// Expects the current tag to be kInteger, and calls ParseUint8 on the
|
|
// current value. Note that DER-encoded integers are arbitrary precision,
|
|
// so this method will fail for valid input that represents an integer
|
|
// outside the range of an uint8_t.
|
|
//
|
|
// Note that on failure the Parser is left in an undefined state (the
|
|
// input may or may not have been advanced).
|
|
bool ReadUint8(uint8_t* out) WARN_UNUSED_RESULT;
|
|
|
|
// Expects the current tag to be kInteger, and calls ParseUint64 on the
|
|
// current value. Note that DER-encoded integers are arbitrary precision,
|
|
// so this method will fail for valid input that represents an integer
|
|
// outside the range of an uint64_t.
|
|
//
|
|
// Note that on failure the Parser is left in an undefined state (the
|
|
// input may or may not have been advanced).
|
|
bool ReadUint64(uint64_t* out) WARN_UNUSED_RESULT;
|
|
|
|
// Reads a BIT STRING. On success fills |out| and returns true.
|
|
//
|
|
// Note that on failure the Parser is left in an undefined state (the
|
|
// input may or may not have been advanced).
|
|
bool ReadBitString(BitString* out) WARN_UNUSED_RESULT;
|
|
|
|
// Reads a GeneralizeTime. On success fills |out| and returns true.
|
|
//
|
|
// Note that on failure the Parser is left in an undefined state (the
|
|
// input may or may not have been advanced).
|
|
bool ReadGeneralizedTime(GeneralizedTime* out) WARN_UNUSED_RESULT;
|
|
|
|
// Lower level methods. The previous methods couple reading data from the
|
|
// input with advancing the Parser's internal pointer to the next TLV; these
|
|
// lower level methods decouple those two steps into methods that read from
|
|
// the current TLV and a method that advances the internal pointer to the
|
|
// next TLV.
|
|
|
|
// Reads the current TLV from the input, putting the tag in |tag| and the raw
|
|
// value in |out|, but does not advance the input. Returns true if the tag
|
|
// and length are successfully read and the output exists.
|
|
bool PeekTagAndValue(Tag* tag, Input* out) WARN_UNUSED_RESULT;
|
|
|
|
// Advances the input to the next TLV. This method only needs to be called
|
|
// after PeekTagAndValue; all other methods will advance the input if they
|
|
// read something.
|
|
bool Advance();
|
|
|
|
private:
|
|
CBS cbs_;
|
|
size_t advance_len_;
|
|
|
|
DISALLOW_COPY(Parser);
|
|
};
|
|
|
|
} // namespace der
|
|
|
|
} // namespace net
|
|
|
|
#endif // NET_DER_PARSER_H_
|