1 /*
2  * Copyright (C) 2013 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef ASN1_DECODER_H_
18 #define ASN1_DECODER_H_
19 
20 #include <stddef.h>
21 #include <stdint.h>
22 
23 class asn1_context {
24  public:
asn1_context(const uint8_t * buffer,size_t length)25   asn1_context(const uint8_t* buffer, size_t length) : p_(buffer), length_(length), app_type_(0) {}
26   int asn1_constructed_type() const;
27   asn1_context* asn1_constructed_get();
28   bool asn1_constructed_skip_all();
29   asn1_context* asn1_sequence_get();
30   asn1_context* asn1_set_get();
31   bool asn1_sequence_next();
32   bool asn1_oid_get(const uint8_t** oid, size_t* length);
33   bool asn1_octet_string_get(const uint8_t** octet_string, size_t* length);
34 
35  private:
36   static constexpr int kMaskConstructed = 0xE0;
37   static constexpr int kMaskTag = 0x7F;
38   static constexpr int kMaskAppType = 0x1F;
39 
40   static constexpr int kTagOctetString = 0x04;
41   static constexpr int kTagOid = 0x06;
42   static constexpr int kTagSequence = 0x30;
43   static constexpr int kTagSet = 0x31;
44   static constexpr int kTagConstructed = 0xA0;
45 
46   int peek_byte() const;
47   int get_byte();
48   bool skip_bytes(size_t num_skip);
49   bool decode_length(size_t* out_len);
50 
51   const uint8_t* p_;
52   size_t length_;
53   int app_type_;
54 };
55 
56 #endif /* ASN1_DECODER_H_ */
57