/src/botan/src/lib/asn1/ber_dec.cpp

Source (jump to first uncovered line)
/*
* BER Decoder
* (C) 1999-2008,2015,2017,2018 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/ber_dec.h>

#include <botan/bigint.h>
#include <botan/internal/loadstor.h>
#include <botan/internal/safeint.h>
#include <memory>

namespace Botan {

namespace {

/*
* This value is somewhat arbitrary. OpenSSL allows up to 128 nested
* indefinite length sequences. If you increase this, also increase the
* limit in the test in test_asn1.cpp
*/
const size_t ALLOWED_EOC_NESTINGS = 16;

/*
* BER decode an ASN.1 type tag
*/
size_t decode_tag(DataSource* ber, ASN1_Type& type_tag, ASN1_Class& class_tag) {
   uint8_t b;
   if(!ber->read_byte(b)) {
      type_tag = ASN1_Type::NoObject;
      class_tag = ASN1_Class::NoObject;
      return 0;
   }

   if((b & 0x1F) != 0x1F) {
      type_tag = ASN1_Type(b & 0x1F);
      class_tag = ASN1_Class(b & 0xE0);
      return 1;
   }

   size_t tag_bytes = 1;
   class_tag = ASN1_Class(b & 0xE0);

   size_t tag_buf = 0;
   while(true) {
      if(!ber->read_byte(b)) {
         throw BER_Decoding_Error("Long-form tag truncated");
      }
      if(tag_buf & 0xFF000000) {
         throw BER_Decoding_Error("Long-form tag overflowed 32 bits");
      }
      ++tag_bytes;
      tag_buf = (tag_buf << 7) | (b & 0x7F);
      if((b & 0x80) == 0) {
         break;
      }
   }
   type_tag = ASN1_Type(tag_buf);
   return tag_bytes;
}

/*
* Find the EOC marker
*/
size_t find_eoc(DataSource* src, size_t allow_indef);

/*
* BER decode an ASN.1 length field
*/
size_t decode_length(DataSource* ber, size_t& field_size, size_t allow_indef) {
   uint8_t b;
   if(!ber->read_byte(b)) {
      throw BER_Decoding_Error("Length field not found");
   }
   field_size = 1;
   if((b & 0x80) == 0) {
      return b;
   }

   field_size += (b & 0x7F);
   if(field_size > 5) {
      throw BER_Decoding_Error("Length field is too large");
   }

   if(field_size == 1) {
      if(allow_indef == 0) {
         throw BER_Decoding_Error("Nested EOC markers too deep, rejecting to avoid stack exhaustion");
      } else {
         return find_eoc(ber, allow_indef - 1);
      }
   }

   size_t length = 0;

   for(size_t i = 0; i != field_size - 1; ++i) {
      if(get_byte<0>(length) != 0) {
         throw BER_Decoding_Error("Field length overflow");
      }
      if(!ber->read_byte(b)) {
         throw BER_Decoding_Error("Corrupted length field");
      }
      length = (length << 8) | b;
   }
   return length;
}

/*
* Find the EOC marker
*/
size_t find_eoc(DataSource* ber, size_t allow_indef) {
   secure_vector<uint8_t> buffer(BOTAN_DEFAULT_BUFFER_SIZE), data;

   while(true) {
      const size_t got = ber->peek(buffer.data(), buffer.size(), data.size());
      if(got == 0) {
         break;
      }

      data += std::make_pair(buffer.data(), got);
   }

   DataSource_Memory source(data);
   data.clear();

   size_t length = 0;
   while(true) {
      ASN1_Type type_tag;
      ASN1_Class class_tag;
      size_t tag_size = decode_tag(&source, type_tag, class_tag);
      if(type_tag == ASN1_Type::NoObject) {
         break;
      }

      size_t length_size = 0;
      size_t item_size = decode_length(&source, length_size, allow_indef);
      source.discard_next(item_size);

      length = BOTAN_CHECKED_ADD(length, item_size);
      length = BOTAN_CHECKED_ADD(length, tag_size);
      length = BOTAN_CHECKED_ADD(length, length_size);

      if(type_tag == ASN1_Type::Eoc && class_tag == ASN1_Class::Universal) {
         break;
      }
   }
   return length;
}

class DataSource_BERObject final : public DataSource {
   public:
      size_t read(uint8_t out[], size_t length) override {
         BOTAN_ASSERT_NOMSG(m_offset <= m_obj.length());
         const size_t got = std::min<size_t>(m_obj.length() - m_offset, length);
         copy_mem(out, m_obj.bits() + m_offset, got);
         m_offset += got;
         return got;
      }

      size_t peek(uint8_t out[], size_t length, size_t peek_offset) const override {
         BOTAN_ASSERT_NOMSG(m_offset <= m_obj.length());
         const size_t bytes_left = m_obj.length() - m_offset;

         if(peek_offset >= bytes_left) {
            return 0;
         }

         const size_t got = std::min(bytes_left - peek_offset, length);
         copy_mem(out, m_obj.bits() + m_offset + peek_offset, got);
         return got;
      }

      bool check_available(size_t n) override {
         BOTAN_ASSERT_NOMSG(m_offset <= m_obj.length());
         return (n <= (m_obj.length() - m_offset));
      }

      bool end_of_data() const override { return get_bytes_read() == m_obj.length(); }

      size_t get_bytes_read() const override { return m_offset; }

      explicit DataSource_BERObject(BER_Object&& obj) : m_obj(std::move(obj)), m_offset(0) {}

   private:
      BER_Object m_obj;
      size_t m_offset;
};

}  // namespace

/*
* Check if more objects are there
*/
bool BER_Decoder::more_items() const {
   if(m_source->end_of_data() && !m_pushed.is_set()) {
      return false;
   }
   return true;
}

/*
* Verify that no bytes remain in the source
*/
BER_Decoder& BER_Decoder::verify_end() {
   return verify_end("BER_Decoder::verify_end called, but data remains");
}

/*
* Verify that no bytes remain in the source
*/
BER_Decoder& BER_Decoder::verify_end(std::string_view err) {
   if(!m_source->end_of_data() || m_pushed.is_set()) {
      throw Decoding_Error(err);
   }
   return (*this);
}

/*
* Discard all the bytes remaining in the source
*/
BER_Decoder& BER_Decoder::discard_remaining() {
   uint8_t buf;
   while(m_source->read_byte(buf)) {}
   return (*this);
}

/*
* Return the BER encoding of the next object
*/
BER_Object BER_Decoder::get_next_object() {
   BER_Object next;

   if(m_pushed.is_set()) {
      std::swap(next, m_pushed);
      return next;
   }

   for(;;) {
      ASN1_Type type_tag;
      ASN1_Class class_tag;
      decode_tag(m_source, type_tag, class_tag);
      next.set_tagging(type_tag, class_tag);
      if(next.is_set() == false) {  // no more objects
         return next;
      }

      size_t field_size;
      const size_t length = decode_length(m_source, field_size, ALLOWED_EOC_NESTINGS);
      if(!m_source->check_available(length)) {
         throw BER_Decoding_Error("Value truncated");
      }

      uint8_t* out = next.mutable_bits(length);
      if(m_source->read(out, length) != length) {
         throw BER_Decoding_Error("Value truncated");
      }

      if(next.tagging() == static_cast<uint32_t>(ASN1_Type::Eoc)) {
         continue;
      } else {
         break;
      }
   }

   return next;
}

/*
* Push a object back into the stream
*/
void BER_Decoder::push_back(const BER_Object& obj) {
   if(m_pushed.is_set()) {
      throw Invalid_State("BER_Decoder: Only one push back is allowed");
   }
   m_pushed = obj;
}

void BER_Decoder::push_back(BER_Object&& obj) {
   if(m_pushed.is_set()) {
      throw Invalid_State("BER_Decoder: Only one push back is allowed");
   }
   m_pushed = std::move(obj);
}

BER_Decoder BER_Decoder::start_cons(ASN1_Type type_tag, ASN1_Class class_tag) {
   BER_Object obj = get_next_object();
   obj.assert_is_a(type_tag, class_tag | ASN1_Class::Constructed);
   return BER_Decoder(std::move(obj), this);
}

/*
* Finish decoding a CONSTRUCTED type
*/
BER_Decoder& BER_Decoder::end_cons() {
   if(!m_parent) {
      throw Invalid_State("BER_Decoder::end_cons called with null parent");
   }
   if(!m_source->end_of_data()) {
      throw Decoding_Error("BER_Decoder::end_cons called with data left");
   }
   return (*m_parent);
}

BER_Decoder::BER_Decoder(BER_Object&& obj, BER_Decoder* parent) {
   m_data_src = std::make_unique<DataSource_BERObject>(std::move(obj));
   m_source = m_data_src.get();
   m_parent = parent;
}

/*
* BER_Decoder Constructor
*/
BER_Decoder::BER_Decoder(DataSource& src) {
   m_source = &src;
}

/*
* BER_Decoder Constructor
 */
BER_Decoder::BER_Decoder(const uint8_t data[], size_t length) {
   m_data_src = std::make_unique<DataSource_Memory>(data, length);
   m_source = m_data_src.get();
}

/*
* BER_Decoder Constructor
*/
BER_Decoder::BER_Decoder(const secure_vector<uint8_t>& data) {
   m_data_src = std::make_unique<DataSource_Memory>(data);
   m_source = m_data_src.get();
}

/*
* BER_Decoder Constructor
*/
BER_Decoder::BER_Decoder(const std::vector<uint8_t>& data) {
   m_data_src = std::make_unique<DataSource_Memory>(data.data(), data.size());
   m_source = m_data_src.get();
}

/*
* BER_Decoder Copy Constructor
*/
BER_Decoder::BER_Decoder(const BER_Decoder& other) {
   m_source = other.m_source;

   // take ownership
   std::swap(m_data_src, other.m_data_src);
   m_parent = other.m_parent;
}

/*
* Request for an object to decode itself
*/
BER_Decoder& BER_Decoder::decode(ASN1_Object& obj, ASN1_Type /*unused*/, ASN1_Class /*unused*/) {
   obj.decode_from(*this);
   return (*this);
}

/*
* Decode a BER encoded NULL
*/
BER_Decoder& BER_Decoder::decode_null() {
   BER_Object obj = get_next_object();
   obj.assert_is_a(ASN1_Type::Null, ASN1_Class::Universal);
   if(obj.length() > 0) {
      throw BER_Decoding_Error("NULL object had nonzero size");
   }
   return (*this);
}

BER_Decoder& BER_Decoder::decode_octet_string_bigint(BigInt& out) {
   secure_vector<uint8_t> out_vec;
   decode(out_vec, ASN1_Type::OctetString);
   out = BigInt::decode(out_vec.data(), out_vec.size());
   return (*this);
}

/*
* Decode a BER encoded BOOLEAN
*/
BER_Decoder& BER_Decoder::decode(bool& out, ASN1_Type type_tag, ASN1_Class class_tag) {
   BER_Object obj = get_next_object();
   obj.assert_is_a(type_tag, class_tag);

   if(obj.length() != 1) {
      throw BER_Decoding_Error("BER boolean value had invalid size");
   }

   out = (obj.bits()[0]) ? true : false;
   return (*this);
}

/*
* Decode a small BER encoded INTEGER
*/
BER_Decoder& BER_Decoder::decode(size_t& out, ASN1_Type type_tag, ASN1_Class class_tag) {
   BigInt integer;
   decode(integer, type_tag, class_tag);

   if(integer.is_negative()) {
      throw BER_Decoding_Error("Decoded small integer value was negative");
   }

   if(integer.bits() > 32) {
      throw BER_Decoding_Error("Decoded integer value larger than expected");
   }

   out = 0;
   for(size_t i = 0; i != 4; ++i) {
      out = (out << 8) | integer.byte_at(3 - i);
   }

   return (*this);
}

/*
* Decode a small BER encoded INTEGER
*/
uint64_t BER_Decoder::decode_constrained_integer(ASN1_Type type_tag, ASN1_Class class_tag, size_t T_bytes) {
   if(T_bytes > 8) {
      throw BER_Decoding_Error("Can't decode small integer over 8 bytes");
   }

   BigInt integer;
   decode(integer, type_tag, class_tag);

   if(integer.bits() > 8 * T_bytes) {
      throw BER_Decoding_Error("Decoded integer value larger than expected");
   }

   uint64_t out = 0;
   for(size_t i = 0; i != 8; ++i) {
      out = (out << 8) | integer.byte_at(7 - i);
   }

   return out;
}

/*
* Decode a BER encoded INTEGER
*/
BER_Decoder& BER_Decoder::decode(BigInt& out, ASN1_Type type_tag, ASN1_Class class_tag) {
   BER_Object obj = get_next_object();
   obj.assert_is_a(type_tag, class_tag);

   if(obj.length() == 0) {
      out.clear();
   } else {
      const bool negative = (obj.bits()[0] & 0x80) ? true : false;

      if(negative) {
         secure_vector<uint8_t> vec(obj.bits(), obj.bits() + obj.length());
         for(size_t i = obj.length(); i > 0; --i) {
            if(vec[i - 1]--) {
               break;
            }
         }
         for(size_t i = 0; i != obj.length(); ++i) {
            vec[i] = ~vec[i];
         }
         out = BigInt(vec.data(), vec.size());
         out.flip_sign();
      } else {
         out = BigInt(obj.bits(), obj.length());
      }
   }

   return (*this);
}

namespace {

template <typename Alloc>
void asn1_decode_binary_string(std::vector<uint8_t, Alloc>& buffer,
                               const BER_Object& obj,
                               ASN1_Type real_type,
                               ASN1_Type type_tag,
                               ASN1_Class class_tag) {
   obj.assert_is_a(type_tag, class_tag);

   if(real_type == ASN1_Type::OctetString) {
      buffer.assign(obj.bits(), obj.bits() + obj.length());
   } else {
      if(obj.length() == 0) {
         throw BER_Decoding_Error("Invalid BIT STRING");
      }
      if(obj.bits()[0] >= 8) {
         throw BER_Decoding_Error("Bad number of unused bits in BIT STRING");
      }

      buffer.resize(obj.length() - 1);

      if(obj.length() > 1) {
         copy_mem(buffer.data(), obj.bits() + 1, obj.length() - 1);
      }
   }
}

}  // namespace

/*
* BER decode a BIT STRING or OCTET STRING
*/
BER_Decoder& BER_Decoder::decode(secure_vector<uint8_t>& buffer,
                                 ASN1_Type real_type,
                                 ASN1_Type type_tag,
                                 ASN1_Class class_tag) {
   if(real_type != ASN1_Type::OctetString && real_type != ASN1_Type::BitString) {
      throw BER_Bad_Tag("Bad tag for {BIT,OCTET} STRING", static_cast<uint32_t>(real_type));
   }

   asn1_decode_binary_string(buffer, get_next_object(), real_type, type_tag, class_tag);
   return (*this);
}

BER_Decoder& BER_Decoder::decode(std::vector<uint8_t>& buffer,
                                 ASN1_Type real_type,
                                 ASN1_Type type_tag,
                                 ASN1_Class class_tag) {
   if(real_type != ASN1_Type::OctetString && real_type != ASN1_Type::BitString) {
      throw BER_Bad_Tag("Bad tag for {BIT,OCTET} STRING", static_cast<uint32_t>(real_type));
   }

   asn1_decode_binary_string(buffer, get_next_object(), real_type, type_tag, class_tag);
   return (*this);
}

}  // namespace Botan

Coverage Report

Created: 2023-12-08 07:00

Line	Count	Source (jump to first uncovered line)
1		/*
2		* BER Decoder
3		* (C) 1999-2008,2015,2017,2018 Jack Lloyd
4		*
5		* Botan is released under the Simplified BSD License (see license.txt)
6		*/
7
8		#include <botan/ber_dec.h>
9
10		#include <botan/bigint.h>
11		#include <botan/internal/loadstor.h>
12		#include <botan/internal/safeint.h>
13		#include <memory>
14
15		namespace Botan {
16
17		namespace {
18
19		/*
20		* This value is somewhat arbitrary. OpenSSL allows up to 128 nested
21		* indefinite length sequences. If you increase this, also increase the
22		* limit in the test in test_asn1.cpp
23		*/
24		const size_t ALLOWED_EOC_NESTINGS = 16;
25
26		/*
27		* BER decode an ASN.1 type tag
28		*/
29	0	size_t decode_tag(DataSource* ber, ASN1_Type& type_tag, ASN1_Class& class_tag) {
30	0	uint8_t b;
31	0	if(!ber->read_byte(b)) {
32	0	type_tag = ASN1_Type::NoObject;
33	0	class_tag = ASN1_Class::NoObject;
34	0	return 0;
35	0	}
36
37	0	if((b & 0x1F) != 0x1F) {
38	0	type_tag = ASN1_Type(b & 0x1F);
39	0	class_tag = ASN1_Class(b & 0xE0);
40	0	return 1;
41	0	}
42
43	0	size_t tag_bytes = 1;
44	0	class_tag = ASN1_Class(b & 0xE0);
45
46	0	size_t tag_buf = 0;
47	0	while(true) {
48	0	if(!ber->read_byte(b)) {
49	0	throw BER_Decoding_Error("Long-form tag truncated");
50	0	}
51	0	if(tag_buf & 0xFF000000) {
52	0	throw BER_Decoding_Error("Long-form tag overflowed 32 bits");
53	0	}
54	0	++tag_bytes;
55	0	tag_buf = (tag_buf << 7) \| (b & 0x7F);
56	0	if((b & 0x80) == 0) {
57	0	break;
58	0	}
59	0	}
60	0	type_tag = ASN1_Type(tag_buf);
61	0	return tag_bytes;
62	0	}
63
64		/*
65		* Find the EOC marker
66		*/
67		size_t find_eoc(DataSource* src, size_t allow_indef);
68
69		/*
70		* BER decode an ASN.1 length field
71		*/
72	0	size_t decode_length(DataSource* ber, size_t& field_size, size_t allow_indef) {
73	0	uint8_t b;
74	0	if(!ber->read_byte(b)) {
75	0	throw BER_Decoding_Error("Length field not found");
76	0	}
77	0	field_size = 1;
78	0	if((b & 0x80) == 0) {
79	0	return b;
80	0	}
81
82	0	field_size += (b & 0x7F);
83	0	if(field_size > 5) {
84	0	throw BER_Decoding_Error("Length field is too large");
85	0	}
86
87	0	if(field_size == 1) {
88	0	if(allow_indef == 0) {
89	0	throw BER_Decoding_Error("Nested EOC markers too deep, rejecting to avoid stack exhaustion");
90	0	} else {
91	0	return find_eoc(ber, allow_indef - 1);
92	0	}
93	0	}
94
95	0	size_t length = 0;
96
97	0	for(size_t i = 0; i != field_size - 1; ++i) {
98	0	if(get_byte<0>(length) != 0) {
99	0	throw BER_Decoding_Error("Field length overflow");
100	0	}
101	0	if(!ber->read_byte(b)) {
102	0	throw BER_Decoding_Error("Corrupted length field");
103	0	}
104	0	length = (length << 8) \| b;
105	0	}
106	0	return length;
107	0	}
108
109		/*
110		* Find the EOC marker
111		*/
112	0	size_t find_eoc(DataSource* ber, size_t allow_indef) {
113	0	secure_vector<uint8_t> buffer(BOTAN_DEFAULT_BUFFER_SIZE), data;
114
115	0	while(true) {
116	0	const size_t got = ber->peek(buffer.data(), buffer.size(), data.size());
117	0	if(got == 0) {
118	0	break;
119	0	}
120
121	0	data += std::make_pair(buffer.data(), got);
122	0	}
123
124	0	DataSource_Memory source(data);
125	0	data.clear();
126
127	0	size_t length = 0;
128	0	while(true) {
129	0	ASN1_Type type_tag;
130	0	ASN1_Class class_tag;
131	0	size_t tag_size = decode_tag(&source, type_tag, class_tag);
132	0	if(type_tag == ASN1_Type::NoObject) {
133	0	break;
134	0	}
135
136	0	size_t length_size = 0;
137	0	size_t item_size = decode_length(&source, length_size, allow_indef);
138	0	source.discard_next(item_size);
139
140	0	length = BOTAN_CHECKED_ADD(length, item_size);
141	0	length = BOTAN_CHECKED_ADD(length, tag_size);
142	0	length = BOTAN_CHECKED_ADD(length, length_size);
143
144	0	if(type_tag == ASN1_Type::Eoc && class_tag == ASN1_Class::Universal) {
145	0	break;
146	0	}
147	0	}
148	0	return length;
149	0	}
150
151		class DataSource_BERObject final : public DataSource {
152		public:
153	0	size_t read(uint8_t out[], size_t length) override {
154	0	BOTAN_ASSERT_NOMSG(m_offset <= m_obj.length());
155	0	const size_t got = std::min<size_t>(m_obj.length() - m_offset, length);
156	0	copy_mem(out, m_obj.bits() + m_offset, got);
157	0	m_offset += got;
158	0	return got;
159	0	}
160
161	0	size_t peek(uint8_t out[], size_t length, size_t peek_offset) const override {
162	0	BOTAN_ASSERT_NOMSG(m_offset <= m_obj.length());
163	0	const size_t bytes_left = m_obj.length() - m_offset;
164
165	0	if(peek_offset >= bytes_left) {
166	0	return 0;
167	0	}
168
169	0	const size_t got = std::min(bytes_left - peek_offset, length);
170	0	copy_mem(out, m_obj.bits() + m_offset + peek_offset, got);
171	0	return got;
172	0	}
173
174	0	bool check_available(size_t n) override {
175	0	BOTAN_ASSERT_NOMSG(m_offset <= m_obj.length());
176	0	return (n <= (m_obj.length() - m_offset));
177	0	}
178
179	0	bool end_of_data() const override { return get_bytes_read() == m_obj.length(); }
180
181	0	size_t get_bytes_read() const override { return m_offset; }
182
183	0	explicit DataSource_BERObject(BER_Object&& obj) : m_obj(std::move(obj)), m_offset(0) {}
184
185		private:
186		BER_Object m_obj;
187		size_t m_offset;
188		};
189
190		} // namespace
191
192		/*
193		* Check if more objects are there
194		*/
195	0	bool BER_Decoder::more_items() const {
196	0	if(m_source->end_of_data() && !m_pushed.is_set()) {
197	0	return false;
198	0	}
199	0	return true;
200	0	}
201
202		/*
203		* Verify that no bytes remain in the source
204		*/
205	0	BER_Decoder& BER_Decoder::verify_end() {
206	0	return verify_end("BER_Decoder::verify_end called, but data remains");
207	0	}
208
209		/*
210		* Verify that no bytes remain in the source
211		*/
212	0	BER_Decoder& BER_Decoder::verify_end(std::string_view err) {
213	0	if(!m_source->end_of_data() \|\| m_pushed.is_set()) {
214	0	throw Decoding_Error(err);
215	0	}
216	0	return (*this);
217	0	}
218
219		/*
220		* Discard all the bytes remaining in the source
221		*/
222	0	BER_Decoder& BER_Decoder::discard_remaining() {
223	0	uint8_t buf;
224	0	while(m_source->read_byte(buf)) {}
225	0	return (*this);
226	0	}
227
228		/*
229		* Return the BER encoding of the next object
230		*/
231	0	BER_Object BER_Decoder::get_next_object() {
232	0	BER_Object next;
233
234	0	if(m_pushed.is_set()) {
235	0	std::swap(next, m_pushed);
236	0	return next;
237	0	}
238
239	0	for(;;) {
240	0	ASN1_Type type_tag;
241	0	ASN1_Class class_tag;
242	0	decode_tag(m_source, type_tag, class_tag);
243	0	next.set_tagging(type_tag, class_tag);
244	0	if(next.is_set() == false) { // no more objects
245	0	return next;
246	0	}
247
248	0	size_t field_size;
249	0	const size_t length = decode_length(m_source, field_size, ALLOWED_EOC_NESTINGS);
250	0	if(!m_source->check_available(length)) {
251	0	throw BER_Decoding_Error("Value truncated");
252	0	}
253
254	0	uint8_t* out = next.mutable_bits(length);
255	0	if(m_source->read(out, length) != length) {
256	0	throw BER_Decoding_Error("Value truncated");
257	0	}
258
259	0	if(next.tagging() == static_cast<uint32_t>(ASN1_Type::Eoc)) {
260	0	continue;
261	0	} else {
262	0	break;
263	0	}
264	0	}
265
266	0	return next;
267	0	}
268
269		/*
270		* Push a object back into the stream
271		*/
272	0	void BER_Decoder::push_back(const BER_Object& obj) {
273	0	if(m_pushed.is_set()) {
274	0	throw Invalid_State("BER_Decoder: Only one push back is allowed");
275	0	}
276	0	m_pushed = obj;
277	0	}
278
279	0	void BER_Decoder::push_back(BER_Object&& obj) {
280	0	if(m_pushed.is_set()) {
281	0	throw Invalid_State("BER_Decoder: Only one push back is allowed");
282	0	}
283	0	m_pushed = std::move(obj);
284	0	}
285
286	0	BER_Decoder BER_Decoder::start_cons(ASN1_Type type_tag, ASN1_Class class_tag) {
287	0	BER_Object obj = get_next_object();
288	0	obj.assert_is_a(type_tag, class_tag \| ASN1_Class::Constructed);
289	0	return BER_Decoder(std::move(obj), this);
290	0	}
291
292		/*
293		* Finish decoding a CONSTRUCTED type
294		*/
295	0	BER_Decoder& BER_Decoder::end_cons() {
296	0	if(!m_parent) {
297	0	throw Invalid_State("BER_Decoder::end_cons called with null parent");
298	0	}
299	0	if(!m_source->end_of_data()) {
300	0	throw Decoding_Error("BER_Decoder::end_cons called with data left");
301	0	}
302	0	return (*m_parent);
303	0	}
304
305	0	BER_Decoder::BER_Decoder(BER_Object&& obj, BER_Decoder* parent) {
306	0	m_data_src = std::make_unique<DataSource_BERObject>(std::move(obj));
307	0	m_source = m_data_src.get();
308	0	m_parent = parent;
309	0	}
310
311		/*
312		* BER_Decoder Constructor
313		*/
314	0	BER_Decoder::BER_Decoder(DataSource& src) {
315	0	m_source = &src;
316	0	}
317
318		/*
319		* BER_Decoder Constructor
320		*/
321	0	BER_Decoder::BER_Decoder(const uint8_t data[], size_t length) {
322	0	m_data_src = std::make_unique<DataSource_Memory>(data, length);
323	0	m_source = m_data_src.get();
324	0	}
325
326		/*
327		* BER_Decoder Constructor
328		*/
329	0	BER_Decoder::BER_Decoder(const secure_vector<uint8_t>& data) {
330	0	m_data_src = std::make_unique<DataSource_Memory>(data);
331	0	m_source = m_data_src.get();
332	0	}
333
334		/*
335		* BER_Decoder Constructor
336		*/
337	0	BER_Decoder::BER_Decoder(const std::vector<uint8_t>& data) {
338	0	m_data_src = std::make_unique<DataSource_Memory>(data.data(), data.size());
339	0	m_source = m_data_src.get();
340	0	}
341
342		/*
343		* BER_Decoder Copy Constructor
344		*/
345	0	BER_Decoder::BER_Decoder(const BER_Decoder& other) {
346	0	m_source = other.m_source;
347
348		// take ownership
349	0	std::swap(m_data_src, other.m_data_src);
350	0	m_parent = other.m_parent;
351	0	}
352
353		/*
354		* Request for an object to decode itself
355		*/
356	0	BER_Decoder& BER_Decoder::decode(ASN1_Object& obj, ASN1_Type /unused/, ASN1_Class /unused/) {
357	0	obj.decode_from(*this);
358	0	return (*this);
359	0	}
360
361		/*
362		* Decode a BER encoded NULL
363		*/
364	0	BER_Decoder& BER_Decoder::decode_null() {
365	0	BER_Object obj = get_next_object();
366	0	obj.assert_is_a(ASN1_Type::Null, ASN1_Class::Universal);
367	0	if(obj.length() > 0) {
368	0	throw BER_Decoding_Error("NULL object had nonzero size");
369	0	}
370	0	return (*this);
371	0	}
372
373	0	BER_Decoder& BER_Decoder::decode_octet_string_bigint(BigInt& out) {
374	0	secure_vector<uint8_t> out_vec;
375	0	decode(out_vec, ASN1_Type::OctetString);
376	0	out = BigInt::decode(out_vec.data(), out_vec.size());
377	0	return (*this);
378	0	}
379
380		/*
381		* Decode a BER encoded BOOLEAN
382		*/
383	0	BER_Decoder& BER_Decoder::decode(bool& out, ASN1_Type type_tag, ASN1_Class class_tag) {
384	0	BER_Object obj = get_next_object();
385	0	obj.assert_is_a(type_tag, class_tag);
386
387	0	if(obj.length() != 1) {
388	0	throw BER_Decoding_Error("BER boolean value had invalid size");
389	0	}
390
391	0	out = (obj.bits()[0]) ? true : false;
392	0	return (*this);
393	0	}
394
395		/*
396		* Decode a small BER encoded INTEGER
397		*/
398	0	BER_Decoder& BER_Decoder::decode(size_t& out, ASN1_Type type_tag, ASN1_Class class_tag) {
399	0	BigInt integer;
400	0	decode(integer, type_tag, class_tag);
401
402	0	if(integer.is_negative()) {
403	0	throw BER_Decoding_Error("Decoded small integer value was negative");
404	0	}
405
406	0	if(integer.bits() > 32) {
407	0	throw BER_Decoding_Error("Decoded integer value larger than expected");
408	0	}
409
410	0	out = 0;
411	0	for(size_t i = 0; i != 4; ++i) {
412	0	out = (out << 8) \| integer.byte_at(3 - i);
413	0	}
414
415	0	return (*this);
416	0	}
417
418		/*
419		* Decode a small BER encoded INTEGER
420		*/
421	0	uint64_t BER_Decoder::decode_constrained_integer(ASN1_Type type_tag, ASN1_Class class_tag, size_t T_bytes) {
422	0	if(T_bytes > 8) {
423	0	throw BER_Decoding_Error("Can't decode small integer over 8 bytes");
424	0	}
425
426	0	BigInt integer;
427	0	decode(integer, type_tag, class_tag);
428
429	0	if(integer.bits() > 8 * T_bytes) {
430	0	throw BER_Decoding_Error("Decoded integer value larger than expected");
431	0	}
432
433	0	uint64_t out = 0;
434	0	for(size_t i = 0; i != 8; ++i) {
435	0	out = (out << 8) \| integer.byte_at(7 - i);
436	0	}
437
438	0	return out;
439	0	}
440
441		/*
442		* Decode a BER encoded INTEGER
443		*/
444	0	BER_Decoder& BER_Decoder::decode(BigInt& out, ASN1_Type type_tag, ASN1_Class class_tag) {
445	0	BER_Object obj = get_next_object();
446	0	obj.assert_is_a(type_tag, class_tag);
447
448	0	if(obj.length() == 0) {
449	0	out.clear();
450	0	} else {
451	0	const bool negative = (obj.bits()[0] & 0x80) ? true : false;
452
453	0	if(negative) {
454	0	secure_vector<uint8_t> vec(obj.bits(), obj.bits() + obj.length());
455	0	for(size_t i = obj.length(); i > 0; --i) {
456	0	if(vec[i - 1]--) {
457	0	break;
458	0	}
459	0	}
460	0	for(size_t i = 0; i != obj.length(); ++i) {
461	0	vec[i] = ~vec[i];
462	0	}
463	0	out = BigInt(vec.data(), vec.size());
464	0	out.flip_sign();
465	0	} else {
466	0	out = BigInt(obj.bits(), obj.length());
467	0	}
468	0	}
469
470	0	return (*this);
471	0	}
472
473		namespace {
474
475		template <typename Alloc>
476		void asn1_decode_binary_string(std::vector<uint8_t, Alloc>& buffer,
477		const BER_Object& obj,
478		ASN1_Type real_type,
479		ASN1_Type type_tag,
480	0	ASN1_Class class_tag) {
481	0	obj.assert_is_a(type_tag, class_tag);
482
483	0	if(real_type == ASN1_Type::OctetString) {
484	0	buffer.assign(obj.bits(), obj.bits() + obj.length());
485	0	} else {
486	0	if(obj.length() == 0) {
487	0	throw BER_Decoding_Error("Invalid BIT STRING");
488	0	}
489	0	if(obj.bits()[0] >= 8) {
490	0	throw BER_Decoding_Error("Bad number of unused bits in BIT STRING");
491	0	}
492
493	0	buffer.resize(obj.length() - 1);
494
495	0	if(obj.length() > 1) {
496	0	copy_mem(buffer.data(), obj.bits() + 1, obj.length() - 1);
497	0	}
498	0	}
499	0	} Unexecuted instantiation: ber_dec.cpp:void Botan::(anonymous namespace)::asn1_decode_binary_string<Botan::secure_allocator<unsigned char> >(std::__1::vector<unsigned char, Botan::secure_allocator<unsigned char> >&, Botan::BER_Object const&, Botan::ASN1_Type, Botan::ASN1_Type, Botan::ASN1_Class) Unexecuted instantiation: ber_dec.cpp:void Botan::(anonymous namespace)::asn1_decode_binary_string<std::__1::allocator<unsigned char> >(std::__1::vector<unsigned char, std::__1::allocator<unsigned char> >&, Botan::BER_Object const&, Botan::ASN1_Type, Botan::ASN1_Type, Botan::ASN1_Class)
500
501		} // namespace
502
503		/*
504		* BER decode a BIT STRING or OCTET STRING
505		*/
506		BER_Decoder& BER_Decoder::decode(secure_vector<uint8_t>& buffer,
507		ASN1_Type real_type,
508		ASN1_Type type_tag,
509	0	ASN1_Class class_tag) {
510	0	if(real_type != ASN1_Type::OctetString && real_type != ASN1_Type::BitString) {
511	0	throw BER_Bad_Tag("Bad tag for {BIT,OCTET} STRING", static_cast<uint32_t>(real_type));
512	0	}
513
514	0	asn1_decode_binary_string(buffer, get_next_object(), real_type, type_tag, class_tag);
515	0	return (*this);
516	0	}
517
518		BER_Decoder& BER_Decoder::decode(std::vector<uint8_t>& buffer,
519		ASN1_Type real_type,
520		ASN1_Type type_tag,
521	0	ASN1_Class class_tag) {
522	0	if(real_type != ASN1_Type::OctetString && real_type != ASN1_Type::BitString) {
523	0	throw BER_Bad_Tag("Bad tag for {BIT,OCTET} STRING", static_cast<uint32_t>(real_type));
524	0	}
525
526	0	asn1_decode_binary_string(buffer, get_next_object(), real_type, type_tag, class_tag);
527	0	return (*this);
528	0	}
529
530		} // namespace Botan