/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/int_utils.h>
#include <botan/internal/loadstor.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");
      }
      // This is required even by BER (see X.690 section 8.1.2.4.2 sentence c)
      if(tag_bytes == 0 && b == 0x80) {
         throw BER_Decoding_Error("Long form tag with leading zero");
      }
      ++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;
      const size_t tag_size = decode_tag(&source, type_tag, class_tag);
      if(type_tag == ASN1_Type::NoObject) {
         break;
      }

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

      if(auto new_len = checked_add(length, item_size, tag_size, length_size)) {
         length = new_len.value();
      } else {
         throw Decoding_Error("Integer overflow while decoding DER");
      }

      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);
}

const BER_Object& BER_Decoder::peek_next_object() {
   if(!m_pushed.is_set()) {
      m_pushed = get_next_object();
   }

   return m_pushed;
}

/*
* 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::from_bytes(out_vec);
   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._assign_from_bytes(vec);
         out.flip_sign();
      } else {
         out._assign_from_bytes(obj.data());
      }
   }

   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: 2024-06-28 06:39

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/int_utils.h>
12		#include <botan/internal/loadstor.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	240	size_t decode_tag(DataSource* ber, ASN1_Type& type_tag, ASN1_Class& class_tag) {
30	240	uint8_t b;
31	240	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	240	if((b & 0x1F) != 0x1F) {
38	240	type_tag = ASN1_Type(b & 0x1F);
39	240	class_tag = ASN1_Class(b & 0xE0);
40	240	return 1;
41	240	}
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		// This is required even by BER (see X.690 section 8.1.2.4.2 sentence c)
55	0	if(tag_bytes == 0 && b == 0x80) {
56	0	throw BER_Decoding_Error("Long form tag with leading zero");
57	0	}
58	0	++tag_bytes;
59	0	tag_buf = (tag_buf << 7) \| (b & 0x7F);
60	0	if((b & 0x80) == 0) {
61	0	break;
62	0	}
63	0	}
64	0	type_tag = ASN1_Type(tag_buf);
65	0	return tag_bytes;
66	0	}
67
68		/*
69		* Find the EOC marker
70		*/
71		size_t find_eoc(DataSource* src, size_t allow_indef);
72
73		/*
74		* BER decode an ASN.1 length field
75		*/
76	240	size_t decode_length(DataSource* ber, size_t& field_size, size_t allow_indef) {
77	240	uint8_t b;
78	240	if(!ber->read_byte(b)) {
79	0	throw BER_Decoding_Error("Length field not found");
80	0	}
81	240	field_size = 1;
82	240	if((b & 0x80) == 0) {
83	237	return b;
84	237	}
85
86	3	field_size += (b & 0x7F);
87	3	if(field_size > 5) {
88	0	throw BER_Decoding_Error("Length field is too large");
89	0	}
90
91	3	if(field_size == 1) {
92	0	if(allow_indef == 0) {
93	0	throw BER_Decoding_Error("Nested EOC markers too deep, rejecting to avoid stack exhaustion");
94	0	} else {
95	0	return find_eoc(ber, allow_indef - 1);
96	0	}
97	0	}
98
99	3	size_t length = 0;
100
101	6	for(size_t i = 0; i != field_size - 1; ++i) {
102	3	if(get_byte<0>(length) != 0) {
103	0	throw BER_Decoding_Error("Field length overflow");
104	0	}
105	3	if(!ber->read_byte(b)) {
106	0	throw BER_Decoding_Error("Corrupted length field");
107	0	}
108	3	length = (length << 8) \| b;
109	3	}
110	3	return length;
111	3	}
112
113		/*
114		* Find the EOC marker
115		*/
116	0	size_t find_eoc(DataSource* ber, size_t allow_indef) {
117	0	secure_vector<uint8_t> buffer(BOTAN_DEFAULT_BUFFER_SIZE), data;
118
119	0	while(true) {
120	0	const size_t got = ber->peek(buffer.data(), buffer.size(), data.size());
121	0	if(got == 0) {
122	0	break;
123	0	}
124
125	0	data += std::make_pair(buffer.data(), got);
126	0	}
127
128	0	DataSource_Memory source(data);
129	0	data.clear();
130
131	0	size_t length = 0;
132	0	while(true) {
133	0	ASN1_Type type_tag;
134	0	ASN1_Class class_tag;
135	0	const size_t tag_size = decode_tag(&source, type_tag, class_tag);
136	0	if(type_tag == ASN1_Type::NoObject) {
137	0	break;
138	0	}
139
140	0	size_t length_size = 0;
141	0	const size_t item_size = decode_length(&source, length_size, allow_indef);
142	0	source.discard_next(item_size);
143
144	0	if(auto new_len = checked_add(length, item_size, tag_size, length_size)) {
145	0	length = new_len.value();
146	0	} else {
147	0	throw Decoding_Error("Integer overflow while decoding DER");
148	0	}
149
150	0	if(type_tag == ASN1_Type::Eoc && class_tag == ASN1_Class::Universal) {
151	0	break;
152	0	}
153	0	}
154	0	return length;
155	0	}
156
157		class DataSource_BERObject final : public DataSource {
158		public:
159	480	size_t read(uint8_t out[], size_t length) override {
160	480	BOTAN_ASSERT_NOMSG(m_offset <= m_obj.length());
161	480	const size_t got = std::min<size_t>(m_obj.length() - m_offset, length);
162	480	copy_mem(out, m_obj.bits() + m_offset, got);
163	480	m_offset += got;
164	480	return got;
165	480	}
166
167	0	size_t peek(uint8_t out[], size_t length, size_t peek_offset) const override {
168	0	BOTAN_ASSERT_NOMSG(m_offset <= m_obj.length());
169	0	const size_t bytes_left = m_obj.length() - m_offset;
170
171	0	if(peek_offset >= bytes_left) {
172	0	return 0;
173	0	}
174
175	0	const size_t got = std::min(bytes_left - peek_offset, length);
176	0	copy_mem(out, m_obj.bits() + m_offset + peek_offset, got);
177	0	return got;
178	0	}
179
180	160	bool check_available(size_t n) override {
181	160	BOTAN_ASSERT_NOMSG(m_offset <= m_obj.length());
182	160	return (n <= (m_obj.length() - m_offset));
183	160	}
184
185	240	bool end_of_data() const override { return get_bytes_read() == m_obj.length(); }
186
187	240	size_t get_bytes_read() const override { return m_offset; }
188
189	80	explicit DataSource_BERObject(BER_Object&& obj) : m_obj(std::move(obj)), m_offset(0) {}
190
191		private:
192		BER_Object m_obj;
193		size_t m_offset;
194		};
195
196		} // namespace
197
198		/*
199		* Check if more objects are there
200		*/
201	240	bool BER_Decoder::more_items() const {
202	240	if(m_source->end_of_data() && !m_pushed.is_set()) {
203	80	return false;
204	80	}
205	160	return true;
206	240	}
207
208		/*
209		* Verify that no bytes remain in the source
210		*/
211	0	BER_Decoder& BER_Decoder::verify_end() {
212	0	return verify_end("BER_Decoder::verify_end called, but data remains");
213	0	}
214
215		/*
216		* Verify that no bytes remain in the source
217		*/
218	0	BER_Decoder& BER_Decoder::verify_end(std::string_view err) {
219	0	if(!m_source->end_of_data() \|\| m_pushed.is_set()) {
220	0	throw Decoding_Error(err);
221	0	}
222	0	return (*this);
223	0	}
224
225		/*
226		* Discard all the bytes remaining in the source
227		*/
228	0	BER_Decoder& BER_Decoder::discard_remaining() {
229	0	uint8_t buf;
230	0	while(m_source->read_byte(buf)) {}
231	0	return (*this);
232	0	}
233
234	0	const BER_Object& BER_Decoder::peek_next_object() {
235	0	if(!m_pushed.is_set()) {
236	0	m_pushed = get_next_object();
237	0	}
238
239	0	return m_pushed;
240	0	}
241
242		/*
243		* Return the BER encoding of the next object
244		*/
245	240	BER_Object BER_Decoder::get_next_object() {
246	240	BER_Object next;
247
248	240	if(m_pushed.is_set()) {
249	0	std::swap(next, m_pushed);
250	0	return next;
251	0	}
252
253	240	for(;;) {
254	240	ASN1_Type type_tag;
255	240	ASN1_Class class_tag;
256	240	decode_tag(m_source, type_tag, class_tag);
257	240	next.set_tagging(type_tag, class_tag);
258	240	if(next.is_set() == false) { // no more objects
259	0	return next;
260	0	}
261
262	240	size_t field_size;
263	240	const size_t length = decode_length(m_source, field_size, ALLOWED_EOC_NESTINGS);
264	240	if(!m_source->check_available(length)) {
265	0	throw BER_Decoding_Error("Value truncated");
266	0	}
267
268	240	uint8_t* out = next.mutable_bits(length);
269	240	if(m_source->read(out, length) != length) {
270	0	throw BER_Decoding_Error("Value truncated");
271	0	}
272
273	240	if(next.tagging() == static_cast<uint32_t>(ASN1_Type::Eoc)) {
274	0	continue;
275	240	} else {
276	240	break;
277	240	}
278	240	}
279
280	240	return next;
281	240	}
282
283		/*
284		* Push a object back into the stream
285		*/
286	0	void BER_Decoder::push_back(const BER_Object& obj) {
287	0	if(m_pushed.is_set()) {
288	0	throw Invalid_State("BER_Decoder: Only one push back is allowed");
289	0	}
290	0	m_pushed = obj;
291	0	}
292
293	0	void BER_Decoder::push_back(BER_Object&& obj) {
294	0	if(m_pushed.is_set()) {
295	0	throw Invalid_State("BER_Decoder: Only one push back is allowed");
296	0	}
297	0	m_pushed = std::move(obj);
298	0	}
299
300	80	BER_Decoder BER_Decoder::start_cons(ASN1_Type type_tag, ASN1_Class class_tag) {
301	80	BER_Object obj = get_next_object();
302	80	obj.assert_is_a(type_tag, class_tag \| ASN1_Class::Constructed);
303	80	return BER_Decoder(std::move(obj), this);
304	80	}
305
306		/*
307		* Finish decoding a CONSTRUCTED type
308		*/
309	0	BER_Decoder& BER_Decoder::end_cons() {
310	0	if(!m_parent) {
311	0	throw Invalid_State("BER_Decoder::end_cons called with null parent");
312	0	}
313	0	if(!m_source->end_of_data()) {
314	0	throw Decoding_Error("BER_Decoder::end_cons called with data left");
315	0	}
316	0	return (*m_parent);
317	0	}
318
319	80	BER_Decoder::BER_Decoder(BER_Object&& obj, BER_Decoder* parent) {
320	80	m_data_src = std::make_unique<DataSource_BERObject>(std::move(obj));
321	80	m_source = m_data_src.get();
322	80	m_parent = parent;
323	80	}
324
325		/*
326		* BER_Decoder Constructor
327		*/
328	0	BER_Decoder::BER_Decoder(DataSource& src) {
329	0	m_source = &src;
330	0	}
331
332		/*
333		* BER_Decoder Constructor
334		*/
335	0	BER_Decoder::BER_Decoder(const uint8_t data[], size_t length) {
336	0	m_data_src = std::make_unique<DataSource_Memory>(data, length);
337	0	m_source = m_data_src.get();
338	0	}
339
340		/*
341		* BER_Decoder Constructor
342		*/
343	0	BER_Decoder::BER_Decoder(const secure_vector<uint8_t>& data) {
344	0	m_data_src = std::make_unique<DataSource_Memory>(data);
345	0	m_source = m_data_src.get();
346	0	}
347
348		/*
349		* BER_Decoder Constructor
350		*/
351	80	BER_Decoder::BER_Decoder(const std::vector<uint8_t>& data) {
352	80	m_data_src = std::make_unique<DataSource_Memory>(data.data(), data.size());
353	80	m_source = m_data_src.get();
354	80	}
355
356		/*
357		* BER_Decoder Copy Constructor
358		*/
359	0	BER_Decoder::BER_Decoder(const BER_Decoder& other) {
360	0	m_source = other.m_source;
361
362		// take ownership
363	0	std::swap(m_data_src, other.m_data_src);
364	0	m_parent = other.m_parent;
365	0	}
366
367		/*
368		* Request for an object to decode itself
369		*/
370	0	BER_Decoder& BER_Decoder::decode(ASN1_Object& obj, ASN1_Type /unused/, ASN1_Class /unused/) {
371	0	obj.decode_from(*this);
372	0	return (*this);
373	0	}
374
375		/*
376		* Decode a BER encoded NULL
377		*/
378	0	BER_Decoder& BER_Decoder::decode_null() {
379	0	BER_Object obj = get_next_object();
380	0	obj.assert_is_a(ASN1_Type::Null, ASN1_Class::Universal);
381	0	if(obj.length() > 0) {
382	0	throw BER_Decoding_Error("NULL object had nonzero size");
383	0	}
384	0	return (*this);
385	0	}
386
387	0	BER_Decoder& BER_Decoder::decode_octet_string_bigint(BigInt& out) {
388	0	secure_vector<uint8_t> out_vec;
389	0	decode(out_vec, ASN1_Type::OctetString);
390	0	out = BigInt::from_bytes(out_vec);
391	0	return (*this);
392	0	}
393
394		/*
395		* Decode a BER encoded BOOLEAN
396		*/
397	0	BER_Decoder& BER_Decoder::decode(bool& out, ASN1_Type type_tag, ASN1_Class class_tag) {
398	0	BER_Object obj = get_next_object();
399	0	obj.assert_is_a(type_tag, class_tag);
400
401	0	if(obj.length() != 1) {
402	0	throw BER_Decoding_Error("BER boolean value had invalid size");
403	0	}
404
405	0	out = (obj.bits()[0]) ? true : false;
406	0	return (*this);
407	0	}
408
409		/*
410		* Decode a small BER encoded INTEGER
411		*/
412	0	BER_Decoder& BER_Decoder::decode(size_t& out, ASN1_Type type_tag, ASN1_Class class_tag) {
413	0	BigInt integer;
414	0	decode(integer, type_tag, class_tag);
415
416	0	if(integer.is_negative()) {
417	0	throw BER_Decoding_Error("Decoded small integer value was negative");
418	0	}
419
420	0	if(integer.bits() > 32) {
421	0	throw BER_Decoding_Error("Decoded integer value larger than expected");
422	0	}
423
424	0	out = 0;
425	0	for(size_t i = 0; i != 4; ++i) {
426	0	out = (out << 8) \| integer.byte_at(3 - i);
427	0	}
428
429	0	return (*this);
430	0	}
431
432		/*
433		* Decode a small BER encoded INTEGER
434		*/
435	0	uint64_t BER_Decoder::decode_constrained_integer(ASN1_Type type_tag, ASN1_Class class_tag, size_t T_bytes) {
436	0	if(T_bytes > 8) {
437	0	throw BER_Decoding_Error("Can't decode small integer over 8 bytes");
438	0	}
439
440	0	BigInt integer;
441	0	decode(integer, type_tag, class_tag);
442
443	0	if(integer.bits() > 8 * T_bytes) {
444	0	throw BER_Decoding_Error("Decoded integer value larger than expected");
445	0	}
446
447	0	uint64_t out = 0;
448	0	for(size_t i = 0; i != 8; ++i) {
449	0	out = (out << 8) \| integer.byte_at(7 - i);
450	0	}
451
452	0	return out;
453	0	}
454
455		/*
456		* Decode a BER encoded INTEGER
457		*/
458	160	BER_Decoder& BER_Decoder::decode(BigInt& out, ASN1_Type type_tag, ASN1_Class class_tag) {
459	160	BER_Object obj = get_next_object();
460	160	obj.assert_is_a(type_tag, class_tag);
461
462	160	if(obj.length() == 0) {
463	0	out.clear();
464	160	} else {
465	160	const bool negative = (obj.bits()[0] & 0x80) ? true : false;
466
467	160	if(negative) {
468	0	secure_vector<uint8_t> vec(obj.bits(), obj.bits() + obj.length());
469	0	for(size_t i = obj.length(); i > 0; --i) {
470	0	if(vec[i - 1]--) {
471	0	break;
472	0	}
473	0	}
474	0	for(size_t i = 0; i != obj.length(); ++i) {
475	0	vec[i] = ~vec[i];
476	0	}
477	0	out._assign_from_bytes(vec);
478	0	out.flip_sign();
479	160	} else {
480	160	out._assign_from_bytes(obj.data());
481	160	}
482	160	}
483
484	160	return (*this);
485	160	}
486
487		namespace {
488
489		template <typename Alloc>
490		void asn1_decode_binary_string(std::vector<uint8_t, Alloc>& buffer,
491		const BER_Object& obj,
492		ASN1_Type real_type,
493		ASN1_Type type_tag,
494	0	ASN1_Class class_tag) {
495	0	obj.assert_is_a(type_tag, class_tag);
496
497	0	if(real_type == ASN1_Type::OctetString) {
498	0	buffer.assign(obj.bits(), obj.bits() + obj.length());
499	0	} else {
500	0	if(obj.length() == 0) {
501	0	throw BER_Decoding_Error("Invalid BIT STRING");
502	0	}
503	0	if(obj.bits()[0] >= 8) {
504	0	throw BER_Decoding_Error("Bad number of unused bits in BIT STRING");
505	0	}
506
507	0	buffer.resize(obj.length() - 1);
508
509	0	if(obj.length() > 1) {
510	0	copy_mem(buffer.data(), obj.bits() + 1, obj.length() - 1);
511	0	}
512	0	}
513	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)
514
515		} // namespace
516
517		/*
518		* BER decode a BIT STRING or OCTET STRING
519		*/
520		BER_Decoder& BER_Decoder::decode(secure_vector<uint8_t>& buffer,
521		ASN1_Type real_type,
522		ASN1_Type type_tag,
523	0	ASN1_Class class_tag) {
524	0	if(real_type != ASN1_Type::OctetString && real_type != ASN1_Type::BitString) {
525	0	throw BER_Bad_Tag("Bad tag for {BIT,OCTET} STRING", static_cast<uint32_t>(real_type));
526	0	}
527
528	0	asn1_decode_binary_string(buffer, get_next_object(), real_type, type_tag, class_tag);
529	0	return (*this);
530	0	}
531
532		BER_Decoder& BER_Decoder::decode(std::vector<uint8_t>& buffer,
533		ASN1_Type real_type,
534		ASN1_Type type_tag,
535	0	ASN1_Class class_tag) {
536	0	if(real_type != ASN1_Type::OctetString && real_type != ASN1_Type::BitString) {
537	0	throw BER_Bad_Tag("Bad tag for {BIT,OCTET} STRING", static_cast<uint32_t>(real_type));
538	0	}
539
540	0	asn1_decode_binary_string(buffer, get_next_object(), real_type, type_tag, class_tag);
541	0	return (*this);
542	0	}
543
544		} // namespace Botan