asn1_obj.cpp

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/*
* ASN.1 Internals
* (C) 1999-2007,2018 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
 
#include <botan/asn1_obj.h>
 
#include <botan/assert.h>
#include <botan/data_src.h>
#include <botan/der_enc.h>
#include <botan/mem_ops.h>
#include <botan/internal/fmt.h>
#include <botan/internal/mem_utils.h>
#include <sstream>
#include <utility>
 
namespace Botan {
 
std::vector<uint8_t> ASN1_Object::BER_encode() const {
   std::vector<uint8_t> output;
   DER_Encoder der(output);
   this->encode_into(der);
   return output;
}
 
ASN1_BitString::ASN1_BitString(std::vector<uint8_t> bytes, size_t unused_bits) :
      m_bytes(std::move(bytes)), m_unused_bits(unused_bits) {
   if(m_unused_bits >= 8) {
      throw Invalid_Argument("ASN1_BitString: Invalid unused bit count");
   }
 
   if(m_bytes.empty() && m_unused_bits != 0) {
      throw Invalid_Argument("ASN1_BitString: Empty BIT STRING cannot have unused bits");
   }
 
   if(m_unused_bits > 0 && (m_bytes.back() & ((1U << m_unused_bits) - 1)) != 0) {
      throw Invalid_Argument("ASN1_BitString: Unused bits must be zero");
   }
}
 
ASN1_BitString::ASN1_BitString(std::span<const uint8_t> bytes, size_t unused_bits) :
      ASN1_BitString(std::vector<uint8_t>(bytes.begin(), bytes.end()), unused_bits) {}
 
size_t ASN1_BitString::bit_length() const {
   return 8 * m_bytes.size() - m_unused_bits;
}
 
bool ASN1_BitString::bit_at(size_t bit) const {
   if(bit >= bit_length()) {
      throw Invalid_Argument("ASN1_BitString: Bit index out of range");
   }
 
   return (m_bytes[bit / 8] & (0x80 >> (bit % 8))) != 0;
}
 
BER_Object::~BER_Object() {
   secure_scrub_memory(m_value);
}
 
/*
* Check a type invariant on BER data
*/
void BER_Object::assert_is_a(ASN1_Type expected_type_tag, ASN1_Class expected_class_tag, std::string_view descr) const {
   if(!this->is_a(expected_type_tag, expected_class_tag)) {
      std::stringstream msg;
 
      msg << "Tag mismatch when decoding " << descr << " got ";
 
      if(m_class_tag == ASN1_Class::NoObject && m_type_tag == ASN1_Type::NoObject) {
         msg << "EOF";
      } else {
         if(m_class_tag == ASN1_Class::Universal || m_class_tag == ASN1_Class::Constructed) {
            msg << asn1_tag_to_string(m_type_tag);
         } else {
            msg << std::to_string(static_cast<uint32_t>(m_type_tag));
         }
 
         msg << "/" << asn1_class_to_string(m_class_tag);
      }
 
      msg << " expected ";
 
      if(expected_class_tag == ASN1_Class::Universal || expected_class_tag == ASN1_Class::Constructed) {
         msg << asn1_tag_to_string(expected_type_tag);
      } else {
         msg << std::to_string(static_cast<uint32_t>(expected_type_tag));
      }
 
      msg << "/" << asn1_class_to_string(expected_class_tag);
 
      throw BER_Decoding_Error(msg.str());
   }
}
 
bool BER_Object::is_a(ASN1_Type expected_type_tag, ASN1_Class expected_class_tag) const {
   return (m_type_tag == expected_type_tag && m_class_tag == expected_class_tag);
}
 
bool BER_Object::is_a(int expected_type_tag, ASN1_Class expected_class_tag) const {
   return is_a(ASN1_Type(expected_type_tag), expected_class_tag);
}
 
void BER_Object::set_tagging(ASN1_Type type_tag, ASN1_Class class_tag) {
   m_type_tag = type_tag;
   m_class_tag = class_tag;
}
 
std::string asn1_class_to_string(ASN1_Class type) {
   switch(type) {
      case ASN1_Class::Universal:
         return "UNIVERSAL";
      case ASN1_Class::Constructed:
         return "CONSTRUCTED";
      case ASN1_Class::ContextSpecific:
         return "CONTEXT_SPECIFIC";
      case ASN1_Class::Application:
         return "APPLICATION";
      case ASN1_Class::Private:
         return "PRIVATE";
      case ASN1_Class::NoObject:
         return "NO_OBJECT";
      default:
         return "CLASS(" + std::to_string(static_cast<size_t>(type)) + ")";
   }
}
 
std::string asn1_tag_to_string(ASN1_Type type) {
   switch(type) {
      case ASN1_Type::Sequence:
         return "SEQUENCE";
 
      case ASN1_Type::Set:
         return "SET";
 
      case ASN1_Type::PrintableString:
         return "PRINTABLE STRING";
 
      case ASN1_Type::NumericString:
         return "NUMERIC STRING";
 
      case ASN1_Type::Ia5String:
         return "IA5 STRING";
 
      case ASN1_Type::TeletexString:
         return "T61 STRING";
 
      case ASN1_Type::Utf8String:
         return "UTF8 STRING";
 
      case ASN1_Type::VisibleString:
         return "VISIBLE STRING";
 
      case ASN1_Type::BmpString:
         return "BMP STRING";
 
      case ASN1_Type::UniversalString:
         return "UNIVERSAL STRING";
 
      case ASN1_Type::UtcTime:
         return "UTC TIME";
 
      case ASN1_Type::GeneralizedTime:
         return "GENERALIZED TIME";
 
      case ASN1_Type::OctetString:
         return "OCTET STRING";
 
      case ASN1_Type::BitString:
         return "BIT STRING";
 
      case ASN1_Type::Enumerated:
         return "ENUMERATED";
 
      case ASN1_Type::Integer:
         return "INTEGER";
 
      case ASN1_Type::Null:
         return "NULL";
 
      case ASN1_Type::ObjectId:
         return "OBJECT";
 
      case ASN1_Type::Boolean:
         return "BOOLEAN";
 
      case ASN1_Type::NoObject:
         return "NO_OBJECT";
 
      default:
         return "TAG(" + std::to_string(static_cast<uint32_t>(type)) + ")";
   }
}
 
/*
* BER Decoding Exceptions
*/
BER_Decoding_Error::BER_Decoding_Error(std::string_view err) : Decoding_Error(fmt("BER: {}", err)) {}
 
BER_Bad_Tag::BER_Bad_Tag(std::string_view str, uint32_t tagging) : BER_Decoding_Error(fmt("{}: {}", str, tagging)) {}
 
namespace ASN1 {
 
/*
* Put some arbitrary bytes into a SEQUENCE
*/
std::vector<uint8_t> put_in_sequence(const std::vector<uint8_t>& contents) {
   return ASN1::put_in_sequence(contents.data(), contents.size());
}
 
std::vector<uint8_t> put_in_sequence(const uint8_t bits[], size_t len) {
   std::vector<uint8_t> output = der_sequence_header(len);
   output.reserve(output.size() + len);
   if(len > 0) {
      output.insert(output.end(), bits, bits + len);
   }
   return output;
}
 
/*
* Convert a BER object into a string object
*/
std::string to_string(const BER_Object& obj) {
   return bytes_to_string(obj.data());
}
 
/*
* Do heuristic tests for BER data
*/
bool maybe_BER(DataSource& source) {
   uint8_t first_u8 = 0;
   if(source.peek_byte(first_u8) == 0) {
      BOTAN_ASSERT_EQUAL(source.read_byte(first_u8), 0, "Expected EOF");
      throw Stream_IO_Error("ASN1::maybe_BER: Source was empty");
   }
 
   const auto cons_seq = static_cast<uint8_t>(ASN1_Class::Constructed) | static_cast<uint8_t>(ASN1_Type::Sequence);
   return first_u8 == cons_seq;
}
 
}  // namespace ASN1
 
}  // namespace Botan