1 files changed, 270 insertions, 0 deletions
diff --git a/src/ber_dec.cpp b/src/ber_dec.cpp
new file mode 100644
index 000000000..f9550fc83
--- /dev/null
+++ b/src/ber_dec.cpp
@@ -0,0 +1,270 @@
+/*************************************************
+* BER Decoder Source File                        *
+* (C) 1999-2006 The Botan Project                *
+*************************************************/
+
+#include <botan/ber_dec.h>
+#include <botan/asn1_int.h>
+#include <botan/bit_ops.h>
+
+namespace Botan {
+
+namespace {
+
+/*************************************************
+* BER decode an ASN.1 type tag                   *
+*************************************************/
+u32bit decode_tag(DataSource* ber, ASN1_Tag& type_tag, ASN1_Tag& class_tag)
+   {
+   byte b;
+   if(!ber->read_byte(b))
+      {
+      class_tag = type_tag = NO_OBJECT;
+      return 0;
+      }
+
+   if((b & 0x1F) != 0x1F)
+      {
+      type_tag = ASN1_Tag(b & 0x1F);
+      class_tag = ASN1_Tag(b & 0xE0);
+      return 1;
+      }
+
+   u32bit tag_bytes = 1;
+   class_tag = ASN1_Tag(b & 0xE0);
+
+   u32bit 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_Tag(tag_buf);
+   return tag_bytes;
+   }
+
+/*************************************************
+* Find the EOC marker                            *
+*************************************************/
+u32bit find_eoc(DataSource*);
+
+/*************************************************
+* BER decode an ASN.1 length field               *
+*************************************************/
+u32bit decode_length(DataSource* ber, u32bit& field_size)
+   {
+   byte 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 == 1) return find_eoc(ber);
+   if(field_size > 5)
+      throw BER_Decoding_Error("Length field is too large");
+
+   u32bit length = 0;
+
+   for(u32bit j = 0; j != field_size - 1; ++j)
+      {
+      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;
+   }
+
+/*************************************************
+* BER decode an ASN.1 length field               *
+*************************************************/
+u32bit decode_length(DataSource* ber)
+   {
+   u32bit dummy;
+   return decode_length(ber, dummy);
+   }
+
+/*************************************************
+* Find the EOC marker                            *
+*************************************************/
+u32bit find_eoc(DataSource* ber)
+   {
+   SecureVector<byte> buffer(DEFAULT_BUFFERSIZE), data;
+
+   while(true)
+      {
+      const u32bit got = ber->peek(buffer, buffer.size(), data.size());
+      if(got == 0)
+         break;
+      data.append(buffer, got);
+      }
+
+   DataSource_Memory source(data);
+   data.destroy();
+
+   u32bit length = 0;
+   while(true)
+      {
+      ASN1_Tag type_tag, class_tag;
+      u32bit tag_size = decode_tag(&source, type_tag, class_tag);
+      if(type_tag == NO_OBJECT)
+         break;
+
+      u32bit length_size = 0;
+      u32bit item_size = decode_length(&source, length_size);
+      source.discard_next(item_size);
+
+      length += item_size + length_size + tag_size;
+
+      if(type_tag == EOC)
+         break;
+      }
+   return length;
+   }
+
+}
+
+/*************************************************
+* Check if more objects are there                *
+*************************************************/
+bool BER_Decoder::more_items() const
+   {
+   if(source->end_of_data() && (pushed.type_tag == NO_OBJECT))
+      return false;
+   return true;
+   }
+
+/*************************************************
+* Verify that no bytes remain in the source      *
+*************************************************/
+void BER_Decoder::verify_end() const
+   {
+   if(!source->end_of_data() || (pushed.type_tag != NO_OBJECT))
+      throw Invalid_State("BER_Decoder::verify_end called, but data remains");
+   }
+
+/*************************************************
+* Return all the bytes remaining in the source   *
+*************************************************/
+SecureVector<byte> BER_Decoder::get_remaining()
+   {
+   SecureVector<byte> out;
+   byte buf;
+   while(source->read_byte(buf))
+      out.append(buf);
+   return out;
+   }
+
+/*************************************************
+* Discard all the bytes remaining in the source  *
+*************************************************/
+void BER_Decoder::discard_remaining()
+   {
+   byte buf;
+   while(source->read_byte(buf))
+      ;
+   }
+
+/*************************************************
+* Return the BER encoding of the next object     *
+*************************************************/
+BER_Object BER_Decoder::get_next_object()
+   {
+   BER_Object next;
+
+   if(pushed.type_tag != NO_OBJECT)
+      {
+      next = pushed;
+      pushed.class_tag = pushed.type_tag = NO_OBJECT;
+      return next;
+      }
+
+   decode_tag(source, next.type_tag, next.class_tag);
+   if(next.type_tag == NO_OBJECT)
+      return next;
+
+   u32bit length = decode_length(source);
+   next.value.create(length);
+   if(source->read(next.value, length) != length)
+      throw BER_Decoding_Error("Value truncated");
+
+   if(next.type_tag == EOC && next.class_tag == UNIVERSAL)
+      return get_next_object();
+
+   return next;
+   }
+
+/*************************************************
+* Push a object back into the stream             *
+*************************************************/
+void BER_Decoder::push_back(const BER_Object& obj)
+   {
+   if(pushed.type_tag != NO_OBJECT)
+      throw Invalid_State("BER_Decoder: Only one push back is allowed");
+   pushed = obj;
+   }
+
+/*************************************************
+* BER_Decoder Constructor                        *
+*************************************************/
+BER_Decoder::BER_Decoder(DataSource& src)
+   {
+   source = &src;
+   owns = false;
+   pushed.type_tag = pushed.class_tag = NO_OBJECT;
+   }
+
+/*************************************************
+* BER_Decoder Constructor                        *
+ *************************************************/
+BER_Decoder::BER_Decoder(const byte data[], u32bit length)
+   {
+   source = new DataSource_Memory(data, length);
+   owns = true;
+   pushed.type_tag = pushed.class_tag = NO_OBJECT;
+   }
+
+/*************************************************
+* BER_Decoder Constructor                        *
+*************************************************/
+BER_Decoder::BER_Decoder(const MemoryRegion<byte>& data)
+   {
+   source = new DataSource_Memory(data);
+   owns = true;
+   pushed.type_tag = pushed.class_tag = NO_OBJECT;
+   }
+
+/*************************************************
+* BER_Decoder Copy Constructor                   *
+*************************************************/
+BER_Decoder::BER_Decoder(const BER_Decoder& other)
+   {
+   source = other.source;
+   owns = false;
+   if(other.owns)
+      {
+      other.owns = false;
+      owns = true;
+      }
+   pushed.type_tag = pushed.class_tag = NO_OBJECT;
+   }
+
+/*************************************************
+* BER_Decoder Destructor                         *
+*************************************************/
+BER_Decoder::~BER_Decoder()
+   {
+   if(owns)
+      delete source;
+   source = 0;
+   }
+
+}