1 files changed, 471 insertions, 0 deletions
diff --git a/botan/src/asn1/ber_dec.cpp b/botan/src/asn1/ber_dec.cpp
new file mode 100644
index 0000000..ce60466
--- /dev/null
+++ b/botan/src/asn1/ber_dec.cpp
@@ -0,0 +1,471 @@
+/*
+* BER Decoder
+* (C) 1999-2008 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/ber_dec.h>
+#include <botan/bigint.h>
+#include <botan/loadstor.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 a type invariant on BER data
+*/
+void BER_Object::assert_is_a(ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   if(this->type_tag != type_tag || this->class_tag != class_tag)
+      throw BER_Decoding_Error("Tag mismatch when decoding");
+   }
+
+/*
+* 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
+*/
+BER_Decoder& BER_Decoder::verify_end()
+   {
+   if(!source->end_of_data() || (pushed.type_tag != NO_OBJECT))
+      throw Invalid_State("BER_Decoder::verify_end called, but data remains");
+   return (*this);
+   }
+
+/*
+* Save all the bytes remaining in the source
+*/
+BER_Decoder& BER_Decoder::raw_bytes(MemoryRegion<byte>& out)
+   {
+   out.destroy();
+   byte buf;
+   while(source->read_byte(buf))
+      out.append(buf);
+   return (*this);
+   }
+
+/*
+* Discard all the bytes remaining in the source
+*/
+BER_Decoder& BER_Decoder::discard_remaining()
+   {
+   byte buf;
+   while(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(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;
+   }
+
+/*
+* Begin decoding a CONSTRUCTED type
+*/
+BER_Decoder BER_Decoder::start_cons(ASN1_Tag type_tag,
+                                    ASN1_Tag class_tag)
+   {
+   BER_Object obj = get_next_object();
+   obj.assert_is_a(type_tag, ASN1_Tag(class_tag | CONSTRUCTED));
+
+   BER_Decoder result(obj.value, obj.value.size());
+   result.parent = this;
+   return result;
+   }
+
+/*
+* Finish decoding a CONSTRUCTED type
+*/
+BER_Decoder& BER_Decoder::end_cons()
+   {
+   if(!parent)
+      throw Invalid_State("BER_Decoder::end_cons called with NULL parent");
+   if(!source->end_of_data())
+      throw Decoding_Error("BER_Decoder::end_cons called with data left");
+   return (*parent);
+   }
+
+/*
+* BER_Decoder Constructor
+*/
+BER_Decoder::BER_Decoder(DataSource& src)
+   {
+   source = &src;
+   owns = false;
+   pushed.type_tag = pushed.class_tag = NO_OBJECT;
+   parent = 0;
+   }
+
+/*
+* 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;
+   parent = 0;
+   }
+
+/*
+* 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;
+   parent = 0;
+   }
+
+/*
+* 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;
+   parent = other.parent;
+   }
+
+/*
+* BER_Decoder Destructor
+*/
+BER_Decoder::~BER_Decoder()
+   {
+   if(owns)
+      delete source;
+   source = 0;
+   }
+
+/*
+* Request for an object to decode itself
+*/
+BER_Decoder& BER_Decoder::decode(ASN1_Object& obj)
+   {
+   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(NULL_TAG, UNIVERSAL);
+   if(obj.value.size())
+      throw BER_Decoding_Error("NULL object had nonzero size");
+   return (*this);
+   }
+
+/*
+* Decode a BER encoded BOOLEAN
+*/
+BER_Decoder& BER_Decoder::decode(bool& out)
+   {
+   return decode(out, BOOLEAN, UNIVERSAL);
+   }
+
+/*
+* Decode a small BER encoded INTEGER
+*/
+BER_Decoder& BER_Decoder::decode(u32bit& out)
+   {
+   return decode(out, INTEGER, UNIVERSAL);
+   }
+
+/*
+* Decode a BER encoded INTEGER
+*/
+BER_Decoder& BER_Decoder::decode(BigInt& out)
+   {
+   return decode(out, INTEGER, UNIVERSAL);
+   }
+
+/*
+* Decode a BER encoded BOOLEAN
+*/
+BER_Decoder& BER_Decoder::decode(bool& out,
+                                 ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   BER_Object obj = get_next_object();
+   obj.assert_is_a(type_tag, class_tag);
+
+   if(obj.value.size() != 1)
+      throw BER_Decoding_Error("BER boolean value had invalid size");
+
+   out = (obj.value[0]) ? true : false;
+   return (*this);
+   }
+
+/*
+* Decode a small BER encoded INTEGER
+*/
+BER_Decoder& BER_Decoder::decode(u32bit& out,
+                                 ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   BigInt integer;
+   decode(integer, type_tag, class_tag);
+   out = integer.to_u32bit();
+   return (*this);
+   }
+
+/*
+* Decode a BER encoded INTEGER
+*/
+BER_Decoder& BER_Decoder::decode(BigInt& out,
+                                 ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   BER_Object obj = get_next_object();
+   obj.assert_is_a(type_tag, class_tag);
+
+   if(obj.value.is_empty())
+      out = 0;
+   else
+      {
+      const bool negative = (obj.value[0] & 0x80) ? true : false;
+
+      if(negative)
+         {
+         for(u32bit j = obj.value.size(); j > 0; --j)
+            if(obj.value[j-1]--)
+               break;
+         for(u32bit j = 0; j != obj.value.size(); ++j)
+            obj.value[j] = ~obj.value[j];
+         }
+
+      out = BigInt(obj.value, obj.value.size());
+
+      if(negative)
+         out.flip_sign();
+      }
+
+   return (*this);
+   }
+
+/*
+* BER decode a BIT STRING or OCTET STRING
+*/
+BER_Decoder& BER_Decoder::decode(MemoryRegion<byte>& out, ASN1_Tag real_type)
+   {
+   return decode(out, real_type, real_type, UNIVERSAL);
+   }
+
+/*
+* BER decode a BIT STRING or OCTET STRING
+*/
+BER_Decoder& BER_Decoder::decode(MemoryRegion<byte>& buffer,
+                                 ASN1_Tag real_type,
+                                 ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   if(real_type != OCTET_STRING && real_type != BIT_STRING)
+      throw BER_Bad_Tag("Bad tag for {BIT,OCTET} STRING", real_type);
+
+   BER_Object obj = get_next_object();
+   obj.assert_is_a(type_tag, class_tag);
+
+   if(real_type == OCTET_STRING)
+      buffer = obj.value;
+   else
+      {
+      if(obj.value[0] >= 8)
+         throw BER_Decoding_Error("Bad number of unused bits in BIT STRING");
+      buffer.set(obj.value + 1, obj.value.size() - 1);
+      }
+   return (*this);
+   }
+
+/*
+* Decode an OPTIONAL string type
+*/
+BER_Decoder& BER_Decoder::decode_optional_string(MemoryRegion<byte>& out,
+                                                 ASN1_Tag real_type,
+                                                 u16bit type_no)
+   {
+   BER_Object obj = get_next_object();
+
+   ASN1_Tag type_tag = static_cast<ASN1_Tag>(type_no);
+
+   out.clear();
+   push_back(obj);
+
+   if(obj.type_tag == type_tag && obj.class_tag == CONTEXT_SPECIFIC)
+      decode(out, real_type, type_tag, CONTEXT_SPECIFIC);
+
+   return (*this);
+   }
+
+}