1 files changed, 186 insertions, 0 deletions
diff --git a/src/tls/tls_reader.h b/src/tls/tls_reader.h
new file mode 100644
index 000000000..3a45235b5
--- /dev/null
+++ b/src/tls/tls_reader.h
@@ -0,0 +1,186 @@
+/*
+* TLS Data Reader
+* (C) 2010 Jack Lloyd
+*
+* Released under the terms of the Botan license
+*/
+
+#ifndef BOTAN_TLS_READER_H__
+#define BOTAN_TLS_READER_H__
+
+#include <botan/secmem.h>
+#include <botan/loadstor.h>
+
+namespace Botan {
+
+/**
+* Helper class for decoding TLS protocol messages
+*/
+class TLS_Data_Reader
+   {
+   public:
+      TLS_Data_Reader(const MemoryRegion<byte>& buf_in) :
+         buf(buf_in), offset(0) {}
+
+      size_t remaining_bytes() const
+         {
+         return buf.size() - offset;
+         }
+
+      bool has_remaining() const
+         {
+         return (remaining_bytes() > 0);
+         }
+
+      void discard_next(size_t bytes)
+         {
+         assert_at_least(bytes);
+         offset += bytes;
+         }
+
+      u16bit get_u16bit()
+         {
+         assert_at_least(2);
+         u16bit result = make_u16bit(buf[offset], buf[offset+1]);
+         offset += 2;
+         return result;
+         }
+
+      byte get_byte()
+         {
+         assert_at_least(1);
+         byte result = buf[offset];
+         offset += 1;
+         return result;
+         }
+
+      template<typename T, typename Container>
+      Container get_elem(size_t num_elems)
+         {
+         assert_at_least(num_elems * sizeof(T));
+
+         Container result(num_elems);
+
+         for(size_t i = 0; i != num_elems; ++i)
+            result[i] = load_be<T>(&buf[offset], i);
+
+         offset += num_elems * sizeof(T);
+
+         return result;
+         }
+
+      template<typename T>
+      SecureVector<T> get_range(size_t len_bytes,
+                                size_t min_elems,
+                                size_t max_elems)
+         {
+         const size_t num_elems =
+            get_num_elems(len_bytes, sizeof(T), min_elems, max_elems);
+
+         return get_elem<T, SecureVector<T> >(num_elems);
+         }
+
+      template<typename T>
+      std::vector<T> get_range_vector(size_t len_bytes,
+                                      size_t min_elems,
+                                      size_t max_elems)
+         {
+         const size_t num_elems =
+            get_num_elems(len_bytes, sizeof(T), min_elems, max_elems);
+
+         return get_elem<T, std::vector<T> >(num_elems);
+         }
+
+      template<typename T>
+      SecureVector<T> get_fixed(size_t size)
+         {
+         return get_elem<T, SecureVector<T> >(size);
+         }
+
+   private:
+      size_t get_length_field(size_t len_bytes)
+         {
+         assert_at_least(len_bytes);
+
+         if(len_bytes == 1)
+            return get_byte();
+         else if(len_bytes == 2)
+            return get_u16bit();
+
+         throw Decoding_Error("TLS_Data_Reader: Bad length size");
+         }
+
+      size_t get_num_elems(size_t len_bytes,
+                           size_t T_size,
+                           size_t min_elems,
+                           size_t max_elems)
+         {
+         const size_t byte_length = get_length_field(len_bytes);
+
+         if(byte_length % T_size != 0)
+            throw Decoding_Error("TLS_Data_Reader: Size isn't multiple of T");
+
+         const size_t num_elems = byte_length / T_size;
+
+         if(num_elems < min_elems || num_elems > max_elems)
+            throw Decoding_Error("TLS_Data_Reader: Range outside paramaters");
+
+         return num_elems;
+         }
+
+      void assert_at_least(size_t n) const
+         {
+         if(buf.size() - offset < n)
+            throw Decoding_Error("TLS_Data_Reader: Corrupt packet");
+         }
+
+      const MemoryRegion<byte>& buf;
+      size_t offset;
+   };
+
+/**
+* Helper function for encoding length-tagged vectors
+*/
+template<typename T>
+void append_tls_length_value(MemoryRegion<byte>& buf,
+                             const T* vals,
+                             size_t vals_size,
+                             size_t tag_size)
+   {
+   const size_t T_size = sizeof(T);
+   const size_t val_bytes = T_size * vals_size;
+
+   if(tag_size != 1 && tag_size != 2)
+      throw std::invalid_argument("append_tls_length_value: invalid tag size");
+
+   if((tag_size == 1 && val_bytes > 255) ||
+      (tag_size == 2 && val_bytes > 65535))
+      throw std::invalid_argument("append_tls_length_value: value too large");
+
+   for(size_t i = 0; i != tag_size; ++i)
+      buf.push_back(get_byte(sizeof(val_bytes)-tag_size+i, val_bytes));
+
+   for(size_t i = 0; i != vals_size; ++i)
+      for(size_t j = 0; j != T_size; ++j)
+         buf.push_back(get_byte(j, vals[i]));
+   }
+
+template<typename T>
+void append_tls_length_value(MemoryRegion<byte>& buf,
+                             const MemoryRegion<T>& vals,
+                             size_t tag_size)
+   {
+   append_tls_length_value(buf, &vals[0], vals.size(), tag_size);
+   }
+
+template<typename T>
+void append_tls_length_value(MemoryRegion<byte>& buf,
+                             const std::vector<T>& vals,
+                             size_t tag_size)
+   {
+   append_tls_length_value(buf, &vals[0], vals.size(), tag_size);
+   }
+
+}
+
+#endif