Add a helper function for encoding TLS values with length tagging

6 files changed, 60 insertions, 47 deletions

diff --git a/src/ssl/c_kex.cpp b/src/ssl/c_kex.cpp
index 3ce4a2f06..0f20b819c 100644
--- a/src/ssl/c_kex.cpp
+++ b/src/ssl/c_kex.cpp
@@ -77,17 +77,14 @@ Client_Key_Exchange::Client_Key_Exchange(const MemoryRegion<byte>& contents,
 */
 SecureVector<byte> Client_Key_Exchange::serialize() const
    {
-   SecureVector<byte> buf;
-
    if(include_length)
       {
-      u16bit key_size = key_material.size();
-      buf.push_back(get_byte(0, key_size));
-      buf.push_back(get_byte(1, key_size));
+      SecureVector<byte> buf;
+      append_tls_length_value(buf, key_material, 2);
+      return buf;
       }
-   buf += key_material;
-
-   return buf;
+   else
+      return key_material;
    }
 
 /**
diff --git a/src/ssl/cert_req.cpp b/src/ssl/cert_req.cpp
index f30bc2fd7..e72ffe735 100644
--- a/src/ssl/cert_req.cpp
+++ b/src/ssl/cert_req.cpp
@@ -6,6 +6,7 @@
 */
 
 #include <botan/internal/tls_messages.h>
+#include <botan/internal/tls_reader.h>
 #include <botan/der_enc.h>
 #include <botan/ber_dec.h>
 #include <botan/loadstor.h>
@@ -37,20 +38,13 @@ SecureVector<byte> Certificate_Req::serialize() const
    {
    SecureVector<byte> buf;
 
-   buf.push_back(types.size());
-   for(u32bit i = 0; i != types.size(); i++)
-      buf.push_back(types[i]);
+   append_tls_length_value(buf, types, 1);
 
    DER_Encoder encoder;
    for(u32bit i = 0; i != names.size(); i++)
       encoder.encode(names[i]);
 
-   SecureVector<byte> der_names = encoder.get_contents();
-   u16bit names_size = der_names.size();
-
-   buf.push_back(get_byte(0, names_size));
-   buf.push_back(get_byte(1, names_size));
-   buf += der_names;
+   append_tls_length_value(buf, encoder.get_contents(), 2);
 
    return buf;
    }
diff --git a/src/ssl/hello.cpp b/src/ssl/hello.cpp
index b0f18d28f..5228807b4 100644
--- a/src/ssl/hello.cpp
+++ b/src/ssl/hello.cpp
@@ -86,22 +86,9 @@ SecureVector<byte> Client_Hello::serialize() const
    buf.push_back(static_cast<byte>(c_version     ));
    buf += c_random;
 
-   buf.push_back(static_cast<byte>(sess_id.size()));
-   buf += sess_id;
-
-   u16bit suites_size = 2*suites.size();
-
-   buf.push_back(get_byte(0, suites_size));
-   buf.push_back(get_byte(1, suites_size));
-   for(u32bit i = 0; i != suites.size(); i++)
-      {
-      buf.push_back(get_byte(0, suites[i]));
-      buf.push_back(get_byte(1, suites[i]));
-      }
-
-   buf.push_back(static_cast<byte>(comp_algos.size()));
-   for(u32bit i = 0; i != comp_algos.size(); i++)
-      buf.push_back(comp_algos[i]);
+   append_tls_length_value(buf, sess_id, 1);
+   append_tls_length_value(buf, suites, 2);
+   append_tls_length_value(buf, comp_algos, 1);
 
    return buf;
    }
@@ -265,8 +252,7 @@ SecureVector<byte> Server_Hello::serialize() const
    buf.push_back(static_cast<byte>(s_version     ));
    buf += s_random;
 
-   buf.push_back(static_cast<byte>(sess_id.size()));
-   buf += sess_id;
+   append_tls_length_value(buf, sess_id, 1);
 
    buf.push_back(get_byte(0, suite));
    buf.push_back(get_byte(1, suite));
diff --git a/src/ssl/info.txt b/src/ssl/info.txt
index 8460e68e4..161b51569 100644
--- a/src/ssl/info.txt
+++ b/src/ssl/info.txt
@@ -52,7 +52,7 @@ md5
 rng
 rsa
 sha1
-ssl3_mac
+ssl3mac
 ssl_prf
 tls_prf
 x509
diff --git a/src/ssl/s_kex.cpp b/src/ssl/s_kex.cpp
index b04cad3ea..f9a595fe9 100644
--- a/src/ssl/s_kex.cpp
+++ b/src/ssl/s_kex.cpp
@@ -6,6 +6,7 @@
 */
 
 #include <botan/internal/tls_messages.h>
+#include <botan/internal/tls_reader.h>
 #include <botan/pubkey.h>
 #include <botan/dh.h>
 #include <botan/rsa.h>
@@ -74,10 +75,7 @@ Server_Key_Exchange::Server_Key_Exchange(RandomNumberGenerator& rng,
 SecureVector<byte> Server_Key_Exchange::serialize() const
    {
    SecureVector<byte> buf = serialize_params();
-   u16bit sig_len = signature.size();
-   buf.push_back(get_byte(0, sig_len));
-   buf.push_back(get_byte(1, sig_len));
-   buf += signature;
+   append_tls_length_value(buf, signature, 2);
    return buf;
    }
 
@@ -87,15 +85,10 @@ SecureVector<byte> Server_Key_Exchange::serialize() const
 SecureVector<byte> Server_Key_Exchange::serialize_params() const
    {
    SecureVector<byte> buf;
+
    for(u32bit j = 0; j != params.size(); j++)
-      {
-      SecureVector<byte> param = BigInt::encode(params[j]);
-      u16bit param_size = param.size();
+      append_tls_length_value(buf, BigInt::encode(params[j]), 2);
 
-      buf.push_back(get_byte(0, param_size));
-      buf.push_back(get_byte(1, param_size));
-      buf += param;
-      }
    return buf;
    }
 
diff --git a/src/ssl/tls_reader.h b/src/ssl/tls_reader.h
index 641d1ecdb..733e9bdc9 100644
--- a/src/ssl/tls_reader.h
+++ b/src/ssl/tls_reader.h
@@ -138,6 +138,49 @@ class TLS_Data_Reader
       u32bit offset;
    };
 
+/**
+* Helper function for encoding length-tagged vectors
+*/
+template<typename T>
+void append_tls_length_value(MemoryRegion<byte>& buf,
+                             const T* vals,
+                             u32bit vals_size,
+                             u32bit tag_size)
+   {
+   const u32bit T_size = sizeof(T);
+   const u32bit 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(u32bit i = 0; i != tag_size; ++i)
+      buf.push_back(get_byte(4-tag_size+i, val_bytes));
+
+   for(u32bit i = 0; i != vals_size; ++i)
+      for(u32bit 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,
+                             u32bit 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,
+                             u32bit tag_size)
+   {
+   append_tls_length_value(buf, &vals[0], vals.size(), tag_size);
+   }
+
 }
 
 #endif