Add support for reading SSLv2 client hellos

5 files changed, 86 insertions, 8 deletions

diff --git a/src/ssl/hello.cpp b/src/ssl/hello.cpp
index a23d51c24..b93234813 100644
--- a/src/ssl/hello.cpp
+++ b/src/ssl/hello.cpp
@@ -106,6 +106,40 @@ SecureVector<byte> Client_Hello::serialize() const
    return buf;
    }
 
+void Client_Hello::deserialize_sslv2(const MemoryRegion<byte>& buf)
+   {
+   if(buf.size() < 12 || buf[0] != 1)
+      throw Decoding_Error("Client_Hello: SSLv2 hello corrupted");
+
+   const u32bit cipher_spec_len = make_u16bit(buf[3], buf[4]);
+   const u32bit sess_id_len = make_u16bit(buf[5], buf[6]);
+   const u32bit challenge_len = make_u16bit(buf[7], buf[8]);
+
+   const u32bit expected_size =
+      (9 + sess_id_len + cipher_spec_len + challenge_len);
+
+   if(buf.size() != expected_size)
+      throw Decoding_Error("Client_Hello: SSLv2 hello corrupted");
+
+   if(sess_id_len != 0 || cipher_spec_len % 3 != 0 ||
+      (challenge_len < 16 || challenge_len > 32))
+      {
+      throw Decoding_Error("Client_Hello: SSLv2 hello corrupted");
+      }
+
+   for(u32bit i = 9; i != 9 + cipher_spec_len; i += 3)
+      {
+      if(buf[i] != 0) // a SSLv2 cipherspec; ignore it
+         continue;
+
+      suites.push_back(make_u16bit(buf[i+1], buf[i+2]));
+      }
+
+   c_version = static_cast<Version_Code>(make_u16bit(buf[1], buf[2]));
+
+   c_random.set(&buf[9+cipher_spec_len+sess_id_len], challenge_len);
+   }
+
 /**
 * Deserialize a Client Hello message
 */
diff --git a/src/ssl/rec_read.cpp b/src/ssl/rec_read.cpp
index 8f8e5dc1e..f07744c2a 100644
--- a/src/ssl/rec_read.cpp
+++ b/src/ssl/rec_read.cpp
@@ -124,6 +124,35 @@ u32bit Record_Reader::get_record(byte& msg_type,
    */
    input_queue.peek(header, sizeof(header));
 
+   // SSLv2-format client hello?
+   if(header[0] & 0x80 && header[2] == 1 && header[3] == 3)
+      {
+      u32bit record_len = make_u16bit(header[0], header[1]) & 0x7FFF;
+
+      if(have_in_queue < record_len + 2)
+         return (record_len + 2 - have_in_queue);
+
+      msg_type = HANDSHAKE;
+      output.resize(record_len + 4);
+
+      input_queue.read(&output[2], record_len + 2);
+      output[0] = CLIENT_HELLO_SSLV2;
+      output[1] = 0;
+      output[2] = header[0] & 0x7F;
+      output[3] = header[1];
+
+      return 0;
+      }
+
+   if(header[0] != CHANGE_CIPHER_SPEC &&
+      header[0] != ALERT &&
+      header[0] != HANDSHAKE &&
+      header[0] != APPLICATION_DATA)
+      {
+      throw TLS_Exception(UNEXPECTED_MESSAGE,
+                          "Record_Reader: Unknown record type");
+      }
+
    const u16bit version    = make_u16bit(header[1], header[2]);
    const u16bit record_len = make_u16bit(header[3], header[4]);
 
diff --git a/src/ssl/tls_magic.h b/src/ssl/tls_magic.h
index 35a9fc925..25cd0986a 100644
--- a/src/ssl/tls_magic.h
+++ b/src/ssl/tls_magic.h
@@ -40,6 +40,7 @@ enum Record_Type {
 enum Handshake_Type {
    HELLO_REQUEST       = 0,
    CLIENT_HELLO        = 1,
+   CLIENT_HELLO_SSLV2  = 255, // not a wire value
    SERVER_HELLO        = 2,
    CERTIFICATE         = 11,
    SERVER_KEX          = 12,
diff --git a/src/ssl/tls_messages.h b/src/ssl/tls_messages.h
index 1f72c05f7..42f81b1fe 100644
--- a/src/ssl/tls_messages.h
+++ b/src/ssl/tls_messages.h
@@ -56,10 +56,19 @@ class BOTAN_DLL Client_Hello : public HandshakeMessage
       Client_Hello(RandomNumberGenerator& rng,
                    Record_Writer&, const TLS_Policy*, HandshakeHash&);
 
-      Client_Hello(const MemoryRegion<byte>& buf) { deserialize(buf); }
+      Client_Hello(const MemoryRegion<byte>& buf,
+                   Handshake_Type type)
+         {
+         if(type == CLIENT_HELLO)
+            deserialize(buf);
+         else
+            deserialize_sslv2(buf);
+         }
+
    private:
       SecureVector<byte> serialize() const;
       void deserialize(const MemoryRegion<byte>&);
+      void deserialize_sslv2(const MemoryRegion<byte>&);
 
       Version_Code c_version;
       SecureVector<byte> sess_id, c_random;
diff --git a/src/ssl/tls_server.cpp b/src/ssl/tls_server.cpp
index 4e9c3583f..1c8d28c95 100644
--- a/src/ssl/tls_server.cpp
+++ b/src/ssl/tls_server.cpp
@@ -43,7 +43,7 @@ void server_check_state(Handshake_Type new_msg, Handshake_State* state)
             Unexpected_Message("State transition error from " + err) {}
       };
 
-   if(new_msg == CLIENT_HELLO)
+   if(new_msg == CLIENT_HELLO || new_msg == CLIENT_HELLO_SSLV2)
       {
       if(state->server_hello)
          throw State_Transition_Error("ClientHello");
@@ -330,18 +330,23 @@ void TLS_Server::process_handshake_msg(Handshake_Type type,
 
    if(type != HANDSHAKE_CCS && type != FINISHED)
       {
-      state->hash.update(static_cast<byte>(type));
-      u32bit record_length = contents.size();
-      for(u32bit j = 0; j != 3; j++)
-         state->hash.update(get_byte(j+1, record_length));
+
+      if(type != CLIENT_HELLO_SSLV2)
+         {
+         state->hash.update(static_cast<byte>(type));
+         u32bit record_length = contents.size();
+         for(u32bit j = 0; j != 3; j++)
+            state->hash.update(get_byte(j+1, record_length));
+         }
+
       state->hash.update(contents);
       }
 
-   if(type == CLIENT_HELLO)
+   if(type == CLIENT_HELLO || type == CLIENT_HELLO_SSLV2)
       {
       server_check_state(type, state);
 
-      state->client_hello = new Client_Hello(contents);
+      state->client_hello = new Client_Hello(contents, type);
 
       client_requested_hostname = state->client_hello->hostname();