BUG#11879051: FIRST REPLY LENGTH LIMIT (255) CAN BE VIOLATED

BEFORE: First packet sent by client-side plugin (generated by Windows
function InitializeSecurityContext()) could be longer than 255 bytes 
violating the limitation imposed by authentication protocol.

AFTER: Handshake protocol is  changed so that if first client's reply is 
longer than 254 bytes then  it is be sent in 2 parts. However, for replies
shorter than 255 bytes nothing changes.

ADDITIONAL CHANGES: 
- The generic packet processing loop  (Handshake::packet_processing_loop) 
has been refactored. Communication with the peer has been abstracted
into virtual methods read/write_packet() which are implemented in client 
and server and transparently do the required splitting and gluing of packets.
- Make it possible to optionally use dbug library in the plugin.
- Add code for testing splitting of long first client reply.

libmysql/authentication_win/CMakeLists.txt

@@ -18,7 +18,9 @@
 #
 
 ADD_DEFINITIONS(-DSECURITY_WIN32)
-ADD_DEFINITIONS(-DDEBUG_ERRROR_LOG)	# no error logging in production builds
+ADD_DEFINITIONS(-DDEBUG_ERRROR_LOG)  # no error logging in production builds
+ADD_DEFINITIONS(-DWINAUTH_USE_DBUG_LIB)      # it is OK to use dbug library in statically
+                                             # linked plugin
 
 SET(HEADERS common.h handshake.h)
 SET(PLUGIN_SOURCES plugin_client.cc handshake_client.cc log_client.cc common.cc handshake.cc)

libmysql/authentication_win/common.h

@@ -41,54 +41,65 @@ struct error_log_level
   typedef enum {INFO, WARNING, ERROR}  type;
 };
 
-#undef  DBUG_ASSERT
-#ifndef DBUG_OFF
-#define DBUG_ASSERT(X)  assert(X)
+
+/*
+  If DEBUG_ERROR_LOG is defined then error logging happens only
+  in debug-copiled code. Otherwise ERROR_LOG() expands to 
+  error_log_print() even in production code. Note that in client
+  plugin, error_log_print() will print nothing if opt_auth_win_clinet_log
+  is 0.
+
+  Note: Macro ERROR_LOG() can use printf-like format string like this:
+
+    ERROR_LOG(Level, ("format string", args));
+
+  The implementation should handle it correctly. Currently it is passed 
+  to fprintf() (see error_log_vprint() function).
+*/
+
+extern "C" int opt_auth_win_client_log;
+
+#if defined(DEBUG_ERROR_LOG) && defined(DBUG_OFF)
+#define ERROR_LOG(Level, Msg)     do {} while (0)
 #else
-#define DBUG_ASSERT(X)  do {} while (0)
+#define ERROR_LOG(Level, Msg)     error_log_print< error_log_level::Level > Msg
 #endif
 
-extern "C" int opt_auth_win_client_log;
 
-/*
-  Note1: Double level of indirection in definition of DBUG_PRINT allows to
-  temporary redefine or disable DBUG_PRINT macro and then easily return to
-  the original definition (in terms of DBUG_PRINT_DO).
+void error_log_vprint(error_log_level::type level,
+                        const char *fmt, va_list args);
 
-  Note2: DBUG_PRINT() can use printf-like format string like this:
+template <error_log_level::type Level>
+void error_log_print(const char *fmt, ...)
+{
+  va_list args;
+  va_start(args, fmt);
+  error_log_vprint(Level, fmt, args);
+  va_end(args);
+}
 
-    DBUG_PRINT(Keyword, ("format string", args));
+typedef char Error_message_buf[1024];
+const char* get_last_error_message(Error_message_buf);
 
-  The implementation should handle it correctly. Currently it is passed 
-  to fprintf() (see debug_msg() function).
+
+/*
+  Internal implementation of debug message printing which does not use
+  dbug library. This is invoked via macro:
+
+    DBUG_PRINT_DO(Keyword, ("format string", args));
+
+  This is supposed to be used as an implementation of DBUG_PRINT() macro,
+  unless the dbug library implementation is used or debug messages are disabled.
 */
 
 #ifndef DBUG_OFF
+
 #define DBUG_PRINT_DO(Keyword, Msg) \
   do { \
     if (2 > opt_auth_win_client_log) break; \
     fprintf(stderr, "winauth: %s: ", Keyword); \
     debug_msg Msg; \
   } while (0)
-#else
-#define DBUG_PRINT_DO(K, M)  do {} while (0)
-#endif
-
-#undef  DBUG_PRINT
-#define DBUG_PRINT(Keyword, Msg)  DBUG_PRINT_DO(Keyword, Msg)
-
-/*
-  If DEBUG_ERROR_LOG is defined then error logging happens only
-  in debug-copiled code. Otherwise ERROR_LOG() expands to 
-  error_log_print() even in production code. Note that in client
-  plugin, error_log_print() will print nothing if opt_auth_win_clinet_log
-  is 0.
-*/
-#if defined(DEBUG_ERROR_LOG) && defined(DBUG_OFF)
-#define ERROR_LOG(Level, Msg)     do {} while (0)
-#else
-#define ERROR_LOG(Level, Msg)     error_log_print< error_log_level::Level > Msg
-#endif
 
 inline
 void debug_msg(const char *fmt, ...)
@@ -101,21 +112,38 @@ void debug_msg(const char *fmt, ...)
   va_end(args);
 }
 
+#else
+#define DBUG_PRINT_DO(K, M)  do {} while (0)
+#endif
 
-void error_log_vprint(error_log_level::type level,
-                        const char *fmt, va_list args);
 
-template <error_log_level::type Level>
-void error_log_print(const char *fmt, ...)
-{
-  va_list args;
-  va_start(args, fmt);
-  error_log_vprint(Level, fmt, args);
-  va_end(args);
-}
+#ifndef WINAUTH_USE_DBUG_LIB
 
-typedef char Error_message_buf[1024];
-const char* get_last_error_message(Error_message_buf);
+#undef  DBUG_PRINT
+#define DBUG_PRINT(Keyword, Msg)  DBUG_PRINT_DO(Keyword, Msg)
+
+/*
+  Redefine few more debug macros to make sure that no symbols from
+  dbug library are used.
+*/
+
+#undef DBUG_ENTER
+#define DBUG_ENTER(X)  do {} while (0)
+
+#undef DBUG_RETURN
+#define DBUG_RETURN(X) return (X)
+
+#undef DBUG_ASSERT
+#ifndef DBUG_OFF
+#define DBUG_ASSERT(X) assert (X)
+#else
+#define DBUG_ASSERT(X) do {} while (0)
+#endif
+
+#undef DBUG_DUMP
+#define DBUG_DUMP(A,B,C) do {} while (0)
+
+#endif
 
 
 /** Blob class *************************************************************/
@@ -158,15 +186,21 @@ public:
     return m_len;
   }
 
-  byte operator[](unsigned pos) const
+  byte& operator[](unsigned pos) const
   {
-    return pos < len() ? m_ptr[pos] : 0x00;
+    static byte out_of_range= 0;  // alas, no exceptions...
+    return pos < len() ? m_ptr[pos] : out_of_range;
   }
 
   bool is_null() const
   {
     return m_ptr == NULL;
   }
+
+  void trim(size_t l)
+  {
+    m_len= l;
+  }
 };
 
 

libmysql/authentication_win/handshake.cc

@@ -90,17 +90,19 @@ Handshake::~Handshake()
 
   @note In case of error, appropriate error message is logged.
 */
-int Handshake::packet_processing_loop(Connection &con)
+int Handshake::packet_processing_loop()
 {
-  unsigned round= 1;
+  m_round= 0;
 
   do {
+    ++m_round;
     // Read packet send by the peer
+
     DBUG_PRINT("info", ("Waiting for packet"));
-    Blob packet= con.read();
-    if (con.error() || packet.is_null())
+    Blob packet= read_packet();
+    if (error())
     {
-      ERROR_LOG(ERROR, ("Error reading packet in round %d", round));
+      ERROR_LOG(ERROR, ("Error reading packet in round %d", m_round));
       return 1;
     }
     DBUG_PRINT("info", ("Got packet of length %d", packet.len()));
@@ -113,7 +115,7 @@ int Handshake::packet_processing_loop(Connection &con)
 
     if (error())
     {
-      ERROR_LOG(ERROR, ("Error processing packet in round %d", round));
+      ERROR_LOG(ERROR, ("Error processing packet in round %d", m_round));
       return 1;
     }
 
@@ -124,14 +126,13 @@ int Handshake::packet_processing_loop(Connection &con)
 
     if (!new_data.is_null())
     {
-      ++round;
-      DBUG_PRINT("info", ("Round %d started", round));
+      DBUG_PRINT("info", ("Round %d started", m_round));
 
       DBUG_PRINT("info", ("Sending packet of length %d", new_data.len()));
-      int ret= con.write(new_data);
+      int ret= write_packet(new_data);
       if (ret)
       {
-        ERROR_LOG(ERROR, ("Error writing packet in round %d", round));
+        ERROR_LOG(ERROR, ("Error writing packet in round %d", m_round));
         return 1;
       }
       DBUG_PRINT("info", ("Data sent"));
@@ -139,7 +140,7 @@ int Handshake::packet_processing_loop(Connection &con)
     else if (!is_complete())
     {
       ERROR_LOG(ERROR, ("No data to send in round %d"
-                        " but handshake is not complete", round));
+                        " but handshake is not complete", m_round));
       return 1;
     }
 
@@ -148,16 +149,16 @@ int Handshake::packet_processing_loop(Connection &con)
       too many rounds.
     */
 
-    if (round > MAX_HANDSHAKE_ROUNDS)
+    if (m_round > MAX_HANDSHAKE_ROUNDS)
     {
       ERROR_LOG(ERROR, ("Authentication handshake could not be completed"
-                        " after %d rounds", round));
+                        " after %d rounds", m_round));
       return 1;
     }
 
   } while(!is_complete());
 
-  ERROR_LOG(INFO, ("Handshake completed after %d rounds", round));
+  ERROR_LOG(INFO, ("Handshake completed after %d rounds", m_round));
   return 0;
 }
 

libmysql/authentication_win/handshake.h

@@ -100,7 +100,7 @@ public:
   Handshake(const char *ssp, side_t side);
   virtual ~Handshake();
 
-  int Handshake::packet_processing_loop(Connection &con);
+  int Handshake::packet_processing_loop();
 
   bool virtual is_complete() const
   {
@@ -126,6 +126,13 @@ protected:
   /// Stores attributes of the created security context.
   ULONG  m_atts;
 
+  /**
+    Round of the handshake (starting from round 1). One round
+    consist of reading packet from the other side, processing it and
+    optionally sending a reply (see @c packet_processing_loop()).
+  */
+  unsigned int m_round;
+
   /// If non-zero, stores error code of the last failed operation.
   int  m_error;
 
@@ -152,7 +159,13 @@ protected:
     @return A blob with data to be sent to the other end or null blob if
     no more data needs to be exchanged.
   */
-  virtual Blob process_data(const Blob &data)= 0;
+  virtual Blob process_data(const Blob &data) =0;
+
+  /// Read packet from the other end.
+  virtual Blob read_packet()  =0;
+
+  /// Write packet to the other end.
+  virtual int  write_packet(Blob &data) =0;
 
 #ifndef DBUG_OFF