ACE Tutorial 015
Building a protocol stream
The encryption implementation isn't any smarter than that of the
compressor. Still, the hooks are there for you to insert your
favorite library.
// page21.html,v 1.12 1999/09/22 03:13:54 jcej Exp
#include "Crypt.h"
#include "ace/SOCK_Stream.h"
/* The expected constructor...
*/
Crypt::Crypt( void )
: Protocol_Task()
{
}
Crypt::~Crypt(void)
{
}
/* To send the data we'll apply a signature and encryption.
*/
int Crypt::send(ACE_Message_Block *message, ACE_Time_Value *timeout)
{
ACE_DEBUG ((LM_INFO, "(%P|%t) Crypt::send() encrypting (%s)\n", message->rd_ptr() ));
// I suspect that some encryptors might change the data size.
// It probably isn't safe to create a same-size destination buffer.
ACE_Message_Block * encrypted = new ACE_Message_Block( message->size() );
// Perform a bogus encryption algorithm and add our safety
// signature. Adding the original data size is also probably
// a good idea that I haven't encorporated here.
ACE_OS::sprintf( encrypted->wr_ptr(), "ED:%s", message->rd_ptr() );
encrypted->wr_ptr( strlen(encrypted->wr_ptr())+1 );
// Send the encrypted data down the stream to the next module
this->put_next( encrypted );
// We're done here.
message->release();
return( 0 );
}
/* The upstream movement requires that we decrypt what the peer has
given us.
*/
int Crypt::recv(ACE_Message_Block *message, ACE_Time_Value *timeout)
{
ACE_DEBUG ((LM_INFO, "(%P|%t) Crypt::recv() decrypting (%s)\n", message->rd_ptr() ));
// Create a destination for the decrypted data. The same
// block size caveat exists of course.
ACE_Message_Block * decrypted = new ACE_Message_Block( message->size() );
// Check the signature as expected.
if( ACE_OS::strncmp( message->rd_ptr(), "ED:", 3 ) )
{
ACE_DEBUG ((LM_INFO, "(%P|%t) Improperly encrypted data.\n" ));
message->release();
return(-1);
}
// Don't forget to skip past the signature before decrypting
// or things will be quite exciting!
message->rd_ptr( 3 );
// Perform a bogus decryption algorithm
ACE_OS::sprintf( decrypted->wr_ptr(), "%s", message->rd_ptr() );
decrypted->wr_ptr( strlen(decrypted->wr_ptr())+1 );
// Send the decrypted data down the stream to the next module
this->put_next( decrypted );
// We're done here.
message->release();
return( 0 );
}
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