On Saturday 31 March 2007 00:26, David Schwartz wrote: > > I see, so if I disable PARTIAL_WRITES, will that mean that it will return > > values as I wrote up there? > > PARTIAL_WRITES has no effect on the meaning of the return value. It just > controls whether or not the internal write logic tries to continue writing > if the underlying write partially completes. With or without PARTIAL_WRITES > enabled, if the socket buffer and internal SSL buffers get full after some > of the data has been accepted, you will get a partial write if the socket > is non-blocking. > > > Otherwise I fail to see the difference between allowin partial > > writes and not. > > The difference for a non-blocking socket, is that with PARTIAL_WRITES > disabled, the underlying internal write operation will be retried until it > is unable to accept any bytes at all. With PARTIAL_WRITES enabled, only one > call to the underlying internal write operation will be made. > > > Furthermore, that would mean that I should actually call > > SSL_write with new > > arguments on the same packet. > > I don't know what you mean by "the same packet". Packets are below the TCP > level and have no meaning at or above the TCP level.
Sorry, was a bit cryptic there I guess. With packet I meant, chunk of application data that I want to send. like unsigned char *buffer = "Hello"; /* this is what I call packet */ > > SSL_write(ssl, buffer + written, len - written); > > > > or am I being retarded here ? > > If a previous SSL_write has successfully queued some bytes for sending, you > don't want to send those same bytes again. In any non-blocking socket > application, you have to handle partial writes (a form of *success*) by > saving the rest of the data for when your next write attempt. It's just this I'm having a hard trouble to grasp. Normally with say 'write' I would do // pseudo code while(written < len) written += write(fd, my_packet + written, len - written); But because SSL_write handles an internal queue and calls for sending the same argument all the time I thought I would do: while( SSL_write(ssl, my_packet, len) <= 0 ) /* I assume I get SSL_WANTS_WRITE here */ Meaning, SSL_write only returns 0 - get_error returns SSL_WANTS_WRITE But with partial writes (or perhaps even otherwise) I will have to send that I could not send before while( (ret=SSL_write(ssl, my_packet + written, len - written)) <= 0 || written < len) written+=ret; /* something like that */ Meaning, SSL_write will return 0 for SSL_WANTS_WRITE if something failed and it wants to get called again, with the SAME value (my_packet + written, len-written). And return for instance the number 5 if 5 bytes has been written. Therefore, thereafter I must call (my_packet + written(5), len-written(5)) and continue to do so as long as I get SSL_WANTS_WRITE Am I wrong with this? I have also seen in the write function that a value called ret (return value on success?) is stored with the value of the initial 'len'. Which made me think that under some circuimstances the SSL_write would actually return SSL_write(buffer, len) - 0 - SSL_WANTS_WRITE SSL_write(buffer,len) - 0 - SSL_WANTS_WRITE SSL_write(buffer,len) - len - everything done Thanks for trying to explain this to me. I'm just sorry I couldn't get it the first time :/ /Tommy Wallberg ______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List openssl-users@openssl.org Automated List Manager [EMAIL PROTECTED]
