[openssl-users] Blocking SSL_write possibly buffering?

Emil Dotchevski emildotchevski at gmail.com
Mon Oct 26 20:36:49 UTC 2015


I am using OpenSSL in *blocking* mode, with SSL_MODE_AUTO_RETRY set. I have
this situation:

Peer 1 (server):
SSL_write 16K bytes --> success
SSL_write N bytes, N<16K --> success
SSL_read (correctly hangs waiting for data)

Peer 2 (client):
SSL_read 16K+N bytes --> hangs

That is, Peer 1 breaks a data buffer that's larger than 16K in two pieces
and it succeeds writing both pieces but does no more writes (calls
SSL_read), while Peer 2 attempts to read the whole thing and hangs.

I'm reasoning that I'd get this behavior if for some reason the second call
to SSL_write decided to buffer up the data rather than sending it
immediately, but my reading of the documentation is that it's not supposed
to do that.

Any help is greatly appreciated!

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