My client can not receive data in blocking mode

Michael Wojcik Michael.Wojcik at
Fri Sep 27 18:50:17 UTC 2019

From: openssl-users [mailto:openssl-users-bounces at] On Behalf Of llf at
Sent: Friday, September 27, 2019 11:42

> The data seems be cached on the server and not be sent out.

Is it? Have you run a network trace? Have you tried waiting longer than 100ms?

If your server is sending a segment shorter than the MSS, you may be seeing Nagle / Delayed ACK interaction. If that's holding up the end of a TLS record, then select will indicate the socket is readable but a subsequent SSL_read will block until the remainder of the record has been received.

A network trace, even without decryption, will give you some idea of when data is being sent, and how much.

Michael Wojcik
Distinguished Engineer, Micro Focus

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