On Mon, Jun 10, 2019 at 07:16:26AM +0000, shalu dhamija via openssl-users wrote: > Actually while setting the callback, we can not pass the user-defined/application data. You can however attach it to the SSL connection handle as "ex_data": https://github.com/vdukhovni/postfix/blob/master/postfix/src/tls/tls_misc.c#L300-L304 https://github.com/vdukhovni/postfix/blob/master/postfix/src/tls/tls_server.c#L395-L406 https://github.com/vdukhovni/postfix/blob/master/postfix/src/tls/tls_server.c#L812-L817 and retrieve it from the SSL handle as needed: https://github.com/vdukhovni/postfix/blob/master/postfix/src/tls/tls_server.c#L265 -- Viktor.