NetBSD/lib/libcrypto/man/SSL_shutdown.3

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.\" $NetBSD: SSL_shutdown.3,v 1.1 2001/04/12 10:45:44 itojun Exp $
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.\" ======================================================================
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.IX Title "SSL_shutdown 3"
.TH SSL_shutdown 3 "0.9.6a" "2001-04-12" "OpenSSL"
.UC
.SH "NAME"
SSL_shutdown \- shut down a \s-1TLS/SSL\s0 connection
.SH "LIBRARY"
libcrypto, -lcrypto
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/ssl.h>
.Ve
.Vb 1
\& int SSL_shutdown(SSL *ssl);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fISSL_shutdown()\fR shuts down an active \s-1TLS/SSL\s0 connection. It sends the
\&\*(L"close notify\*(R" shutdown alert to the peer.
.SH "NOTES"
.IX Header "NOTES"
\&\fISSL_shutdown()\fR tries to send the \*(L"close notify\*(R" shutdown alert to the peer.
Whether the operation succeeds or not, the \s-1SSL_SENT_SHUTDOWN\s0 flag is set and
a currently open session is considered closed and good and will be kept in the
session cache for further reuse.
.PP
The behaviour of \fISSL_shutdown()\fR depends on the underlying \s-1BIO\s0.
.PP
If the underlying \s-1BIO\s0 is \fBblocking\fR, \fISSL_shutdown()\fR will only return once the
handshake has been finished or an error occurred.
.PP
If the underlying \s-1BIO\s0 is \fBnon-blocking\fR, \fISSL_shutdown()\fR will also return
when the underlying \s-1BIO\s0 could not satisfy the needs of \fISSL_shutdown()\fR
to continue the handshake. In this case a call to \fISSL_get_error()\fR with the
return value of \fISSL_shutdown()\fR will yield \fB\s-1SSL_ERROR_WANT_READ\s0\fR or
\&\fB\s-1SSL_ERROR_WANT_WRITE\s0\fR. The calling process then must repeat the call after
taking appropriate action to satisfy the needs of \fISSL_shutdown()\fR.
The action depends on the underlying \s-1BIO\s0. When using a non-blocking socket,
nothing is to be done, but \fIselect()\fR can be used to check for the required
condition. When using a buffering \s-1BIO\s0, like a \s-1BIO\s0 pair, data must be written
into or retrieved out of the \s-1BIO\s0 before being able to continue.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
The following return values can occur:
.Ip "1" 4
.IX Item "1"
The shutdown was successfully completed.
.Ip "0" 4
The shutdown was not successful. Call \fISSL_get_error()\fR with the return
value \fBret\fR to find out the reason.
.Ip "\-1" 4
.IX Item "-1"
The shutdown was not successful because a fatal error occurred either
at the protocol level or a connection failure occurred. It can also occur of
action is need to continue the operation for non-blocking BIOs.
Call \fISSL_get_error()\fR with the return value \fBret\fR to find out the reason.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
SSL_get_error(3), SSL_connect(3),
SSL_accept(3), SSL_set_shutdown(3),
SSL_clear(3), SSL_free(3),
ssl(3), openssl_bio(3)