1 .\" $NetBSD: SSL_CTX_set_mode.3,v 1.14 2015/06/12 17:01:14 christos Exp $
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135 .\" ========================================================================
137 .IX Title "SSL_CTX_set_mode 3"
138 .TH SSL_CTX_set_mode 3 "2015-01-13" "1.0.1n" "OpenSSL"
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144 SSL_CTX_set_mode, SSL_set_mode, SSL_CTX_get_mode, SSL_get_mode \- manipulate SSL engine mode
148 .IX Header "SYNOPSIS"
150 \& #include <openssl/ssl.h>
152 \& long SSL_CTX_set_mode(SSL_CTX *ctx, long mode);
153 \& long SSL_set_mode(SSL *ssl, long mode);
155 \& long SSL_CTX_get_mode(SSL_CTX *ctx);
156 \& long SSL_get_mode(SSL *ssl);
159 .IX Header "DESCRIPTION"
160 \&\fISSL_CTX_set_mode()\fR adds the mode set via bitmask in \fBmode\fR to \fBctx\fR.
161 Options already set before are not cleared.
163 \&\fISSL_set_mode()\fR adds the mode set via bitmask in \fBmode\fR to \fBssl\fR.
164 Options already set before are not cleared.
166 \&\fISSL_CTX_get_mode()\fR returns the mode set for \fBctx\fR.
168 \&\fISSL_get_mode()\fR returns the mode set for \fBssl\fR.
171 The following mode changes are available:
172 .IP "\s-1SSL_MODE_ENABLE_PARTIAL_WRITE\s0" 4
173 .IX Item "SSL_MODE_ENABLE_PARTIAL_WRITE"
174 Allow SSL_write(..., n) to return r with 0 < r < n (i.e. report success
175 when just a single record has been written). When not set (the default),
176 \&\fISSL_write()\fR will only report success once the complete chunk was written.
177 Once \fISSL_write()\fR returns with r, r bytes have been successfully written
178 and the next call to \fISSL_write()\fR must only send the n\-r bytes left,
179 imitating the behaviour of \fIwrite()\fR.
180 .IP "\s-1SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER\s0" 4
181 .IX Item "SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER"
182 Make it possible to retry \fISSL_write()\fR with changed buffer location
183 (the buffer contents must stay the same). This is not the default to avoid
184 the misconception that non-blocking \fISSL_write()\fR behaves like
185 non-blocking \fIwrite()\fR.
186 .IP "\s-1SSL_MODE_AUTO_RETRY\s0" 4
187 .IX Item "SSL_MODE_AUTO_RETRY"
188 Never bother the application with retries if the transport is blocking.
189 If a renegotiation take place during normal operation, a
190 \&\fISSL_read\fR\|(3) or \fISSL_write\fR\|(3) would return
191 with \-1 and indicate the need to retry with \s-1SSL_ERROR_WANT_READ.\s0
192 In a non-blocking environment applications must be prepared to handle
193 incomplete read/write operations.
194 In a blocking environment, applications are not always prepared to
195 deal with read/write operations returning without success report. The
196 flag \s-1SSL_MODE_AUTO_RETRY\s0 will cause read/write operations to only
197 return after the handshake and successful completion.
198 .IP "\s-1SSL_MODE_RELEASE_BUFFERS\s0" 4
199 .IX Item "SSL_MODE_RELEASE_BUFFERS"
200 When we no longer need a read buffer or a write buffer for a given \s-1SSL,\s0
201 then release the memory we were using to hold it. Released memory is
202 either appended to a list of unused \s-1RAM\s0 chunks on the \s-1SSL_CTX,\s0 or simply
203 freed if the list of unused chunks would become longer than
204 \&\s-1SSL_CTX\-\s0>freelist_max_len, which defaults to 32. Using this flag can
205 save around 34k per idle \s-1SSL\s0 connection.
206 This flag has no effect on \s-1SSL\s0 v2 connections, or on \s-1DTLS\s0 connections.
207 .IP "\s-1SSL_MODE_SEND_FALLBACK_SCSV\s0" 4
208 .IX Item "SSL_MODE_SEND_FALLBACK_SCSV"
209 Send \s-1TLS_FALLBACK_SCSV\s0 in the ClientHello.
210 To be set only by applications that reconnect with a downgraded protocol
211 version; see draft\-ietf\-tls\-downgrade\-scsv\-00 for details.
213 \&\s-1DO NOT ENABLE THIS\s0 if your application attempts a normal handshake.
214 Only use this in explicit fallback retries, following the guidance
215 in draft\-ietf\-tls\-downgrade\-scsv\-00.
217 .IX Header "RETURN VALUES"
218 \&\fISSL_CTX_set_mode()\fR and \fISSL_set_mode()\fR return the new mode bitmask
219 after adding \fBmode\fR.
221 \&\fISSL_CTX_get_mode()\fR and \fISSL_get_mode()\fR return the current bitmask.
223 .IX Header "SEE ALSO"
224 \&\fIssl\fR\|(3), \fISSL_read\fR\|(3), \fISSL_write\fR\|(3)
227 \&\s-1SSL_MODE_AUTO_RETRY\s0 as been added in OpenSSL 0.9.6.