2 ''' $RCSfile$$Revision$$Date$
20 .ie \\n(.$>=3 .ne \\$3
36 ''' Set up \*(-- to give an unbreakable dash;
37 ''' string Tr holds user defined translation string.
38 ''' Bell System Logo is used as a dummy character.
44 .if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
45 .if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch
48 ''' \*(M", \*(S", \*(N" and \*(T" are the equivalent of
49 ''' \*(L" and \*(R", except that they are used on ".xx" lines,
50 ''' such as .IP and .SH, which do another additional levels of
51 ''' double-quote interpretation
80 .\" If the F register is turned on, we'll generate
81 .\" index entries out stderr for the following things:
86 .\" X<> Xref (embedded
87 .\" Of course, you have to process the output yourself
88 .\" in some meaninful fashion.
91 .tm Index:\\$1\t\\n%\t"\\$2"
96 .TH SSL_write 3 "0.9.7d" "2/Sep/2004" "OpenSSL"
100 .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
101 .de CQ \" put $1 in typewriter font
107 \\&\\$2 \\$3 \\$4 \\$5 \\$6 \\$7
110 .\" @(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2
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144 . ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
145 . ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
146 . ds ? \s-2c\h'-\w'c'u*7/10'\u\h'\*(#H'\zi\d\s+2\h'\w'c'u*8/10'
147 . ds ! \s-2\(or\s+2\h'-\w'\(or'u'\v'-.8m'.\v'.8m'
148 . ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
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161 .ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
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170 . \" for low resolution devices (crt and lpr)
171 .if \n(.H>23 .if \n(.V>19 \
175 . ds v \h'-1'\o'\(aa\(ga'
191 SSL_write \- write bytes to a TLS/SSL connection.
195 \& #include <openssl/ssl.h>
198 \& int SSL_write(SSL *ssl, const void *buf, int num);
201 \fISSL_write()\fR writes \fBnum\fR bytes from the buffer \fBbuf\fR into the specified
202 \fBssl\fR connection.
204 If necessary, \fISSL_write()\fR will negotiate a TLS/SSL session, if
205 not already explicitly performed by SSL_connect(3) or
206 SSL_accept(3). If the
207 peer requests a re-negotiation, it will be performed transparently during
208 the \fISSL_write()\fR operation. The behaviour of \fISSL_write()\fR depends on the
211 For the transparent negotiation to succeed, the \fBssl\fR must have been
212 initialized to client or server mode. This is being done by calling
213 SSL_set_connect_state(3) or \fISSL_set_accept_state()\fR
214 before the first call to an SSL_read(3) or \fISSL_write()\fR function.
216 If the underlying BIO is \fBblocking\fR, \fISSL_write()\fR will only return, once the
217 write operation has been finished or an error occurred, except when a
218 renegotiation take place, in which case a SSL_ERROR_WANT_READ may occur.
219 This behaviour can be controlled with the SSL_MODE_AUTO_RETRY flag of the
220 SSL_CTX_set_mode(3) call.
222 If the underlying BIO is \fBnon-blocking\fR, \fISSL_write()\fR will also return,
223 when the underlying BIO could not satisfy the needs of \fISSL_write()\fR
224 to continue the operation. In this case a call to
225 SSL_get_error(3) with the
226 return value of \fISSL_write()\fR will yield \fBSSL_ERROR_WANT_READ\fR or
227 \fBSSL_ERROR_WANT_WRITE\fR. As at any time a re-negotiation is possible, a
228 call to \fISSL_write()\fR can also cause read operations! The calling process
229 then must repeat the call after taking appropriate action to satisfy the
230 needs of \fISSL_write()\fR. The action depends on the underlying BIO. When using a
231 non-blocking socket, nothing is to be done, but \fIselect()\fR can be used to check
232 for the required condition. When using a buffering BIO, like a BIO pair, data
233 must be written into or retrieved out of the BIO before being able to continue.
235 \fISSL_write()\fR will only return with success, when the complete contents
236 of \fBbuf\fR of length \fBnum\fR has been written. This default behaviour
237 can be changed with the SSL_MODE_ENABLE_PARTIAL_WRITE option of
238 SSL_CTX_set_mode(3). When this flag is set,
239 \fISSL_write()\fR will also return with success, when a partial write has been
240 successfully completed. In this case the \fISSL_write()\fR operation is considered
241 completed. The bytes are sent and a new \fISSL_write()\fR operation with a new
242 buffer (with the already sent bytes removed) must be started.
243 A partial write is performed with the size of a message block, which is
244 16kB for SSLv3/TLSv1.
246 When an \fISSL_write()\fR operation has to be repeated because of
247 \fBSSL_ERROR_WANT_READ\fR or \fBSSL_ERROR_WANT_WRITE\fR, it must be repeated
248 with the same arguments.
250 When calling \fISSL_write()\fR with num=0 bytes to be sent the behaviour is
253 The following return values can occur:
255 The write operation was successful, the return value is the number of
256 bytes actually written to the \s-1TLS/SSL\s0 connection.
258 The write operation was not successful. Probably the underlying connection
259 was closed. Call \fISSL_get_error()\fR with the return value \fBret\fR to find out,
260 whether an error occurred or the connection was shut down cleanly
261 (\s-1SSL_ERROR_ZERO_RETURN\s0).
263 SSLv2 (deprecated) does not support a shutdown alert protocol, so it can
264 only be detected, whether the underlying connection was closed. It cannot
265 be checked, why the closure happened.
267 The write operation was not successful, because either an error occurred
268 or action must be taken by the calling process. Call \fISSL_get_error()\fR with the
269 return value \fBret\fR to find out the reason.
271 SSL_get_error(3), SSL_read(3),
272 SSL_CTX_set_mode(3), SSL_CTX_new(3),
273 SSL_connect(3), SSL_accept(3)
274 SSL_set_connect_state(3),
278 .IX Title "SSL_write 3"
279 .IX Name "SSL_write - write bytes to a TLS/SSL connection."
283 .IX Header "SYNOPSIS"
285 .IX Header "DESCRIPTION"
291 .IX Header "RETURN VALUES"
299 .IX Header "SEE ALSO"