.\" Automatically generated by Pod::Man version 1.15
.\" Mon Jan 13 19:35:37 2003
.\"
.\" Standard preamble:
.\" ======================================================================
.de Sh \" Subsection heading
.br
.if t .Sp
.ne 5
.PP
\fB\\$1\fR
.PP
..
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Ip \" List item
.br
.ie \\n(.$>=3 .ne \\$3
.el .ne 3
.IP "\\$1" \\$2
..
.de Vb \" Begin verbatim text
.ft CW
.nf
.ne \\$1
..
.de Ve \" End verbatim text
.ft R

.fi
..
.\" Set up some character translations and predefined strings.  \*(-- will
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
.\" double quote, and \*(R" will give a right double quote.  | will give a
.\" real vertical bar.  \*(C+ will give a nicer C++.  Capital omega is used
.\" to do unbreakable dashes and therefore won't be available.  \*(C` and
.\" \*(C' expand to `' in nroff, nothing in troff, for use with C<>
.tr \(*W-|\(bv\*(Tr
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
.ie n \{\
.    ds -- \(*W-
.    ds PI pi
.    if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
.    if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\"  diablo 12 pitch
.    ds L" ""
.    ds R" ""
.    ds C` ""
.    ds C' ""
'br\}
.el\{\
.    ds -- \|\(em\|
.    ds PI \(*p
.    ds L" ``
.    ds R" ''
'br\}
.\"
.\" If the F register is turned on, we'll generate index entries on stderr
.\" for titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and
.\" index entries marked with X<> in POD.  Of course, you'll have to process
.\" the output yourself in some meaningful fashion.
.if \nF \{\
.    de IX
.    tm Index:\\$1\t\\n%\t"\\$2"
..
.    nr % 0
.    rr F
.\}
.\"
.\" For nroff, turn off justification.  Always turn off hyphenation; it
.\" makes way too many mistakes in technical documents.
.hy 0
.if n .na
.\"
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
.\" Fear.  Run.  Save yourself.  No user-serviceable parts.
.bd B 3
.    \" fudge factors for nroff and troff
.if n \{\
.    ds #H 0
.    ds #V .8m
.    ds #F .3m
.    ds #[ \f1
.    ds #] \fP
.\}
.if t \{\
.    ds #H ((1u-(\\\\n(.fu%2u))*.13m)
.    ds #V .6m
.    ds #F 0
.    ds #[ \&
.    ds #] \&
.\}
.    \" simple accents for nroff and troff
.if n \{\
.    ds ' \&
.    ds ` \&
.    ds ^ \&
.    ds , \&
.    ds ~ ~
.    ds /
.\}
.if t \{\
.    ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
.    ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
.    ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
.    ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
.    ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
.    ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
.\}
.    \" troff and (daisy-wheel) nroff accents
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
.ds ae a\h'-(\w'a'u*4/10)'e
.ds Ae A\h'-(\w'A'u*4/10)'E
.    \" corrections for vroff
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
.    \" for low resolution devices (crt and lpr)
.if \n(.H>23 .if \n(.V>19 \
\{\
.    ds : e
.    ds 8 ss
.    ds o a
.    ds d- d\h'-1'\(ga
.    ds D- D\h'-1'\(hy
.    ds th \o'bp'
.    ds Th \o'LP'
.    ds ae ae
.    ds Ae AE
.\}
.rm #[ #] #H #V #F C
.\" ======================================================================
.\"
.IX Title "SSL_write 3"
.TH SSL_write 3 "0.9.7" "2003-01-13" "OpenSSL"
.UC
.SH "NAME"
SSL_write \- write bytes to a \s-1TLS/SSL\s0 connection.
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/ssl.h>
.Ve
.Vb 1
\& int SSL_write(SSL *ssl, const void *buf, int num);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fISSL_write()\fR writes \fBnum\fR bytes from the buffer \fBbuf\fR into the specified
\&\fBssl\fR connection.
.SH "NOTES"
.IX Header "NOTES"
If necessary, \fISSL_write()\fR will negotiate a \s-1TLS/SSL\s0 session, if
not already explicitly performed by SSL_connect(3) or
SSL_accept(3). If the
peer requests a re-negotiation, it will be performed transparently during
the \fISSL_write()\fR operation. The behaviour of \fISSL_write()\fR depends on the
underlying \s-1BIO\s0. 
.PP
For the transparent negotiation to succeed, the \fBssl\fR must have been
initialized to client or server mode. This is being done by calling
SSL_set_connect_state(3) or \fISSL_set_accept_state()\fR
before the first call to an SSL_read(3) or \fISSL_write()\fR function.
.PP
If the underlying \s-1BIO\s0 is \fBblocking\fR, \fISSL_write()\fR will only return, once the
write operation has been finished or an error occurred, except when a
renegotiation take place, in which case a \s-1SSL_ERROR_WANT_READ\s0 may occur. 
This behaviour can be controlled with the \s-1SSL_MODE_AUTO_RETRY\s0 flag of the
SSL_CTX_set_mode(3) call.
.PP
If the underlying \s-1BIO\s0 is \fBnon-blocking\fR, \fISSL_write()\fR will also return,
when the underlying \s-1BIO\s0 could not satisfy the needs of \fISSL_write()\fR
to continue the operation. In this case a call to
SSL_get_error(3) with the
return value of \fISSL_write()\fR will yield \fB\s-1SSL_ERROR_WANT_READ\s0\fR or
\&\fB\s-1SSL_ERROR_WANT_WRITE\s0\fR. As at any time a re-negotiation is possible, a
call to \fISSL_write()\fR can also cause read operations! The calling process
then must repeat the call after taking appropriate action to satisfy the
needs of \fISSL_write()\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.
.PP
\&\fISSL_write()\fR will only return with success, when the complete contents
of \fBbuf\fR of length \fBnum\fR has been written. This default behaviour
can be changed with the \s-1SSL_MODE_ENABLE_PARTIAL_WRITE\s0 option of
SSL_CTX_set_mode(3). When this flag is set,
\&\fISSL_write()\fR will also return with success, when a partial write has been
successfully completed. In this case the \fISSL_write()\fR operation is considered
completed. The bytes are sent and a new \fISSL_write()\fR operation with a new
buffer (with the already sent bytes removed) must be started.
A partial write is performed with the size of a message block, which is
16kB for SSLv3/TLSv1.
.SH "WARNING"
.IX Header "WARNING"
When an \fISSL_write()\fR operation has to be repeated because of
\&\fB\s-1SSL_ERROR_WANT_READ\s0\fR or \fB\s-1SSL_ERROR_WANT_WRITE\s0\fR, it must be repeated
with the same arguments.
.PP
When calling \fISSL_write()\fR with num=0 bytes to be sent the behaviour is
undefined.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
The following return values can occur:
.Ip ">0" 4
.IX Item ">0"
The write operation was successful, the return value is the number of
bytes actually written to the \s-1TLS/SSL\s0 connection.
.Ip "0" 4
The write operation was not successful. Probably the underlying connection
was closed. Call \fISSL_get_error()\fR with the return value \fBret\fR to find out,
whether an error occurred or the connection was shut down cleanly
(\s-1SSL_ERROR_ZERO_RETURN\s0).
.Sp
SSLv2 (deprecated) does not support a shutdown alert protocol, so it can
only be detected, whether the underlying connection was closed. It cannot
be checked, why the closure happened.
.Ip "<0" 4
.IX Item "<0"
The write operation was not successful, because either an error occurred
or action must be taken by the calling process. 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_read(3),
SSL_CTX_set_mode(3), SSL_CTX_new(3),
SSL_connect(3), SSL_accept(3)
SSL_set_connect_state(3),
ssl(3), bio(3)