NetBSD/lib/libcrypto/man/SSL_CTX_set_msg_callback.3

.\"	$NetBSD: SSL_CTX_set_msg_callback.3,v 1.1 2003/07/24 14:16:44 itojun Exp $
.\"
.\" Automatically generated by Pod::Man version 1.02
.\" Thu Jul 24 13:08:12 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_CTX_set_msg_callback 3"
.TH SSL_CTX_set_msg_callback 3 "0.9.7b" "2002-08-15" "OpenSSL"
.UC
.SH "NAME"
SSL_CTX_set_msg_callback, SSL_CTX_set_msg_callback_arg, SSL_set_msg_callback, SSL_get_msg_callback_arg \- install callback for observing protocol messages
.SH "LIBRARY"
libcrypto, -lcrypto
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/ssl.h>
.Ve
.Vb 2
\& void SSL_CTX_set_msg_callback(SSL_CTX *ctx, void (*cb)(int write_p, int version, int content_type, const void *buf, size_t len, SSL *ssl, void *arg));
\& void SSL_CTX_set_msg_callback_arg(SSL_CTX *ctx, void *arg);
.Ve
.Vb 2
\& void SSL_set_msg_callback(SSL_CTX *ctx, void (*cb)(int write_p, int version, int content_type, const void *buf, size_t len, SSL *ssl, void *arg));
\& void SSL_set_msg_callback_arg(SSL_CTX *ctx, void *arg);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fISSL_CTX_set_msg_callback()\fR or \fISSL_set_msg_callback()\fR can be used to
define a message callback function \fIcb\fR for observing all \s-1SSL/TLS\s0
protocol messages (such as handshake messages) that are received or
sent.  \fISSL_CTX_set_msg_callback_arg()\fR and \fISSL_set_msg_callback_arg()\fR
can be used to set argument \fIarg\fR to the callback function, which is
available for arbitrary application use.
.PP
\&\fISSL_CTX_set_msg_callback()\fR and \fISSL_CTX_set_msg_callback_arg()\fR specify
default settings that will be copied to new \fB\s-1SSL\s0\fR objects by
SSL_new(3). \fISSL_set_msg_callback()\fR and
\&\fISSL_set_msg_callback_arg()\fR modify the actual settings of an \fB\s-1SSL\s0\fR
object. Using a \fB0\fR pointer for \fIcb\fR disables the message callback.
.PP
When \fIcb\fR is called by the \s-1SSL/TLS\s0 library for a protocol message,
the function arguments have the following meaning:
.Ip "\fIwrite_p\fR" 4
.IX Item "write_p"
This flag is \fB0\fR when a protocol message has been received and \fB1\fR
when a protocol message has been sent.
.Ip "\fIversion\fR" 4
.IX Item "version"
The protocol version according to which the protocol message is
interpreted by the library. Currently, this is one of
\&\fB\s-1SSL2_VERSION\s0\fR, \fB\s-1SSL3_VERSION\s0\fR and \fB\s-1TLS1_VERSION\s0\fR (for \s-1SSL\s0 2.0, \s-1SSL\s0
3.0 and \s-1TLS\s0 1.0, respectively).
.Ip "\fIcontent_type\fR" 4
.IX Item "content_type"
In the case of \s-1SSL\s0 2.0, this is always \fB0\fR.  In the case of \s-1SSL\s0 3.0
or \s-1TLS\s0 1.0, this is one of the \fBContentType\fR values defined in the
protocol specification (\fBchange_cipher_spec(20)\fR, \fBalert(21)\fR,
\&\fBhandshake(22)\fR; but never \fBapplication_data(23)\fR because the
callback will only be called for protocol messages).
.Ip "\fIbuf\fR, \fIlen\fR" 4
.IX Item "buf, len"
\&\fIbuf\fR points to a buffer containing the protocol message, which
consists of \fIlen\fR bytes. The buffer is no longer valid after the
callback function has returned.
.Ip "\fIssl\fR" 4
.IX Item "ssl"
The \fB\s-1SSL\s0\fR object that received or sent the message.
.Ip "\fIarg\fR" 4
.IX Item "arg"
The user-defined argument optionally defined by
\&\fISSL_CTX_set_msg_callback_arg()\fR or \fISSL_set_msg_callback_arg()\fR.
.SH "NOTES"
.IX Header "NOTES"
Protocol messages are passed to the callback function after decryption
and fragment collection where applicable. (Thus record boundaries are
not visible.)
.PP
If processing a received protocol message results in an error,
the callback function may not be called.  For example, the callback
function will never see messages that are considered too large to be
processed.
.PP
Due to automatic protocol version negotiation, \fIversion\fR is not
necessarily the protocol version used by the sender of the message: If
a \s-1TLS\s0 1.0 ClientHello message is received by an \s-1SSL\s0 3.0\-only server,
\&\fIversion\fR will be \fB\s-1SSL3_VERSION\s0\fR.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
ssl(3), SSL_new(3)
.SH "HISTORY"
.IX Header "HISTORY"
\&\fISSL_CTX_set_msg_callback()\fR, \fISSL_CTX_set_msg_callback_arg()\fR,
\&\fISSL_set_msg_callback()\fR and \fISSL_get_msg_callback_arg()\fR were added in OpenSSL 0.9.7.