- update OpenSSL to 0.9.8

[dragonfly.git] / secure / lib / libcrypto / man / BIO_s_accept.3

.\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.14
.\"
.\" 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 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.
.    \" 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 "BIO_s_accept 3"
.TH BIO_s_accept 3 "2005-07-06" "0.9.8" "OpenSSL"
.SH "NAME"
BIO_s_accept, BIO_set_accept_port, BIO_get_accept_port,
BIO_set_nbio_accept, BIO_set_accept_bios, BIO_set_bind_mode,
BIO_get_bind_mode, BIO_do_accept \- accept BIO
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/bio.h>
.Ve
.PP
.Vb 1
\& BIO_METHOD *BIO_s_accept(void);
.Ve
.PP
.Vb 2
\& long BIO_set_accept_port(BIO *b, char *name);
\& char *BIO_get_accept_port(BIO *b);
.Ve
.PP
.Vb 1
\& BIO *BIO_new_accept(char *host_port);
.Ve
.PP
.Vb 2
\& long BIO_set_nbio_accept(BIO *b, int n);
\& long BIO_set_accept_bios(BIO *b, char *bio);
.Ve
.PP
.Vb 2
\& long BIO_set_bind_mode(BIO *b, long mode);
\& long BIO_get_bind_mode(BIO *b, long dummy);
.Ve
.PP
.Vb 3
\& #define BIO_BIND_NORMAL                0
\& #define BIO_BIND_REUSEADDR_IF_UNUSED   1
\& #define BIO_BIND_REUSEADDR             2
.Ve
.PP
.Vb 1
\& int BIO_do_accept(BIO *b);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fIBIO_s_accept()\fR returns the accept \s-1BIO\s0 method. This is a wrapper
round the platform's \s-1TCP/IP\s0 socket accept routines.
.PP
Using accept BIOs, \s-1TCP/IP\s0 connections can be accepted and data
transferred using only \s-1BIO\s0 routines. In this way any platform
specific operations are hidden by the \s-1BIO\s0 abstraction.
.PP
Read and write operations on an accept \s-1BIO\s0 will perform I/O
on the underlying connection. If no connection is established
and the port (see below) is set up properly then the \s-1BIO\s0
waits for an incoming connection.
.PP
Accept BIOs support \fIBIO_puts()\fR but not \fIBIO_gets()\fR.
.PP
If the close flag is set on an accept \s-1BIO\s0 then any active
connection on that chain is shutdown and the socket closed when
the \s-1BIO\s0 is freed.
.PP
Calling \fIBIO_reset()\fR on a accept \s-1BIO\s0 will close any active
connection and reset the \s-1BIO\s0 into a state where it awaits another
incoming connection.
.PP
\&\fIBIO_get_fd()\fR and \fIBIO_set_fd()\fR can be called to retrieve or set
the accept socket. See \fIBIO_s_fd\fR\|(3)
.PP
\&\fIBIO_set_accept_port()\fR uses the string \fBname\fR to set the accept
port. The port is represented as a string of the form \*(L"host:port\*(R",
where \*(L"host\*(R" is the interface to use and \*(L"port\*(R" is the port.
Either or both values can be \*(L"*\*(R" which is interpreted as meaning
any interface or port respectively. \*(L"port\*(R" has the same syntax
as the port specified in \fIBIO_set_conn_port()\fR for connect BIOs,
that is it can be a numerical port string or a string to lookup
using \fIgetservbyname()\fR and a string table.
.PP
\&\fIBIO_new_accept()\fR combines \fIBIO_new()\fR and \fIBIO_set_accept_port()\fR into
a single call: that is it creates a new accept \s-1BIO\s0 with port
\&\fBhost_port\fR.
.PP
\&\fIBIO_set_nbio_accept()\fR sets the accept socket to blocking mode
(the default) if \fBn\fR is 0 or non blocking mode if \fBn\fR is 1.
.PP
\&\fIBIO_set_accept_bios()\fR can be used to set a chain of BIOs which
will be duplicated and prepended to the chain when an incoming
connection is received. This is useful if, for example, a 
buffering or \s-1SSL\s0 \s-1BIO\s0 is required for each connection. The
chain of BIOs must not be freed after this call, they will
be automatically freed when the accept \s-1BIO\s0 is freed.
.PP
\&\fIBIO_set_bind_mode()\fR and \fIBIO_get_bind_mode()\fR set and retrieve
the current bind mode. If \s-1BIO_BIND_NORMAL\s0 (the default) is set
then another socket cannot be bound to the same port. If
\&\s-1BIO_BIND_REUSEADDR\s0 is set then other sockets can bind to the
same port. If \s-1BIO_BIND_REUSEADDR_IF_UNUSED\s0 is set then and
attempt is first made to use \s-1BIO_BIN_NORMAL\s0, if this fails
and the port is not in use then a second attempt is made
using \s-1BIO_BIND_REUSEADDR\s0.
.PP
\&\fIBIO_do_accept()\fR serves two functions. When it is first
called, after the accept \s-1BIO\s0 has been setup, it will attempt
to create the accept socket and bind an address to it. Second
and subsequent calls to \fIBIO_do_accept()\fR will await an incoming
connection, or request a retry in non blocking mode.
.SH "NOTES"
.IX Header "NOTES"
When an accept \s-1BIO\s0 is at the end of a chain it will await an
incoming connection before processing I/O calls. When an accept
\&\s-1BIO\s0 is not at then end of a chain it passes I/O calls to the next
\&\s-1BIO\s0 in the chain.
.PP
When a connection is established a new socket \s-1BIO\s0 is created for
the connection and appended to the chain. That is the chain is now
accept\->socket. This effectively means that attempting I/O on
an initial accept socket will await an incoming connection then
perform I/O on it.
.PP
If any additional BIOs have been set using \fIBIO_set_accept_bios()\fR
then they are placed between the socket and the accept \s-1BIO\s0,
that is the chain will be accept\->otherbios\->socket.
.PP
If a server wishes to process multiple connections (as is normally
the case) then the accept \s-1BIO\s0 must be made available for further
incoming connections. This can be done by waiting for a connection and
then calling:
.PP
.Vb 1
\& connection = BIO_pop(accept);
.Ve
.PP
After this call \fBconnection\fR will contain a \s-1BIO\s0 for the recently
established connection and \fBaccept\fR will now be a single \s-1BIO\s0
again which can be used to await further incoming connections.
If no further connections will be accepted the \fBaccept\fR can
be freed using \fIBIO_free()\fR.
.PP
If only a single connection will be processed it is possible to
perform I/O using the accept \s-1BIO\s0 itself. This is often undesirable
however because the accept \s-1BIO\s0 will still accept additional incoming
connections. This can be resolved by using \fIBIO_pop()\fR (see above)
and freeing up the accept \s-1BIO\s0 after the initial connection.
.PP
If the underlying accept socket is non-blocking and \fIBIO_do_accept()\fR is
called to await an incoming connection it is possible for
\&\fIBIO_should_io_special()\fR with the reason \s-1BIO_RR_ACCEPT\s0. If this happens
then it is an indication that an accept attempt would block: the application
should take appropriate action to wait until the underlying socket has
accepted a connection and retry the call.
.PP
\&\fIBIO_set_accept_port()\fR, \fIBIO_get_accept_port()\fR, \fIBIO_set_nbio_accept()\fR,
\&\fIBIO_set_accept_bios()\fR, \fIBIO_set_bind_mode()\fR, \fIBIO_get_bind_mode()\fR and
\&\fIBIO_do_accept()\fR are macros.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\s-1TBA\s0
.SH "EXAMPLE"
.IX Header "EXAMPLE"
This example accepts two connections on port 4444, sends messages
down each and finally closes both down.
.PP
.Vb 3
\& BIO *abio, *cbio, *cbio2;
\& ERR_load_crypto_strings();
\& abio = BIO_new_accept("4444");
.Ve
.PP
.Vb 6
\& /* First call to BIO_accept() sets up accept BIO */
\& if(BIO_do_accept(abio) <= 0) {
\&        fprintf(stderr, "Error setting up accept\en");
\&        ERR_print_errors_fp(stderr);
\&        exit(0);                
\& }
.Ve
.PP
.Vb 23
\& /* Wait for incoming connection */
\& if(BIO_do_accept(abio) <= 0) {
\&        fprintf(stderr, "Error accepting connection\en");
\&        ERR_print_errors_fp(stderr);
\&        exit(0);                
\& }
\& fprintf(stderr, "Connection 1 established\en");
\& /* Retrieve BIO for connection */
\& cbio = BIO_pop(abio);
\& BIO_puts(cbio, "Connection 1: Sending out Data on initial connection\en");
\& fprintf(stderr, "Sent out data on connection 1\en");
\& /* Wait for another connection */
\& if(BIO_do_accept(abio) <= 0) {
\&        fprintf(stderr, "Error accepting connection\en");
\&        ERR_print_errors_fp(stderr);
\&        exit(0);                
\& }
\& fprintf(stderr, "Connection 2 established\en");
\& /* Close accept BIO to refuse further connections */
\& cbio2 = BIO_pop(abio);
\& BIO_free(abio);
\& BIO_puts(cbio2, "Connection 2: Sending out Data on second\en");
\& fprintf(stderr, "Sent out data on connection 2\en");
.Ve
.PP
.Vb 4
\& BIO_puts(cbio, "Connection 1: Second connection established\en");
\& /* Close the two established connections */
\& BIO_free(cbio);
\& BIO_free(cbio2);
.Ve
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\s-1TBA\s0