Edit File: BIO_set_accept_bios.3
.\" Automatically generated by Pod::Man 4.11 (Pod::Simple 3.35) .\" .\" Standard preamble: .\" ======================================================================== .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. \*(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- .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" '' . ds C` . ds C' 'br\} .\" .\" Escape single quotes in literal strings from groff's Unicode transform. .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" .\" If the F register is >0, we'll generate index entries on stderr for .\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index .\" entries marked with X<> in POD. Of course, you'll have to process the .\" output yourself in some meaningful fashion. .\" .\" Avoid warning from groff about undefined register 'F'. .de IX .. .nr rF 0 .if \n(.g .if rF .nr rF 1 .if (\n(rF:(\n(.g==0)) \{\ . if \nF \{\ . de IX . tm Index:\\$1\t\\n%\t"\\$2" .. . if !\nF==2 \{\ . nr % 0 . nr F 2 . \} . \} .\} .rr rF .\" .\" 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 "2019-12-20" "1.0.2u" "OpenSSL" .\" For nroff, turn off justification. Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" BIO_s_accept, BIO_set_accept_port, BIO_get_accept_port, BIO_new_accept, 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> \& \& BIO_METHOD *BIO_s_accept(void); \& \& long BIO_set_accept_port(BIO *b, char *name); \& char *BIO_get_accept_port(BIO *b); \& \& BIO *BIO_new_accept(char *host_port); \& \& long BIO_set_nbio_accept(BIO *b, int n); \& long BIO_set_accept_bios(BIO *b, char *bio); \& \& long BIO_set_bind_mode(BIO *b, long mode); \& long BIO_get_bind_mode(BIO *b, long dummy); \& \& #define BIO_BIND_NORMAL 0 \& #define BIO_BIND_REUSEADDR_IF_UNUSED 1 \& #define BIO_BIND_REUSEADDR 2 \& \& int BIO_do_accept(BIO *b); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" \&\fBBIO_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 \fBBIO_puts()\fR but not \fBBIO_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 \fBBIO_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 \&\fBBIO_get_fd()\fR and \fBBIO_set_fd()\fR can be called to retrieve or set the accept socket. See \fBBIO_s_fd\fR\|(3) .PP \&\fBBIO_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. The host can be can be \*(L"*\*(R" which is interpreted as meaning any interface; \*(L"port\*(R" has the same syntax as the port specified in \fBBIO_set_conn_port()\fR for connect BIOs, that is it can be a numerical port string or a string to lookup using \fBgetservbyname()\fR and a string table. .PP \&\fBBIO_new_accept()\fR combines \fBBIO_new()\fR and \fBBIO_set_accept_port()\fR into a single call: that is it creates a new accept \s-1BIO\s0 with port \&\fBhost_port\fR. .PP \&\fBBIO_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 \&\fBBIO_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 BIO\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 \&\fBBIO_set_bind_mode()\fR and \fBBIO_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 \&\fBBIO_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 \fBBIO_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 \fBBIO_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 \fBBIO_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 \fBBIO_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 \fBBIO_do_accept()\fR is called to await an incoming connection it is possible for \&\fBBIO_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 \&\fBBIO_set_accept_port()\fR, \fBBIO_get_accept_port()\fR, \fBBIO_set_nbio_accept()\fR, \&\fBBIO_set_accept_bios()\fR, \fBBIO_set_bind_mode()\fR, \fBBIO_get_bind_mode()\fR and \&\fBBIO_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"); \& \& /* 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); \& } \& \& /* 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"); \& \& 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