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129 .\" ========================================================================
131 .IX Title "BIO_S_ACCEPT 3"
132 .TH BIO_S_ACCEPT 3 "2018-11-20" "1.1.1a" "OpenSSL"
133 .\" For nroff, turn off justification. Always turn off hyphenation; it makes
134 .\" way too many mistakes in technical documents.
138 BIO_s_accept, BIO_set_accept_name, BIO_set_accept_port, BIO_get_accept_name, BIO_get_accept_port, BIO_new_accept, BIO_set_nbio_accept, BIO_set_accept_bios, BIO_get_peer_name, BIO_get_peer_port, BIO_get_accept_ip_family, BIO_set_accept_ip_family, BIO_set_bind_mode, BIO_get_bind_mode, BIO_do_accept \- accept BIO
140 .IX Header "SYNOPSIS"
142 \& #include <openssl/bio.h>
144 \& const BIO_METHOD *BIO_s_accept(void);
146 \& long BIO_set_accept_name(BIO *b, char *name);
147 \& char *BIO_get_accept_name(BIO *b);
149 \& long BIO_set_accept_port(BIO *b, char *port);
150 \& char *BIO_get_accept_port(BIO *b);
152 \& BIO *BIO_new_accept(char *host_port);
154 \& long BIO_set_nbio_accept(BIO *b, int n);
155 \& long BIO_set_accept_bios(BIO *b, char *bio);
157 \& char *BIO_get_peer_name(BIO *b);
158 \& char *BIO_get_peer_port(BIO *b);
159 \& long BIO_get_accept_ip_family(BIO *b);
160 \& long BIO_set_accept_ip_family(BIO *b, long family);
162 \& long BIO_set_bind_mode(BIO *b, long mode);
163 \& long BIO_get_bind_mode(BIO *b);
165 \& int BIO_do_accept(BIO *b);
168 .IX Header "DESCRIPTION"
169 \&\fIBIO_s_accept()\fR returns the accept \s-1BIO\s0 method. This is a wrapper
170 round the platform's \s-1TCP/IP\s0 socket accept routines.
172 Using accept BIOs, \s-1TCP/IP\s0 connections can be accepted and data
173 transferred using only \s-1BIO\s0 routines. In this way any platform
174 specific operations are hidden by the \s-1BIO\s0 abstraction.
176 Read and write operations on an accept \s-1BIO\s0 will perform I/O
177 on the underlying connection. If no connection is established
178 and the port (see below) is set up properly then the \s-1BIO\s0
179 waits for an incoming connection.
181 Accept BIOs support \fIBIO_puts()\fR but not \fIBIO_gets()\fR.
183 If the close flag is set on an accept \s-1BIO\s0 then any active
184 connection on that chain is shutdown and the socket closed when
185 the \s-1BIO\s0 is freed.
187 Calling \fIBIO_reset()\fR on an accept \s-1BIO\s0 will close any active
188 connection and reset the \s-1BIO\s0 into a state where it awaits another
191 \&\fIBIO_get_fd()\fR and \fIBIO_set_fd()\fR can be called to retrieve or set
192 the accept socket. See \fIBIO_s_fd\fR\|(3)
194 \&\fIBIO_set_accept_name()\fR uses the string \fBname\fR to set the accept
195 name. The name is represented as a string of the form \*(L"host:port\*(R",
196 where \*(L"host\*(R" is the interface to use and \*(L"port\*(R" is the port.
197 The host can be \*(L"*\*(R" or empty which is interpreted as meaning
198 any interface. If the host is an IPv6 address, it has to be
199 enclosed in brackets, for example \*(L"[::1]:https\*(R". \*(L"port\*(R" has the
200 same syntax as the port specified in \fIBIO_set_conn_port()\fR for
201 connect BIOs, that is it can be a numerical port string or a
202 string to lookup using \fIgetservbyname()\fR and a string table.
204 \&\fIBIO_set_accept_port()\fR uses the string \fBport\fR to set the accept
205 port. \*(L"port\*(R" has the same syntax as the port specified in
206 \&\fIBIO_set_conn_port()\fR for connect BIOs, that is it can be a numerical
207 port string or a string to lookup using \fIgetservbyname()\fR and a string
210 \&\fIBIO_new_accept()\fR combines \fIBIO_new()\fR and \fIBIO_set_accept_name()\fR into
211 a single call: that is it creates a new accept \s-1BIO\s0 with port
214 \&\fIBIO_set_nbio_accept()\fR sets the accept socket to blocking mode
215 (the default) if \fBn\fR is 0 or non blocking mode if \fBn\fR is 1.
217 \&\fIBIO_set_accept_bios()\fR can be used to set a chain of BIOs which
218 will be duplicated and prepended to the chain when an incoming
219 connection is received. This is useful if, for example, a
220 buffering or \s-1SSL BIO\s0 is required for each connection. The
221 chain of BIOs must not be freed after this call, they will
222 be automatically freed when the accept \s-1BIO\s0 is freed.
224 \&\fIBIO_set_bind_mode()\fR and \fIBIO_get_bind_mode()\fR set and retrieve
225 the current bind mode. If \fB\s-1BIO_BIND_NORMAL\s0\fR (the default) is set
226 then another socket cannot be bound to the same port. If
227 \&\fB\s-1BIO_BIND_REUSEADDR\s0\fR is set then other sockets can bind to the
228 same port. If \fB\s-1BIO_BIND_REUSEADDR_IF_UNUSED\s0\fR is set then and
229 attempt is first made to use \s-1BIO_BIN_NORMAL,\s0 if this fails
230 and the port is not in use then a second attempt is made
231 using \fB\s-1BIO_BIND_REUSEADDR\s0\fR.
233 \&\fIBIO_do_accept()\fR serves two functions. When it is first
234 called, after the accept \s-1BIO\s0 has been setup, it will attempt
235 to create the accept socket and bind an address to it. Second
236 and subsequent calls to \fIBIO_do_accept()\fR will await an incoming
237 connection, or request a retry in non blocking mode.
240 When an accept \s-1BIO\s0 is at the end of a chain it will await an
241 incoming connection before processing I/O calls. When an accept
242 \&\s-1BIO\s0 is not at then end of a chain it passes I/O calls to the next
243 \&\s-1BIO\s0 in the chain.
245 When a connection is established a new socket \s-1BIO\s0 is created for
246 the connection and appended to the chain. That is the chain is now
247 accept\->socket. This effectively means that attempting I/O on
248 an initial accept socket will await an incoming connection then
251 If any additional BIOs have been set using \fIBIO_set_accept_bios()\fR
252 then they are placed between the socket and the accept \s-1BIO,\s0
253 that is the chain will be accept\->otherbios\->socket.
255 If a server wishes to process multiple connections (as is normally
256 the case) then the accept \s-1BIO\s0 must be made available for further
257 incoming connections. This can be done by waiting for a connection and
261 \& connection = BIO_pop(accept);
264 After this call \fBconnection\fR will contain a \s-1BIO\s0 for the recently
265 established connection and \fBaccept\fR will now be a single \s-1BIO\s0
266 again which can be used to await further incoming connections.
267 If no further connections will be accepted the \fBaccept\fR can
268 be freed using \fIBIO_free()\fR.
270 If only a single connection will be processed it is possible to
271 perform I/O using the accept \s-1BIO\s0 itself. This is often undesirable
272 however because the accept \s-1BIO\s0 will still accept additional incoming
273 connections. This can be resolved by using \fIBIO_pop()\fR (see above)
274 and freeing up the accept \s-1BIO\s0 after the initial connection.
276 If the underlying accept socket is non-blocking and \fIBIO_do_accept()\fR is
277 called to await an incoming connection it is possible for
278 \&\fIBIO_should_io_special()\fR with the reason \s-1BIO_RR_ACCEPT.\s0 If this happens
279 then it is an indication that an accept attempt would block: the application
280 should take appropriate action to wait until the underlying socket has
281 accepted a connection and retry the call.
283 \&\fIBIO_set_accept_name()\fR, \fIBIO_get_accept_name()\fR, \fIBIO_set_accept_port()\fR,
284 \&\fIBIO_get_accept_port()\fR, \fIBIO_set_nbio_accept()\fR, \fIBIO_set_accept_bios()\fR,
285 \&\fIBIO_get_peer_name()\fR, \fIBIO_get_peer_port()\fR,
286 \&\fIBIO_get_accept_ip_family()\fR, \fIBIO_set_accept_ip_family()\fR,
287 \&\fIBIO_set_bind_mode()\fR, \fIBIO_get_bind_mode()\fR and \fIBIO_do_accept()\fR are macros.
289 .IX Header "RETURN VALUES"
290 \&\fIBIO_do_accept()\fR,
291 \&\fIBIO_set_accept_name()\fR, \fIBIO_set_accept_port()\fR, \fIBIO_set_nbio_accept()\fR,
292 \&\fIBIO_set_accept_bios()\fR, \fIBIO_set_accept_ip_family()\fR, and \fIBIO_set_bind_mode()\fR
293 return 1 for success and 0 or \-1 for failure.
295 \&\fIBIO_get_accept_name()\fR returns the accept name or \s-1NULL\s0 on error.
296 \&\fIBIO_get_peer_name()\fR returns the peer name or \s-1NULL\s0 on error.
298 \&\fIBIO_get_accept_port()\fR returns the accept port as a string or \s-1NULL\s0 on error.
299 \&\fIBIO_get_peer_port()\fR returns the peer port as a string or \s-1NULL\s0 on error.
300 \&\fIBIO_get_accept_ip_family()\fR returns the \s-1IP\s0 family or \-1 on error.
302 \&\fIBIO_get_bind_mode()\fR returns the set of \fB\s-1BIO_BIND\s0\fR flags, or \-1 on failure.
304 \&\fIBIO_new_accept()\fR returns a \s-1BIO\s0 or \s-1NULL\s0 on error.
307 This example accepts two connections on port 4444, sends messages
308 down each and finally closes both down.
311 \& BIO *abio, *cbio, *cbio2;
313 \& /* First call to BIO_accept() sets up accept BIO */
314 \& abio = BIO_new_accept("4444");
315 \& if (BIO_do_accept(abio) <= 0) {
316 \& fprintf(stderr, "Error setting up accept\en");
317 \& ERR_print_errors_fp(stderr);
321 \& /* Wait for incoming connection */
322 \& if (BIO_do_accept(abio) <= 0) {
323 \& fprintf(stderr, "Error accepting connection\en");
324 \& ERR_print_errors_fp(stderr);
327 \& fprintf(stderr, "Connection 1 established\en");
329 \& /* Retrieve BIO for connection */
330 \& cbio = BIO_pop(abio);
331 \& BIO_puts(cbio, "Connection 1: Sending out Data on initial connection\en");
332 \& fprintf(stderr, "Sent out data on connection 1\en");
334 \& /* Wait for another connection */
335 \& if (BIO_do_accept(abio) <= 0) {
336 \& fprintf(stderr, "Error accepting connection\en");
337 \& ERR_print_errors_fp(stderr);
340 \& fprintf(stderr, "Connection 2 established\en");
342 \& /* Close accept BIO to refuse further connections */
343 \& cbio2 = BIO_pop(abio);
345 \& BIO_puts(cbio2, "Connection 2: Sending out Data on second\en");
346 \& fprintf(stderr, "Sent out data on connection 2\en");
348 \& BIO_puts(cbio, "Connection 1: Second connection established\en");
350 \& /* Close the two established connections */
355 .IX Header "COPYRIGHT"
356 Copyright 2000\-2018 The OpenSSL Project Authors. All Rights Reserved.
358 Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use
359 this file except in compliance with the License. You can obtain a copy
360 in the file \s-1LICENSE\s0 in the source distribution or at
361 <https://www.openssl.org/source/license.html>.