Update build for OpenSSL-0.9.8j upgrade.
[dragonfly.git] / secure / lib / libcrypto / man / BIO_s_accept.3
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132.\" ========================================================================
133.\"
134.IX Title "BIO_s_accept 3"
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135.TH BIO_s_accept 3 "2009-01-11" "0.9.8j" "OpenSSL"
136.\" For nroff, turn off justification. Always turn off hyphenation; it makes
137.\" way too many mistakes in technical documents.
138.if n .ad l
139.nh
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140.SH "NAME"
141BIO_s_accept, BIO_set_accept_port, BIO_get_accept_port,
142BIO_set_nbio_accept, BIO_set_accept_bios, BIO_set_bind_mode,
74dab6c2 143BIO_get_bind_mode, BIO_do_accept \- accept BIO
984263bc 144.SH "SYNOPSIS"
8b0cefbb 145.IX Header "SYNOPSIS"
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146.Vb 1
147\& #include <openssl/bio.h>
e257b235 148\&
984263bc 149\& BIO_METHOD *BIO_s_accept(void);
e257b235 150\&
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151\& long BIO_set_accept_port(BIO *b, char *name);
152\& char *BIO_get_accept_port(BIO *b);
e257b235 153\&
984263bc 154\& BIO *BIO_new_accept(char *host_port);
e257b235 155\&
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156\& long BIO_set_nbio_accept(BIO *b, int n);
157\& long BIO_set_accept_bios(BIO *b, char *bio);
e257b235 158\&
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159\& long BIO_set_bind_mode(BIO *b, long mode);
160\& long BIO_get_bind_mode(BIO *b, long dummy);
e257b235 161\&
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162\& #define BIO_BIND_NORMAL 0
163\& #define BIO_BIND_REUSEADDR_IF_UNUSED 1
164\& #define BIO_BIND_REUSEADDR 2
e257b235 165\&
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166\& int BIO_do_accept(BIO *b);
167.Ve
168.SH "DESCRIPTION"
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169.IX Header "DESCRIPTION"
170\&\fIBIO_s_accept()\fR returns the accept \s-1BIO\s0 method. This is a wrapper
171round the platform's \s-1TCP/IP\s0 socket accept routines.
984263bc 172.PP
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173Using accept BIOs, \s-1TCP/IP\s0 connections can be accepted and data
174transferred using only \s-1BIO\s0 routines. In this way any platform
175specific operations are hidden by the \s-1BIO\s0 abstraction.
984263bc 176.PP
8b0cefbb 177Read and write operations on an accept \s-1BIO\s0 will perform I/O
984263bc 178on the underlying connection. If no connection is established
8b0cefbb 179and the port (see below) is set up properly then the \s-1BIO\s0
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180waits for an incoming connection.
181.PP
182Accept BIOs support \fIBIO_puts()\fR but not \fIBIO_gets()\fR.
183.PP
8b0cefbb 184If the close flag is set on an accept \s-1BIO\s0 then any active
984263bc 185connection on that chain is shutdown and the socket closed when
8b0cefbb 186the \s-1BIO\s0 is freed.
984263bc 187.PP
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188Calling \fIBIO_reset()\fR on a accept \s-1BIO\s0 will close any active
189connection and reset the \s-1BIO\s0 into a state where it awaits another
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190incoming connection.
191.PP
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192\&\fIBIO_get_fd()\fR and \fIBIO_set_fd()\fR can be called to retrieve or set
193the accept socket. See \fIBIO_s_fd\fR\|(3)
984263bc 194.PP
8b0cefbb 195\&\fIBIO_set_accept_port()\fR uses the string \fBname\fR to set the accept
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196port. The port is represented as a string of the form \*(L"host:port\*(R",
197where \*(L"host\*(R" is the interface to use and \*(L"port\*(R" is the port.
198Either or both values can be \*(L"*\*(R" which is interpreted as meaning
199any interface or port respectively. \*(L"port\*(R" has the same syntax
200as the port specified in \fIBIO_set_conn_port()\fR for connect BIOs,
201that is it can be a numerical port string or a string to lookup
202using \fIgetservbyname()\fR and a string table.
203.PP
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204\&\fIBIO_new_accept()\fR combines \fIBIO_new()\fR and \fIBIO_set_accept_port()\fR into
205a single call: that is it creates a new accept \s-1BIO\s0 with port
206\&\fBhost_port\fR.
984263bc 207.PP
8b0cefbb 208\&\fIBIO_set_nbio_accept()\fR sets the accept socket to blocking mode
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209(the default) if \fBn\fR is 0 or non blocking mode if \fBn\fR is 1.
210.PP
8b0cefbb 211\&\fIBIO_set_accept_bios()\fR can be used to set a chain of BIOs which
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212will be duplicated and prepended to the chain when an incoming
213connection is received. This is useful if, for example, a
8b0cefbb 214buffering or \s-1SSL\s0 \s-1BIO\s0 is required for each connection. The
984263bc 215chain of BIOs must not be freed after this call, they will
8b0cefbb 216be automatically freed when the accept \s-1BIO\s0 is freed.
984263bc 217.PP
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218\&\fIBIO_set_bind_mode()\fR and \fIBIO_get_bind_mode()\fR set and retrieve
219the current bind mode. If \s-1BIO_BIND_NORMAL\s0 (the default) is set
984263bc 220then another socket cannot be bound to the same port. If
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221\&\s-1BIO_BIND_REUSEADDR\s0 is set then other sockets can bind to the
222same port. If \s-1BIO_BIND_REUSEADDR_IF_UNUSED\s0 is set then and
223attempt is first made to use \s-1BIO_BIN_NORMAL\s0, if this fails
984263bc 224and the port is not in use then a second attempt is made
8b0cefbb 225using \s-1BIO_BIND_REUSEADDR\s0.
984263bc 226.PP
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227\&\fIBIO_do_accept()\fR serves two functions. When it is first
228called, after the accept \s-1BIO\s0 has been setup, it will attempt
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229to create the accept socket and bind an address to it. Second
230and subsequent calls to \fIBIO_do_accept()\fR will await an incoming
231connection, or request a retry in non blocking mode.
232.SH "NOTES"
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233.IX Header "NOTES"
234When an accept \s-1BIO\s0 is at the end of a chain it will await an
984263bc 235incoming connection before processing I/O calls. When an accept
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236\&\s-1BIO\s0 is not at then end of a chain it passes I/O calls to the next
237\&\s-1BIO\s0 in the chain.
984263bc 238.PP
8b0cefbb 239When a connection is established a new socket \s-1BIO\s0 is created for
984263bc 240the connection and appended to the chain. That is the chain is now
8b0cefbb 241accept\->socket. This effectively means that attempting I/O on
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242an initial accept socket will await an incoming connection then
243perform I/O on it.
244.PP
245If any additional BIOs have been set using \fIBIO_set_accept_bios()\fR
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246then they are placed between the socket and the accept \s-1BIO\s0,
247that is the chain will be accept\->otherbios\->socket.
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248.PP
249If a server wishes to process multiple connections (as is normally
8b0cefbb 250the case) then the accept \s-1BIO\s0 must be made available for further
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251incoming connections. This can be done by waiting for a connection and
252then calling:
253.PP
254.Vb 1
255\& connection = BIO_pop(accept);
256.Ve
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257.PP
258After this call \fBconnection\fR will contain a \s-1BIO\s0 for the recently
259established connection and \fBaccept\fR will now be a single \s-1BIO\s0
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260again which can be used to await further incoming connections.
261If no further connections will be accepted the \fBaccept\fR can
262be freed using \fIBIO_free()\fR.
263.PP
264If only a single connection will be processed it is possible to
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265perform I/O using the accept \s-1BIO\s0 itself. This is often undesirable
266however because the accept \s-1BIO\s0 will still accept additional incoming
984263bc 267connections. This can be resolved by using \fIBIO_pop()\fR (see above)
8b0cefbb 268and freeing up the accept \s-1BIO\s0 after the initial connection.
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269.PP
270If the underlying accept socket is non-blocking and \fIBIO_do_accept()\fR is
271called to await an incoming connection it is possible for
8b0cefbb 272\&\fIBIO_should_io_special()\fR with the reason \s-1BIO_RR_ACCEPT\s0. If this happens
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273then it is an indication that an accept attempt would block: the application
274should take appropriate action to wait until the underlying socket has
275accepted a connection and retry the call.
276.PP
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277\&\fIBIO_set_accept_port()\fR, \fIBIO_get_accept_port()\fR, \fIBIO_set_nbio_accept()\fR,
278\&\fIBIO_set_accept_bios()\fR, \fIBIO_set_bind_mode()\fR, \fIBIO_get_bind_mode()\fR and
279\&\fIBIO_do_accept()\fR are macros.
984263bc 280.SH "RETURN VALUES"
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281.IX Header "RETURN VALUES"
282\&\s-1TBA\s0
984263bc 283.SH "EXAMPLE"
8b0cefbb 284.IX Header "EXAMPLE"
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285This example accepts two connections on port 4444, sends messages
286down each and finally closes both down.
287.PP
288.Vb 3
289\& BIO *abio, *cbio, *cbio2;
290\& ERR_load_crypto_strings();
291\& abio = BIO_new_accept("4444");
e257b235 292\&
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293\& /* First call to BIO_accept() sets up accept BIO */
294\& if(BIO_do_accept(abio) <= 0) {
295\& fprintf(stderr, "Error setting up accept\en");
296\& ERR_print_errors_fp(stderr);
297\& exit(0);
298\& }
e257b235 299\&
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300\& /* Wait for incoming connection */
301\& if(BIO_do_accept(abio) <= 0) {
302\& fprintf(stderr, "Error accepting connection\en");
303\& ERR_print_errors_fp(stderr);
304\& exit(0);
305\& }
306\& fprintf(stderr, "Connection 1 established\en");
307\& /* Retrieve BIO for connection */
308\& cbio = BIO_pop(abio);
309\& BIO_puts(cbio, "Connection 1: Sending out Data on initial connection\en");
310\& fprintf(stderr, "Sent out data on connection 1\en");
311\& /* Wait for another connection */
312\& if(BIO_do_accept(abio) <= 0) {
313\& fprintf(stderr, "Error accepting connection\en");
314\& ERR_print_errors_fp(stderr);
315\& exit(0);
316\& }
317\& fprintf(stderr, "Connection 2 established\en");
318\& /* Close accept BIO to refuse further connections */
319\& cbio2 = BIO_pop(abio);
320\& BIO_free(abio);
321\& BIO_puts(cbio2, "Connection 2: Sending out Data on second\en");
322\& fprintf(stderr, "Sent out data on connection 2\en");
e257b235 323\&
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324\& BIO_puts(cbio, "Connection 1: Second connection established\en");
325\& /* Close the two established connections */
326\& BIO_free(cbio);
327\& BIO_free(cbio2);
328.Ve
329.SH "SEE ALSO"
330.IX Header "SEE ALSO"
8b0cefbb 331\&\s-1TBA\s0