Update files for OpenSSL-1.0.0f import.
[dragonfly.git] / secure / lib / libcrypto / man / BIO_s_accept.3
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124.\" ========================================================================
125.\"
126.IX Title "BIO_s_accept 3"
e3261593 127.TH BIO_s_accept 3 "2012-01-04" "1.0.0f" "OpenSSL"
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128.\" For nroff, turn off justification. Always turn off hyphenation; it makes
129.\" way too many mistakes in technical documents.
130.if n .ad l
131.nh
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132.SH "NAME"
133BIO_s_accept, BIO_set_accept_port, BIO_get_accept_port,
134BIO_set_nbio_accept, BIO_set_accept_bios, BIO_set_bind_mode,
74dab6c2 135BIO_get_bind_mode, BIO_do_accept \- accept BIO
984263bc 136.SH "SYNOPSIS"
8b0cefbb 137.IX Header "SYNOPSIS"
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138.Vb 1
139\& #include <openssl/bio.h>
e257b235 140\&
984263bc 141\& BIO_METHOD *BIO_s_accept(void);
e257b235 142\&
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143\& long BIO_set_accept_port(BIO *b, char *name);
144\& char *BIO_get_accept_port(BIO *b);
e257b235 145\&
984263bc 146\& BIO *BIO_new_accept(char *host_port);
e257b235 147\&
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148\& long BIO_set_nbio_accept(BIO *b, int n);
149\& long BIO_set_accept_bios(BIO *b, char *bio);
e257b235 150\&
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151\& long BIO_set_bind_mode(BIO *b, long mode);
152\& long BIO_get_bind_mode(BIO *b, long dummy);
e257b235 153\&
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154\& #define BIO_BIND_NORMAL 0
155\& #define BIO_BIND_REUSEADDR_IF_UNUSED 1
156\& #define BIO_BIND_REUSEADDR 2
e257b235 157\&
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158\& int BIO_do_accept(BIO *b);
159.Ve
160.SH "DESCRIPTION"
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161.IX Header "DESCRIPTION"
162\&\fIBIO_s_accept()\fR returns the accept \s-1BIO\s0 method. This is a wrapper
163round the platform's \s-1TCP/IP\s0 socket accept routines.
984263bc 164.PP
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165Using accept BIOs, \s-1TCP/IP\s0 connections can be accepted and data
166transferred using only \s-1BIO\s0 routines. In this way any platform
167specific operations are hidden by the \s-1BIO\s0 abstraction.
984263bc 168.PP
8b0cefbb 169Read and write operations on an accept \s-1BIO\s0 will perform I/O
984263bc 170on the underlying connection. If no connection is established
8b0cefbb 171and the port (see below) is set up properly then the \s-1BIO\s0
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172waits for an incoming connection.
173.PP
174Accept BIOs support \fIBIO_puts()\fR but not \fIBIO_gets()\fR.
175.PP
8b0cefbb 176If the close flag is set on an accept \s-1BIO\s0 then any active
984263bc 177connection on that chain is shutdown and the socket closed when
8b0cefbb 178the \s-1BIO\s0 is freed.
984263bc 179.PP
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180Calling \fIBIO_reset()\fR on a accept \s-1BIO\s0 will close any active
181connection and reset the \s-1BIO\s0 into a state where it awaits another
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182incoming connection.
183.PP
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184\&\fIBIO_get_fd()\fR and \fIBIO_set_fd()\fR can be called to retrieve or set
185the accept socket. See \fIBIO_s_fd\fR\|(3)
984263bc 186.PP
8b0cefbb 187\&\fIBIO_set_accept_port()\fR uses the string \fBname\fR to set the accept
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188port. The port is represented as a string of the form \*(L"host:port\*(R",
189where \*(L"host\*(R" is the interface to use and \*(L"port\*(R" is the port.
190Either or both values can be \*(L"*\*(R" which is interpreted as meaning
191any interface or port respectively. \*(L"port\*(R" has the same syntax
192as the port specified in \fIBIO_set_conn_port()\fR for connect BIOs,
193that is it can be a numerical port string or a string to lookup
194using \fIgetservbyname()\fR and a string table.
195.PP
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196\&\fIBIO_new_accept()\fR combines \fIBIO_new()\fR and \fIBIO_set_accept_port()\fR into
197a single call: that is it creates a new accept \s-1BIO\s0 with port
198\&\fBhost_port\fR.
984263bc 199.PP
8b0cefbb 200\&\fIBIO_set_nbio_accept()\fR sets the accept socket to blocking mode
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201(the default) if \fBn\fR is 0 or non blocking mode if \fBn\fR is 1.
202.PP
8b0cefbb 203\&\fIBIO_set_accept_bios()\fR can be used to set a chain of BIOs which
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204will be duplicated and prepended to the chain when an incoming
205connection is received. This is useful if, for example, a
8b0cefbb 206buffering or \s-1SSL\s0 \s-1BIO\s0 is required for each connection. The
984263bc 207chain of BIOs must not be freed after this call, they will
8b0cefbb 208be automatically freed when the accept \s-1BIO\s0 is freed.
984263bc 209.PP
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210\&\fIBIO_set_bind_mode()\fR and \fIBIO_get_bind_mode()\fR set and retrieve
211the current bind mode. If \s-1BIO_BIND_NORMAL\s0 (the default) is set
984263bc 212then another socket cannot be bound to the same port. If
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213\&\s-1BIO_BIND_REUSEADDR\s0 is set then other sockets can bind to the
214same port. If \s-1BIO_BIND_REUSEADDR_IF_UNUSED\s0 is set then and
215attempt is first made to use \s-1BIO_BIN_NORMAL\s0, if this fails
984263bc 216and the port is not in use then a second attempt is made
8b0cefbb 217using \s-1BIO_BIND_REUSEADDR\s0.
984263bc 218.PP
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219\&\fIBIO_do_accept()\fR serves two functions. When it is first
220called, after the accept \s-1BIO\s0 has been setup, it will attempt
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221to create the accept socket and bind an address to it. Second
222and subsequent calls to \fIBIO_do_accept()\fR will await an incoming
223connection, or request a retry in non blocking mode.
224.SH "NOTES"
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225.IX Header "NOTES"
226When an accept \s-1BIO\s0 is at the end of a chain it will await an
984263bc 227incoming connection before processing I/O calls. When an accept
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228\&\s-1BIO\s0 is not at then end of a chain it passes I/O calls to the next
229\&\s-1BIO\s0 in the chain.
984263bc 230.PP
8b0cefbb 231When a connection is established a new socket \s-1BIO\s0 is created for
984263bc 232the connection and appended to the chain. That is the chain is now
8b0cefbb 233accept\->socket. This effectively means that attempting I/O on
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234an initial accept socket will await an incoming connection then
235perform I/O on it.
236.PP
237If any additional BIOs have been set using \fIBIO_set_accept_bios()\fR
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238then they are placed between the socket and the accept \s-1BIO\s0,
239that is the chain will be accept\->otherbios\->socket.
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240.PP
241If a server wishes to process multiple connections (as is normally
8b0cefbb 242the case) then the accept \s-1BIO\s0 must be made available for further
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243incoming connections. This can be done by waiting for a connection and
244then calling:
245.PP
246.Vb 1
247\& connection = BIO_pop(accept);
248.Ve
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249.PP
250After this call \fBconnection\fR will contain a \s-1BIO\s0 for the recently
251established connection and \fBaccept\fR will now be a single \s-1BIO\s0
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252again which can be used to await further incoming connections.
253If no further connections will be accepted the \fBaccept\fR can
254be freed using \fIBIO_free()\fR.
255.PP
256If only a single connection will be processed it is possible to
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257perform I/O using the accept \s-1BIO\s0 itself. This is often undesirable
258however because the accept \s-1BIO\s0 will still accept additional incoming
984263bc 259connections. This can be resolved by using \fIBIO_pop()\fR (see above)
8b0cefbb 260and freeing up the accept \s-1BIO\s0 after the initial connection.
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261.PP
262If the underlying accept socket is non-blocking and \fIBIO_do_accept()\fR is
263called to await an incoming connection it is possible for
8b0cefbb 264\&\fIBIO_should_io_special()\fR with the reason \s-1BIO_RR_ACCEPT\s0. If this happens
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265then it is an indication that an accept attempt would block: the application
266should take appropriate action to wait until the underlying socket has
267accepted a connection and retry the call.
268.PP
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269\&\fIBIO_set_accept_port()\fR, \fIBIO_get_accept_port()\fR, \fIBIO_set_nbio_accept()\fR,
270\&\fIBIO_set_accept_bios()\fR, \fIBIO_set_bind_mode()\fR, \fIBIO_get_bind_mode()\fR and
271\&\fIBIO_do_accept()\fR are macros.
984263bc 272.SH "RETURN VALUES"
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273.IX Header "RETURN VALUES"
274\&\s-1TBA\s0
984263bc 275.SH "EXAMPLE"
8b0cefbb 276.IX Header "EXAMPLE"
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277This example accepts two connections on port 4444, sends messages
278down each and finally closes both down.
279.PP
280.Vb 3
281\& BIO *abio, *cbio, *cbio2;
282\& ERR_load_crypto_strings();
283\& abio = BIO_new_accept("4444");
e257b235 284\&
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285\& /* First call to BIO_accept() sets up accept BIO */
286\& if(BIO_do_accept(abio) <= 0) {
287\& fprintf(stderr, "Error setting up accept\en");
288\& ERR_print_errors_fp(stderr);
289\& exit(0);
290\& }
e257b235 291\&
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292\& /* Wait for incoming connection */
293\& if(BIO_do_accept(abio) <= 0) {
294\& fprintf(stderr, "Error accepting connection\en");
295\& ERR_print_errors_fp(stderr);
296\& exit(0);
297\& }
298\& fprintf(stderr, "Connection 1 established\en");
299\& /* Retrieve BIO for connection */
300\& cbio = BIO_pop(abio);
301\& BIO_puts(cbio, "Connection 1: Sending out Data on initial connection\en");
302\& fprintf(stderr, "Sent out data on connection 1\en");
303\& /* Wait for another connection */
304\& if(BIO_do_accept(abio) <= 0) {
305\& fprintf(stderr, "Error accepting connection\en");
306\& ERR_print_errors_fp(stderr);
307\& exit(0);
308\& }
309\& fprintf(stderr, "Connection 2 established\en");
310\& /* Close accept BIO to refuse further connections */
311\& cbio2 = BIO_pop(abio);
312\& BIO_free(abio);
313\& BIO_puts(cbio2, "Connection 2: Sending out Data on second\en");
314\& fprintf(stderr, "Sent out data on connection 2\en");
e257b235 315\&
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316\& BIO_puts(cbio, "Connection 1: Second connection established\en");
317\& /* Close the two established connections */
318\& BIO_free(cbio);
319\& BIO_free(cbio2);
320.Ve
321.SH "SEE ALSO"
322.IX Header "SEE ALSO"
8b0cefbb 323\&\s-1TBA\s0