1BIO_S_ACCEPT(3)                     OpenSSL                    BIO_S_ACCEPT(3)
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NAME

6       BIO_s_accept, BIO_set_accept_name, BIO_set_accept_port,
7       BIO_get_accept_name, BIO_get_accept_port, BIO_new_accept,
8       BIO_set_nbio_accept, BIO_set_accept_bios, BIO_get_peer_name,
9       BIO_get_peer_port, BIO_get_accept_ip_family, BIO_set_accept_ip_family,
10       BIO_set_bind_mode, BIO_get_bind_mode, BIO_do_accept - accept BIO
11

SYNOPSIS

13        #include <openssl/bio.h>
14
15        const BIO_METHOD *BIO_s_accept(void);
16
17        long BIO_set_accept_name(BIO *b, char *name);
18        char *BIO_get_accept_name(BIO *b);
19
20        long BIO_set_accept_port(BIO *b, char *port);
21        char *BIO_get_accept_port(BIO *b);
22
23        BIO *BIO_new_accept(char *host_port);
24
25        long BIO_set_nbio_accept(BIO *b, int n);
26        long BIO_set_accept_bios(BIO *b, char *bio);
27
28        char *BIO_get_peer_name(BIO *b);
29        char *BIO_get_peer_port(BIO *b);
30        long BIO_get_accept_ip_family(BIO *b);
31        long BIO_set_accept_ip_family(BIO *b, long family);
32
33        long BIO_set_bind_mode(BIO *b, long mode);
34        long BIO_get_bind_mode(BIO *b);
35
36        int BIO_do_accept(BIO *b);
37

DESCRIPTION

39       BIO_s_accept() returns the accept BIO method. This is a wrapper round
40       the platform's TCP/IP socket accept routines.
41
42       Using accept BIOs, TCP/IP connections can be accepted and data
43       transferred using only BIO routines. In this way any platform specific
44       operations are hidden by the BIO abstraction.
45
46       Read and write operations on an accept BIO will perform I/O on the
47       underlying connection. If no connection is established and the port
48       (see below) is set up properly then the BIO waits for an incoming
49       connection.
50
51       Accept BIOs support BIO_puts() but not BIO_gets().
52
53       If the close flag is set on an accept BIO then any active connection on
54       that chain is shutdown and the socket closed when the BIO is freed.
55
56       Calling BIO_reset() on an accept BIO will close any active connection
57       and reset the BIO into a state where it awaits another incoming
58       connection.
59
60       BIO_get_fd() and BIO_set_fd() can be called to retrieve or set the
61       accept socket. See BIO_s_fd(3)
62
63       BIO_set_accept_name() uses the string name to set the accept name. The
64       name is represented as a string of the form "host:port", where "host"
65       is the interface to use and "port" is the port.  The host can be "*" or
66       empty which is interpreted as meaning any interface.  If the host is an
67       IPv6 address, it has to be enclosed in brackets, for example
68       "[::1]:https".  "port" has the same syntax as the port specified in
69       BIO_set_conn_port() for connect BIOs, that is it can be a numerical
70       port string or a string to lookup using getservbyname() and a string
71       table.
72
73       BIO_set_accept_port() uses the string port to set the accept port.
74       "port" has the same syntax as the port specified in BIO_set_conn_port()
75       for connect BIOs, that is it can be a numerical port string or a string
76       to lookup using getservbyname() and a string table.
77
78       BIO_new_accept() combines BIO_new() and BIO_set_accept_name() into a
79       single call: that is it creates a new accept BIO with port host_port.
80
81       BIO_set_nbio_accept() sets the accept socket to blocking mode (the
82       default) if n is 0 or non blocking mode if n is 1.
83
84       BIO_set_accept_bios() can be used to set a chain of BIOs which will be
85       duplicated and prepended to the chain when an incoming connection is
86       received. This is useful if, for example, a buffering or SSL BIO is
87       required for each connection. The chain of BIOs must not be freed after
88       this call, they will be automatically freed when the accept BIO is
89       freed.
90
91       BIO_set_bind_mode() and BIO_get_bind_mode() set and retrieve the
92       current bind mode. If BIO_BIND_NORMAL (the default) is set then another
93       socket cannot be bound to the same port. If BIO_BIND_REUSEADDR is set
94       then other sockets can bind to the same port. If
95       BIO_BIND_REUSEADDR_IF_UNUSED is set then and attempt is first made to
96       use BIO_BIN_NORMAL, if this fails and the port is not in use then a
97       second attempt is made using BIO_BIND_REUSEADDR.
98
99       BIO_do_accept() serves two functions. When it is first called, after
100       the accept BIO has been setup, it will attempt to create the accept
101       socket and bind an address to it. Second and subsequent calls to
102       BIO_do_accept() will await an incoming connection, or request a retry
103       in non blocking mode.
104

NOTES

106       When an accept BIO is at the end of a chain it will await an incoming
107       connection before processing I/O calls. When an accept BIO is not at
108       then end of a chain it passes I/O calls to the next BIO in the chain.
109
110       When a connection is established a new socket BIO is created for the
111       connection and appended to the chain. That is the chain is now
112       accept->socket. This effectively means that attempting I/O on an
113       initial accept socket will await an incoming connection then perform
114       I/O on it.
115
116       If any additional BIOs have been set using BIO_set_accept_bios() then
117       they are placed between the socket and the accept BIO, that is the
118       chain will be accept->otherbios->socket.
119
120       If a server wishes to process multiple connections (as is normally the
121       case) then the accept BIO must be made available for further incoming
122       connections. This can be done by waiting for a connection and then
123       calling:
124
125        connection = BIO_pop(accept);
126
127       After this call connection will contain a BIO for the recently
128       established connection and accept will now be a single BIO again which
129       can be used to await further incoming connections.  If no further
130       connections will be accepted the accept can be freed using BIO_free().
131
132       If only a single connection will be processed it is possible to perform
133       I/O using the accept BIO itself. This is often undesirable however
134       because the accept BIO will still accept additional incoming
135       connections. This can be resolved by using BIO_pop() (see above) and
136       freeing up the accept BIO after the initial connection.
137
138       If the underlying accept socket is non-blocking and BIO_do_accept() is
139       called to await an incoming connection it is possible for
140       BIO_should_io_special() with the reason BIO_RR_ACCEPT. If this happens
141       then it is an indication that an accept attempt would block: the
142       application should take appropriate action to wait until the underlying
143       socket has accepted a connection and retry the call.
144
145       BIO_set_accept_name(), BIO_get_accept_name(), BIO_set_accept_port(),
146       BIO_get_accept_port(), BIO_set_nbio_accept(), BIO_set_accept_bios(),
147       BIO_get_peer_name(), BIO_get_peer_port(), BIO_get_accept_ip_family(),
148       BIO_set_accept_ip_family(), BIO_set_bind_mode(), BIO_get_bind_mode()
149       and BIO_do_accept() are macros.
150

RETURN VALUES

152       BIO_do_accept(), BIO_set_accept_name(), BIO_set_accept_port(),
153       BIO_set_nbio_accept(), BIO_set_accept_bios(),
154       BIO_set_accept_ip_family(), and BIO_set_bind_mode() return 1 for
155       success and 0 or -1 for failure.
156
157       BIO_get_accept_name() returns the accept name or NULL on error.
158       BIO_get_peer_name() returns the peer name or NULL on error.
159
160       BIO_get_accept_port() returns the accept port as a string or NULL on
161       error.  BIO_get_peer_port() returns the peer port as a string or NULL
162       on error.  BIO_get_accept_ip_family() returns the IP family or -1 on
163       error.
164
165       BIO_get_bind_mode() returns the set of BIO_BIND flags, or -1 on
166       failure.
167
168       BIO_new_accept() returns a BIO or NULL on error.
169

EXAMPLES

171       This example accepts two connections on port 4444, sends messages down
172       each and finally closes both down.
173
174        BIO *abio, *cbio, *cbio2;
175
176        /* First call to BIO_accept() sets up accept BIO */
177        abio = BIO_new_accept("4444");
178        if (BIO_do_accept(abio) <= 0) {
179            fprintf(stderr, "Error setting up accept\n");
180            ERR_print_errors_fp(stderr);
181            exit(1);
182        }
183
184        /* Wait for incoming connection */
185        if (BIO_do_accept(abio) <= 0) {
186            fprintf(stderr, "Error accepting connection\n");
187            ERR_print_errors_fp(stderr);
188            exit(1);
189        }
190        fprintf(stderr, "Connection 1 established\n");
191
192        /* Retrieve BIO for connection */
193        cbio = BIO_pop(abio);
194        BIO_puts(cbio, "Connection 1: Sending out Data on initial connection\n");
195        fprintf(stderr, "Sent out data on connection 1\n");
196
197        /* Wait for another connection */
198        if (BIO_do_accept(abio) <= 0) {
199            fprintf(stderr, "Error accepting connection\n");
200            ERR_print_errors_fp(stderr);
201            exit(1);
202        }
203        fprintf(stderr, "Connection 2 established\n");
204
205        /* Close accept BIO to refuse further connections */
206        cbio2 = BIO_pop(abio);
207        BIO_free(abio);
208        BIO_puts(cbio2, "Connection 2: Sending out Data on second\n");
209        fprintf(stderr, "Sent out data on connection 2\n");
210
211        BIO_puts(cbio, "Connection 1: Second connection established\n");
212
213        /* Close the two established connections */
214        BIO_free(cbio);
215        BIO_free(cbio2);
216
218       Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
219
220       Licensed under the OpenSSL license (the "License").  You may not use
221       this file except in compliance with the License.  You can obtain a copy
222       in the file LICENSE in the source distribution or at
223       <https://www.openssl.org/source/license.html>.
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2271.1.1d                            2019-10-03                   BIO_S_ACCEPT(3)
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