5 BIO_s_accept, BIO_set_nbio, BIO_set_accept_port, BIO_get_accept_port,
6 BIO_set_nbio_accept, BIO_set_accept_bios, BIO_set_bind_mode,
7 BIO_get_bind_mode, BIO_do_accept - accept BIO
11 #include <openssl/bio.h>
13 BIO_METHOD * BIO_s_accept(void);
15 #define BIO_set_accept_port(b,name) BIO_ctrl(b,BIO_C_SET_ACCEPT,0,(char *)name)
16 #define BIO_get_accept_port(b) BIO_ptr_ctrl(b,BIO_C_GET_ACCEPT,0)
18 BIO *BIO_new_accept(char *host_port);
20 #define BIO_set_nbio_accept(b,n) BIO_ctrl(b,BIO_C_SET_ACCEPT,1,(n)?"a":NULL)
21 #define BIO_set_accept_bios(b,bio) BIO_ctrl(b,BIO_C_SET_ACCEPT,2,(char *)bio)
23 #define BIO_set_bind_mode(b,mode) BIO_ctrl(b,BIO_C_SET_BIND_MODE,mode,NULL)
24 #define BIO_get_bind_mode(b,mode) BIO_ctrl(b,BIO_C_GET_BIND_MODE,0,NULL)
26 #define BIO_BIND_NORMAL 0
27 #define BIO_BIND_REUSEADDR_IF_UNUSED 1
28 #define BIO_BIND_REUSEADDR 2
30 #define BIO_do_accept(b) BIO_do_handshake(b)
34 BIO_s_accept() returns the accept BIO method. This is a wrapper
35 round the platform's TCP/IP socket accept routines.
37 Using accept BIOs TCP/IP connections can be accepted and data
38 transferred using only BIO routines. In this way any platform
39 specific operations are hidden by the BIO abstraction.
41 Read and write operations on an accept BIO will perform I/O
42 on the underlying connection. If no connection is established
43 and the port (see below) is set up properly then the BIO
44 waits for an incoming connection.
46 Accept BIOs support BIO_puts() but not BIO_gets().
48 If the close flag is set on an accept BIO then any active
49 connection on that chain is shutdown and the socket closed when
52 Calling BIO_reset() on a accept BIO will close any active
53 connection and reset the BIO into a state where it awaits another
56 BIO_get_fd() and BIO_set_fd() can be called to retrieve or set
57 the accept socket. See L<BIO_s_fd(3)|BIO_s_fd(3)>
59 BIO_set_accept_port() uses the string B<name> to set the accept
60 port. The port is represented as a string of the form "host:port",
61 where "host" is the interface to use and "port" is the port.
62 Either or both values can be "*" which is interpreted as meaning
63 any interface or port respectively. "port" has the same syntax
64 as the port specified in BIO_set_conn_port() for connect BIOs,
65 that is it can be a numerical port string or a string to lookup
66 using getservbyname() and a string table.
68 BIO_new_accept() combines BIO_new() and BIO_set_accept_port() into
69 a single call: that is it creates a new accept BIO with port
72 BIO_set_nbio_accept() sets the accept socket to blocking mode
73 (the default) if B<n> is 0 or non blocking mode if B<n> is 1.
75 BIO_set_accept_bios() can be used to set a chain of BIOs which
76 will be duplicated and prepended to the chain when an incoming
77 connection is received. This is useful if, for example, a
78 buffering BIO is required for each connection.
80 BIO_set_bind_mode() and BIO_get_bind_mode() set and retrieve
81 the current bind mode. If BIO_BIND_NORMAL (the default) is set
82 then another socket cannot be bound to the same port. If
83 BIO_BIND_REUSEADDR is set then other sockets can bind to the
84 same port. If BIO_BIND_REUSEADDR_IF_UNUSED is set then and
85 attempt is first made to use BIO_BIN_NORMAL, if this fails
86 and the port is not in use then a second attempt is made
87 using BIO_BIND_REUSEADDR.
89 BIO_do_accept() serves two functions. When it is first
90 called, after the accept BIO has been setup, it will attempt
91 to create the accept socket and bind an address to it. Second
92 and subsequent calls to BIO_do_accept() will await an incoming
97 When an accept BIO is at the end of a chain it will await an
98 incoming connection before processing I/O calls. When an accept
99 BIO is not at then end of a chain it passes I/O calls to the next
102 When a connection is established a new socket BIO is created for
103 the conection and appended to the chain. That is the chain is now
104 accept->socket. This effectively means that attempting I/O on
105 an initial accept socket will await an incoming connection then
108 If any additional BIOs have been set using BIO_set_accept_bios()
109 then they are placed between the socket and the accept BIO,
110 that is the chain will be accept->otherbios->socket.
112 If a server wishes to process multiple connections (as is normally
113 the case) then the accept BIO must be made available for further
114 incoming connections. This can be done by waiting for a connection and
117 connection = BIO_pop(accept);
119 After this call B<connection> will contain a BIO for the recently
120 established connection and B<accept> will now be a single BIO
121 again which can be used to await further incoming connections.
122 If no further connections will be accepted the B<accept> can
123 be freed using BIO_free().
125 If only a single connection will be processed it is possible to
126 perform I/O using the accept BIO itself. This is often undesirable
127 however because the accept BIO will still accept additional incoming
128 connections. This can be resolved by using BIO_pop() (see above)
129 and freeing up the accept BIO after the initial connection.
137 This example accepts two connections on port 4444, sends messages
138 down each and finally closes both down.
140 BIO *abio, *cbio, *cbio2;
141 ERR_load_crypto_strings();
142 abio = BIO_new_accept("4444");
144 /* First call to BIO_accept() sets up accept BIO */
145 if(BIO_do_accept(abio) <= 0) {
146 fprintf(stderr, "Error setting up accept\n");
147 ERR_print_errors_fp(stderr);
151 /* Wait for incoming connection */
152 if(BIO_do_accept(abio) <= 0) {
153 fprintf(stderr, "Error accepting connection\n");
154 ERR_print_errors_fp(stderr);
157 fprintf(stderr, "Connection 1 established\n");
158 /* Retrieve BIO for connection */
159 cbio = BIO_pop(abio);
160 BIO_puts(cbio, "Connection 1: Sending out Data on initial connection\n");
161 fprintf(stderr, "Sent out data on connection 1\n");
162 /* Wait for another connection */
163 if(BIO_do_accept(abio) <= 0) {
164 fprintf(stderr, "Error accepting connection\n");
165 ERR_print_errors_fp(stderr);
168 fprintf(stderr, "Connection 2 established\n");
169 /* Close accept BIO to refuse further connections */
170 cbio2 = BIO_pop(abio);
172 BIO_puts(cbio2, "Connection 2: Sending out Data on second\n");
173 fprintf(stderr, "Sent out data on connection 2\n");
175 BIO_puts(cbio, "Connection 1: Second connection established\n");
176 /* Close the two established connections */