BIO_s_accept, BIO_set_accept_port, BIO_get_accept_port,
BIO_set_nbio_accept, BIO_set_accept_bios,
BIO_set_bind_mode, BIO_get_bind_mode, BIO_do_accept -
Accept BIO
#include <openssl/bio.h>
BIO_METHOD * BIO_s_accept(
void ); #define BIO_set_accept_port(b,name)
BIO_ctrl(b,BIO_C_SET_ACCEPT,0,(char *)name) #define
BIO_get_accept_port(b) BIO_ptr_ctrl(b,BIO_C_GET_ACCEPT,0)
BIO *BIO_new_accept(
char *host_port ); #define
BIO_set_nbio_accept(b,n)
BIO_ctrl(b,BIO_C_SET_ACCEPT,1,(n)?"a":NULL) #define
BIO_set_accept_bios(b,bio)
BIO_ctrl(b,BIO_C_SET_ACCEPT,2,(char *)bio)
#define BIO_set_bind_mode(b,mode)
BIO_ctrl(b,BIO_C_SET_BIND_MODE,mode,NULL) #define
BIO_get_bind_mode(b,mode)
BIO_ctrl(b,BIO_C_GET_BIND_MODE,0,NULL)
#define BIO_BIND_NORMAL 0 #define BIO_BIND_REUSEADDR_IF_UNUSED
1 #define BIO_BIND_REUSEADDR 2
#define BIO_do_accept(b) BIO_do_handshake(b)
The BIO_s_accept() function returns the accept BIO method.
This is a wrapper round the platform's TCP/IP socket
accept routines.
Using accept BIOs, TCP/IP connections can be accepted and
data transferred using only BIO routines. In this way any
platform specific operations are hidden by the BIO
abstraction.
Read and write operations on an accept BIO will perform
I/O on the underlying connection. If no connection is
established and the port is set up properly then the BIO
waits for an incoming connection.
Accept BIOs support BIO_puts() but not BIO_gets().
If the close option is set on an accept BIO then any
active connection on that chain is shutdown and the socket
closed when the BIO is freed.
Calling BIO_reset() on a accept BIO will close any active
connection and reset the BIO into a state where it awaits
another incoming connection.
The BIO_get_fd() and BIO_set_fd() functions can be called
to retrieve or set the accept socket. See BIO_s_fd(3)
BIO_set_accept_port() uses the string name to set the
accept port. The port is represented as a string of the
form host:port, where host is the interface to use and
port is the port. Either or both values can be * which is
interpreted as meaning any interface or port respectively.
Port has the same syntax as the port specified in
BIO_set_conn_port() for connect BIOs; it can be a numerical
port string or a string to lookup using getservbyname()
and a string table.
BIO_new_accept() combines BIO_new() and
BIO_set_accept_port() into a single call; it creates a new
accept BIO with port host_port.
BIO_set_nbio_accept() sets the accept socket to blocking
mode (the default) if n is 0 or nonblocking mode if n is
1.
The BIO_set_accept_bios() function can be used to set a
chain of BIOs which will be duplicated and prepended to
the chain when an incoming connection is received. This is
useful if, for example, a buffering or SSL BIO is
required for each connection. The chain of BIOs must not
be freed after this call. They will be automatically freed
when the accept BIO is freed.
The BIO_set_bind_mode() and BIO_get_bind_mode() functions
set and retrieve the current bind mode. If BIO_BIND_NORMAL
(the default) is set, then another socket cannot be bound
to the same port. If BIO_BIND_REUSEADDR is set, then other
sockets can bind to the same port. If BIO_BIND_REUSEADDR_IF_UNUSED
is set, then an attempt is first made to
use BIO_BIN_NORMAL. If this fails and the port is not in
use, then a second attempt is made using BIO_BIND_REUSEADDR.
BIO_do_accept() serves two functions. When it is first
called, after the accept BIO has been setup, it will
attempt to create the accept socket and bind an address to
it. Second and subsequent calls to BIO_do_accept() will
await an incoming connection.
When an accept BIO is at the end of a chain it will await
an incoming connection before processing I/O calls. When
an accept BIO is not at then end of a chain it passes I/O
calls to the next BIO in the chain.
When a connection is established a new socket BIO is created
for the connection and appended to the chain. The
chain is now accept->socket. This effectively means that
attempting I/O on an initial accept socket will await an
incoming connection then perform I/O on it.
If any additional BIOs have been set using the
BIO_set_accept_bios() function then they are placed
between the socket and the accept BIO. The chain will be
accept->otherbios->socket.
If a server wishes to process multiple connections (as is
normally the case), then the accept BIO must be made
available for further incoming connections. This can be
done by waiting for a connection and then calling:
connection = BIO_pop(accept);
After this call, connection will contain a BIO for the
recently established connection and accept will be a single
BIO again which can be used to await further incoming
connections. If no further connections will be accepted,
the accept can be freed using the BIO_free() function.
If only a single connection will be processed it is possible
to perform I/O using the accept BIO. This is often
undesirable however because the accept BIO will still
accept additional incoming connections. This can be
resolved by using the BIO_pop() function and freeing up
the accept BIO after the initial connection.
TBA
This example accepts two connections on port 4444, sends
messages down each and finally closes both down.
BIO *abio, *cbio, *cbio2;
ERR_load_crypto_strings();
abio = BIO_new_accept("4444");
/* First call to BIO_accept() sets up accept BIO */
if(BIO_do_accept(abio) <= 0) { fprintf(stderr,
"Error setting up accept\n");
ERR_print_errors_fp(stderr); exit(0);
}
/* Wait for incoming connection */
if(BIO_do_accept(abio) <= 0) { fprintf(stderr,
"Error accepting connection\n");
ERR_print_errors_fp(stderr); exit(0);
}
fprintf(stderr, "Connection 1 established\n");
/* Retrieve BIO for connection */
cbio = BIO_pop(abio);
BIO_puts(cbio, "Connection 1: Sending out Data on initial
connection\n");
fprintf(stderr, "Sent out data on connection 1\n");
/* Wait for another connection */
if(BIO_do_accept(abio) <= 0) { fprintf(stderr,
"Error accepting connection\n");
ERR_print_errors_fp(stderr); exit(0);
}
fprintf(stderr, "Connection 2 established\n");
/* Close accept BIO to refuse further connections */
cbio2 = BIO_pop(abio);
BIO_free(abio);
BIO_puts(cbio2, "Connection 2: Sending out Data on second\n");
fprintf(stderr, "Sent out data on connection 2\n");
BIO_puts(cbio, "Connection 1: Second connection established\n");
/* Close the two established connections */
BIO_free(cbio);
BIO_free(cbio2);
TBA
BIO_s_accept(3)
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