BIO_s_accept(3)             OpenSSL             BIO_s_accept(3)





NAME
       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

SYNOPSIS
        #include <openssl/bio.h>

        BIO_METHOD *BIO_s_accept(void);

        long BIO_set_accept_port(BIO *b, char *name);
        char *BIO_get_accept_port(BIO *b);

        BIO *BIO_new_accept(char *host_port);

        long BIO_set_nbio_accept(BIO *b, int n);
        long BIO_set_accept_bios(BIO *b, char *bio);

        long BIO_set_bind_mode(BIO *b, long mode);
        long BIO_get_bind_mode(BIO *b, long dummy);

        #define BIO_BIND_NORMAL                0
        #define BIO_BIND_REUSEADDR_IF_UNUSED   1
        #define BIO_BIND_REUSEADDR             2

        int BIO_do_accept(BIO *b);

DESCRIPTION
       BIO_s_accept() returns the accept BIO method. This is a
       wrapper round the platform's TCP/IP socket accept rou-
       tines.

       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 (see below) is set up properly
       then the BIO waits for an incoming connection.

       Accept BIOs support BIO_puts() but not BIO_gets().

       If the close flag 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.

       BIO_get_fd() and BIO_set_fd() 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,
       that is 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: that is 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 non blocking mode if n
       is 1.

       BIO_set_accept_bios() 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.

       BIO_set_bind_mode() and BIO_get_bind_mode() 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_REUSE-
       ADDR_IF_UNUSED is set then and 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_REUSE-
       ADDR.

       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, or request a retry in
       non blocking mode.

NOTES
       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.
       That is the chain is now accept->socket. This effec-
       tively 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
       BIO_set_accept_bios() then they are placed between the
       socket and the accept BIO, that is 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 now 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 BIO_free().

       If only a single connection will be processed it is pos-
       sible to perform I/O using the accept BIO itself. This
       is often undesirable however because the accept BIO will
       still accept additional incoming connections. This can
       be resolved by using BIO_pop() (see above) and freeing
       up the accept BIO after the initial connection.

       If the underlying accept socket is non-blocking and
       BIO_do_accept() is called to await an incoming connec-
       tion it is possible for BIO_should_io_special() with the
       reason BIO_RR_ACCEPT. If this happens then it is an
       indication that an accept attempt would block: the
       application should take appropriate action to wait until
       the underlying socket has accepted a connection and
       retry the call.

       BIO_set_accept_port(), BIO_get_accept_port(),
       BIO_set_nbio_accept(), BIO_set_accept_bios(),
       BIO_set_bind_mode(), BIO_get_bind_mode() and
       BIO_do_accept() are macros.

RETURN VALUES
       TBA

EXAMPLE
       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);

SEE ALSO
       TBA



0.9.7c                     2002-12-12           BIO_s_accept(3)
