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  man pages->Tru64 Unix man pages -> BIO_s_accept (3)              



NAME    [Toc]    [Back]

       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    [Toc]    [Back]

        #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_ctrl(b,BIO_C_SET_ACCEPT,1,(n)?"a":NULL)        #define
       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

       #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)

DESCRIPTION    [Toc]    [Back]

       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

       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

       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.

NOTES    [Toc]    [Back]

       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

       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.

RETURN VALUES    [Toc]    [Back]


EXAMPLES    [Toc]    [Back]

       This example accepts two connections on port  4444,  sends
       messages down each and finally closes both down.
        BIO *abio, *cbio, *cbio2;
        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
        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_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 */

SEE ALSO    [Toc]    [Back]


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