Index for Section 3

Alphabetical listing for B

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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 );

       #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)

DESCRIPTION
  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.

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. 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.

RETURN VALUES
  TBA

EXAMPLES
  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

Index for Section 3

Alphabetical listing for B

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