MirBSD manpage: BIO_do_accept(3), BIO_get_accept_port(3), BIO_get_bind_mode(3), BIO_set_accept_bios(3), BIO_set_accept_port(3), BIO_set_bind_mode(3), BIO_set_nbio_accept(3), BIO_s_accept(3)

BIO_S_ACCEPT(3)              OpenSSL              BIO_S_ACCEPT(3)


     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);

      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             2

      int BIO_do_accept(BIO *b);


     BIO_s_accept() 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 abstrac-

     Read and write operations on an accept BIO will perform I/O
     on the underlying connection. If no connection is esta-
     blished 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.

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BIO_S_ACCEPT(3)              OpenSSL              BIO_S_ACCEPT(3)

     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 get-
     servbyname() 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 connec-
     tion. The chain of BIOs must not be freed after this call,
     they will be automatically freed when the accept BIO is

     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_REUSEADDR_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

     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


     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

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BIO_S_ACCEPT(3)              OpenSSL              BIO_S_ACCEPT(3)

     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
     BIO_set_accept_bios() then they are placed between the
     socket and the accept BIO, that is the chain will be

     If a server wishes to process multiple connections (as is
     normally the case) then the accept BIO must be made avail-
     able 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 possible
     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 connection 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.




     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");

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BIO_S_ACCEPT(3)              OpenSSL              BIO_S_ACCEPT(3)

      /* First call to BIO_accept() sets up accept BIO */
      if(BIO_do_accept(abio) <= 0) {
             fprintf(stderr, "Error setting up accept\n");

      /* Wait for incoming connection */
      if(BIO_do_accept(abio) <= 0) {
             fprintf(stderr, "Error accepting connection\n");
      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");
      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 */



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