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BIO_set_accept_bios.3
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This is a wrapper round the platform's \s-1TCP/IP\s0 socket accept routines. .PP Using accept BIOs, \s-1TCP/IP\s0 connections can be accepted and data transferred using only \s-1BIO\s0 routines. In this way any platform specific operations are hidden by the \s-1BIO\s0 abstraction. .PP Read and write operations on an accept \s-1BIO\s0 will perform I/O on the underlying connection. If no connection is established and the port (see below) is set up properly then the \s-1BIO\s0 waits for an incoming connection. .PP Accept BIOs support \fIBIO_puts()\fR but not \fIBIO_gets()\fR. .PP If the close flag is set on an accept \s-1BIO\s0 then any active connection on that chain is shutdown and the socket closed when the \s-1BIO\s0 is freed. .PP Calling \fIBIO_reset()\fR on a accept \s-1BIO\s0 will close any active connection and reset the \s-1BIO\s0 into a state where it awaits another incoming connection. .PP \&\fIBIO_get_fd()\fR and \fIBIO_set_fd()\fR can be called to retrieve or set the accept socket. See \fIBIO_s_fd\fR\|(3) .PP \&\fIBIO_set_accept_port()\fR uses the string \fBname\fR to set the accept port. The port is represented as a string of the form \*(L"host:port\*(R", where \*(L"host\*(R" is the interface to use and \*(L"port\*(R" is the port. The host can be can be \*(L"*\*(R" which is interpreted as meaning any interface; \*(L"port\*(R" has the same syntax as the port specified in \fIBIO_set_conn_port()\fR for connect BIOs, that is it can be a numerical port string or a string to lookup using \fIgetservbyname()\fR and a string table. .PP \&\fIBIO_new_accept()\fR combines \fIBIO_new()\fR and \fIBIO_set_accept_port()\fR into a single call: that is it creates a new accept \s-1BIO\s0 with port \&\fBhost_port\fR. .PP \&\fIBIO_set_nbio_accept()\fR sets the accept socket to blocking mode (the default) if \fBn\fR is 0 or non blocking mode if \fBn\fR is 1. .PP \&\fIBIO_set_accept_bios()\fR 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 \s-1SSL\s0 \s-1BIO\s0 is required for each connection. The chain of BIOs must not be freed after this call, they will be automatically freed when the accept \s-1BIO\s0 is freed. .PP \&\fIBIO_set_bind_mode()\fR and \fIBIO_get_bind_mode()\fR set and retrieve the current bind mode. If \s-1BIO_BIND_NORMAL\s0 (the default) is set then another socket cannot be bound to the same port. If \&\s-1BIO_BIND_REUSEADDR\s0 is set then other sockets can bind to the same port. If \s-1BIO_BIND_REUSEADDR_IF_UNUSED\s0 is set then and attempt is first made to use \s-1BIO_BIN_NORMAL\s0, if this fails and the port is not in use then a second attempt is made using \s-1BIO_BIND_REUSEADDR\s0. .PP \&\fIBIO_do_accept()\fR serves two functions. When it is first called, after the accept \s-1BIO\s0 has been setup, it will attempt to create the accept socket and bind an address to it. Second and subsequent calls to \fIBIO_do_accept()\fR will await an incoming connection, or request a retry in non blocking mode. .SH "NOTES" .IX Header "NOTES" When an accept \s-1BIO\s0 is at the end of a chain it will await an incoming connection before processing I/O calls. When an accept \&\s-1BIO\s0 is not at then end of a chain it passes I/O calls to the next \&\s-1BIO\s0 in the chain. .PP When a connection is established a new socket \s-1BIO\s0 is created for the connection and appended to the chain. That is 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. .PP If any additional BIOs have been set using \fIBIO_set_accept_bios()\fR then they are placed between the socket and the accept \s-1BIO\s0, that is the chain will be accept\->otherbios\->socket. .PP If a server wishes to process multiple connections (as is normally the case) then the accept \s-1BIO\s0 must be made available for further incoming connections. This can be done by waiting for a connection and then calling: .PP .Vb 1 \& connection = BIO_pop(accept); .Ve .PP After this call \fBconnection\fR will contain a \s-1BIO\s0 for the recently established connection and \fBaccept\fR will now be a single \s-1BIO\s0 again which can be used to await further incoming connections. If no further connections will be accepted the \fBaccept\fR can be freed using \fIBIO_free()\fR. .PP If only a single connection will be processed it is possible to perform I/O using the accept \s-1BIO\s0 itself. This is often undesirable however because the accept \s-1BIO\s0 will still accept additional incoming connections. This can be resolved by using \fIBIO_pop()\fR (see above) and freeing up the accept \s-1BIO\s0 after the initial connection. .PP If the underlying accept socket is non-blocking and \fIBIO_do_accept()\fR is called to await an incoming connection it is possible for \&\fIBIO_should_io_special()\fR with the reason \s-1BIO_RR_ACCEPT\s0. 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. .PP \&\fIBIO_set_accept_port()\fR, \fIBIO_get_accept_port()\fR, \fIBIO_set_nbio_accept()\fR, \&\fIBIO_set_accept_bios()\fR, \fIBIO_set_bind_mode()\fR, \fIBIO_get_bind_mode()\fR and \&\fIBIO_do_accept()\fR are macros. .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\s-1TBA\s0 .SH "EXAMPLE" .IX Header "EXAMPLE" This example accepts two connections on port 4444, sends messages down each and finally closes both down. .PP .Vb 3 \& BIO *abio, *cbio, *cbio2; \& ERR_load_crypto_strings(); \& abio = BIO_new_accept("4444"); .Ve .PP .Vb 6 \& /* First call to BIO_accept() sets up accept BIO */ \& if(BIO_do_accept(abio) <= 0) { \& fprintf(stderr, "Error setting up accept\en"); \& ERR_print_errors_fp(stderr); \& exit(0); \& } .Ve .PP .Vb 23 \& /* Wait for incoming connection */ \& if(BIO_do_accept(abio) <= 0) { \& fprintf(stderr, "Error accepting connection\en"); \& ERR_print_errors_fp(stderr); \& exit(0); \& } \& fprintf(stderr, "Connection 1 established\en"); \& /* Retrieve BIO for connection */ \& cbio = BIO_pop(abio); \& BIO_puts(cbio, "Connection 1: Sending out Data on initial connection\en"); \& fprintf(stderr, "Sent out data on connection 1\en"); \& /* Wait for another connection */ \& if(BIO_do_accept(abio) <= 0) { \& fprintf(stderr, "Error accepting connection\en"); \& ERR_print_errors_fp(stderr); \& exit(0); \& } \& fprintf(stderr, "Connection 2 established\en"); \& /* Close accept BIO to refuse further connections */ \& cbio2 = BIO_pop(abio); \& BIO_free(abio); \& BIO_puts(cbio2, "Connection 2: Sending out Data on second\en"); \& fprintf(stderr, "Sent out data on connection 2\en"); .Ve .PP .Vb 4 \& BIO_puts(cbio, "Connection 1: Second connection established\en"); \& /* Close the two established connections */ \& BIO_free(cbio); \& BIO_free(cbio2); .Ve .SH "SEE ALSO" .IX Header "SEE ALSO" \&\s-1TBA\s0