openldap/doc/man/man3/lber-sockbuf.3

.TH LBER_SOCKBUF 3 "RELEASEDATE" "OpenLDAP LDVERSION"
.\" $OpenLDAP$
.\" Copyright 1998-2020 The OpenLDAP Foundation All Rights Reserved.
.\" Copying restrictions apply.  See COPYRIGHT/LICENSE.
.SH NAME
ber_sockbuf_alloc, ber_sockbuf_free, ber_sockbuf_ctrl, ber_sockbuf_add_io, ber_sockbuf_remove_io, Sockbuf_IO \- OpenLDAP LBER I/O infrastructure
.SH LIBRARY
OpenLDAP LBER (liblber, \-llber)
.SH SYNOPSIS
.B #include <lber.h>
.LP
.B Sockbuf *ber_sockbuf_alloc( void );
.LP
.BI "void ber_sockbuf_free(Sockbuf *" sb ");"
.LP
.BI "int ber_sockbuf_ctrl(Sockbuf *" sb ", int " opt ", void *" arg ");"
.LP
.BI "int ber_sockbuf_add_io(Sockbuf *" sb ", Sockbuf_IO *" sbio ", int " layer ", void *" arg ");"
.LP
.BI "int ber_sockbuf_remove_io(Sockbuf *" sb ", Sockbuf_IO *" sbio ", int " layer ");"
.LP
.nf
.B typedef struct sockbuf_io_desc {
.BI "int " sbiod_level ";"
.BI "Sockbuf *" sbiod_sb ";"
.BI "Sockbuf_IO *" sbiod_io ";"
.BI "void *" sbiod_pvt ";"
.BI "struct sockbuf_io_desc *" sbiod_next ";"
.B } Sockbuf_IO_Desc;
.LP
.B typedef struct sockbuf_io {
.BI "int (*" sbi_setup ")(Sockbuf_IO_Desc *" sbiod ", void *" arg ");"
.BI "int (*" sbi_remove ")(Sockbuf_IO_Desc *" sbiod ");"
.BI "int (*" sbi_ctrl ")(Sockbuf_IO_Desc *" sbiod ", int " opt ", void *" arg ");"
.BI "ber_slen_t (*" sbi_read ")(Sockbuf_IO_Desc *" sbiod ", void *" buf ", ber_len_t " len ");"
.BI "ber_slen_t (*" sbi_write ")(Sockbuf_IO_Desc *" sbiod ", void *" buf ", ber_len_t " len ");"
.BI "int (*" sbi_close ")(Sockbuf_IO_Desc *" sbiod ");"
.B } Sockbuf_IO;

.SH DESCRIPTION
.LP
These routines are used to manage the low level I/O operations performed
by the Lightweight BER library. They are called implicitly by the other
libraries and usually do not need to be called directly from applications.
The I/O framework is modularized and new transport layers can be supported
by appropriately defining a
.B Sockbuf_IO
structure and installing it onto an existing
.BR Sockbuf .
.B Sockbuf
structures are allocated and freed by
.BR ber_sockbuf_alloc ()
and
.BR ber_sockbuf_free (),
respectively. The
.BR ber_sockbuf_ctrl ()
function is used to get and set options related to a
.B Sockbuf
or to a specific I/O layer of the
.BR Sockbuf .
The
.BR ber_sockbuf_add_io ()
and
.BR ber_sockbuf_remove_io ()
functions are used to add and remove specific I/O layers on a
.BR Sockbuf .

Options for
.BR ber_sockbuf_ctrl ()
include:
.TP
.B LBER_SB_OPT_HAS_IO
Takes a
.B Sockbuf_IO *
argument and returns 1 if the given handler is installed
on the
.BR Sockbuf ,
otherwise returns 0.
.TP
.B LBER_SB_OPT_GET_FD
Retrieves the file descriptor associated to the
.BR Sockbuf ;
.B arg
must be a
.BR "ber_socket_t *" .
The return value will be 1 if a valid descriptor was present, \-1 otherwise.
.TP
.B LBER_SB_OPT_SET_FD
Sets the file descriptor of the
.B Sockbuf
to the descriptor pointed to by
.BR arg ;
.B arg
must be a
.BR "ber_socket_t *" .
The return value will always be 1.
.TP
.B LBER_SB_OPT_SET_NONBLOCK
Toggles the non-blocking state of the file descriptor associated to
the
.BR Sockbuf .
.B arg
should be NULL to disable and non-NULL to enable the non-blocking state.
The return value will be 1 for success, \-1 otherwise.
.TP
.B LBER_SB_OPT_DRAIN
Flush (read and discard) all available input on the
.BR Sockbuf .
The return value will be 1.
.TP
.B LBER_SB_OPT_NEEDS_READ
Returns non-zero if input is waiting to be read.
.TP
.B LBER_SB_OPT_NEEDS_WRITE
Returns non-zero if the
.B Sockbuf
is ready to be written.
.TP
.B LBER_SB_OPT_GET_MAX_INCOMING
Returns the maximum allowed size of an incoming message;
.B arg
must be a
.BR "ber_len_t *" .
The return value will be 1.
.TP
.B LBER_SB_OPT_SET_MAX_INCOMING
Sets the maximum allowed size of an incoming message;
.B arg
must be a
.BR "ber_len_t *" .
The return value will be 1.

.LP
Options not in this list will be passed down to each
.B Sockbuf_IO
handler in turn until one of them processes it. If the option is not handled
.BR ber_sockbuf_ctrl ()
will return 0.

.LP
Multiple
.B Sockbuf_IO
handlers can be stacked in multiple layers to provide various functionality.
Currently defined layers include
.TP
.B LBER_SBIOD_LEVEL_PROVIDER
the lowest layer, talking directly to a network 
.TP
.B LBER_SBIOD_LEVEL_TRANSPORT
an intermediate layer
.TP
.B LBER_SBIOD_LEVEL_APPLICATION
a higher layer
.LP
Currently defined
.B Sockbuf_IO
handlers in liblber include
.TP
.B ber_sockbuf_io_tcp
The default stream-oriented provider
.TP
.B ber_sockbuf_io_fd
A stream-oriented provider for local IPC sockets
.TP
.B ber_sockbuf_io_dgram
A datagram-oriented provider. This handler is only present if the liblber
library was built with LDAP_CONNECTIONLESS defined.
.TP
.B ber_sockbuf_io_readahead
A buffering layer, usually used with a datagram provider to hide the
datagram semantics from upper layers.
.TP
.B ber_sockbuf_io_debug
A generic handler that outputs hex dumps of all traffic. This handler
may be inserted multiple times at arbitrary layers to show the flow
of data between other handlers.
.LP
Additional handlers may be present in libldap if support for them was
enabled:
.TP
.B ldap_pvt_sockbuf_io_sasl
An application layer handler for SASL encoding/decoding.
.TP
.B sb_tls_sbio
A transport layer handler for SSL/TLS encoding/decoding. Note that this
handler is private to the library and is not exposed in the API.
.LP
The provided handlers are all instantiated implicitly by libldap, and
applications generally will not need to directly manipulate them.

.SH SEE ALSO
.BR lber-decode (3),
.BR lber-encode (3),
.BR lber-types (3),
.BR ldap_get_option (3)

.LP
.SH ACKNOWLEDGEMENTS
.so ../Project