LBER_SOCKBUF(3) Library Functions Manual LBER_SOCKBUF(3)
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
LIBRARY
OpenLDAP LBER (liblber, -llber)
SYNOPSIS
#include <lber.h>
Sockbuf *ber_sockbuf_alloc( void );
void ber_sockbuf_free(Sockbuf *sb);
int ber_sockbuf_ctrl(Sockbuf *sb, int opt, void *arg);
int ber_sockbuf_add_io(Sockbuf *sb, Sockbuf_IO *sbio, int layer, void *arg);
int ber_sockbuf_remove_io(Sockbuf *sb, Sockbuf_IO *sbio, int layer);
typedef struct sockbuf_io_desc {
int sbiod_level;
Sockbuf *sbiod_sb;
Sockbuf_IO *sbiod_io;
void *sbiod_pvt;
struct sockbuf_io_desc *sbiod_next;
} Sockbuf_IO_Desc;
typedef struct sockbuf_io {
int (*sbi_setup)(Sockbuf_IO_Desc *sbiod, void *arg);
int (*sbi_remove)(Sockbuf_IO_Desc *sbiod);
int (*sbi_ctrl)(Sockbuf_IO_Desc *sbiod, int opt, void *arg);
ber_slen_t (*sbi_read)(Sockbuf_IO_Desc *sbiod, void *buf, ber_len_t len);
ber_slen_t (*sbi_write)(Sockbuf_IO_Desc *sbiod, void *buf, ber_len_t len);
int (*sbi_close)(Sockbuf_IO_Desc *sbiod);
} Sockbuf_IO;
DESCRIPTION
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 Sock‐
buf_IO structure and installing it onto an existing Sockbuf. Sockbuf structures are allocated and freed by
ber_sockbuf_alloc() and ber_sockbuf_free(), respectively. The ber_sockbuf_ctrl() function is used to get and
set options related to a Sockbuf or to a specific I/O layer of the Sockbuf. The ber_sockbuf_add_io() and
ber_sockbuf_remove_io() functions are used to add and remove specific I/O layers on a Sockbuf.
Options for ber_sockbuf_ctrl() include:
LBER_SB_OPT_HAS_IO
Takes a Sockbuf_IO * argument and returns 1 if the given handler is installed on the Sockbuf, otherwise
returns 0.
LBER_SB_OPT_GET_FD
Retrieves the file descriptor associated to the Sockbuf; arg must be a ber_socket_t *. The return
value will be 1 if a valid descriptor was present, -1 otherwise.
LBER_SB_OPT_NEEDS_READ
Returns non-zero if input is waiting to be read.
LBER_SB_OPT_NEEDS_WRITE
Returns non-zero if the Sockbuf is ready to be written.
LBER_SB_OPT_GET_MAX_INCOMING
Returns the maximum allowed size of an incoming message; arg must be a ber_len_t *. The return value
will be 1.
LBER_SB_OPT_SET_MAX_INCOMING
Sets the maximum allowed size of an incoming message; arg must be a ber_len_t *. The return value will
be 1.
Options not in this list will be passed down to each Sockbuf_IO handler in turn until one of them processes
it. If the option is not handled ber_sockbuf_ctrl() will return 0.
Multiple Sockbuf_IO handlers can be stacked in multiple layers to provide various functionality. Currently
defined layers include
LBER_SBIOD_LEVEL_PROVIDER
the lowest layer, talking directly to a network
LBER_SBIOD_LEVEL_TRANSPORT
an intermediate layer
LBER_SBIOD_LEVEL_APPLICATION
a higher layer
Currently defined Sockbuf_IO handlers in liblber include
ber_sockbuf_io_tcp
The default stream-oriented provider
ber_sockbuf_io_fd
A stream-oriented provider for local IPC sockets
ber_sockbuf_io_dgram
A datagram-oriented provider. This handler is only present if the liblber library was built with
LDAP_CONNECTIONLESS defined.
ber_sockbuf_io_readahead
A buffering layer, usually used with a datagram provider to hide the datagram semantics from upper lay‐
ers.
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.
Additional handlers may be present in libldap if support for them was enabled:
lber-decode(3), lber-encode(3), lber-types(3), ldap_get_option(3)
ACKNOWLEDGEMENTS
OpenLDAP Software is developed and maintained by The OpenLDAP Project <http://www.openldap.org/>. OpenLDAP
Software is derived from University of Michigan LDAP 3.3 Release.
OpenLDAP 2.4.40 2014/09/20 LBER_SOCKBUF(3)
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