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 Sockbuf_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_SET_FD
Sets the file descriptor of the Sockbuf to the descriptor
pointed to by arg; arg must be a ber_socket_t *. The return
value will always be 1.
LBER_SB_OPT_SET_NONBLOCK
Toggles the non-blocking state of the file descriptor associated
to the Sockbuf. 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.
LBER_SB_OPT_DRAIN
Flush (read and discard) all available input on the Sockbuf.
The return value will be 1.
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 layers.
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:
ldap_pvt_sockbuf_io_sasl
An application layer handler for SASL encoding/decoding.
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.
The provided handlers are all instantiated implicitly by libldap, and
applications generally will not need to directly manipulate them.
SEE ALSO
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.
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