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LBER_SOCKBUF(3)                                                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_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  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:

       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.



OpenLDAP 2.4.40                   2014/09/20                   LBER_SOCKBUF(3)