LBER_SOCKBUF(3)                                                LBER_SOCKBUF(3)



NAME
       ber_sockbuf_alloc,    ber_sockbuf_free,   ber_sockbuf_ctrl,   ber_sock-
       buf_add_io, ber_sockbuf_remove_io, Sockbuf_IO - OpenLDAP LBER  I/O  in-
       frastructure

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  per-
       formed  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 lay-
       ers 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 pro-
       vide 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  Univer-
       sity of Michigan LDAP 3.3 Release.



OpenLDAP 2.4.11                   2008/07/16                   LBER_SOCKBUF(3)
