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.