Manual Pages for UNIX Operating System command usage for man t_getinfo

Networking Services Library Functions             t_getinfo(3NSL)



NAME
     t_getinfo - get protocol-specific service information

SYNOPSIS
     #include 



     int t_getinfo(int fd, struct t_info *info);


DESCRIPTION
     This routine is part of the  XTI  interfaces  which  evolved
     from the TLI interfaces. XTI represents the future evolution
     of these interfaces. However, TLI interfaces  are  supported
     for  compatibility.  When  using  a TLI routine that has the
     same name as an XTI routine, the  tiuser.h header file  must
     be  used.   Refer  to  the   TLI COMPATIBILITY section for a
     description of differences between the two interfaces.


     This function returns the  current  characteristics  of  the
     underlying  transport  protocol  and/or transport connection
     associated with file descriptor fd. The info pointer is used
     to  return  the  same  information returned by t_open(3NSL),
     although not necessarily precisely  the  same  values.  This
     function enables a transport user to access this information
     during any phase of communication.


     This argument points to a t_info  structure  which  contains
     the following members:

       t_scalar_t addr;     /*max size in octets of the transport protocol address*/
       t_scalar_t options;  /*max number of bytes of protocol-specific options  */
       t_scalar_t tsdu;     /*max size in octets of a transport service data unit */
       t_scalar_t etsdu;    /*max size in octets of an expedited transport service*/
                            /*data unit (ETSDU) */
       t_scalar_t connect;  /*max number of octets allowed on connection */
                            /*establishment functions */
       t_scalar_t discon;   /*max number of octets of data allowed on t_snddis()  */
                            /*and t_rcvdis() functions */
       t_scalar_t servtype; /*service type supported by the transport provider */
       t_scalar_t flags;    /*other info about the transport provider */



     The values of the fields have the following meanings:

     addr        A value greater than zero indicates the  maximum
                 size of a transport protocol address and a value
                 of  T_INVALID (-2) specifies that the  transport



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Networking Services Library Functions             t_getinfo(3NSL)



                 provider  does  not provide user access to tran-
                 sport protocol addresses.


     options     A value greater than zero indicates the  maximum
                 number  of  bytes  of  protocol-specific options
                 supported  by  the  provider,  and  a  value  of
                 T_INVALID (-2) specifies that the transport pro-
                 vider does not support user-settable options.


     tsdu        A value greater than zero specifies the  maximum
                 size  in octets of a transport service data unit
                 (TSDU); a value of  T_NULL (zero) specifies that
                 the transport provider does not support the con-
                 cept of TSDU, although it does support the send-
                 ing  of  a datastream with no logical boundaries
                 preserved  across  a  connection;  a  value   of
                 T_INFINITE (-1) specifies that there is no limit
                 on the size in octets of a TSDU; and a value  of
                 T_INVALID  (-2)  specifies  that the transfer of
                 normal data is not supported  by  the  transport
                 provider.


     etsdu       A value greater than zero specifies the  maximum
                 size in octets of an expedited transport service
                 data unit (ETSDU); a  value  of   T_NULL  (zero)
                 specifies  that  the transport provider does not
                 support the concept of ETSDU, although  it  does
                 support  the sending of an expedited data stream
                 with no logical boundaries  preserved  across  a
                 connection;  a  value of  T_INFINITE (-1) speci-
                 fies that there is no  limit  on  the  size  (in
                 octets)  of  an ETSDU; and a value of  T_INVALID
                 (-2) specifies that the  transfer  of  expedited
                 data is not supported by the transport provider.
                 Note that the semantics of expedited data may be
                 quite  different for different transport provid-
                 ers.


     connect     A value greater than zero specifies the  maximum
                 number  of  octets  that  may be associated with
                 connection establishment functions and  a  value
                 of  T_INVALID (-2) specifies that  the transport
                 provider does not allow data  to  be  sent  with
                 connection establishment functions.


     discon      If the  T_ORDRELDATA bit in flags  is  clear,  a
                 value  greater  than  zero specifies the maximum



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Networking Services Library Functions             t_getinfo(3NSL)



                 number of octets that may be associated with the
                 t_snddis(3NSL) and t_rcvdis(3NSL) functions, and
                 a value of  T_INVALID (-2) specifies  that   the
                 transport  provider  does  not  allow data to be
                 sent with the abortive release functions. If the
                 T_ORDRELDATA  bit  is  set  in  flags,  a  value
                 greater than zero specifies the  maximum  number
                 of  octets  that  may  be  associated  with  the
                 t_sndreldata(),  t_rcvreldata(),  t_snddis(3NSL)
                 and  t_rcvdis(3NSL) functions.


     servtype    This field specifies the service type  supported
                 by the transport provider, as described below.


     flags       This is a bit field used to specify other infor-
                 mation  about  the  communications provider.  If
                 the  T_ORDRELDATA bit is set, the communications
                 provider supports sending user data with an ord-
                 erly release. If the  T_SENDZERO bit is  set  in
                 flags,  this indicates that the underlying tran-
                 sport provider supports  the  sending  of  zero-
                 length TSDUs.



     If a transport user is concerned with protocol independence,
     the  above  sizes may be accessed to determine how large the
     buffers must be to hold each piece of information.  Alterna-
     tively,  the  t_alloc(3NSL) function may be used to allocate
     these buffers. An error will  result  if  a  transport  user
     exceeds  the allowed data size on any function. The value of
     each field may change as a result of protocol  option  nego-
     tiation during connection establishment (the t_optmgmt(3NSL)
     call has no effect on the values returned  by  t_getinfo()).
     These  values  will only change from the values presented to
     t_open(3NSL)  after  the  endpoint  enters  the   T_DATAXFER
     state.


     The servtype field of info specifies one  of  the  following
     values on return:

     T_COTS         The    transport    provider    supports    a
                    connection-mode  service but does not support
                    the optional orderly release facility.


     T_COTS_ORD     The    transport    provider    supports    a
                    connection-mode  service  with  the  optional
                    orderly release facility.



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Networking Services Library Functions             t_getinfo(3NSL)



     T_CLTS         The    transport    provider    supports    a
                    connectionless-mode service. For this service
                    type, t_open(3NSL) will return  T_INVALID  (-
                    1) for etsdu, connect and discon.


RETURN VALUES
     Upon successful completion, a value of  0 is returned.  Oth-
     erwise,  a  value  of   -1 is returned and t_errno is set to
     indicate an error.

VALID STATES
     ALL - apart from T_UNINIT.

ERRORS
     On failure, t_errno is set to one of the following:

     TBADF      The specified file descriptor does not refer to a
                transport endpoint.


     TPROTO     This error indicates that a communication problem
                has  been  detected between XTI and the transport
                provider for which there is no other suitable XTI
                error (t_errno).


     TSYSERR    A system error has occurred during  execution  of
                this function.


TLI COMPATIBILITY
     The XTI and TLI interface definitions have common names  but
     use different header files. This, and other semantic differ-
     ences between the two interfaces are described in  the  sub-
     sections below.

  Interface Header
     The XTI interfaces use the header file,  xti.h.  TLI  inter-
     faces  should  not  use  this  header.   They should use the
     header:

       #include 


  Error Description Values
     The t_errno value TPROTO can be set by the XTI interface but
     not by the TLI interface.

  The t_info Structure
     For TLI , the t_info structure referenced by info lacks  the
     following structure member:



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Networking Services Library Functions             t_getinfo(3NSL)



       t_scalar_t flags;    /* other info about the transport provider */



     This member was added to struct t_info  in  the  XTI  inter-
     faces.


     When a value of -1 is observed as the return value in  vari-
     ous  t_info  structure  members, it signifies that the tran-
     sport provider can handle an infinite length  buffer  for  a
     corresponding  attribute, such as address data, option data,
     TSDU (octet size), ETSDU (octet size), connection data,  and
     disconnection  data. The corresponding structure members are
     addr, options, tsdu, estdu,  connect,  and  discon,  respec-
     tively.

ATTRIBUTES
     See attributes(5)  for descriptions of the following  attri-
     butes:



     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | MT Level                    | Safe                        |
    |_____________________________|_____________________________|


SEE ALSO
     t_alloc(3NSL),        t_open(3NSL),         t_optmgmt(3NSL),
     t_rcvdis(3NSL), t_snddis(3NSL), attributes(5)






















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