TOPTMGMT(3N)              DG/UX 4.30               TOPTMGMT(3N)



     NAME
          t_optmgmt - manage options for a transport endpoint

     SYNOPSIS
          #include <tiuser.h>

          int toptmgmt(fd, req, ret)
          int fd;
          struct toptmgmt *req;
          struct toptmgmt *ret;

     DESCRIPTION
          The toptmgmt function enables a transport user to retrieve,
          verify, or negotiate protocol options with the transport
          provider.  Fd identifies a bound transport endpoint.

          The req and ret arguments point to a t_optmgmt structure
          containing the following members:

               struct netbuf opt;
               long flags;

          The opt field identifies protocol options and the flags
          field is used to specify the action to take with those
          options.

          The options are represented by a netbuf [see intro(3); also
          for len, buf and maxlen] structure in a manner similar to
          the address in tbind.  Req is used to request a specific
          action of the provider and to send options to the provider.
          Len specifies the number of bytes in the options, buf points
          to the options buffer, and maxlen has no meaning for the req
          argument.  The transport provider may return options and
          flag values to the user through ret.  For ret, maxlen
          specifies the maximum size of the options buffer and buf
          points to the buffer where the options are to be placed.  On
          return, len specifies the number of bytes of options
          returned.  Maxlen has no meaning for the req argument, but
          must be set in the ret argument to specify the maximum
          number of bytes the options buffer can hold.  The actual
          structure and content of the options is imposed by the
          transport provider.

          The flags field of req can specify one of the following
          actions:

          T_NEGOTIATE    This action enables the user to negotiate the
                         values of the options specified in req with
                         the transport provider.  The provider will
                         evaluate the requested options and negotiate
                         the values, returning the negotiated values
                         through ret.



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     TOPTMGMT(3N)              DG/UX 4.30               TOPTMGMT(3N)



          T_CHECK        This action enables the user to verify
                         whether the options specified in req are
                         supported by the transport provider.  On
                         return, the flags field of ret will have
                         either T_SUCCESS or T_FAILURE set to indicate
                         to the user whether the options are
                         supported.  These flags are only meaningful
                         for the T_CHECK request.

          T_DEFAULT      This action enables a user to retrieve the
                         default options supported by the transport
                         provider into the opt field of ret.  In req,
                         the len field of opt must be zero and the buf
                         field may be NULL.

          If issued as part of the connectionless-mode service,
          toptmgmt may block due to flow control constraints.  The
          function will not complete until the transport provider has
          processed all previously sent data units.

          On failure, t_errno may be set to one of the following:

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

          [TOUTSTATE]    The function was issued in the wrong
                         sequence.

          [TACCES]       The user does not have permission to
                         negotiate the specified options.

          [TBADOPT]      The specified protocol options were in an
                         incorrect format or contained illegal
                         information.

          [TBADFLAG]     An invalid flag was specified.

          [TBUFOVFLW]    The number of bytes allowed for an incoming
                         argument is not sufficient to store the value
                         of that argument.  The information to be
                         returned in ret will be discarded.

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

     SEE ALSO
          intro(3), t_getinfo(3N), t_open(3N).

     DIAGNOSTICS
          toptmgmt returns 0 on success and -1 on failure and t_errno
          is set to indicate the error.




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