t6recvfrom(3N)

NAME
     t6recvfrom - Read security attributes and data from a trusted endpoint

SYNOPSIS
     cc [ flags ... ] file -lt6

     #include <sys/t6attrs.h>

     int t6recvfrom(int fd, char *buf, int len, int flags,
          struct sockaddr *from, int *fromlen,
          t6attr_t attr_ptr, t6mask_t *new_attrs);

DESCRIPTION
     t6recvfrom() receives data and its associated security attributes from a
     communication endpoint.  The from and fromlen parameters are only used if
     you wish to receive the source address for the data.  This may not be
     applicable for some trusted endpoints.  If not used, these fields should
     be set to 0.  If from is not a NULL pointer, the source address of the
     message is filled in.  fromlen is a value-result parameter, initialized
     to the size of the buffer associated with from, and modified on return to
     indicate the actual size of the address stored there.  The length of the
     message is returned.  If a message is too long to fit in the supplied
     buffer, excess bytes may be discarded depending on the type of socket the
     message is received from (see socket(3N)).

     The flags parameter is formed by ORing one or more of the following:

     MSG_OOB
          Read any out-of-band data present on the socket rather than the
          regular in-band data.  If attr_ptr is non-NULL, out-of-band data
          security attributes are also retrieved.

     MSG_PEEK
          Peek at the data present on the socket; the data is returned, but
          not consumed, so that a subsequent receive operation will see the
          same data.  If attr_ptr is non-NULL, security attributes of the data
          are also peeked.

     attr_ptr specifies a control structure in which to store those attributes
     the caller wishes to retrieve. To get an attribute from the control
     structure, see t6get_attr(3N).  Any attribute that the receiving process
     does not care to receive may not be specified in the control structure.
     This minimizes the attribute translation time when passing the attributes
     out of the kernel.

     If the t6new_attr(3N) call was made previously with a setting of ON, the
     security attributes of the received data will be returned only if they
     have changed from the last set read.  *new_attrs is set to the mask of
     those attributes actually returned. If new attributes are detected, all
     attributes requested by the receiving process are returned, not just
     those that have changed.
     Again, it is critical that the return value always be checked.  It is the
     number of bytes actually received, or -1 with the error code stored in
     errno.  Revocation of access is possible if the received data changes to
     a level not accessible to the receiving process.

ERRORS
     Errors generated by t6recvfrom() is indicated by the global variable
     errno.

     The calls fail if:

     [EBADF]        fd is an invalid file descriptor.

     [EINTR]        The operation was interrupted by delivery of a signal
                    before any data was available to be received.

     [EIO]          An I/O error occurred while reading from or writing to the
                    file system.

     [ENOMEM]       There was insufficient user memory available for the
                    operation to complete.

     [ENOSR]        There were insufficient STREAMS resources available for
                    the operation to complete.

     [ENOTSOCK]     fd is not a socket.

     [ESTALE]       A stale NFS file handle exists.

RETURN VALUE
     t6recvfrom() returns -1 on failure, and the number of bytes read on
     successful completion.

SEE ALSO
     libt6(3N), t6get_attr(3N), t6sendto(3N).

SOURCE
     Trusted Systems Interoperability Group

NOTES