dl_unitdata_req.7

7号信令功能代码,为开源代码

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.so lis.macros
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.\"
.\"
.TH DL_UNITDATA_REQ 7 "2004/01/12 23:45:16" "LiS-2_16_18-8" "Linux STREAMS"
.SH NAME
.B DL_UNITDATA_REQ (dl_unitdata_req_t)
\- conveys one DLSDU from the DLS user to the DLS provider for transmission
to a peer DLS user.  Because connectionless data transfer is an
unacknowledged service, the DLS provider makes no guarantees of delivery of
connectionless DLSDUs.  It is the responsibility of the DLS user to do
any necessary sequencing or retransmission of DLSDUs in the event of a
presumed loss.
.SH SYNOPSIS
The message consists of one
.B M_PROTO
message block containing the structure shown below, followed by one or more
.B M_DATA
blocks containing at least one byte of data.  The amount of user data that may
be transferred in a single DLSDU is limited.  This limit is conveyed by the
parameter
.I dl_max_sdu
in the
.BR DL_INFO_ACK (7)
primitive.
.sp
.nf
\fC\s-1\
typedef struct {
    t_uscalar_t         dl_primitive;
    t_uscalar_t         dl_dest_addr_length;
    t_uscalar_t         dl_dest_addr_offset;
    dl_priority_t       dl_priority;
} dl_unitdata_req_t;
\fR\s+1
.fi
.SH PARAMETERS
.TP
.I dl_primitive
conveys
.BR DL_UNITDATA_REQ .
.TP
.I dl_dest_addr_length
conveys the length of the DLSAP address of the destination DLS user.  If the
destination user is implemented using DLPI, this address is the full DLSAP
address returned on the
.BR DL_BIND_ACK (7).
.TP
.I dl_dest_addr_offset
conveys the offset from the beginning of the
.B M_PROTO
message block where the destination DLSAP address begins.
.TP
.I dl_priority
indicates the priority value within the supported range for this
particular DLSDU.
.SH STATE
The message is valid in state
.BR DL_IDLE .
.SH "NEW STATE"
The resulting state is unchanged.
.SH RESPONSE
If the DLS provider accepts the data for transmission, there is no response.
This does not, however, guarantee that the data will be delivered to the
destination DLS user, since the connectionless data transfer is not a
confirmed service.  If the request is erroneous, message
.BR DL_UDERROR_IND (7)
is returned, and the resulting state is unchanged.
.PP
If for some reason the request cannot be processed, the DLS provider
may generate a
.BR DL_UDERROR_IND (7)
to report the problem.  There is, however, no guarantee that such an error
report will be generated for all undeliverable data units, since
connectionless data transfer is not a confirmed service.
.SH ERRORS
.TP
.B DL_BADADDR
The destination DLSAP address was in an incorrect format or contained
invalid information.
.TP
.B DL_BADDATA
The amount of data in the current DLSDU exceeded the DLS provider's
DLSDU limit.
.TP
.B DL_OUTSTATE
The primitive was issued from an invalid state.
.TP
.B DL_UNSUPPORTED
Requested priority not supplied by provider.
.SH VERSIONS
.PP
This manpage was written for
.B LiS\c
.
.[
LiS
.]
.br
The Data Link Provider Interface first appeared in SVR 4.
.[
svr4
.]
.br
This interface conforms to DLPI Revision 2.
.XX
.[
dlpi
.]
.[
magic
.]
.[
advprog
.]
.[
$LIST$
.]
.T2