164 lines
5.7 KiB
Plaintext
164 lines
5.7 KiB
Plaintext
.NC "Network Service Interface"
|
|
.sh 1 "Connectionless Network Service"
|
|
.pp
|
|
This section describes the interface to the ISO connectionless network service.
|
|
There are really two interfaces to the CLNS: the internal interface
|
|
and the IPC interface.
|
|
The internal interface is based on
|
|
procedure calls. It is used only within the kernel. The IPC interface
|
|
allows a user process to access the CLNS directly. This is used only
|
|
for testing and debugging purposes.
|
|
.sh 2 "Primitives"
|
|
.pp
|
|
The CLNS is, by definition, connectionless. Therefore, there are no
|
|
primitives associated with connection establishment or connection release.
|
|
There is one primitive associated with data transfer: N-UNITDATA.
|
|
The parameters to a N-UNITDATA request are: source NSAP address,
|
|
destination NSAP address, quality of service, and user data.
|
|
The parameters of a N-UNITDATA indication are identical to those of the
|
|
request.
|
|
In this implementation, the quality of service parameter is not supported.
|
|
.sh 2 "Internal Interface"
|
|
.pp
|
|
Within the kernel, an N-UNITDATA request is effected by the procedure
|
|
\fIclnp_output()\fR:
|
|
.(b
|
|
\fC
|
|
.TS
|
|
tab(+);
|
|
l s s.
|
|
clnp_output(m0, isop, datalen, flags)
|
|
.T&
|
|
l l l.
|
|
+struct mbuf+*m0;+/* data */
|
|
+struct isopcb+*isop;+/* ISO protocol control block */
|
|
+int+datalen;+
|
|
+int+flags;+/* flags */
|
|
.TE
|
|
\fR
|
|
.)b
|
|
This procedure will construct a DT NPDU, route it, and transmit it on
|
|
the appropriate subnetwork. \fIM0\fR is an mbuf chain containing the
|
|
user data portion of the N-UNITDATA request. \fIIsopcb\fR is the iso protocol
|
|
control block previously allocated. \fIClnp_output\fR will use the following
|
|
fields: \fIisop_laddr\fR, isop_faddr, isop_route, isop_options,
|
|
isop_optindex, \fI and \fRisop_clnpcache\fR.
|
|
\fIDatalen\fR specifies the number of bytes of user data.
|
|
The \fIflags\fR parameter will be discussed in a subsequent chapter.
|
|
.pp
|
|
A N-UNITDATA indication occurs when a DT NPDU arrives. The indication is
|
|
generated by calling the appropriate upper layer protocol input routine.
|
|
In the case of TP, the procedure \fItpclnp_input()\fR is called:
|
|
.(b
|
|
\fC
|
|
.TS
|
|
tab(+);
|
|
l s s.
|
|
tpclnp_input(m, src, dst, len)
|
|
.T&
|
|
l l l.
|
|
+struct mbuf+*m;+/* DT NPDU */
|
|
+struct iso_addr+*src;+/* source of packet */
|
|
+struct iso_addr+*dst;+/* destination of packet */
|
|
+int+len;+/* length of clnp header */
|
|
.TE
|
|
\fR
|
|
.)b
|
|
\fIM\fR contains the entire DT NPDU packet. \fILen\fR indicates the size
|
|
of the CLNP header. In other words, the user data of the DT NPDU begins
|
|
\fIlen\fR bytes into \fIm\fR. \fISrc\fR and \fIdst\fR indicate the
|
|
source and destination NSAP addresses of the packet.
|
|
.sh 3 "CLNP/Subnetwork Interface"
|
|
.pp
|
|
The design of the interface between the subnetwork and the CLNP is
|
|
determined by the design of the Unix network interface drivers. CLNP
|
|
follows the conventional mechanisms for exchanging packets with a network
|
|
interface. See the section on Network Interface Drivers in Chapter Five
|
|
for more information on these conventions.
|
|
.sh 2 "IPC (\*(lqRaw\*(rq) Interface"
|
|
.pp
|
|
The IPC interface to the CLNS allows direct (called \*(lqraw\*(rq)
|
|
access to CLNP.
|
|
This interface is intended for testing and debugging only.
|
|
Its use results in the
|
|
transmission of CLNP datagrams with nonstandard identification fields.
|
|
These raw packets may be rejected by a system not employing the same
|
|
convention. See the section on network implementation for more information
|
|
about the conventions.
|
|
.pp
|
|
In order to gain access to the raw interface
|
|
a \fIsocket\fR, with address family AF_ISO and type SOCK_RAW must be created.
|
|
With this socket in hand,
|
|
the system calls \fIsendto()\fR and \fIrecvfrom()\fR can be used to
|
|
transmit and receive raw CLNP datagrams.
|
|
.sh 3 "Sending raw datagrams"
|
|
.pp
|
|
The format of the \fIsendto()\fR system call is:
|
|
.(b
|
|
\fC
|
|
.TS
|
|
tab(+);
|
|
l s s.
|
|
cc = sendto(s, msg, len, flags, to, tolen)
|
|
.T&
|
|
l l l.
|
|
int+cc,s;
|
|
char+*msg;
|
|
int+len,flags;
|
|
struct sockaddr+*to;
|
|
int+to;
|
|
.TE
|
|
\fR
|
|
.)b
|
|
\f\fIS\fR is the socket previously created. \fIMsg\fR is a pointer to
|
|
the data for the NPDU. CLNP will prepend a header to this data before
|
|
transmission. \fILen\fR specifies the number of bytes of data. The
|
|
\fIflags\fR parameter is unused and should be zero. \fITo\fR specifies the
|
|
NSAP address to be used as the destination address. The size (in bytes)
|
|
of \fIto\fR is given in \fItolen\fR. CLNP will automatically insert
|
|
the source address based upon the route taken by the packet. The number of
|
|
user data bytes transmitted is returned as \fIcc\fR. See \fIsendto(2)\fR
|
|
for more information on this system call.
|
|
.sh 3 "Receiving raw datagrams"
|
|
.pp
|
|
The format of the \fIrecvfrom()\fR system call is:
|
|
.(b
|
|
\fC
|
|
.TS
|
|
tab(+);
|
|
l s s.
|
|
cc = recvfrom(s, buf, len, flags, from, fromlen)
|
|
.T&
|
|
l l l.
|
|
int+cc,s;
|
|
char+*buf;
|
|
int+len,flags;
|
|
struct sockaddr+*from;
|
|
int+*fromlen;
|
|
.TE
|
|
\fR
|
|
.)b
|
|
When used with a CLNP raw socket \fIs\fR, \fIrecvfrom()\fR will read a
|
|
NPDU from the CLNS. If no packet is available, the call will block.
|
|
\fIBuf\fR specifies a buffer of \fIlen\fR bytes into which the NPDU will
|
|
be read. The entire packet, including the header, will be read into the
|
|
buffer. The \fIflags\fR parameter is unused, and should be zero. If
|
|
\fIfrom\fR is non-zero, the source address of the NPDU is filled in.
|
|
\fIFromlen\fR is a value-result parameter, initialized to the size of
|
|
the buffer associated with \fIfrom\fR, and modified on return to
|
|
indicate the actual size of the address stored there. The total number
|
|
of bytes received (header and data) is returned as \fIcc\fR.
|
|
See \fIrecvfrom(2)\fR for more information about this system call.
|
|
.sh 1 "Connection Oriented Network Service"
|
|
.pp
|
|
The ARGO Connection Oriented Network Service (CONS) is not a complete
|
|
implementation of the
|
|
OSI network service.
|
|
It is that subset of the OSI network service that is used
|
|
by ARGO Transport and by ARGO CLNP.
|
|
.\" FIGURE
|
|
.so ../wisc/figs/NS_primitives.nr
|
|
.pp
|
|
.CF
|
|
shows which CONS service elements are provided.
|