isotpsend: add SF_BROADCAST support for functional addressing

When CAN_ISOTP_SF_BROADCAST is set in the CAN_ISOTP_OPTS flags the
CAN_ISOTP socket is switched into functional addressing mode, where
only single frame (SF) protocol data units can be send on the specified
CAN interface and the given tp.tx_id after bind().

In opposite to normal and extended addressing this socket does not
register a CAN-ID for reception which would be needed for a 1-to-1
ISOTP connection with a segmented bi-directional data transfer.

The new option '-S' sets the CAN_ISOTP_SF_BROADCAST to test the option
with different length settings, e.g. link layer data lengths.

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>

isotpsend.c

@@ -72,6 +72,7 @@ void print_usage(char *prg)
 	fprintf(stderr, "         -f <time ns>  (ignore FC and force local tx stmin value in nanosecs)\n");
 	fprintf(stderr, "         -D <len>      (send a fixed PDU with len bytes - no STDIN data)\n");
 	fprintf(stderr, "         -b            (block until the PDU transmission is completed)\n");
+	fprintf(stderr, "         -S            (SF broadcast mode for functional addressing)\n");
 	fprintf(stderr, "         -L <mtu>:<tx_dl>:<tx_flags>  (link layer options for CAN FD)\n");
 	fprintf(stderr, "\nCAN IDs and addresses are given and expected in hexadecimal values.\n");
 	fprintf(stderr, "The pdu data is expected on STDIN in space separated ASCII hex values.\n");
@@ -94,7 +95,7 @@ int main(int argc, char **argv)
 
     addr.can_addr.tp.tx_id = addr.can_addr.tp.rx_id = NO_CAN_ID;
 
-    while ((opt = getopt(argc, argv, "s:d:x:p:P:t:f:D:bL:?")) != -1) {
+    while ((opt = getopt(argc, argv, "s:d:x:p:P:t:f:D:bSL:?")) != -1) {
 	    switch (opt) {
 	    case 's':
 		    addr.can_addr.tp.tx_id = strtoul(optarg, (char **)NULL, 16);
@@ -181,6 +182,10 @@ int main(int argc, char **argv)
 		    opts.flags |= CAN_ISOTP_WAIT_TX_DONE;
 		    break;
 
+	    case 'S':
+		    opts.flags |= CAN_ISOTP_SF_BROADCAST;
+		    break;
+
 	    case 'L':
 		    if (sscanf(optarg, "%hhu:%hhu:%hhu",
 			       &llopts.mtu,
@@ -207,7 +212,8 @@ int main(int argc, char **argv)
 
     if ((argc - optind != 1) ||
 	(addr.can_addr.tp.tx_id == NO_CAN_ID) ||
-	(addr.can_addr.tp.rx_id == NO_CAN_ID)) {
+	((addr.can_addr.tp.rx_id == NO_CAN_ID) &&
+	 (!(opts.flags & CAN_ISOTP_SF_BROADCAST)))) {
 	    print_usage(basename(argv[0]));
 	    exit(1);
     }