pmc: optional legacy zero length TLV for GET actions.

This patch makes the original behavior of sending the
TLV values for GET actions with a length of zero.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>

phc2sys.c

@@ -372,7 +372,7 @@ static void *get_mgt_data(struct ptp_message *msg)
 static int init_pmc(struct clock *clock, int domain_number)
 {
 	clock->pmc = pmc_create(TRANS_UDS, "/var/run/phc2sys", 0,
-				domain_number, 0);
+				domain_number, 0, 1);
 	if (!clock->pmc) {
 		pr_err("failed to create pmc");
 		return -1;

pmc.8

@@ -1,4 +1,4 @@
-.TH PMC 8 "November 2012" "linuxptp"
+.TH PMC 8 "July 2013" "linuxptp"
 .SH NAME
 pmc \- PTP management client
 
@@ -22,6 +22,8 @@ pmc \- PTP management client
 .BI \-t " transport-specific-field"
 ] [
 .B \-v
+] [
+.B \-z
 ] [ command ] ...
 
 .SH DESCRIPTION
@@ -76,6 +78,13 @@ Display a help message.
 .TP
 .B \-v
 Prints the software version and exits.
+.TP
+.B \-z
+The official interpretation of the 1588 standard mandates sending
+GET actions with valid (but meaningless) TLV values. Therefore the
+pmc program normally sends GET requests with properly formed TLV
+values. This option enables the legacy option of sending zero
+length TLV values instead.
 
 .SH MANAGEMENT IDS
 

pmc.c

@@ -659,6 +659,7 @@ static void usage(char *progname)
 		"           for network and '/var/run/pmc' for UDS.\n"
 		" -t [hex]  transport specific field, default 0x0\n"
 		" -v        prints the software version and exits\n"
+		" -z        send zero length TLV values with the GET actions\n"
 		"\n",
 		progname);
 }
@@ -666,7 +667,7 @@ static void usage(char *progname)
 int main(int argc, char *argv[])
 {
 	char *iface_name = NULL, *progname;
-	int c, cnt, length, tmo = -1, batch_mode = 0;
+	int c, cnt, length, tmo = -1, batch_mode = 0, zero_datalen = 0;
 	char line[1024], *command = NULL;
 	enum transport_type transport_type = TRANS_UDP_IPV4;
 	UInteger8 boundary_hops = 1, domain_number = 0, transport_specific = 0;
@@ -677,7 +678,7 @@ int main(int argc, char *argv[])
 	/* Process the command line arguments. */
 	progname = strrchr(argv[0], '/');
 	progname = progname ? 1+progname : argv[0];
-	while (EOF != (c = getopt(argc, argv, "246u""b:d:hi:t:v"))) {
+	while (EOF != (c = getopt(argc, argv, "246u""b:d:hi:t:vz"))) {
 		switch (c) {
 		case '2':
 			transport_type = TRANS_IEEE_802_3;
@@ -707,6 +708,9 @@ int main(int argc, char *argv[])
 		case 'v':
 			version_show(stdout);
 			return 0;
+		case 'z':
+			zero_datalen = 1;
+			break;
 		case 'h':
 			usage(progname);
 			return 0;
@@ -730,7 +734,8 @@ int main(int argc, char *argv[])
 	print_set_syslog(1);
 	print_set_verbose(1);
 
-	pmc = pmc_create(transport_type, iface_name, boundary_hops, domain_number, transport_specific);
+	pmc = pmc_create(transport_type, iface_name, boundary_hops,
+			 domain_number, transport_specific, zero_datalen);
 	if (!pmc) {
 		fprintf(stderr, "failed to create pmc\n");
 		return -1;

pmc_common.c

@@ -62,7 +62,7 @@ struct pmc {
 
 struct pmc *pmc_create(enum transport_type transport_type, char *iface_name,
 		       UInteger8 boundary_hops, UInteger8 domain_number,
-		       UInteger8 transport_specific)
+		       UInteger8 transport_specific, int zero_datalen)
 {
 	struct pmc *pmc;
 
@@ -92,6 +92,7 @@ struct pmc *pmc_create(enum transport_type transport_type, char *iface_name,
 		pr_err("failed to open transport");
 		goto failed;
 	}
+	pmc->zero_length_gets = zero_datalen ? 1 : 0;
 
 	return pmc;
 

pmc_common.h

@@ -27,7 +27,7 @@ struct pmc;
 
 struct pmc *pmc_create(enum transport_type transport_type, char *iface_name,
 		       UInteger8 boundary_hops, UInteger8 domain_number,
-		       UInteger8 transport_specific);
+		       UInteger8 transport_specific, int zero_datalen);
 
 void pmc_destroy(struct pmc *pmc);