SCCP: implement variable limit on Optional Data (CR,CC,CREF,RLSD)

When the Optional Data surpasses 130 bytes, it is not sent as part of
SCCP CR, CC, CREF or RLSD messages, but gets sent separately in a Data
Form 1.

Make this 130 user configurable. This is specified to be 130 bytes
exactly, but to interop with non-conforming peers, make this limit
adjustable per cs7 instance, via osmo_sccp_vty_init().

Add and test new VTY config:

	cs7 instance N
	 sccp max-optional-data (<0-999999>|standard)

Related: ITU-T Q.713 4.2 to 4.5
Related: Ia68dad973ef18513b52f5accb5264c557c7295ea osmo-ttcn3-hacks
Related: SYS#6423
Change-Id: If35697234796af8943691b2de62218e7dc93a08c

1 files changed, 35 insertions, 0 deletions

diff --git a/src/sccp_vty.c b/src/sccp_vty.c
index 13fe402..90fb914 100644
--- a/src/sccp_vty.c
+++ b/src/sccp_vty.c
@@ -37,6 +37,8 @@
 #include <osmocom/sigtran/osmo_ss7.h>
 #include <osmocom/sigtran/protocol/mtp.h>
 
+#include <osmocom/sccp/sccp_types.h>
+
 #include "xua_internal.h"
 #include "sccp_internal.h"
 
@@ -165,6 +167,36 @@ DEFUN_ATTR(sccp_timer, sccp_timer_cmd,
 	return CMD_SUCCESS;
 }
 
+DEFUN_ATTR(sccp_max_optional_data, sccp_max_optional_data_cmd,
+	   "sccp max-optional-data (<0-999999>|standard)",
+	   "Configure SCCP behavior\n"
+	   "Adjust the upper bound for the optional data length (the payload) for CR, CC, CREF and RLSD messages."
+	   " For any Optional Data part larger than this value in octets, send CR, CC, CREF and RLSD"
+	   " messages without any payload, and send the data payload in a separate Data Form 1 message."
+	   " ITU-T Q.713 sections 4.2 thru 4.5 define a limit of 130 bytes for the 'Data' parameter. This limit can be"
+	   " adjusted here. May be useful for interop with nonstandard SCCP peers.\n"
+	   "Set a non-standard maximum allowed number of bytes\n"
+	   "Use the ITU-T Q.713 4.2 to 4.5 standard value of 130\n",
+	   CMD_ATTR_IMMEDIATE)
+{
+	struct osmo_ss7_instance *ss7 = vty->index;
+	int val;
+
+	if (!strcmp(argv[0], "standard"))
+		val = SCCP_MAX_OPTIONAL_DATA;
+	else
+		val = atoi(argv[0]);
+
+	osmo_ss7_ensure_sccp(ss7);
+	if (!ss7->sccp) {
+		vty_out(vty, "%% Error: cannot instantiate SCCP instance%s", VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	ss7->sccp->max_optional_data = val;
+	return CMD_SUCCESS;
+}
+
 static const char *osmo_sccp_timer_val_name(const struct osmo_sccp_timer_val *val)
 {
 	static char buf[16];
@@ -227,6 +259,8 @@ static void write_sccp_timers(struct vty *vty, const char *indent,
 void osmo_sccp_vty_write_cs7_node(struct vty *vty, const char *indent, struct osmo_sccp_instance *inst)
 {
 	write_sccp_timers(vty, indent, inst, false);
+	if (inst->max_optional_data != SCCP_MAX_OPTIONAL_DATA)
+		vty_out(vty, "%ssccp max-optional-data %u%s", indent, inst->max_optional_data, VTY_NEWLINE);
 }
 
 DEFUN(show_sccp_timers, show_sccp_timers_cmd,
@@ -262,4 +296,5 @@ void osmo_sccp_vty_init(void)
 	install_lib_element_ve(&show_sccp_timers_cmd);
 	gen_sccp_timer_cmd_strs(&sccp_timer_cmd);
 	install_lib_element(L_CS7_NODE, &sccp_timer_cmd);
+	install_lib_element(L_CS7_NODE, &sccp_max_optional_data_cmd);
 }