ipa: VTY config option to explicitly enable/disable SCCP patching

When receiving SCCP messages from an IPA peer/ASP, osmo-stp so far
unconditionally inserted origin/destination point codes int the SCCP
called / calling party addresses.

This behaviro is now made optional with the introduction of the
following per-AS configuration:
	"point-code override patch-sccp (disabled|both)"

The default behavior is switched from 'both' to 'disabled' at the same
time.

Change-Id: I535e2170adadfe755d2bcbf5bbf4556bebb77737
Closes: OS#4219

4 files changed, 41 insertions, 4 deletions

diff --git a/include/osmocom/sigtran/osmo_ss7.h b/include/osmocom/sigtran/osmo_ss7.h
index 14e2b7c..d6ae1d4 100644
--- a/include/osmocom/sigtran/osmo_ss7.h
+++ b/include/osmocom/sigtran/osmo_ss7.h
@@ -290,6 +290,11 @@ osmo_ss7_asp_protocol_name(enum osmo_ss7_asp_protocol mode)
 
 int osmo_ss7_asp_protocol_port(enum osmo_ss7_asp_protocol prot);
 
+enum osmo_ss7_as_patch_sccp_mode {
+	OSMO_SS7_PATCH_NONE,	/* no patching of SCCP */
+	OSMO_SS7_PATCH_BOTH,	/* patch both OPC and DPC into SCCP addresses */
+};
+
 struct osmo_ss7_as {
 	/*! entry in 'ref osmo_ss7_instance.as_list */
 	struct llist_head list;
@@ -314,6 +319,7 @@ struct osmo_ss7_as {
 		uint8_t qos_class;
 		struct {
 			uint32_t dpc;
+			enum osmo_ss7_as_patch_sccp_mode sccp_mode;
 		} pc_override;
 
 		struct osmo_ss7_asp *asps[16];
diff --git a/src/ipa.c b/src/ipa.c
index eeefbe8..d7a929d 100644
--- a/src/ipa.c
+++ b/src/ipa.c
@@ -260,10 +260,12 @@ static int ipa_rx_msg_sccp(struct osmo_ss7_asp *asp, struct msgb *msg)
 	}
 
 	/* Second, patch this into the SCCP message */
-	msg = patch_sccp_with_pc(asp, msg, opc, dpc);
-	if (!msg) {
-		LOGPASP(asp, DLSS7, LOGL_ERROR, "Unable to patch PC into SCCP message; dropping\n");
-		return -1;
+	if (as->cfg.pc_override.sccp_mode == OSMO_SS7_PATCH_BOTH) {
+		msg = patch_sccp_with_pc(asp, msg, opc, dpc);
+		if (!msg) {
+			LOGPASP(asp, DLSS7, LOGL_ERROR, "Unable to patch PC into SCCP message; dropping\n");
+			return -1;
+		}
 	}
 
 	/* Third, create a MTP3/M3UA label with those point codes */
diff --git a/src/osmo_ss7_vty.c b/src/osmo_ss7_vty.c
index cc53b05..35ee5cd 100644
--- a/src/osmo_ss7_vty.c
+++ b/src/osmo_ss7_vty.c
@@ -932,6 +932,30 @@ DEFUN(as_pc_override, as_pc_override_cmd,
 	return CMD_SUCCESS;
 }
 
+DEFUN(as_pc_patch_sccp, as_pc_patch_sccp_cmd,
+	"point-code override patch-sccp (disabled|both)",
+	"Point Code Specific Features\n"
+	"Override (force) a point-code to hard-coded value\n"
+	"Patch point code values into SCCP called/calling address\n"
+	"Don't patch any point codes into SCCP called/calling address\n"
+	"Patch both origin and destination point codes into SCCP called/calling address\n")
+{
+	struct osmo_ss7_as *as = vty->index;
+
+	if (as->cfg.proto != OSMO_SS7_ASP_PROT_IPA) {
+		vty_out(vty, "Only IPA type AS support point-code patch-into-sccp. "
+			"Be happy that you don't need it!%s", VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	if (!strcmp(argv[0], "disabled"))
+		as->cfg.pc_override.sccp_mode = OSMO_SS7_PATCH_NONE;
+	else
+		as->cfg.pc_override.sccp_mode = OSMO_SS7_PATCH_BOTH;
+
+	return CMD_SUCCESS;
+}
+
 static void write_one_as(struct vty *vty, struct osmo_ss7_as *as)
 {
 	struct osmo_ss7_routing_key *rkey;
@@ -973,6 +997,9 @@ static void write_one_as(struct vty *vty, struct osmo_ss7_as *as)
 	if (as->cfg.pc_override.dpc)
 		vty_out(vty, "  point-code override dpc %s%s",
 			osmo_ss7_pointcode_print(as->inst, as->cfg.pc_override.dpc), VTY_NEWLINE);
+
+	if (as->cfg.pc_override.sccp_mode)
+		vty_out(vty, "  point-code override patch-sccp both%s", VTY_NEWLINE);
 }
 
 DEFUN(show_cs7_as, show_cs7_as_cmd,
@@ -1807,6 +1834,7 @@ static void vty_init_shared(void *ctx)
 	install_element(L_CS7_AS_NODE, &as_rout_key_ssn_cmd);
 	install_element(L_CS7_AS_NODE, &as_rout_key_si_ssn_cmd);
 	install_element(L_CS7_AS_NODE, &as_pc_override_cmd);
+	install_element(L_CS7_AS_NODE, &as_pc_patch_sccp_cmd);
 
 	vty_init_addr();
 }
diff --git a/tests/vty/ss7_asp_test.vty b/tests/vty/ss7_asp_test.vty
index cb8dc85..1aa954a 100644
--- a/tests/vty/ss7_asp_test.vty
+++ b/tests/vty/ss7_asp_test.vty
@@ -250,6 +250,7 @@ ss7_asp_vty_test(config-cs7-as)# list
   routing-key RCONTEXT DPC ssn SSN
   routing-key RCONTEXT DPC si (aal2|bicc|b-isup|h248|isup|sat-isup|sccp|tup) ssn SSN
   point-code override dpc PC
+  point-code override patch-sccp (disabled|both)
 
 ss7_asp_vty_test(config-cs7-as)# ?
 ...