Change in libosmo-sccp[master]: osmo_ss7: Truncate route 'mask' to point code bit length

[laforge]

laforge has submitted this change. ( https://gerrit.osmocom.org/c/libosmo-sccp/+/23982 )

Change subject: osmo_ss7: Truncate route 'mask' to point code bit length
......................................................................

osmo_ss7: Truncate route 'mask' to point code bit length

Otherwise we run into the problem that a route with mask 0xffffff
differs from one with a mask of 0x3fff despite having only 14 bit
point code length and them being logically equal.

Change-Id: I5d5c828de45724d93a0461bb0dd7858fd8378acd
Related: SYS#5422
---
M include/osmocom/sigtran/osmo_ss7.h
M src/osmo_ss7.c
2 files changed, 21 insertions(+), 0 deletions(-)

Approvals:
  pespin: Looks good to me, but someone else must approve
  laforge: Looks good to me, approved
  Jenkins Builder: Verified



diff --git a/include/osmocom/sigtran/osmo_ss7.h b/include/osmocom/sigtran/osmo_ss7.h
index b717d53..a278b59 100644
--- a/include/osmocom/sigtran/osmo_ss7.h
+++ b/include/osmocom/sigtran/osmo_ss7.h
@@ -114,6 +114,7 @@
 struct osmo_sccp_instance *osmo_ss7_ensure_sccp(struct osmo_ss7_instance *inst);
 
 uint8_t osmo_ss7_pc_width(const struct osmo_ss7_pc_fmt *pc_fmt);
+uint32_t osmo_ss7_pc_normalize(const struct osmo_ss7_pc_fmt *pc_fmt, uint32_t pc);
 
 /***********************************************************************
  * MTP Users (Users of MTP, such as SCCP or ISUP)
diff --git a/src/osmo_ss7.c b/src/osmo_ss7.c
index 98dfc0c..de072b4 100644
--- a/src/osmo_ss7.c
+++ b/src/osmo_ss7.c
@@ -196,6 +196,15 @@
 	return pc_fmt->component_len[0] + pc_fmt->component_len[1] + pc_fmt->component_len[2];
 }
 
+/* truncate pc or mask to maximum permitted length. This solves
+ * callers specifying arbitrary large masks which then evade duplicate
+ * detection with longer mask lengths */
+uint32_t osmo_ss7_pc_normalize(const struct osmo_ss7_pc_fmt *pc_fmt, uint32_t pc)
+{
+	uint32_t mask = (1 << osmo_ss7_pc_width(pc_fmt))-1;
+	return pc & mask;
+}
+
 /* get the number of bits we must shift the given component of a point
  * code in this ss7_instance */
 static unsigned int get_pc_comp_shift(const struct osmo_ss7_pc_fmt *pc_fmt,
@@ -702,6 +711,9 @@
 	struct osmo_ss7_route *rt;
 
 	OSMO_ASSERT(ss7_initialized);
+
+	dpc = osmo_ss7_pc_normalize(&rtbl->inst->cfg.pc_fmt, dpc);
+
 	/* we assume the routes are sorted by mask length, i.e. more
 	 * specific routes first, and less specific routes with shorter
 	 * mask later */
@@ -720,6 +732,9 @@
 	struct osmo_ss7_route *rt;
 
 	OSMO_ASSERT(ss7_initialized);
+	mask = osmo_ss7_pc_normalize(&rtbl->inst->cfg.pc_fmt, mask);
+	dpc = osmo_ss7_pc_normalize(&rtbl->inst->cfg.pc_fmt, dpc);
+
 	/* we assume the routes are sorted by mask length, i.e. more
 	 * specific routes first, and less specific routes with shorter
 	 * mask later */
@@ -775,6 +790,11 @@
 	struct osmo_ss7_linkset *lset;
 	struct osmo_ss7_as *as = NULL;
 
+	/* truncate mask to maximum.  Let's avoid callers specifying arbitrary large
+	 * masks to ensure we don't fail duplicate detection with longer mask lengths */
+	mask = osmo_ss7_pc_normalize(&rtbl->inst->cfg.pc_fmt, mask);
+	pc = osmo_ss7_pc_normalize(&rtbl->inst->cfg.pc_fmt, pc);
+
 	OSMO_ASSERT(ss7_initialized);
 	lset = osmo_ss7_linkset_find_by_name(rtbl->inst, linkset_name);
 	if (!lset) {

-- 
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Gerrit-Project: libosmo-sccp
Gerrit-Branch: master
Gerrit-Change-Id: I5d5c828de45724d93a0461bb0dd7858fd8378acd
Gerrit-Change-Number: 23982
Gerrit-PatchSet: 4
Gerrit-Owner: laforge <laforge at osmocom.org>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: laforge <laforge at osmocom.org>
Gerrit-Reviewer: pespin <pespin at sysmocom.de>
Gerrit-MessageType: merged
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