db v6: determine 3G AUC IND from VLR nameneels/ind_cs_ps_sep

Each VLR requesting auth tuples should use a distinct IND pool for 3G auth.  So
far we tied the IND to the GSUP peer connection; MSC and SGSN were always
distinct GSUP peers, they ended up using distinct INDs.

However, we have implemented a GSUP proxy, so that, in a distributed setup, a
remotely roaming subscriber has only one direct GSUP peer proxying for both
remote MSC and SGSN. That means as soon as a subscriber roams to a different
site, the site's MSC and SGSN compete for the same IND bucket, waste SQNs
rapidly and cause auth tuple generation load.

So instead of using the local client as IND, persistently keep a list of VLR
names and assign a different IND to each. Use the GSUP source_name as
indicator, which reflects the actual remote VLR's name.

Furthermore, make 100% sure that CS and PS pools can never collide, by keeping
all CS pools odd numbered and all PS pools even numbered.

Persist the site <-> IND assignments in the database.

Add an IND test to db_test.c

Related: OS#4319
Change-Id: I6f0a6bbef3a27507605c3b4a0e1a89bdfd468374

1 files changed, 10 insertions, 1 deletions

diff --git a/sql/hlr.sql b/sql/hlr.sql
index 98e586d..6b05b6d 100644
--- a/sql/hlr.sql
+++ b/sql/hlr.sql
@@ -79,8 +79,17 @@ CREATE TABLE auc_3g (
 	ind_bitlen	INTEGER NOT NULL DEFAULT 5
 );
 
+CREATE TABLE ind (
+	cn_domain INTEGER NOT NULL,
+	-- 3G auth IND bucket to be used for this VLR, where IND = (idx << 1) + cn_domain -1
+	ind     INTEGER PRIMARY KEY,
+	-- VLR identification, usually the GSUP source_name
+	vlr     TEXT NOT NULL,
+	UNIQUE (cn_domain, vlr)
+);
+
 CREATE UNIQUE INDEX idx_subscr_imsi ON subscriber (imsi);
 
 -- Set HLR database schema version number
 -- Note: This constant is currently duplicated in src/db.c and must be kept in sync!
-PRAGMA user_version = 5;
+PRAGMA user_version = 6;