db_hlr.c: add db_subscr_exists_by_msisdn()

Check if a subscriber exists without generating an error log entry if
it does not. This is cheaper than db_subscr_get_by_msisdn(), as it
does not fetch the subscriber entry.

subscriber-create-on-demand will use this function to generate
a random unique MSISDN for new subscribers.

Related: OS#2542
Change-Id: Ibfbc408c966197682ba2b12d166ade4bfeb7abc2

5 files changed, 42 insertions, 0 deletions

diff --git a/src/db.c b/src/db.c
index 9cad263..7de61a2 100644
--- a/src/db.c
+++ b/src/db.c
@@ -80,6 +80,7 @@ static const char *stmt_sql[] = {
 	[DB_STMT_AUC_3G_DELETE] = "DELETE FROM auc_3g WHERE subscriber_id = $subscriber_id",
 	[DB_STMT_SET_LAST_LU_SEEN] = "UPDATE subscriber SET last_lu_seen = datetime($val, 'unixepoch') WHERE id = $subscriber_id",
 	[DB_STMT_EXISTS_BY_IMSI] = "SELECT 1 FROM subscriber WHERE imsi = $imsi",
+	[DB_STMT_EXISTS_BY_MSISDN] = "SELECT 1 FROM subscriber WHERE msisdn = $msisdn",
 };
 
 static void sql3_error_log_cb(void *arg, int err_code, const char *msg)
diff --git a/src/db.h b/src/db.h
index 8543085..12e74f8 100644
--- a/src/db.h
+++ b/src/db.h
@@ -29,6 +29,7 @@ enum stmt_idx {
 	DB_STMT_AUC_3G_DELETE,
 	DB_STMT_SET_LAST_LU_SEEN,
 	DB_STMT_EXISTS_BY_IMSI,
+	DB_STMT_EXISTS_BY_MSISDN,
 	_NUM_DB_STMT
 };
 
@@ -132,6 +133,7 @@ int db_subscr_update_aud_by_id(struct db_context *dbc, int64_t subscr_id,
 int db_subscr_update_imei_by_imsi(struct db_context *dbc, const char* imsi, const char *imei);
 
 int db_subscr_exists_by_imsi(struct db_context *dbc, const char *imsi);
+int db_subscr_exists_by_msisdn(struct db_context *dbc, const char *msisdn);
 
 int db_subscr_get_by_imsi(struct db_context *dbc, const char *imsi,
 			  struct hlr_subscriber *subscr);
diff --git a/src/db_hlr.c b/src/db_hlr.c
index c59daf7..362dcf2 100644
--- a/src/db_hlr.c
+++ b/src/db_hlr.c
@@ -560,6 +560,33 @@ int db_subscr_get_by_imsi(struct db_context *dbc, const char *imsi,
 	return rc;
 }
 
+/*! Check if a subscriber exists in the HLR database.
+ * \param[in, out] dbc  database context.
+ * \param[in] msisdn  ASCII string of MSISDN digits.
+ * \returns 0 if it exists, -ENOENT if it does not exist, -EIO on database error.
+ */
+int db_subscr_exists_by_msisdn(struct db_context *dbc, const char *msisdn)
+{
+	sqlite3_stmt *stmt = dbc->stmt[DB_STMT_EXISTS_BY_MSISDN];
+	const char *err;
+	int rc;
+
+	if (!db_bind_text(stmt, NULL, msisdn))
+		return -EIO;
+
+	rc = sqlite3_step(stmt);
+	db_remove_reset(stmt);
+	if (rc == SQLITE_ROW)
+		return 0; /* exists */
+	if (rc == SQLITE_DONE)
+		return -ENOENT; /* does not exist */
+
+	err = sqlite3_errmsg(dbc->db);
+	LOGP(DAUC, LOGL_ERROR, "Failed to check if subscriber exists "
+		"by MSISDN='%s': %s\n", msisdn, err);
+	return rc;
+}
+
 /*! Retrieve subscriber data from the HLR database.
  * \param[in,out] dbc  database context.
  * \param[in] msisdn  ASCII string of MSISDN digits.
diff --git a/tests/db/db_test.c b/tests/db/db_test.c
index 217a8c5..fdd62c5 100644
--- a/tests/db/db_test.c
+++ b/tests/db/db_test.c
@@ -294,6 +294,11 @@ static void test_subscr_create_update_sel_delete()
 	ASSERT_SEL(imsi, imsi0, 0);
 	ASSERT_SEL(msisdn, "5432101234567891", -ENOENT);
 
+	comment("Check if subscriber exists (by MSISDN)");
+
+	ASSERT_RC(db_subscr_exists_by_msisdn(dbc, "543210123456789"), 0);
+	ASSERT_RC(db_subscr_exists_by_msisdn(dbc, "5432101234567891"), -ENOENT);
+
 	comment("Set MSISDN on non-existent / invalid IMSI");
 
 	ASSERT_RC(db_subscr_update_msisdn_by_imsi(dbc, unknown_imsi, "99"), -ENOENT);
diff --git a/tests/db/db_test.err b/tests/db/db_test.err
index 0701089..4dc77e8 100644
--- a/tests/db/db_test.err
+++ b/tests/db/db_test.err
@@ -219,6 +219,13 @@ db_subscr_get_by_msisdn(dbc, "5432101234567891", &g_subscr) --> -ENOENT
 DAUC Cannot read subscriber from db: MSISDN='5432101234567891': No such subscriber
 
 
+--- Check if subscriber exists (by MSISDN)
+
+db_subscr_exists_by_msisdn(dbc, "543210123456789") --> 0
+
+db_subscr_exists_by_msisdn(dbc, "5432101234567891") --> -ENOENT
+
+
 --- Set MSISDN on non-existent / invalid IMSI
 
 db_subscr_update_msisdn_by_imsi(dbc, unknown_imsi, "99") --> -ENOENT