D-GSM 1/n: add mslookup server in osmo-hlr
Implement the mslookup server to service remote mslookup requests.
This patch merely adds the logic to answer incoming mslookup requests, an
actual method to receive requests (mDNS) follows in a subsequent patch.
- API to configure service names and addresses for the local site (per MSC).
- determine whether a subscriber is on a local MSC
(checking the local proxy will be added in subsequent patch that adds proxy
capability).
- VTY config follows in a subsequent patch.
For a detailed overview of the D-GSM and mslookup related files, please see the
elaborate comment at the top of mslookup.c (already added in an earlier patch).
Change-Id: Ife4a61d71926d08f310a1aeed9d9f1974f64178b
diff --git a/src/mslookup_server.c b/src/mslookup_server.c
new file mode 100644
index 0000000..9c4dc58
--- /dev/null
+++ b/src/mslookup_server.c
@@ -0,0 +1,376 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <string.h>
+#include <errno.h>
+#include <osmocom/core/sockaddr_str.h>
+#include <osmocom/gsm/gsup.h>
+#include <osmocom/mslookup/mslookup.h>
+#include <osmocom/hlr/logging.h>
+#include <osmocom/hlr/hlr.h>
+#include <osmocom/hlr/db.h>
+#include <osmocom/hlr/timestamp.h>
+#include <osmocom/hlr/mslookup_server.h>
+
+static const struct osmo_mslookup_result not_found = {
+ .rc = OSMO_MSLOOKUP_RC_NOT_FOUND,
+ };
+const struct osmo_ipa_name mslookup_server_msc_wildcard = {};
+
+static void set_result(struct osmo_mslookup_result *result,
+ const struct mslookup_service_host *service_host,
+ uint32_t age)
+{
+ if (!osmo_sockaddr_str_is_nonzero(&service_host->host_v4)
+ && !osmo_sockaddr_str_is_nonzero(&service_host->host_v6)) {
+ *result = not_found;
+ return;
+ }
+ result->rc = OSMO_MSLOOKUP_RC_RESULT;
+ result->host_v4 = service_host->host_v4;
+ result->host_v6 = service_host->host_v6;
+ result->age = age;
+}
+
+const struct mslookup_service_host *mslookup_server_get_local_gsup_addr()
+{
+ static struct mslookup_service_host gsup_bind = {};
+ struct mslookup_service_host *host;
+
+ /* Find a HLR/GSUP service set for the server (no VLR unit name) */
+ host = mslookup_server_service_get(&mslookup_server_msc_wildcard, OSMO_MSLOOKUP_SERVICE_HLR_GSUP);
+ if (host)
+ return host;
+
+ /* Try to use the locally configured GSUP bind address */
+ osmo_sockaddr_str_from_str(&gsup_bind.host_v4, g_hlr->gsup_bind_addr, OSMO_GSUP_PORT);
+ if (gsup_bind.host_v4.af == AF_INET6) {
+ gsup_bind.host_v6 = gsup_bind.host_v4;
+ gsup_bind.host_v4 = (struct osmo_sockaddr_str){};
+ }
+ return &gsup_bind;
+}
+
+struct mslookup_server_msc_cfg *mslookup_server_msc_get(const struct osmo_ipa_name *msc_name, bool create)
+{
+ struct llist_head *c = &g_hlr->mslookup.server.local_site_services;
+ struct mslookup_server_msc_cfg *msc;
+
+ if (!msc_name)
+ return NULL;
+
+ llist_for_each_entry(msc, c, entry) {
+ if (osmo_ipa_name_cmp(&msc->name, msc_name))
+ continue;
+ return msc;
+ }
+ if (!create)
+ return NULL;
+
+ msc = talloc_zero(g_hlr, struct mslookup_server_msc_cfg);
+ OSMO_ASSERT(msc);
+ INIT_LLIST_HEAD(&msc->service_hosts);
+ msc->name = *msc_name;
+ llist_add_tail(&msc->entry, c);
+ return msc;
+}
+
+struct mslookup_service_host *mslookup_server_msc_service_get(struct mslookup_server_msc_cfg *msc, const char *service,
+ bool create)
+{
+ struct mslookup_service_host *e;
+ if (!msc)
+ return NULL;
+
+ llist_for_each_entry(e, &msc->service_hosts, entry) {
+ if (!strcmp(e->service, service))
+ return e;
+ }
+
+ if (!create)
+ return NULL;
+
+ e = talloc_zero(msc, struct mslookup_service_host);
+ OSMO_ASSERT(e);
+ OSMO_STRLCPY_ARRAY(e->service, service);
+ llist_add_tail(&e->entry, &msc->service_hosts);
+ return e;
+}
+
+struct mslookup_service_host *mslookup_server_service_get(const struct osmo_ipa_name *msc_name, const char *service)
+{
+ struct mslookup_server_msc_cfg *msc = mslookup_server_msc_get(msc_name, false);
+ if (!msc)
+ return NULL;
+ return mslookup_server_msc_service_get(msc, service, false);
+}
+
+int mslookup_server_msc_service_set(struct mslookup_server_msc_cfg *msc, const char *service,
+ const struct osmo_sockaddr_str *addr)
+{
+ struct mslookup_service_host *e;
+
+ if (!service || !service[0]
+ || strlen(service) > OSMO_MSLOOKUP_SERVICE_MAXLEN)
+ return -EINVAL;
+ if (!addr || !osmo_sockaddr_str_is_nonzero(addr))
+ return -EINVAL;
+
+ e = mslookup_server_msc_service_get(msc, service, true);
+ if (!e)
+ return -EINVAL;
+
+ switch (addr->af) {
+ case AF_INET:
+ e->host_v4 = *addr;
+ break;
+ case AF_INET6:
+ e->host_v6 = *addr;
+ break;
+ default:
+ return -EINVAL;
+ }
+ return 0;
+}
+
+int mslookup_server_msc_service_del(struct mslookup_server_msc_cfg *msc, const char *service,
+ const struct osmo_sockaddr_str *addr)
+{
+ struct mslookup_service_host *e, *n;
+ int deleted = 0;
+
+ if (!msc)
+ return -ENOENT;
+
+ llist_for_each_entry_safe(e, n, &msc->service_hosts, entry) {
+ if (service && strcmp(service, e->service))
+ continue;
+
+ if (addr) {
+ if (!osmo_sockaddr_str_cmp(addr, &e->host_v4)) {
+ e->host_v4 = (struct osmo_sockaddr_str){};
+ /* Removed one addr. If the other is still there, keep the entry. */
+ if (osmo_sockaddr_str_is_nonzero(&e->host_v6))
+ continue;
+ } else if (!osmo_sockaddr_str_cmp(addr, &e->host_v6)) {
+ e->host_v6 = (struct osmo_sockaddr_str){};
+ /* Removed one addr. If the other is still there, keep the entry. */
+ if (osmo_sockaddr_str_is_nonzero(&e->host_v4))
+ continue;
+ } else
+ /* No addr match, keep the entry. */
+ continue;
+ /* Addr matched and none is left. Delete. */
+ }
+ llist_del(&e->entry);
+ talloc_free(e);
+ deleted++;
+ }
+ return deleted;
+}
+
+/* A remote entity is asking us whether we are the home HLR of the given subscriber. */
+static void mslookup_server_rx_hlr_gsup(const struct osmo_mslookup_query *query,
+ struct osmo_mslookup_result *result)
+{
+ const struct mslookup_service_host *host;
+ int rc;
+ switch (query->id.type) {
+ case OSMO_MSLOOKUP_ID_IMSI:
+ rc = db_subscr_exists_by_imsi(g_hlr->dbc, query->id.imsi);
+ break;
+ case OSMO_MSLOOKUP_ID_MSISDN:
+ rc = db_subscr_exists_by_msisdn(g_hlr->dbc, query->id.msisdn);
+ break;
+ default:
+ LOGP(DMSLOOKUP, LOGL_ERROR, "Unknown mslookup ID type: %d\n", query->id.type);
+ *result = not_found;
+ return;
+ }
+
+ if (rc) {
+ LOGP(DMSLOOKUP, LOGL_DEBUG, "%s: does not exist in local HLR\n",
+ osmo_mslookup_result_name_c(OTC_SELECT, query, NULL));
+ *result = not_found;
+ return;
+ }
+
+ LOGP(DMSLOOKUP, LOGL_DEBUG, "%s: found in local HLR\n",
+ osmo_mslookup_result_name_c(OTC_SELECT, query, NULL));
+
+ host = mslookup_server_get_local_gsup_addr();
+
+ set_result(result, host, 0);
+ if (result->rc != OSMO_MSLOOKUP_RC_RESULT) {
+ LOGP(DMSLOOKUP, LOGL_ERROR,
+ "Subscriber found, but error in service '" OSMO_MSLOOKUP_SERVICE_HLR_GSUP "' config:"
+ " v4: " OSMO_SOCKADDR_STR_FMT " v6: " OSMO_SOCKADDR_STR_FMT "\n",
+ OSMO_SOCKADDR_STR_FMT_ARGS(&host->host_v4),
+ OSMO_SOCKADDR_STR_FMT_ARGS(&host->host_v6));
+ }
+}
+
+/* Look in the local HLR record: If the subscriber is "at home" in this HLR and is also currently located at a local
+ * VLR, we will find a valid location updating with vlr_number, and no vlr_via_proxy entry. */
+static bool subscriber_has_done_lu_here_hlr(const struct osmo_mslookup_query *query,
+ uint32_t *lu_age,
+ struct osmo_ipa_name *local_msc_name,
+ struct hlr_subscriber *ret_subscr)
+{
+ struct hlr_subscriber _subscr;
+ int rc;
+ uint32_t age;
+
+ struct hlr_subscriber *subscr = ret_subscr ? : &_subscr;
+
+ switch (query->id.type) {
+ case OSMO_MSLOOKUP_ID_IMSI:
+ rc = db_subscr_get_by_imsi(g_hlr->dbc, query->id.imsi, subscr);
+ break;
+ case OSMO_MSLOOKUP_ID_MSISDN:
+ rc = db_subscr_get_by_msisdn(g_hlr->dbc, query->id.msisdn, subscr);
+ break;
+ default:
+ LOGP(DMSLOOKUP, LOGL_ERROR, "Unknown mslookup ID type: %d\n", query->id.type);
+ return false;
+ }
+
+ if (rc) {
+ LOGP(DMSLOOKUP, LOGL_DEBUG, "%s: does not exist in local HLR\n",
+ osmo_mslookup_result_name_c(OTC_SELECT, query, NULL));
+ return false;
+ }
+
+ if (!subscr->vlr_number[0]) {
+ LOGP(DMSLOOKUP, LOGL_DEBUG, "%s: not attached (vlr_number unset)\n",
+ osmo_mslookup_result_name_c(OTC_SELECT, query, NULL));
+ return false;
+ }
+
+ if (subscr->vlr_via_proxy.len) {
+ /* The VLR is behind a proxy, the subscriber is not attached to a local VLR but a remote one. That
+ * remote proxy should instead respond to the service lookup request. */
+ LOGP(DMSLOOKUP, LOGL_DEBUG, "%s: last attach is not at local VLR, but at VLR '%s' via proxy %s\n",
+ osmo_mslookup_result_name_c(OTC_SELECT, query, NULL),
+ subscr->vlr_number,
+ osmo_ipa_name_to_str(&subscr->vlr_via_proxy));
+ return false;
+ }
+
+ if (!timestamp_age(&subscr->last_lu_seen, &age)) {
+ LOGP(DMSLOOKUP, LOGL_DEBUG, "%s: Invalid last_lu_seen timestamp for subscriber\n",
+ osmo_mslookup_result_name_c(OTC_SELECT, query, NULL));
+ return false;
+ }
+ if (age > g_hlr->mslookup.server.local_attach_max_age) {
+ LOGP(DMSLOOKUP, LOGL_DEBUG, "%s: last attach was here, but too long ago: %us > %us\n",
+ osmo_mslookup_result_name_c(OTC_SELECT, query, NULL),
+ age, g_hlr->mslookup.server.local_attach_max_age);
+ return false;
+ }
+
+ *lu_age = age;
+ osmo_ipa_name_set_str(local_msc_name, subscr->vlr_number);
+ LOGP(DMSLOOKUP, LOGL_DEBUG, "%s: attached %u seconds ago at local VLR %s\n",
+ osmo_mslookup_result_name_c(OTC_SELECT, query, NULL),
+ age, osmo_ipa_name_to_str(local_msc_name));
+
+ return true;
+}
+
+static bool subscriber_has_done_lu_here(const struct osmo_mslookup_query *query,
+ uint32_t *lu_age_p,
+ struct osmo_ipa_name *local_msc_name)
+{
+ bool attached_here;
+ uint32_t lu_age = 0;
+ struct osmo_ipa_name msc_name = {};
+
+ /* First ask the local HLR db, but if the local proxy record indicates a more recent LU, use that instead.
+ * For all usual cases, only one of these will reflect a LU, even if a subscriber had more than one home HLR:
+ * - if the subscriber is known here, we will never proxy.
+ * - if the subscriber is not known here, this local HLR db will never record a LU.
+ * However, if a subscriber was being proxied to a remote home HLR, and if then the subscriber was also added to
+ * the local HLR database, there might occur a situation where both reflect a LU. So, to be safe against all
+ * situations, compare the two entries.
+ */
+ attached_here = subscriber_has_done_lu_here_hlr(query, &lu_age, &msc_name, NULL);
+
+ /* Future: If proxy has a younger lu, replace. */
+
+ if (attached_here && !msc_name.len) {
+ LOGP(DMSLOOKUP, LOGL_ERROR, "%s: attached here, but no VLR name known\n",
+ osmo_mslookup_result_name_c(OTC_SELECT, query, NULL));
+ return false;
+ }
+
+ if (!attached_here) {
+ /* Already logged "not attached" for both local-db and proxy attach */
+ return false;
+ }
+
+ LOGP(DMSLOOKUP, LOGL_INFO, "%s: attached here, at VLR %s\n",
+ osmo_mslookup_result_name_c(OTC_SELECT, query, NULL),
+ osmo_ipa_name_to_str(&msc_name));
+ *lu_age_p = lu_age;
+ *local_msc_name = msc_name;
+ return true;
+}
+
+/* A remote entity is asking us whether we are providing the given service for the given subscriber. */
+void mslookup_server_rx(const struct osmo_mslookup_query *query,
+ struct osmo_mslookup_result *result)
+{
+ const struct mslookup_service_host *service_host;
+ uint32_t age;
+ struct osmo_ipa_name msc_name;
+
+ /* A request for a home HLR: answer exactly if this is the subscriber's home HLR, i.e. the IMSI is listed in the
+ * HLR database. */
+ if (strcmp(query->service, OSMO_MSLOOKUP_SERVICE_HLR_GSUP) == 0)
+ return mslookup_server_rx_hlr_gsup(query, result);
+
+ /* All other service types: answer when the subscriber has done a LU that is either listed in the local HLR or
+ * in the GSUP proxy database: i.e. if the subscriber has done a Location Updating at an VLR belonging to this
+ * HLR. Respond with whichever services are configured in the osmo-hlr.cfg. */
+ if (!subscriber_has_done_lu_here(query, &age, &msc_name)) {
+ *result = not_found;
+ return;
+ }
+
+ /* We've detected a LU here. The VLR where the LU happened is stored in msc_unit_name, and the LU age is stored
+ * in 'age'. Figure out the address configured for that VLR and service name. */
+ service_host = mslookup_server_service_get(&msc_name, query->service);
+
+ if (!service_host) {
+ /* Find such service set globally (no VLR unit name) */
+ service_host = mslookup_server_service_get(&mslookup_server_msc_wildcard, query->service);
+ }
+
+ if (!service_host) {
+ LOGP(DMSLOOKUP, LOGL_ERROR,
+ "%s: subscriber found, but no service %s configured, cannot service lookup request\n",
+ osmo_mslookup_result_name_c(OTC_SELECT, query, NULL),
+ osmo_quote_str_c(OTC_SELECT, query->service, -1));
+ *result = not_found;
+ return;
+ }
+
+ set_result(result, service_host, age);
+}