bsc: Move the connection tracking code out of main file

1 files changed, 516 insertions, 0 deletions

diff --git a/src/sccp_state.c b/src/sccp_state.c
new file mode 100644
index 0000000..3f89521
--- /dev/null
+++ b/src/sccp_state.c
@@ -0,0 +1,516 @@
+/* The routines to handle the state */
+/*
+ * (C) 2010-2011 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2010-2011 by On-Waves
+ * 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 <mtp_data.h>
+#include <mtp_level3.h>
+#include <bss_patch.h>
+#include <bssap_sccp.h>
+#include <bsc_data.h>
+#include <cellmgr_debug.h>
+#include <bsc_sccp.h>
+
+#include <osmocore/talloc.h>
+
+#include <osmocom/vty/vty.h>
+#include <osmocom/vty/telnet_interface.h>
+
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <fcntl.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <unistd.h>
+
+static void send_reset_ack(struct mtp_link_set *link, int sls);
+static void bsc_resources_released(struct bsc_msc_forward *bsc);
+static void handle_local_sccp(struct mtp_link_set *link, struct msgb *inp, struct sccp_parse_result *res, int sls);
+static void clear_connections(struct bsc_msc_forward *bsc);
+static void send_local_rlsd(struct mtp_link_set *link, struct sccp_parse_result *res);
+
+/* send a RSIP to the MGCP GW */
+static void mgcp_reset(struct bsc_msc_forward *fw)
+{
+        static const char mgcp_reset[] = {
+            "RSIP 1 13@mgw MGCP 1.0\r\n"
+        };
+
+	mgcp_forward(fw, (const uint8_t *) mgcp_reset, strlen(mgcp_reset));
+}
+
+/*
+ * methods called from the MTP Level3 part
+ */
+void mtp_link_set_forward_sccp(struct mtp_link_set *link, struct msgb *_msg, int sls)
+{
+	int rc;
+	struct sccp_parse_result result;
+	struct bsc_msc_forward *fw = link->fw;
+
+	rc = bss_patch_filter_msg(_msg, &result);
+	if (rc == BSS_FILTER_RESET) {
+		LOGP(DMSC, LOGL_NOTICE, "Filtering BSS Reset from the BSC\n");
+		mgcp_reset(fw);
+		send_reset_ack(link, sls);
+		return;
+	}
+
+	/* special responder */
+	if (fw->msc_link_down) {
+		if (rc == BSS_FILTER_RESET_ACK && fw->reset_count > 0) {
+			LOGP(DMSC, LOGL_ERROR, "Received reset ack for closing.\n");
+			clear_connections(fw);
+			bsc_resources_released(fw);
+			return;
+		}
+
+		if (rc != 0 && rc != BSS_FILTER_RLSD && rc != BSS_FILTER_RLC) {
+			LOGP(DMSC, LOGL_ERROR, "Ignoring unparsable msg during closedown.\n");
+			return;
+		}
+
+		return handle_local_sccp(link, _msg, &result, sls);
+	}
+
+	/* update the connection state */
+	update_con_state(link->fw, rc, &result, _msg, 0, sls);
+
+	if (rc == BSS_FILTER_CLEAR_COMPL) {
+		send_local_rlsd(link, &result);
+	} else if (rc == BSS_FILTER_RLC || rc == BSS_FILTER_RLSD) {
+		LOGP(DMSC, LOGL_DEBUG, "Not forwarding RLC/RLSD to the MSC.\n");
+		return;
+	}
+
+
+	msc_send_msg(fw, rc, &result, _msg);
+}
+
+void mtp_link_set_forward_isup(struct mtp_link_set *set, struct msgb *msg, int sls)
+{
+	LOGP(DINP, LOGL_ERROR, "ISUP is not handled.\n");
+}
+
+/*
+ * handle local message in close down mode
+ */
+static void handle_local_sccp(struct mtp_link_set *link, struct msgb *inpt, struct sccp_parse_result *result, int sls)
+{
+	/* Handle msg with a reject */
+	if (inpt->l2h[0] == SCCP_MSG_TYPE_CR) {
+		struct sccp_connection_request *cr;
+		struct msgb *msg;
+
+		LOGP(DINP, LOGL_NOTICE, "Handling CR localy.\n");
+		cr = (struct sccp_connection_request *) inpt->l2h;
+		msg = create_sccp_refuse(&cr->source_local_reference);
+		if (msg) {
+			mtp_link_set_submit_sccp_data(link, sls, msg->l2h, msgb_l2len(msg));
+			msgb_free(msg);
+		}
+		return;
+	} else if (inpt->l2h[0] == SCCP_MSG_TYPE_DT1 && result->data_len >= 3) {
+		struct active_sccp_con *con;
+		struct sccp_data_form1 *form1;
+		struct msgb *msg;
+
+		if (inpt->l3h[0] == 0 && inpt->l3h[2] == BSS_MAP_MSG_CLEAR_COMPLETE) {
+			LOGP(DINP, LOGL_DEBUG, "Received Clear Complete. Sending Release.\n");
+
+			form1 = (struct sccp_data_form1 *) inpt->l2h;
+
+			llist_for_each_entry(con, &link->fw->sccp_connections, entry) {
+				if (memcmp(&form1->destination_local_reference,
+					   &con->dst_ref, sizeof(con->dst_ref)) == 0) {
+					LOGP(DINP, LOGL_DEBUG, "Sending a release request now.\n");
+					msg = create_sccp_rlsd(&con->dst_ref, &con->src_ref);
+					if (msg) {
+						mtp_link_set_submit_sccp_data(link, con->sls, msg->l2h, msgb_l2len(msg));
+						msgb_free(msg);
+					}
+					return;
+				}
+			}
+
+			LOGP(DINP, LOGL_ERROR, "Could not find connection for the Clear Command.\n");
+		}
+	} else if (inpt->l2h[0] == SCCP_MSG_TYPE_UDT && result->data_len >= 3) {
+		if (inpt->l3h[0] == 0 && inpt->l3h[2] == BSS_MAP_MSG_RESET_ACKNOWLEDGE) {
+			LOGP(DINP, LOGL_NOTICE, "Reset ACK. Connecting to the MSC again.\n");
+			bsc_resources_released(link->fw);
+			return;
+		}
+	}
+
+
+	/* Update the state, maybe the connection was released? */
+	update_con_state(link->fw, 0, result, inpt, 0, sls);
+	if (llist_empty(&link->fw->sccp_connections))
+		bsc_resources_released(link->fw);
+	return;
+}
+
+static void clear_connections(struct bsc_msc_forward *fw)
+{
+	struct active_sccp_con *tmp, *con;
+
+	llist_for_each_entry_safe(con, tmp, &fw->sccp_connections, entry) {
+		free_con(con);
+	}
+
+	link_clear_all(fw->bsc);
+}
+
+void bsc_resources_released(struct bsc_msc_forward *fw)
+{
+	bsc_del_timer(&fw->reset_timeout);
+}
+
+static void bsc_reset_timeout(void *_data)
+{
+	struct msgb *msg;
+	struct bsc_msc_forward *fw = _data;
+
+	/* no reset */
+	if (fw->reset_count > 0) {
+		LOGP(DINP, LOGL_ERROR, "The BSC did not answer the GSM08.08 reset. Restart MTP\n");
+		mtp_link_set_stop(fw->bsc);
+		clear_connections(fw);
+		link_reset_all(fw->bsc);
+		bsc_resources_released(fw);
+		return;
+	}
+
+	msg = create_reset();
+	if (!msg) {
+		bsc_schedule_timer(&fw->reset_timeout, 10, 0);
+		return;
+	}
+
+	++fw->reset_count;
+	mtp_link_set_submit_sccp_data(fw->bsc, -1, msg->l2h, msgb_l2len(msg));
+	msgb_free(msg);
+	bsc_schedule_timer(&fw->reset_timeout, 20, 0);
+}
+
+/*
+ * We have lost the connection to the MSC. This is tough. We
+ * can not just bring down the MTP link as this will disable
+ * the BTS radio. We will have to do the following:
+ *
+ *  1.) Bring down all open SCCP connections. As this will close
+ *      all radio resources
+ *  2.) Bring down all MGCP endpoints
+ *  3.) Clear the connection data.
+ *
+ * To make things worse we need to buffer the BSC messages... atfer
+ * everything has been sent we will try to connect to the MSC again.
+ *
+ * We will have to veriy that all connections are closed properly..
+ * this means we need to parse response message. In the case the
+ * MTP link is going down while we are sending. We will simply
+ * reconnect to the MSC.
+ */
+void release_bsc_resources(struct bsc_msc_forward *fw)
+{
+	struct active_sccp_con *tmp;
+	struct active_sccp_con *con;
+
+	bsc_del_timer(&fw->reset_timeout);
+
+	/* 2. clear the MGCP endpoints */
+	mgcp_reset(fw);
+
+	/* 1. send BSSMAP Cleanup.. if we have any connection */
+	llist_for_each_entry_safe(con, tmp, &fw->sccp_connections, entry) {
+		if (!con->has_dst_ref) {
+			free_con(con);
+			continue;
+		}
+
+		struct msgb *msg = create_clear_command(&con->src_ref);
+		if (!msg)
+			continue;
+
+		/* wait for the clear commands */
+		mtp_link_set_submit_sccp_data(fw->bsc, con->sls, msg->l2h, msgb_l2len(msg));
+		msgb_free(msg);
+	}
+
+	if (llist_empty(&fw->sccp_connections)) {
+		bsc_resources_released(fw);
+	} else {
+		/* Send a reset in 20 seconds if we fail to bring everything down */
+		fw->reset_timeout.cb = bsc_reset_timeout;
+		fw->reset_timeout.data = fw;
+		fw->reset_count = 0;
+		bsc_schedule_timer(&fw->reset_timeout, 10, 0);
+	}
+}
+
+void mtp_linkset_down(struct mtp_link_set *set)
+{
+	set->available = 0;
+	mtp_link_set_stop(set);
+	clear_connections(set->fw);
+	mgcp_reset(set->fw);
+
+	/* If we have an A link send a reset to the MSC */
+	msc_send_reset(set->fw);
+}
+
+void mtp_linkset_up(struct mtp_link_set *set)
+{
+	set->available = 1;
+
+	/* we have not gone through link down */
+	if (set->fw->msc_link_down) {
+		clear_connections(set->fw);
+		bsc_resources_released(set->fw);
+	}
+
+	mtp_link_set_reset(set);
+}
+
+/**
+ * update the connection state and helpers below
+ */
+static void send_rlc_to_bsc(struct bsc_msc_forward *fw,
+			    unsigned int sls, struct sccp_source_reference *src,
+			    struct sccp_source_reference *dst)
+{
+	struct msgb *msg;
+
+	msg = create_sccp_rlc(src, dst);
+	if (!msg)
+		return;
+
+	mtp_link_set_submit_sccp_data(fw->bsc, sls, msg->l2h, msgb_l2len(msg));
+	msgb_free(msg);
+}
+
+static void handle_rlsd(struct bsc_msc_forward *fw, struct sccp_connection_released *rlsd, int from_msc)
+{
+	struct active_sccp_con *con;
+
+	if (from_msc) {
+		/* search for a connection, reverse src/dest for MSC */
+		con = find_con_by_src_dest_ref(fw, &rlsd->destination_local_reference,
+					       &rlsd->source_local_reference);
+		if (con) {
+			LOGP(DINP, LOGL_DEBUG, "RLSD conn still alive: local: 0x%x remote: 0x%x\n",
+			     sccp_src_ref_to_int(&con->src_ref),
+			     sccp_src_ref_to_int(&con->dst_ref));
+			con->released_from_msc = 1;
+		} else {
+			/* send RLC */
+			LOGP(DINP, LOGL_DEBUG, "Sending RLC for MSC: src: 0x%x dst: 0x%x\n",
+			     sccp_src_ref_to_int(&rlsd->destination_local_reference),
+			     sccp_src_ref_to_int(&rlsd->source_local_reference));
+			msc_send_rlc(fw, &rlsd->destination_local_reference,
+				 &rlsd->source_local_reference);
+		}
+	} else {
+		unsigned int sls = -1;
+		con = find_con_by_src_dest_ref(fw, &rlsd->source_local_reference,
+					       &rlsd->destination_local_reference);
+		if (con) {
+			LOGP(DINP, LOGL_DEBUG, "Timeout on BSC. Sending RLC. src: 0x%x\n",
+			     sccp_src_ref_to_int(&rlsd->source_local_reference));
+
+			if (con->released_from_msc)
+				msc_send_rlc(fw, &con->src_ref, &con->dst_ref);
+			sls = con->sls;
+			free_con(con);
+		} else {
+			LOGP(DINP, LOGL_ERROR, "Timeout on BSC for unknown connection. src: 0x%x\n",
+			     sccp_src_ref_to_int(&rlsd->source_local_reference));
+		}
+
+		/* now send a rlc back to the BSC */
+		send_rlc_to_bsc(fw, sls, &rlsd->destination_local_reference, &rlsd->source_local_reference);
+	}
+}
+
+/**
+ * Update connection state and also send message.....
+ *
+ * RLSD from MSC:
+ *      1.) We don't find the entry in this case we will send a
+ *          forged RLC to the MSC and we are done.
+ *      2.) We find an entry in this we will need to register that
+ *          we need to send a RLC and we are done for now.
+ * RLSD from BSC:
+ *      1.) This is an error we are ignoring for now.
+ * RLC from BSC:
+ *      1.) We are destroying the connection, we might send a RLC to
+ *          the MSC if we are waiting for one.
+ */
+void update_con_state(struct bsc_msc_forward *fw, int rc, struct sccp_parse_result *res, struct msgb *msg, int from_msc, int sls)
+{
+	struct active_sccp_con *con;
+	struct sccp_connection_request *cr;
+	struct sccp_connection_confirm *cc;
+	struct sccp_connection_release_complete *rlc;
+	struct sccp_connection_refused *cref;
+
+	/* was the header okay? */
+	if (rc < 0)
+		return;
+
+	/* the header was size checked */
+	switch (msg->l2h[0]) {
+	case SCCP_MSG_TYPE_CR:
+		if (from_msc) {
+			LOGP(DMSC, LOGL_ERROR, "CR from MSC is not handled.\n");
+			return;
+		}
+
+		cr = (struct sccp_connection_request *) msg->l2h;
+		con = find_con_by_src_ref(fw, &cr->source_local_reference);
+		if (con) {
+			LOGP(DINP, LOGL_ERROR, "Duplicate SRC reference for: 0x%x. Reusing\n",
+				sccp_src_ref_to_int(&con->src_ref));
+			free_con(con);
+		}
+
+		con = talloc_zero(NULL, struct active_sccp_con);
+		if (!con) {
+			LOGP(DINP, LOGL_ERROR, "Failed to allocate\n");
+			return;
+		}
+
+		con->src_ref = cr->source_local_reference;
+		con->sls = sls;
+		con->link = fw->bsc;
+		llist_add_tail(&con->entry, &fw->sccp_connections);
+		LOGP(DINP, LOGL_DEBUG, "Adding CR: local ref: 0x%x\n", sccp_src_ref_to_int(&con->src_ref));
+		break;
+	case SCCP_MSG_TYPE_CC:
+		if (!from_msc) {
+			LOGP(DINP, LOGL_ERROR, "CC from BSC is not handled.\n");
+			return;
+		}
+
+		cc = (struct sccp_connection_confirm *) msg->l2h;
+		con = find_con_by_src_ref(fw, &cc->destination_local_reference);
+		if (con) {
+			con->dst_ref = cc->source_local_reference;
+			con->has_dst_ref = 1;
+			LOGP(DINP, LOGL_DEBUG, "Updating CC: local: 0x%x remote: 0x%x\n",
+				sccp_src_ref_to_int(&con->src_ref), sccp_src_ref_to_int(&con->dst_ref));
+			return;
+		}
+
+		LOGP(DINP, LOGL_ERROR, "CCed connection can not be found: 0x%x\n",
+		     sccp_src_ref_to_int(&cc->destination_local_reference));
+		break;
+	case SCCP_MSG_TYPE_CREF:
+		if (!from_msc) {
+			LOGP(DINP, LOGL_ERROR, "CREF from BSC is not handled.\n");
+			return;
+		}
+
+		cref = (struct sccp_connection_refused *) msg->l2h;
+		con = find_con_by_src_ref(fw, &cref->destination_local_reference);
+		if (con) {
+			LOGP(DINP, LOGL_DEBUG, "Releasing local: 0x%x\n", sccp_src_ref_to_int(&con->src_ref));
+			free_con(con);
+			return;
+		}
+
+		LOGP(DINP, LOGL_ERROR, "CREF from BSC is not handled.\n");
+		break;
+	case SCCP_MSG_TYPE_RLSD:
+		handle_rlsd(fw, (struct sccp_connection_released *) msg->l2h, from_msc);
+		break;
+	case SCCP_MSG_TYPE_RLC:
+		if (from_msc) {
+			LOGP(DINP, LOGL_ERROR, "RLC from MSC is wrong.\n");
+			return;
+		}
+
+		rlc = (struct sccp_connection_release_complete *) msg->l2h;
+		con = find_con_by_src_dest_ref(fw, &rlc->source_local_reference,
+					       &rlc->destination_local_reference);
+		if (con) {
+			LOGP(DINP, LOGL_DEBUG, "Releasing local: 0x%x\n", sccp_src_ref_to_int(&con->src_ref));
+			if (con->released_from_msc)
+				msc_send_rlc(fw, &con->src_ref, &con->dst_ref);
+			free_con(con);
+			return;
+		}
+
+		LOGP(DINP, LOGL_ERROR, "RLC can not be found. 0x%x 0x%x\n",
+		     sccp_src_ref_to_int(&rlc->source_local_reference),
+		     sccp_src_ref_to_int(&rlc->destination_local_reference));
+		break;
+	}
+}
+
+static void send_local_rlsd_for_con(void *data)
+{
+	struct msgb *rlsd;
+	struct active_sccp_con *con = (struct active_sccp_con *) data;
+
+	/* try again in three seconds */
+	con->rlc_timeout.data = con;
+	con->rlc_timeout.cb = send_local_rlsd_for_con;
+	bsc_schedule_timer(&con->rlc_timeout, 3, 0);
+
+	/* we send this to the BSC so we need to switch src and dest */
+	rlsd = create_sccp_rlsd(&con->dst_ref, &con->src_ref);
+	if (!rlsd)
+		return;
+
+	++con->rls_tries;
+	LOGP(DINP, LOGL_DEBUG, "Sending RLSD for 0x%x the %d time.\n",
+	     sccp_src_ref_to_int(&con->src_ref), con->rls_tries);
+	mtp_link_set_submit_sccp_data(con->link, con->sls, rlsd->l2h, msgb_l2len(rlsd));
+	msgb_free(rlsd);
+}
+
+static void send_local_rlsd(struct mtp_link_set *link, struct sccp_parse_result *res)
+{
+	struct active_sccp_con *con;
+
+	LOGP(DINP, LOGL_DEBUG, "Received GSM Clear Complete. Sending RLSD locally.\n");
+
+	con = find_con_by_dest_ref(link->fw, res->destination_local_reference);
+	if (!con)
+		return;
+	con->rls_tries = 0;
+	send_local_rlsd_for_con(con);
+}
+
+static void send_reset_ack(struct mtp_link_set *link, int sls)
+{
+	static const uint8_t reset_ack[] = {
+		0x09, 0x00, 0x03, 0x05, 0x7, 0x02, 0x42, 0xfe,
+		0x02, 0x42, 0xfe, 0x03,
+		0x00, 0x01, 0x31
+	};
+
+	mtp_link_set_submit_sccp_data(link, sls, reset_ack, sizeof(reset_ack));
+}