allow to configure multiple oml remote-ip addresses

At the moment we can only configure a single BSC in the BTS
configuration. This also means that if this single BSC fails for some
reason the BTS has no alternate BSC to connect to. Lets extend the
remote-ip parameter so that it can be used multiple times so that an
operater can configure any number of BSCs that are tried one after
another during BTS startup.

Change-Id: I205f68a3a7f35fee4c38a7cfba2b014237df2727
Related: SYS#4971

1 files changed, 219 insertions, 58 deletions

diff --git a/src/common/abis.c b/src/common/abis.c
index abef8264..3325fabe 100644
--- a/src/common/abis.c
+++ b/src/common/abis.c
@@ -38,11 +38,13 @@
 #include <osmocom/core/msgb.h>
 #include <osmocom/core/signal.h>
 #include <osmocom/core/macaddr.h>
+#include <osmocom/core/fsm.h>
 #include <osmocom/abis/abis.h>
 #include <osmocom/abis/e1_input.h>
 #include <osmocom/abis/ipaccess.h>
 #include <osmocom/gsm/ipa.h>
 
+#include <osmo-bts/abis.h>
 #include <osmo-bts/logging.h>
 #include <osmo-bts/gsm_data.h>
 #include <osmo-bts/bts.h>
@@ -54,6 +56,204 @@
 
 static struct gsm_bts *g_bts;
 
+static struct e1inp_line_ops line_ops;
+
+static struct ipaccess_unit bts_dev_info;
+
+#define S(x) (1 << (x))
+
+enum abis_link_fsm_state {
+	ABIS_LINK_ST_CONNECTING,
+	ABIS_LINK_ST_CONNECTED,
+	ABIS_LINK_ST_FAILED,
+};
+
+static const struct value_string abis_link_fsm_event_names[] = {
+	OSMO_VALUE_STRING(ABIS_LINK_EV_SIGN_LINK_DOWN),
+	OSMO_VALUE_STRING(ABIS_LINK_EV_VTY_RM_ADDR),
+	{}
+};
+
+struct abis_link_fsm_priv {
+	struct llist_head *bsc_oml_host;
+	struct gsm_bts *bts;
+	char *model_name;
+	int line_ctr;
+};
+
+static void abis_link_connected(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct abis_link_fsm_priv *priv = fi->priv;
+	struct gsm_bts *bts = priv->bts;
+	struct gsm_bts_trx *trx;
+	bool oml_rsl_was_connected = false;
+
+	OSMO_ASSERT(event == ABIS_LINK_EV_SIGN_LINK_DOWN);
+
+	/* First remove the OML signalling link */
+	if (bts->oml_link) {
+		struct timespec now;
+
+		e1inp_sign_link_destroy(bts->oml_link);
+
+		/* Log a special notice if the OML connection was dropped relatively quickly. */
+		if (bts->oml_conn_established_timestamp.tv_sec != 0 && clock_gettime(CLOCK_MONOTONIC, &now) == 0 &&
+		    bts->oml_conn_established_timestamp.tv_sec + OSMO_BTS_OML_CONN_EARLY_DISCONNECT >= now.tv_sec) {
+			LOGP(DABIS, LOGL_FATAL, "OML link was closed early within %" PRIu64 " seconds. "
+			     "If this situation persists, please check your BTS and BSC configuration files for errors. "
+			     "A common error is a mismatch between unit_id configuration parameters of BTS and BSC.\n",
+			     (uint64_t) (now.tv_sec - g_bts->oml_conn_established_timestamp.tv_sec));
+		}
+		bts->oml_link = NULL;
+		oml_rsl_was_connected = true;
+	}
+	memset(&g_bts->oml_conn_established_timestamp, 0, sizeof(bts->oml_conn_established_timestamp));
+
+	if (g_bts->osmo_link) {
+		e1inp_sign_link_destroy(g_bts->osmo_link);
+		g_bts->osmo_link = NULL;
+		oml_rsl_was_connected = true;
+	}
+
+	/* Then iterate over the RSL signalling links */
+	llist_for_each_entry(trx, &bts->trx_list, list) {
+		if (trx->rsl_link) {
+			e1inp_sign_link_destroy(trx->rsl_link);
+			trx->rsl_link = NULL;
+			oml_rsl_was_connected = true;
+		}
+	}
+
+	/* Note: if there was an OML or RSL connection present (the BTS was connected to a BSC). Then we will not try
+	 * to connect to an alternate BSC. Instead we will shut down the BTS process. This will ensure that all states
+	 * in the BTS (hardware and software) are reset properly. It is then up to the process management of the host
+	 * to restart osmo-bts. */
+	if (oml_rsl_was_connected)
+		osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_FAILED, 0, 0);
+	else
+		osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_CONNECTING, 0, 0);
+}
+
+static void abis_link_connecting_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state)
+{
+	struct e1inp_line *line;
+	struct abis_link_fsm_priv *priv = fi->priv;
+	struct gsm_bts *bts = priv->bts;
+	struct bsc_oml_host *bsc_oml_host;
+
+	if (priv->bsc_oml_host) {
+		/* Get a BSC host from the list and move the list head one position forward. */
+		bsc_oml_host = (struct bsc_oml_host *)priv->bsc_oml_host;
+		if (priv->bsc_oml_host == llist_last(&bts->bsc_oml_hosts))
+			priv->bsc_oml_host = NULL;
+		else
+			priv->bsc_oml_host = priv->bsc_oml_host->next;
+	} else {
+		LOGP(DABIS, LOGL_FATAL, "No BSC available, A-bis connection establishment failed\n");
+		osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_FAILED, 0, 0);
+		return;
+	}
+
+	LOGP(DABIS, LOGL_NOTICE, "A-bis connection establishment to BSC (%s) in progress...\n", bsc_oml_host->addr);
+
+	/* patch in various data from VTY and other sources */
+	line_ops.cfg.ipa.addr = bsc_oml_host->addr;
+	osmo_get_macaddr(bts_dev_info.mac_addr, "eth0");
+	bts_dev_info.site_id = bts->ip_access.site_id;
+	bts_dev_info.bts_id = bts->ip_access.bts_id;
+	bts_dev_info.unit_name = priv->model_name;
+	if (bts->description)
+		bts_dev_info.unit_name = bts->description;
+	bts_dev_info.location2 = priv->model_name;
+
+	line = e1inp_line_find(priv->line_ctr);
+	if (line) {
+		e1inp_line_get2(line, __FILE__);	/* We want a new reference for returned line */
+	} else
+		line = e1inp_line_create(priv->line_ctr, "ipa");	/* already comes with a reference */
+
+	/* The abis connection may fail and we may have to try again with a different BSC (if configured). The next
+	 * attempt must happen on a different line. */
+	priv->line_ctr++;
+
+	if (!line) {
+		osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_FAILED, 0, 0);
+		return;
+	}
+	e1inp_line_bind_ops(line, &line_ops);
+
+	/* This will open the OML connection now */
+	if (e1inp_line_update(line) < 0) {
+		osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_FAILED, 0, 0);
+		return;
+	}
+
+	/* The TCP connection to the BSC is now in progress. */
+	osmo_fsm_inst_state_chg(fi, ABIS_LINK_ST_CONNECTED, 0, 0);
+}
+
+static void abis_link_failed_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state)
+{
+	struct abis_link_fsm_priv *priv = fi->priv;
+	struct gsm_bts *bts = priv->bts;
+
+	/* None of the configured BSCs was reachable or there was an existing
+	 * OML/RSL connection that beoke. Initiate BTS process shut down now. */
+	bts_model_abis_close(bts);
+}
+
+static void abis_link_allstate(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct abis_link_fsm_priv *priv = fi->priv;
+	struct gsm_bts *bts = priv->bts;
+
+	if (event != ABIS_LINK_EV_VTY_RM_ADDR)
+		return;
+
+	if (priv->bsc_oml_host == data) {
+		if (llist_count(&bts->bsc_oml_hosts) <= 1)
+			priv->bsc_oml_host = NULL;
+		else if (priv->bsc_oml_host == llist_last(&bts->bsc_oml_hosts))
+			priv->bsc_oml_host = priv->bsc_oml_host->prev;
+		else
+			priv->bsc_oml_host = priv->bsc_oml_host->next;
+	}
+}
+
+static struct osmo_fsm_state abis_link_fsm_states[] = {
+	[ABIS_LINK_ST_CONNECTED] = {
+		.name = "CONNECTED",
+		.in_event_mask =
+			S(ABIS_LINK_EV_SIGN_LINK_DOWN),
+		.out_state_mask =
+			S(ABIS_LINK_ST_CONNECTING) |
+			S(ABIS_LINK_ST_FAILED),
+		.action = abis_link_connected,
+	},
+	[ABIS_LINK_ST_CONNECTING] = {
+		.name = "CONNECTING",
+		.out_state_mask =
+			S(ABIS_LINK_ST_CONNECTING) |
+			S(ABIS_LINK_ST_CONNECTED) |
+			S(ABIS_LINK_ST_FAILED),
+		.onenter = abis_link_connecting_onenter,
+	},
+	[ABIS_LINK_ST_FAILED] = {
+		.name = "FAILED",
+		.onenter = abis_link_failed_onenter,
+	},
+};
+
+static struct osmo_fsm abis_link_fsm = {
+	.name = "abis_link",
+	.states = abis_link_fsm_states,
+	.num_states = ARRAY_SIZE(abis_link_fsm_states),
+	.log_subsys = DABIS,
+	.event_names = abis_link_fsm_event_names,
+	.allstate_action = abis_link_allstate,
+	.allstate_event_mask = S(ABIS_LINK_EV_VTY_RM_ADDR),
+};
+
 int abis_oml_sendmsg(struct msgb *msg)
 {
 	struct gsm_bts *bts = msg->trx->bts;
@@ -144,41 +344,8 @@ static struct e1inp_sign_link *sign_link_up(void *unit, struct e1inp_line *line,
 
 static void sign_link_down(struct e1inp_line *line)
 {
-	struct gsm_bts_trx *trx;
 	LOGPIL(line, DABIS, LOGL_ERROR, "Signalling link down\n");
-
-	/* First remove the OML signalling link */
-	if (g_bts->oml_link) {
-		struct timespec now;
-
-		e1inp_sign_link_destroy(g_bts->oml_link);
-
-		/* Log a special notice if the OML connection was dropped relatively quickly. */
-		if (g_bts->oml_conn_established_timestamp.tv_sec != 0 && clock_gettime(CLOCK_MONOTONIC, &now) == 0 &&
-		    g_bts->oml_conn_established_timestamp.tv_sec + OSMO_BTS_OML_CONN_EARLY_DISCONNECT >= now.tv_sec) {
-			LOGP(DABIS, LOGL_FATAL, "OML link was closed early within %" PRIu64 " seconds. "
-			"If this situation persists, please check your BTS and BSC configuration files for errors. "
-			"A common error is a mismatch between unit_id configuration parameters of BTS and BSC.\n",
-			(uint64_t)(now.tv_sec - g_bts->oml_conn_established_timestamp.tv_sec));
-		}
-		g_bts->oml_link = NULL;
-	}
-	memset(&g_bts->oml_conn_established_timestamp, 0, sizeof(g_bts->oml_conn_established_timestamp));
-
-	if (g_bts->osmo_link) {
-		e1inp_sign_link_destroy(g_bts->osmo_link);
-		g_bts->osmo_link = NULL;
-	}
-
-	/* Then iterate over the RSL signalling links */
-	llist_for_each_entry(trx, &g_bts->trx_list, list) {
-		if (trx->rsl_link) {
-			e1inp_sign_link_destroy(trx->rsl_link);
-			trx->rsl_link = NULL;
-		}
-	}
-
-	bts_model_abis_close(g_bts);
+	osmo_fsm_inst_dispatch(g_bts->abis_link_fi, ABIS_LINK_EV_SIGN_LINK_DOWN, NULL);
 }
 
 
@@ -277,33 +444,27 @@ void abis_init(struct gsm_bts *bts)
 	osmo_signal_register_handler(SS_L_INPUT, &inp_s_cbfn, bts);
 }
 
-struct e1inp_line *abis_open(struct gsm_bts *bts, char *dst_host,
-			     char *model_name)
+int abis_open(struct gsm_bts *bts, char *model_name)
 {
-	struct e1inp_line *line;
+	struct abis_link_fsm_priv *abis_link_fsm_priv;
 
-	/* patch in various data from VTY and other sources */
-	line_ops.cfg.ipa.addr = dst_host;
-	osmo_get_macaddr(bts_dev_info.mac_addr, "eth0");
-	bts_dev_info.site_id = bts->ip_access.site_id;
-	bts_dev_info.bts_id = bts->ip_access.bts_id;
-	bts_dev_info.unit_name = model_name;
-	if (bts->description)
-		bts_dev_info.unit_name = bts->description;
-	bts_dev_info.location2 = model_name;
+	if (llist_empty(&bts->bsc_oml_hosts)) {
+		LOGP(DABIS, LOGL_FATAL, "No BSC configured, cannot start BTS without knowing BSC OML IP\n");
+		return -EINVAL;
+	}
 
-	line = e1inp_line_find(0);
-	if (line) {
-		e1inp_line_get2(line, __FILE__); /* We want a new reference for returned line */
-	} else
-		line = e1inp_line_create(0, "ipa"); /* already comes with a reference */
-	if (!line)
-		return NULL;
-	e1inp_line_bind_ops(line, &line_ops);
+	OSMO_ASSERT(osmo_fsm_register(&abis_link_fsm) == 0);
+	bts->abis_link_fi = osmo_fsm_inst_alloc(&abis_link_fsm, bts, NULL, LOGL_DEBUG, "abis_link");
+	OSMO_ASSERT(bts->abis_link_fi);
 
-	/* This will open the OML connection now */
-	if (e1inp_line_update(line) < 0)
-		return NULL;
+	abis_link_fsm_priv = talloc_zero(bts->abis_link_fi, struct abis_link_fsm_priv);
+	OSMO_ASSERT(abis_link_fsm_priv);
+	abis_link_fsm_priv->bsc_oml_host = bts->bsc_oml_hosts.next;
+	abis_link_fsm_priv->bts = bts;
+	abis_link_fsm_priv->model_name = model_name;
+	bts->abis_link_fi->priv = abis_link_fsm_priv;
+
+	osmo_fsm_inst_state_chg_ms(bts->abis_link_fi, ABIS_LINK_ST_CONNECTING, 1, 0);
 
-	return line;
+	return 0;
 }