nat: Make it possible to send MGCP messages through the IPA multiplex

Instead of handling MGCP through the UDP socket, read and write messages
through the ipa connection to the MSC.

3 files changed, 95 insertions, 15 deletions

diff --git a/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c b/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
index 1436ebd35..480a8f6d1 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
@@ -62,7 +62,7 @@
 #include <errno.h>
 #include <unistd.h>
 
-static void mgcp_queue_for_call_agent(struct bsc_nat *nat, struct msgb *output)
+static void send_direct(struct bsc_nat *nat, struct msgb *output)
 {
 	if (osmo_wqueue_enqueue(&nat->mgcp_cfg->gw_fd, output) != 0) {
 		LOGP(DMGCP, LOGL_ERROR, "Failed to queue MGCP msg.\n");
@@ -70,6 +70,14 @@ static void mgcp_queue_for_call_agent(struct bsc_nat *nat, struct msgb *output)
 	}
 }
 
+static void mgcp_queue_for_call_agent(struct bsc_nat *nat, struct msgb *output)
+{
+	if (nat->mgcp_ipa)
+		bsc_nat_send_mgcp_to_msc(nat, output);
+	else
+		send_direct(nat, output);
+}
+
 int bsc_mgcp_nr_multiplexes(int max_endpoints)
 {
 	int div = max_endpoints / 32;
@@ -656,6 +664,38 @@ copy:
 	return output;
 }
 
+/*
+ * This comes from the MSC and we will now parse it. The caller needs
+ * to free the msgb.
+ */
+void bsc_nat_handle_mgcp(struct bsc_nat *nat, struct msgb *msg)
+{
+	struct msgb *resp;
+
+	if (!nat->mgcp_ipa) {
+		LOGP(DMGCP, LOGL_ERROR, "MGCP message not allowed on IPA.\n");
+		return;
+	}
+
+	if (msgb_l2len(msg) > sizeof(nat->mgcp_msg) - 1) {
+		LOGP(DMGCP, LOGL_ERROR, "MGCP msg too big for handling.\n");
+		return;
+	}
+
+	memcpy(nat->mgcp_msg, msg->l2h, msgb_l2len(msg));
+	nat->mgcp_length = msgb_l2len(msg);
+	nat->mgcp_msg[nat->mgcp_length] = '\0';
+
+	/* now handle the message */
+	resp = mgcp_handle_message(nat->mgcp_cfg, msg);
+
+	/* we do have a direct answer... e.g. AUEP */
+	if (resp)
+		mgcp_queue_for_call_agent(nat, resp);
+
+	return;
+}
+
 static int mgcp_do_read(struct osmo_fd *fd)
 {
 	struct bsc_nat *nat;
@@ -705,21 +745,10 @@ static int mgcp_do_write(struct osmo_fd *bfd, struct msgb *msg)
 	return rc;
 }
 
-int bsc_mgcp_nat_init(struct bsc_nat *nat)
+static int init_mgcp_socket(struct bsc_nat *nat, struct mgcp_config *cfg)
 {
-	int on;
 	struct sockaddr_in addr;
-	struct mgcp_config *cfg = nat->mgcp_cfg;
-
-	if (!cfg->call_agent_addr) {
-		LOGP(DMGCP, LOGL_ERROR, "The BSC nat requires the call agent ip to be set.\n");
-		return -1;
-	}
-
-	if (cfg->bts_ip) {
-		LOGP(DMGCP, LOGL_ERROR, "Do not set the BTS ip for the nat.\n");
-		return -1;
-	}
+	int on;
 
 	cfg->gw_fd.bfd.fd = socket(AF_INET, SOCK_DGRAM, 0);
 	if (cfg->gw_fd.bfd.fd < 0) {
@@ -765,6 +794,31 @@ int bsc_mgcp_nat_init(struct bsc_nat *nat)
 		return -1;
 	}
 
+	return 0;
+}
+
+int bsc_mgcp_nat_init(struct bsc_nat *nat)
+{
+	struct mgcp_config *cfg = nat->mgcp_cfg;
+
+	if (!cfg->call_agent_addr) {
+		LOGP(DMGCP, LOGL_ERROR, "The BSC nat requires the call agent ip to be set.\n");
+		return -1;
+	}
+
+	if (cfg->bts_ip) {
+		LOGP(DMGCP, LOGL_ERROR, "Do not set the BTS ip for the nat.\n");
+		return -1;
+	}
+
+	/* initialize the MGCP socket */
+	if (!nat->mgcp_ipa) {
+		int rc =  init_mgcp_socket(nat, cfg);
+		if (rc != 0)
+			return rc;
+	}
+
+
 	/* some more MGCP config handling */
 	cfg->data = nat;
 	cfg->policy_cb = bsc_mgcp_policy_cb;
diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat.c b/openbsc/src/osmo-bsc_nat/bsc_nat.c
index 792d33c23..e70f54952 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat.c
@@ -333,6 +333,12 @@ static void send_mgcp_reset(struct bsc_connection *bsc)
 	bsc_write_mgcp(bsc, mgcp_reset, sizeof mgcp_reset - 1);
 }
 
+void bsc_nat_send_mgcp_to_msc(struct bsc_nat *nat, struct msgb *msg)
+{
+	ipaccess_prepend_header(msg, IPAC_PROTO_MGCP_OLD);
+	queue_for_msc(nat->msc_con, msg);
+}
+
 /*
  * Below is the handling of messages coming
  * from the MSC and need to be forwarded to
@@ -820,8 +826,11 @@ static int ipaccess_msc_read_cb(struct osmo_fd *bfd)
 			initialize_msc_if_needed(msc_con);
 		else if (msg->l2h[0] == IPAC_MSGT_ID_GET)
 			send_id_get_response(msc_con);
-	} else if (hh->proto == IPAC_PROTO_SCCP)
+	} else if (hh->proto == IPAC_PROTO_SCCP) {
 		forward_sccp_to_bts(msc_con, msg);
+	} else if (hh->proto == IPAC_PROTO_MGCP_OLD) {
+		bsc_nat_handle_mgcp(nat, msg);
+	}
 
 	msgb_free(msg);
 	return 0;
diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat_vty.c b/openbsc/src/osmo-bsc_nat/bsc_nat_vty.c
index 7bbc89059..32e5106ae 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat_vty.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat_vty.c
@@ -143,6 +143,8 @@ static int config_write_nat(struct vty *vty)
 		write_acc_lst(vty, lst);
 	llist_for_each_entry(pgroup, &_nat->paging_groups, entry)
 		write_pgroup_lst(vty, pgroup);
+	if (_nat->mgcp_ipa)
+		vty_out(vty, " mgcp-through-msc-ipa%s", VTY_NEWLINE);
 
 	return CMD_SUCCESS;
 }
@@ -657,6 +659,20 @@ DEFUN(cfg_nat_ussd_local,
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_nat_mgcp_ipa,
+      cfg_nat_mgcp_ipa_cmd,
+      "mgcp-through-msc-ipa",
+      "This needs to be set at start. Handle MGCP messages through "
+      "the IPA protocol and not through the UDP socket.\n")
+{
+	if (_nat->mgcp_cfg->data)
+		vty_out(vty,
+			"%%the setting will not be applied right now.%s",
+			VTY_NEWLINE);
+	_nat->mgcp_ipa = 1;
+	return CMD_SUCCESS;
+}
+
 /* per BSC configuration */
 DEFUN(cfg_bsc, cfg_bsc_cmd, "bsc BSC_NR",
       "BSC configuration\n" "Identifier of the BSC\n")
@@ -1086,6 +1102,7 @@ int bsc_nat_vty_init(struct bsc_nat *nat)
 	install_element(NAT_NODE, &cfg_nat_ussd_query_cmd);
 	install_element(NAT_NODE, &cfg_nat_ussd_token_cmd);
 	install_element(NAT_NODE, &cfg_nat_ussd_local_cmd);
+	install_element(NAT_NODE, &cfg_nat_mgcp_ipa_cmd);
 
 	/* access-list */
 	install_element(NAT_NODE, &cfg_lst_imsi_allow_cmd);