msc: Allow to listen for incoming connections.

This is mostly a hack to allow IPA/SCCP routing to SCTP/M2UA/MTP3/SCCP
without going through the full stack. The proper way of doing this
requires another round of abstraction for the mtp_link_set class.

3 files changed, 248 insertions, 5 deletions

diff --git a/include/msc_connection.h b/include/msc_connection.h
index 74319b3..826eb3a 100644
--- a/include/msc_connection.h
+++ b/include/msc_connection.h
@@ -30,14 +30,22 @@
 struct bsc_data;
 struct ss7_application;
 
+enum msc_mode {
+	MSC_MODE_CLIENT,
+	MSC_MODE_SERVER,
+};
+
 struct msc_connection {
 	/* management */
 	struct llist_head entry;
 	int nr;
 	char *name;
+	enum msc_mode mode;
+	int auth;
 
 	/* ip management */
 	int dscp;
+	int port;
 	char *ip;
 	char *token;
 
@@ -62,6 +70,9 @@ struct msc_connection {
 
 	/* application pointer */
 	struct ss7_application *app;
+
+	/* server functions */
+	struct osmo_fd listen_fd;
 };
 
 /* msc related functions */
@@ -80,5 +91,6 @@ void msc_mgcp_reset(struct msc_connection *msc);
 /* Called by the MSC Connection */
 void msc_dispatch_sccp(struct msc_connection *msc, struct msgb *msg);
 
+const char *msc_mode(struct msc_connection *msc);
 
 #endif
diff --git a/src/msc_conn.c b/src/msc_conn.c
index b52b901..e895e77 100644
--- a/src/msc_conn.c
+++ b/src/msc_conn.c
@@ -1,7 +1,7 @@
 /* MSC related stuff... */
 /*
- * (C) 2010-2012 by Holger Hans Peter Freyther <zecke@selfish.org>
- * (C) 2010-2012 by On-Waves
+ * (C) 2010-2013 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2010-2013 by On-Waves
  * All Rights Reserved
  *
  * This program is free software: you can redistribute it and/or modify
@@ -29,10 +29,11 @@
 #include <ss7_application.h>
 #include <mgcp_patch.h>
 
+#include <osmocom/core/socket.h>
 #include <osmocom/core/talloc.h>
-#include <osmocom/gsm/tlv.h>
 #include <osmocom/core/utils.h>
 #include <osmocom/core/write_queue.h>
+#include <osmocom/gsm/tlv.h>
 
 #include <arpa/inet.h>
 #include <sys/socket.h>
@@ -49,6 +50,8 @@
 static void msc_send_id_response(struct msc_connection *bsc);
 static void msc_send(struct msc_connection *bsc, struct msgb *msg, int proto);
 static void msc_schedule_reconnect(struct msc_connection *bsc);
+static int msc_conn_bind(struct msc_connection *bsc);
+static void msc_handle_id_response(struct msc_connection *bsc, struct msgb *msg);
 
 void msc_close_connection(struct msc_connection *fw)
 {
@@ -157,8 +160,22 @@ static int ipaccess_a_fd_cb(struct osmo_fd *bfd)
 			msc_send_id_response(fw);
 		} else if (msg->l2h[0] == IPAC_MSGT_PONG) {
 			osmo_timer_del(&fw->pong_timeout);
+		} else if (msg->l2h[0] == IPAC_MSGT_ID_RESP) {
+			msc_handle_id_response(fw, msg);
 		}
-	} else if (hh->proto == IPAC_PROTO_SCCP) {
+
+		msgb_free(msg);
+		return 0;
+	}
+
+	if (fw->mode == MSC_MODE_SERVER && !fw->auth) {
+		LOGP(DMSC, LOGL_ERROR,
+			"Ignoring non ipa message for unauth user.\n");
+		msgb_free(msg);
+		return -1;
+	}
+
+	if (hh->proto == IPAC_PROTO_SCCP) {
 		msc_dispatch_sccp(fw, msg);
 	} else if (hh->proto == NAT_MUX) {
 		msg = mgcp_patch(fw->app, msg);
@@ -315,7 +332,7 @@ static void msc_reconnect(void *_data)
 	osmo_timer_del(&fw->reconnect_timer);
 	fw->first_contact = 1;
 
-	rc = connect_to_msc(&fw->msc_connection.bfd, fw->ip, 5000, fw->dscp);
+	rc = connect_to_msc(&fw->msc_connection.bfd, fw->ip, fw->port, fw->dscp);
 	if (rc < 0) {
 		fprintf(stderr, "Opening the MSC connection failed. Trying again\n");
 		osmo_timer_schedule(&fw->reconnect_timer, RECONNECT_TIME);
@@ -329,6 +346,8 @@ static void msc_reconnect(void *_data)
 
 static void msc_schedule_reconnect(struct msc_connection *fw)
 {
+	if (fw->mode == MSC_MODE_SERVER)
+		return;
 	osmo_timer_schedule(&fw->reconnect_timer, RECONNECT_TIME);
 }
 
@@ -399,6 +418,14 @@ void msc_send_reset(struct msc_connection *fw)
 		return;
 	}
 
+	/* start the ping/pong but nothing else */
+	if (fw->mode == MSC_MODE_SERVER) {
+		LOGP(DMSC, LOGL_DEBUG, "Not sending BSSMAP resets in server mode.\n");
+		msc_ping_timeout(fw);
+		return;
+	}
+
+
 	msg = create_reset();
 	if (!msg)
 		return;
@@ -411,6 +438,12 @@ static void msc_send_id_response(struct msc_connection *fw)
 {
 	struct msgb *msg;
 
+	if (fw->mode == MSC_MODE_SERVER) {
+		LOGP(DMSC, LOGL_DEBUG,
+			"Not sending our token in server mode.\n");
+		return;
+	}
+
 	msg = msgb_alloc_headroom(4096, 128, "id resp");
 	msg->l2h = msgb_v_put(msg, IPAC_MSGT_ID_RESP);
 	msgb_l16tv_put(msg, strlen(fw->token) + 1,
@@ -434,6 +467,9 @@ struct msc_connection *msc_connection_create(struct bsc_data *bsc, int mgcp)
 		return NULL;
 	}
 
+	msc->mode = MSC_MODE_CLIENT;
+	msc->port = 5000;
+
 	osmo_wqueue_init(&msc->msc_connection, 100);
 	msc->reconnect_timer.cb = msc_reconnect;
 	msc->reconnect_timer.data = msc;
@@ -482,6 +518,169 @@ int msc_connection_start(struct msc_connection *msc)
 		return -1;
 	}
 
+	/* bind and wait if we are a server */
+	if (msc->mode == MSC_MODE_SERVER)
+		return msc_conn_bind(msc);
+
 	msc_schedule_reconnect(msc);
 	return 0;
 }
+
+const char *msc_mode(struct msc_connection *msc)
+{
+	switch (msc->mode) {
+	case MSC_MODE_CLIENT:
+		return "client";
+	case MSC_MODE_SERVER:
+		return "server";
+	}
+
+	return "invalid";
+}
+
+/* Non-clean MSC server socket abstraction.. bind and accept */
+static int msc_send_auth_req(struct msc_connection *msc)
+{
+	struct msgb *msg;
+
+	static const uint8_t id_req[] = {
+		IPAC_MSGT_ID_GET,
+		0x01, IPAC_IDTAG_UNIT,
+		0x01, IPAC_IDTAG_MACADDR,
+		0x01, IPAC_IDTAG_LOCATION1,
+		0x01, IPAC_IDTAG_LOCATION2,
+		0x01, IPAC_IDTAG_EQUIPVERS,
+		0x01, IPAC_IDTAG_SWVERSION,
+		0x01, IPAC_IDTAG_UNITNAME,
+		0x01, IPAC_IDTAG_SERNR,
+	};
+
+	msg = msgb_alloc_headroom(4096, 128, "auth");
+	if (!msg) {
+		LOGP(DMSC, LOGL_ERROR, "Failed to allocate auth.\n");
+		msc_close_connection(msc);
+		return -1;
+	}
+
+	msg->l2h = msgb_put(msg, ARRAY_SIZE(id_req));
+	memcpy(msg->l2h, id_req, ARRAY_SIZE(id_req));
+
+	msc_send(msc, msg, IPAC_PROTO_IPACCESS);
+	return 0;
+}
+
+static void msc_handle_id_response(struct msc_connection *msc, struct msgb *msg)
+{
+	unsigned int len;
+	const char *token;
+
+	/* only for the server */
+	if (msc->mode != MSC_MODE_SERVER) {
+		LOGP(DMSC, LOGL_ERROR, "Unexpected ID response for client.\n");
+		return;
+	}
+
+	if (!msc->token) {
+		LOGP(DMSC, LOGL_ERROR, "No token defined. Giving up.\n");
+		goto clean;
+	}
+
+	if (msgb_l2len(msg) < 4) {
+		LOGP(DMSC, LOGL_ERROR, "Too short message...%u\n",
+				msgb_l2len(msg));
+		goto clean;
+	}
+
+	/* in lack of ipaccess_idtag_parse we have a very basic method */
+	if (msg->l2h[3] != IPAC_IDTAG_UNITNAME) {
+		LOGP(DMSC, LOGL_ERROR, "Expected unitname tag got %d\n",
+			msg->l2h[3]);
+		goto clean;
+	}
+
+	token = (const char *) &msg->l2h[4];
+	len = msgb_l2len(msg) - 4;
+
+	if (len != strlen(msc->token)) {
+		LOGP(DMSC, LOGL_ERROR, "Wrong length %u vs. %u\n",
+			len, strlen(msc->token));
+		goto clean;
+	}
+
+	if (memcmp(msc->token, token, len) != 0) {
+		LOGP(DMSC, LOGL_ERROR, "Token has the wrong size.\n");
+		goto clean;
+	}
+
+	LOGP(DMSC, LOGL_NOTICE, "Authenticated the connection.\n");
+	msc->auth = 1;
+	return;
+clean:
+	msc_close_connection(msc);
+}
+
+static int msc_conn_accept(struct osmo_fd *bsc_fd, unsigned int what)
+{
+	struct sockaddr_in addr;
+	socklen_t len = sizeof(addr);
+	struct msc_connection *msc = bsc_fd->data;
+	int ret;
+
+	LOGP(DMSC, LOGL_NOTICE, "Going to accept a connection.\n");
+
+	ret = accept(bsc_fd->fd, (struct sockaddr *) &addr, &len);
+	if (ret < 0) {
+		LOGP(DMSC, LOGL_ERROR, "Accept failed with fd(%d) errno(%d)\n",
+			ret, errno);
+		return -1;
+	}
+
+	/*
+	 * Close the previous/current connection.
+	 * TODO: switch only once we know it is a valid connection
+	 */
+	msc_close_connection(msc);
+
+	/* re-set the internal state */
+	msc->auth = 0;
+
+	/* adopt the connection */
+	msc->msc_connection.bfd.fd = ret;
+	msc->msc_connection.bfd.when = BSC_FD_READ;
+	ret = osmo_fd_register(&msc->msc_connection.bfd);
+	if (ret < 0) {
+		LOGP(DMSC, LOGL_ERROR, "Failed to register fd.\n");
+		close(msc->msc_connection.bfd.fd);
+		msc->msc_connection.bfd.fd = -1;
+		return -1;
+	}
+
+	/* consider it up and running */
+	msc->msc_link_down = 0;
+
+	/* msc send auth request */
+	msc_send_auth_req(msc);
+	LOGP(DMSC, LOGL_ERROR, "Registered fd %d and waiting for data.\n",
+		msc->msc_connection.bfd.fd);
+
+	return 0;
+}
+
+static int msc_conn_bind(struct msc_connection *msc)
+{
+	int rc;
+
+	LOGP(DMSC, LOGL_NOTICE, "Going to bind and wait for connections.\n");
+
+	rc = osmo_sock_init_ofd(&msc->listen_fd, AF_UNSPEC, SOCK_STREAM,
+			IPPROTO_TCP, "127.0.0.1", msc->port, OSMO_SOCK_F_BIND);
+	if (rc < 0) {
+		LOGP(DMSC, LOGL_NOTICE, "Failed to bind the socket.\n");
+		return rc;
+	}
+
+	msc->listen_fd.data = msc;
+	msc->listen_fd.cb = msc_conn_accept;
+
+	return 0;
+}
diff --git a/src/vty_interface.c b/src/vty_interface.c
index 001ba44..e9326a9 100644
--- a/src/vty_interface.c
+++ b/src/vty_interface.c
@@ -241,7 +241,9 @@ static void write_msc(struct vty *vty, struct msc_connection *msc)
 
 	vty_out(vty, " msc %d%s", msc->nr, VTY_NEWLINE);
 	vty_out(vty, "  description %s%s", name, VTY_NEWLINE);
+	vty_out(vty, "  mode %s%s", msc_mode(msc), VTY_NEWLINE);
 	vty_out(vty, "  ip %s%s", msc->ip, VTY_NEWLINE);
+	vty_out(vty, "  port %d%s", msc->port, VTY_NEWLINE);
 	vty_out(vty, "  token %s%s", msc->token, VTY_NEWLINE);
 	vty_out(vty, "  dscp %d%s", msc->dscp, VTY_NEWLINE);
 	vty_out(vty, "  timeout ping %d%s", msc->ping_time, VTY_NEWLINE);
@@ -759,6 +761,25 @@ DEFUN(cfg_ss7_msc, cfg_ss7_msc_cmd,
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_msc_mode, cfg_msc_mode_cmd,
+      "mode (server|client)",
+      "Change the mode of the A-link\n"
+      "Accept incoming connection\n" "Open outgoing connection\n")
+{
+	struct msc_connection *msc = vty->index;
+
+	switch (argv[0][0]) {
+	case 's':
+		msc->mode = MSC_MODE_SERVER;
+		break;
+	case 'c':
+		msc->mode = MSC_MODE_CLIENT;
+		break;
+	}
+
+	return CMD_SUCCESS;
+}
+
 DEFUN(cfg_msc_ip, cfg_msc_ip_cmd,
       "ip ADDR",
       "IP Address of the MSC\n" "Address\n")
@@ -781,6 +802,15 @@ DEFUN(cfg_msc_ip, cfg_msc_ip_cmd,
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_msc_port, cfg_msc_port_cmd,
+      "port <1-65535>",
+      "Port for the TCP connection\n" "Port Number\n")
+{
+	struct msc_connection *msc = vty->index;
+	msc->port = atoi(argv[0]);
+	return CMD_SUCCESS;
+}
+
 DEFUN(cfg_msc_token, cfg_msc_token_cmd,
       "token TOKEN",
       "Token for the MSC\n" "The token\n")
@@ -1086,7 +1116,9 @@ void cell_vty_init(void)
 	install_element(SS7_NODE, &cfg_ss7_msc_cmd);
 	install_node(&msc_node, config_write_msc);
 	install_defaults(MSC_NODE);
+	install_element(MSC_NODE, &cfg_msc_mode_cmd);
 	install_element(MSC_NODE, &cfg_msc_ip_cmd);
+	install_element(MSC_NODE, &cfg_msc_port_cmd);
 	install_element(MSC_NODE, &cfg_msc_token_cmd);
 	install_element(MSC_NODE, &cfg_msc_dscp_cmd);
 	install_element(MSC_NODE, &cfg_msc_timeout_ping_cmd);