GPRS: Modularize the NS implementation

* move UDP listener code for NSIP from input/ipaccess.c and into gprs_ns.c
* add PDU type, IE and CAUSE values for later IP based 3GPP TS 48.016
* support multiple NS-VCs and their lookup based on NSVC and sockaddr_in
* maintain the remote_state (blocked/alive) for each NSVC
* introduce the concept of GPRS_NS instances, move all global vars to instance
* remove hardcoded calls to gprs_bssgp_rcvmsg() and replace it by callback

WARNING: This is not finished code.  While it will compile, it will not work
yet, as BSSGP needs to be converted to properly indicate the NSVC to which it
needs to send data.

2 files changed, 284 insertions, 31 deletions

diff --git a/openbsc/include/openbsc/gprs_ns.h b/openbsc/include/openbsc/gprs_ns.h
index 9ea4d675..98b31f8d 100644
--- a/openbsc/include/openbsc/gprs_ns.h
+++ b/openbsc/include/openbsc/gprs_ns.h
@@ -1,6 +1,10 @@
 #ifndef _GPRS_NS_H
 #define _GPRS_NS_H
 
+/* GPRS Networks Service (NS) messages on the Gb interface
+ * 3GPP TS 08.16 version 8.0.1 Release 1999 / ETSI TS 101 299 V8.0.1 (2002-05)
+ * 3GPP TS 48.016 version 6.5.0 Release 6 / ETSI TS 148 016 V6.5.0 (2005-11) */
+
 struct gprs_ns_hdr {
 	u_int8_t pdu_type;
 	u_int8_t data[0];
@@ -18,6 +22,15 @@ enum ns_pdu_type {
 	NS_PDUT_STATUS		= 0x08,
 	NS_PDUT_ALIVE		= 0x0a,
 	NS_PDUT_ALIVE_ACK	= 0x0b,
+	/* TS 48.016 Section 10.3.7, Table 10.3.7.1 */
+	SNS_PDUT_ACK		= 0x0c,
+	SNS_PDUT_ADD		= 0x0d,
+	SNS_PDUT_CHANGE_WEIGHT	= 0x0e,
+	SNS_PDUT_CONFIG		= 0x0f,
+	SNS_PDUT_CONFIG_ACK	= 0x10,
+	SNS_PDUT_DELETE		= 0x11,
+	SNS_PDUT_SIZE		= 0x12,
+	SNS_PDUT_SIZE_ACK	= 0x13,
 };
 
 /* TS 08.16, Section 10.3, Table 12 */
@@ -27,6 +40,14 @@ enum ns_ctrl_ie {
 	NS_IE_PDU		= 0x02,
 	NS_IE_BVCI		= 0x03,
 	NS_IE_NSEI		= 0x04,
+	/* TS 48.016 Section 10.3, Table 10.3.1 */
+	NS_IE_IPv4_LIST		= 0x05,
+	NS_IE_IPv6_LIST		= 0x06,
+	NS_IE_MAX_NR_NSVC	= 0x07,
+	NS_IE_IPv4_EP_NR	= 0x08,
+	NS_IE_IPv6_EP_NR	= 0x09,
+	NS_IE_RESET_FLAG	= 0x0a,
+	NS_IE_IP_ADDR		= 0x0b,
 };
 
 /* TS 08.16, Section 10.3.2, Table 13 */
@@ -42,20 +63,43 @@ enum ns_cause {
 	NS_CAUSE_PROTO_ERR_UNSPEC	= 0x0b,
 	NS_CAUSE_INVAL_ESSENT_IE	= 0x0c,
 	NS_CAUSE_MISSING_ESSENT_IE	= 0x0d,
+	/* TS 48.016 Section 10.3.2, Table 10.3.2.1 */
+	NS_CAUSE_INVAL_NR_IPv4_EP	= 0x0e,
+	NS_CAUSE_INVAL_NR_IPv6_EP	= 0x0f,
+	NS_CAUSE_INVAL_NR_NS_VC		= 0x10,
+	NS_CAUSE_INVAL_WEIGH		= 0x11,
+	NS_CAUSE_UNKN_IP_EP		= 0x12,
+	NS_CAUSE_UNKN_IP_ADDR		= 0x13,
+	NS_CAUSE_UNKN_IP_TEST_FAILED	= 0x14,
 };
 
-/* a layer 1 entity transporting NS frames */
-struct gprs_ns_link {
-	union {
-		struct {
-			int fd;
-		} ip;
-	};
+struct gprs_nsvc;
+struct gprs_ns_inst;
+
+enum gprs_ns_evt {
+	GPRS_NS_EVT_UNIT_DATA,
 };
 
+typedef int gprs_ns_cb_t(enum gprs_ns_evt event, struct gprs_nsvc *nsvc,
+			 struct msgb *msg, u_int16_t bvci);
+
+/* Create a new NS protocol instance */
+struct gprs_ns_inst *gprs_ns_instantiate(gprs_ns_cb_t *cb);
+
+/* Destroy a NS protocol instance */
+void gprs_ns_destroy(struct gprs_ns_inst *nsi);
 
-int gprs_ns_rcvmsg(struct msgb *msg, struct sockaddr_in *saddr);
+/* Listen for incoming GPRS packets */
+int nsip_listen(struct gprs_ns_inst *nsi, uint16_t udp_port);
 
-int gprs_ns_sendmsg(struct gprs_ns_link *link, u_int16_t bvci,
+struct sockaddr_in;
+
+/* main entry point, here incoming NS frames enter */
+int gprs_ns_rcvmsg(struct gprs_ns_inst *nsi, struct msgb *msg,
+		   struct sockaddr_in *saddr);
+
+/* main function for higher layers (BSSGP) to send NS messages */
+int gprs_ns_sendmsg(struct gprs_nsvc *nsvc, u_int16_t bvci,
 		    struct msgb *msg);
+
 #endif
diff --git a/openbsc/src/gprs_ns.c b/openbsc/src/gprs_ns.c
index 6fb7d1d9..c5166fa5 100644
--- a/openbsc/src/gprs_ns.c
+++ b/openbsc/src/gprs_ns.c
@@ -1,7 +1,7 @@
 /* GPRS Networks Service (NS) messages on the Gb interface
  * 3GPP TS 08.16 version 8.0.1 Release 1999 / ETSI TS 101 299 V8.0.1 (2002-05) */
 
-/* (C) 2009 by Harald Welte <laforge@gnumonks.org>
+/* (C) 2009-2010 by Harald Welte <laforge@gnumonks.org>
  *
  * All Rights Reserved
  *
@@ -55,6 +55,7 @@
 #include <osmocore/msgb.h>
 #include <osmocore/tlv.h>
 #include <osmocore/talloc.h>
+#include <osmocore/select.h>
 #include <openbsc/debug.h>
 #include <openbsc/gprs_ns.h>
 #include <openbsc/gprs_bssgp.h>
@@ -76,11 +77,13 @@ static const struct tlv_definition ns_att_tlvdef = {
 
 struct gprs_nsvc {
 	struct llist_head list;
+	struct gprs_ns_inst *nsi;
 
 	u_int16_t nsei;		/* end-to-end significance */
 	u_int16_t nsvci;	/* uniquely identifies NS-VC at SGSN */
 
 	u_int32_t state;
+	u_int32_t remote_state;
 
 	struct timer_list alive_timer;
 	int timer_is_tns_alive;
@@ -93,8 +96,67 @@ struct gprs_nsvc {
 	};
 };
 
-/* FIXME: dynamically search for the matching NSVC */
-static struct gprs_nsvc dummy_nsvc = { .state = NSE_S_BLOCKED | NSE_S_ALIVE };
+enum gprs_ns_ll {
+	GPRS_NS_LL_UDP,
+	GPRS_NS_LL_E1,
+};
+
+/* An instance of the NS protocol stack */
+struct gprs_ns_inst {
+	/* callback to the user for incoming UNIT DATA IND */
+	gprs_ns_cb_t *cb;
+
+	/* linked lists of all NSVC in this instance */
+	struct llist_head gprs_nsvcs;
+
+	/* which link-layer are we based on? */
+	enum gprs_ns_ll ll;
+
+	union {
+		/* NS-over-IP specific bits */
+		struct {
+			struct bsc_fd fd;
+		} nsip;
+	};
+};
+
+/* Lookup struct gprs_nsvc based on NSVCI */
+static struct gprs_nsvc *nsvc_by_nsvci(struct gprs_ns_inst *nsi,
+					u_int16_t nsvci)
+{
+	struct gprs_nsvc *nsvc;
+	llist_for_each_entry(nsvc, &nsi->gprs_nsvcs, list) {
+		if (nsvc->nsvci == nsvci)
+			return nsvc;
+	}
+	return NULL;
+}
+
+/* Lookup struct gprs_nsvc based on remote peer socket addr */
+static struct gprs_nsvc *nsvc_by_rem_addr(struct gprs_ns_inst *nsi,
+					  struct sockaddr_in *sin)
+{
+	struct gprs_nsvc *nsvc;
+	llist_for_each_entry(nsvc, &nsi->gprs_nsvcs, list) {
+		if (!memcmp(&nsvc->ip.bts_addr, sin, sizeof(*sin)))
+			return nsvc;
+	}
+	return NULL;
+}
+
+static struct gprs_nsvc *nsvc_create(struct gprs_ns_inst *nsi, u_int16_t nsvci)
+{
+	struct gprs_nsvc *nsvc;
+
+	nsvc = talloc_zero(nsi, struct gprs_nsvc);
+	nsvc->nsvci = nsvci;
+	/* before RESET procedure: BLOCKED and DEAD */
+	nsvc->state = NSE_S_BLOCKED;
+	nsvc->nsi = nsi;
+	llist_add(&nsvc->list, &nsi->gprs_nsvcs);
+
+	return nsvc;
+}
 
 /* Section 10.3.2, Table 13 */
 static const char *ns_cause_str[] = {
@@ -122,9 +184,23 @@ static const char *gprs_ns_cause_str(enum ns_cause cause)
 	return "undefined";
 }
 
+static int nsip_sendmsg(struct msgb *msg, struct gprs_nsvc *nsvc);
+
 static int gprs_ns_tx(struct msgb *msg, struct gprs_nsvc *nsvc)
 {
-	return ipac_gprs_send(msg, &nsvc->ip.bts_addr);
+	int ret;
+
+	switch (nsvc->nsi->ll) {
+	case GPRS_NS_LL_UDP:
+		ret = nsip_sendmsg(msg, nsvc);
+		break;
+	default:
+		LOGP(DGPRS, LOGL_ERROR, "unsupported NS linklayer %u\n", nsvc->nsi->ll);
+		msgb_free(msg);
+		ret = -EIO;
+		break;
+	}
+	return ret;
 }
 
 static int gprs_ns_tx_simple(struct gprs_nsvc *nsvc, u_int8_t pdu_type)
@@ -196,11 +272,10 @@ static int gprs_ns_tx_reset_ack(struct gprs_nsvc *nsvc)
 }
 
 /* Section 9.2.10: transmit side */
-int gprs_ns_sendmsg(struct gprs_ns_link *link, u_int16_t bvci,
+int gprs_ns_sendmsg(struct gprs_nsvc *nsvc, u_int16_t bvci,
 		    struct msgb *msg)
 {
 	struct gprs_ns_hdr *nsh;
-	struct gprs_nsvc *nsvc = &dummy_nsvc;
 
 	nsh = (struct gprs_ns_hdr *) msgb_push(msg, sizeof(*nsh) + 3);
 	if (!nsh) {
@@ -217,7 +292,7 @@ int gprs_ns_sendmsg(struct gprs_ns_link *link, u_int16_t bvci,
 }
 
 /* Section 9.2.10: receive side */
-static int gprs_ns_rx_unitdata(struct msgb *msg)
+static int gprs_ns_rx_unitdata(struct msgb *msg, struct gprs_nsvc *nsvc)
 {
 	struct gprs_ns_hdr *nsh = (struct gprs_ns_hdr *)msg->l2h;
 	u_int16_t bvci;
@@ -227,13 +302,13 @@ static int gprs_ns_rx_unitdata(struct msgb *msg)
 	msg->l3h = &nsh->data[3];
 
 	/* call upper layer (BSSGP) */
-	return gprs_bssgp_rcvmsg(msg, bvci);
+	return nsvc->nsi->cb(GPRS_NS_EVT_UNIT_DATA, nsvc, msg, bvci);
 }
 
 /* Section 9.2.7 */
-static int gprs_ns_rx_status(struct msgb *msg)
+static int gprs_ns_rx_status(struct msgb *msg, struct gprs_nsvc *nsvc)
 {
-	struct gprs_ns_hdr *nsh = msg->l2h;
+	struct gprs_ns_hdr *nsh = (struct gprs_ns_hdr *) msg->l2h;
 	struct tlv_parsed tp;
 	u_int8_t cause;
 	int rc;
@@ -254,10 +329,9 @@ static int gprs_ns_rx_status(struct msgb *msg)
 }
 
 /* Section 7.3 */
-static int gprs_ns_rx_reset(struct msgb *msg)
+static int gprs_ns_rx_reset(struct msgb *msg, struct gprs_nsvc *nsvc)
 {
 	struct gprs_ns_hdr *nsh = (struct gprs_ns_hdr *) msg->l2h;
-	struct gprs_nsvc *nsvc = &dummy_nsvc;
 	struct tlv_parsed tp;
 	u_int8_t *cause;
 	u_int16_t *nsvci, *nsei;
@@ -296,14 +370,24 @@ static int gprs_ns_rx_reset(struct msgb *msg)
 }
 
 /* main entry point, here incoming NS frames enter */
-int gprs_ns_rcvmsg(struct msgb *msg, struct sockaddr_in *saddr)
+int gprs_ns_rcvmsg(struct gprs_ns_inst *nsi, struct msgb *msg,
+		   struct sockaddr_in *saddr)
 {
 	struct gprs_ns_hdr *nsh = (struct gprs_ns_hdr *) msg->l2h;
-	struct gprs_nsvc *nsvc = &dummy_nsvc;
+	struct gprs_nsvc *nsvc;
 	int rc = 0;
 
-	/* FIXME: do this properly! */
-	nsvc->ip.bts_addr = *saddr;
+	/* look up the NSVC based on source address */
+	nsvc = nsvc_by_rem_addr(nsi, saddr);
+	if (!nsvc) {
+		/* Only the RESET procedure creates a new NSVC */
+		if (nsh->pdu_type != NS_PDUT_RESET)
+			return -EIO;
+		nsvc = nsvc_create(nsi, 0xffff);
+		nsvc->ip.bts_addr = *saddr;
+		rc = gprs_ns_rx_reset(msg, nsvc);
+		return rc;
+	}
 
 	switch (nsh->pdu_type) {
 	case NS_PDUT_ALIVE:
@@ -320,16 +404,18 @@ int gprs_ns_rcvmsg(struct msgb *msg, struct sockaddr_in *saddr)
 		break;
 	case NS_PDUT_UNITDATA:
 		/* actual user data */
-		rc = gprs_ns_rx_unitdata(msg);
+		rc = gprs_ns_rx_unitdata(msg, nsvc);
 		break;
 	case NS_PDUT_STATUS:
-		rc = gprs_ns_rx_status(msg);
+		rc = gprs_ns_rx_status(msg, nsvc);
 		break;
 	case NS_PDUT_RESET:
-		rc = gprs_ns_rx_reset(msg);
+		rc = gprs_ns_rx_reset(msg, nsvc);
 		break;
 	case NS_PDUT_RESET_ACK:
-		/* FIXME: mark remote NS-VC as blocked + active */
+		DEBUGP(DGPRS, "NS RESET ACK\n");
+		/* mark remote NS-VC as blocked + active */
+		nsvc->remote_state = NSE_S_BLOCKED | NSE_S_ALIVE;
 		break;
 	case NS_PDUT_UNBLOCK:
 		/* Section 7.2: unblocking procedure */
@@ -338,7 +424,9 @@ int gprs_ns_rcvmsg(struct msgb *msg, struct sockaddr_in *saddr)
 		rc = gprs_ns_tx_simple(nsvc, NS_PDUT_UNBLOCK_ACK);
 		break;
 	case NS_PDUT_UNBLOCK_ACK:
-		/* FIXME: mark remote NS-VC as unblocked + active */
+		DEBUGP(DGPRS, "NS UNBLOCK ACK\n");
+		/* mark remote NS-VC as unblocked + active */
+		nsvc->remote_state = NSE_S_ALIVE;
 		break;
 	case NS_PDUT_BLOCK:
 		DEBUGP(DGPRS, "NS BLOCK\n");
@@ -346,7 +434,9 @@ int gprs_ns_rcvmsg(struct msgb *msg, struct sockaddr_in *saddr)
 		rc = gprs_ns_tx_simple(nsvc, NS_PDUT_UNBLOCK_ACK);
 		break;
 	case NS_PDUT_BLOCK_ACK:
-		/* FIXME: mark remote NS-VC as blocked + active */
+		DEBUGP(DGPRS, "NS BLOCK ACK\n");
+		/* mark remote NS-VC as blocked + active */
+		nsvc->remote_state = NSE_S_BLOCKED | NSE_S_ALIVE;
 		break;
 	default:
 		DEBUGP(DGPRS, "Unknown NS PDU type 0x%02x\n", nsh->pdu_type);
@@ -356,3 +446,122 @@ int gprs_ns_rcvmsg(struct msgb *msg, struct sockaddr_in *saddr)
 	return rc;
 }
 
+struct gprs_ns_inst *gprs_ns_instantiate(gprs_ns_cb_t *cb)
+{
+	struct gprs_ns_inst *nsi = talloc_zero(tall_bsc_ctx, struct gprs_ns_inst);
+
+	nsi->cb = cb;
+	INIT_LLIST_HEAD(&nsi->gprs_nsvcs);
+
+	return NULL;
+}
+
+void gprs_ns_destroy(struct gprs_ns_inst *nsi)
+{
+	/* FIXME: clear all timers */
+
+	/* recursively free the NSI and all its NSVCs */
+	talloc_free(nsi);
+}
+
+
+/* NS-over-IP code, according to 3GPP TS 48.016 Chapter 6.2
+ * We don't support Size Procedure, Configuration Procedure, ChangeWeight Procedure */
+
+/* Read a single NS-over-IP message */
+static struct msgb *read_nsip_msg(struct bsc_fd *bfd, int *error,
+				  struct sockaddr_in *saddr)
+{
+	struct msgb *msg = msgb_alloc(NS_ALLOC_SIZE, "Abis/IP/GPRS-NS");
+	int ret = 0;
+	socklen_t saddr_len = sizeof(*saddr);
+
+	if (!msg) {
+		*error = -ENOMEM;
+		return NULL;
+	}
+
+	ret = recvfrom(bfd->fd, msg->data, NS_ALLOC_SIZE, 0,
+			(struct sockaddr *)saddr, &saddr_len);
+	if (ret < 0) {
+		fprintf(stderr, "recv error  %s\n", strerror(errno));
+		msgb_free(msg);
+		*error = ret;
+		return NULL;
+	} else if (ret == 0) {
+		msgb_free(msg);
+		*error = ret;
+		return NULL;
+	}
+
+	msg->l2h = msg->data;
+	msgb_put(msg, ret);
+
+	return msg;
+}
+
+static int handle_nsip_read(struct bsc_fd *bfd)
+{
+	int error;
+	struct sockaddr_in saddr;
+	struct gprs_ns_inst *nsi = bfd->data;
+	struct msgb *msg = read_nsip_msg(bfd, &error, &saddr);
+
+	if (!msg)
+		return error;
+
+	return gprs_ns_rcvmsg(nsi, msg, &saddr);
+}
+
+static int handle_nsip_write(struct bsc_fd *bfd)
+{
+	/* FIXME: actually send the data here instead of nsip_sendmsg() */
+	return -EIO;
+}
+
+int nsip_sendmsg(struct msgb *msg, struct gprs_nsvc *nsvc)
+{
+	int rc;
+	struct gprs_ns_inst *nsi = nsvc->nsi;
+	struct sockaddr_in *daddr = &nsvc->ip.bts_addr;
+
+	rc = sendto(nsi->nsip.fd.fd, msg->data, msg->len, 0,
+		  (struct sockaddr *)daddr, sizeof(*daddr));
+
+	talloc_free(msg);
+
+	return rc;
+}
+
+/* UDP Port 23000 carries the LLC-in-BSSGP-in-NS protocol stack */
+static int nsip_fd_cb(struct bsc_fd *bfd, unsigned int what)
+{
+	int rc = 0;
+
+	if (what & BSC_FD_READ)
+		rc = handle_nsip_read(bfd);
+	if (what & BSC_FD_WRITE)
+		rc = handle_nsip_write(bfd);
+
+	return rc;
+}
+
+
+/* FIXME: this is currently in input/ipaccess.c */
+extern int make_sock(struct bsc_fd *bfd, int proto, u_int16_t port,
+		     int (*cb)(struct bsc_fd *fd, unsigned int what));
+
+/* Listen for incoming GPRS packets */
+int nsip_listen(struct gprs_ns_inst *nsi, uint16_t udp_port)
+{
+	int ret;
+
+	ret = make_sock(&nsi->nsip.fd, IPPROTO_UDP, udp_port, nsip_fd_cb);
+	if (ret < 0)
+		return ret;
+
+	nsi->ll = GPRS_NS_LL_UDP;
+	nsi->nsip.fd.data = nsi;
+
+	return ret;
+}