#ifndef _GPRS_NS_H
#define _GPRS_NS_H

#include <stdint.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 {
	uint8_t pdu_type;
	uint8_t data[0];
} __attribute__((packed));

/* TS 08.16, Section 10.3.7, Table 14 */
enum ns_pdu_type {
	NS_PDUT_UNITDATA	= 0x00,
	NS_PDUT_RESET		= 0x02,
	NS_PDUT_RESET_ACK	= 0x03,
	NS_PDUT_BLOCK		= 0x04,
	NS_PDUT_BLOCK_ACK	= 0x05,
	NS_PDUT_UNBLOCK		= 0x06,
	NS_PDUT_UNBLOCK_ACK	= 0x07,
	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 */
enum ns_ctrl_ie {
	NS_IE_CAUSE		= 0x00,
	NS_IE_VCI		= 0x01,
	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 */
enum ns_cause {
	NS_CAUSE_TRANSIT_FAIL		= 0x00,
	NS_CAUSE_OM_INTERVENTION	= 0x01,
	NS_CAUSE_EQUIP_FAIL		= 0x02,
	NS_CAUSE_NSVC_BLOCKED		= 0x03,
	NS_CAUSE_NSVC_UNKNOWN		= 0x04,
	NS_CAUSE_BVCI_UNKNOWN		= 0x05,
	NS_CAUSE_SEM_INCORR_PDU		= 0x08,
	NS_CAUSE_PDU_INCOMP_PSTATE	= 0x0a,
	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,
};


/* Our Implementation */
#include <netinet/in.h>
#include <osmocore/linuxlist.h>
#include <osmocore/msgb.h>
#include <osmocore/timer.h>
#include <osmocore/select.h>

#define NSE_S_BLOCKED	0x0001
#define NSE_S_ALIVE	0x0002

enum gprs_ns_ll {
	GPRS_NS_LL_UDP,
	GPRS_NS_LL_E1,
};

enum gprs_ns_evt {
	GPRS_NS_EVT_UNIT_DATA,
};

struct gprs_nsvc;
typedef int gprs_ns_cb_t(enum gprs_ns_evt event, struct gprs_nsvc *nsvc,
			 struct msgb *msg, uint16_t bvci);

/* 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;
	};
};

struct gprs_nsvc {
	struct llist_head list;
	struct gprs_ns_inst *nsi;

	uint16_t nsei;		/* end-to-end significance */
	uint16_t nsvci;	/* uniquely identifies NS-VC at SGSN */

	uint32_t state;
	uint32_t remote_state;

	struct timer_list alive_timer;
	int timer_is_tns_alive;
	int alive_retries;

	int remote_end_is_sgsn;

	union {
		struct {
			struct sockaddr_in bts_addr;
		} ip;
	};
};

/* 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);

/* Listen for incoming GPRS packets */
int nsip_listen(struct gprs_ns_inst *nsi, uint16_t udp_port);

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_ns_inst *nsi, struct msgb *msg);


/* Listen for incoming GPRS packets */
int nsip_listen(struct gprs_ns_inst *nsi, uint16_t udp_port);

/* Establish a connection (from the BSS) to the SGSN */
struct gprs_nsvc *nsip_connect(struct gprs_ns_inst *nsi,
				struct sockaddr_in *dest, uint16_t nsei,
				uint16_t nsvci);
#endif