/*
 * File:        udp.c
 * Purpose:     User Datagram Protocol driver
 *
 * Notes:
 *
 * Modifications:
 *
 */
#include "bas_types.h"
#include "net.h"
#include <stddef.h>

#define DBG_UDP
#if defined(DBG_UDP)
#define dbg(format, arg...) do { xprintf("DEBUG: " format "\r\n", ##arg); } while (0)
#else
#define dbg(format, arg...) do { ; } while (0)
#endif /* DBG_UDP */

typedef struct
{
	uint16_t port;
	void (*handler)(NIF *, NBUF *);
} UDP_BOUND_PORT;

#define UDP_MAX_PORTS   (5)     /* plenty for this implementation */


static UDP_BOUND_PORT udp_port_table[UDP_MAX_PORTS];

static uint16_t udp_port;

void udp_init(void)
{
	int index;

	for (index = 0; index < UDP_MAX_PORTS; ++index)
	{
		udp_port_table[index].port = 0;
	}

	udp_port = DEFAULT_UDP_PORT;    /* next free port */
}

void udp_prime_port(uint16_t init_port)
{
	udp_port = init_port;
}

void udp_bind_port(uint16_t port, void (*handler)(NIF *, NBUF *))
{
	int index;

	for (index = 0; index < UDP_MAX_PORTS; ++index)
	{
		if (udp_port_table[index].port == 0)
		{
			udp_port_table[index].port = port;
			udp_port_table[index].handler = handler;

			return;
		}
	}
}

void udp_free_port(uint16_t port)
{
	int index;

	for (index = 0; index < UDP_MAX_PORTS; ++index)
	{
		if (udp_port_table[index].port == port)
		{
			udp_port_table[index].port = 0;

			return;
		}
	}
}

static void *udp_port_handler(uint16_t port)
{
	int index;

	for (index = 0; index < UDP_MAX_PORTS; ++index)
	{
		if (udp_port_table[index].port == port)
		{
			return (void *)udp_port_table[index].handler;
		}
	}
	return NULL;
}

uint16_t udp_obtain_free_port(void)
{
	uint16_t port;

	port = udp_port;
	if (--udp_port <= 255)
		udp_port = DEFAULT_UDP_PORT;

	return port;
}

int udp_send(NIF *nif, uint8_t *dest, int sport, int dport, NBUF *pNbuf)
{
	if (nif == NULL)
	{
		dbg("%s: nif is NULL\r\n", __FUNCTION__);
		return 0;
	}

	/*
	 * This function takes data and creates a UDP frame and
	 * passes it onto the IP layer
	 */
	udp_frame_hdr *udpframe;

	udpframe = (udp_frame_hdr *) &pNbuf->data[UDP_HDR_OFFSET];

	/* Set UDP source port */
	udpframe->src_port = (uint16_t) sport;

	/* Set UDP destination port */
	udpframe->dest_port = (uint16_t) dport;

	/* Set length */
	udpframe->length = (uint16_t) (pNbuf->length + UDP_HDR_SIZE);

	/* No checksum calcualation needed */
	udpframe->chksum = (uint16_t) 0;

	/* Add the length of the UDP packet to the total length of the packet */
	pNbuf->length += 8;

	return (ip_send(nif, dest, ip_get_myip(nif_get_protocol_info(nif, ETH_FRM_IP)),
				IP_PROTO_UDP, pNbuf));
}

void udp_handler(NIF *nif, NBUF *pNbuf)
{
	/*
	 * This function handles incoming UDP packets
	 */
	udp_frame_hdr *udpframe;
	void (*handler)(NIF *, NBUF *);

	udpframe = (udp_frame_hdr *) &pNbuf->data[pNbuf->offset];

	/*
	 * Adjust the length and valid data offset of the packet we are
	 * passing on
	 */
	pNbuf->length -= UDP_HDR_SIZE;
	pNbuf->offset += UDP_HDR_SIZE;

	/*
	 * Traverse the list of bound ports to see if there is a higher
	 * level protocol to pass the packet on to
	 */
	if ((handler = (void(*)(NIF*, NBUF*)) udp_port_handler(UDP_DEST(udpframe))) != NULL)
		handler(nif, pNbuf);
	else
	{
		xprintf("Received UDP packet for non-supported port\n");
		nbuf_free(pNbuf);
	}

	return;
}