/*****************************************************************************
 *                             Packet Queue                                  *
 *****************************************************************************
 * This module is designed to allow the creation of queues to store packages *
 * waiting for ARP requests to be replied. The queue are updated as packages *
 * expire or are sent to their destination.                                  *
 *****************************************************************************/

#ifndef SR_PQ_H
#define SR_PQ_H

#include <time.h>
#include "sr_protocol.h"
#include "sr_if.h"

/**
 * This structure holds the individual packet queue element.
 **/
struct pq_element{
	/**
	 * The number of ARP requests left before packet drop. 
	 **/ 
	unsigned int arp_count;
	/**
 	 * Pointer to the packet buffer.
	 **/
	uint8_t *packet;
	/**
	 * Length of queued packet.
	 **/
	unsigned int len;
	/**
     * Next queue element.
	 **/
	struct pq_element *next;
};

/**
 * Queue structure.
 **/
struct sr_pq{
	/**
	 * Reference to first element.
	 **/
	struct pq_element *head;	
	/**
	 * Reference to last element.
	 **/
	struct pq_element *tail;
	/**
	 * Number of elements in the queue.
	 **/
	unsigned int length;
	/**
	 * The time untill the next APR request can be sent.
	 **/
	time_t expires;
};

/**
 * Queue up a packet.
 * Author: Nicholas
 **/
void sr_enqueue_packet(struct sr_pq*, uint8_t *, unsigned int);
/**
 * Remove a packet from the queue.
 * Author: Nicholas
 **/
uint8_t *sr_dequeue_packet(struct sr_pq *, unsigned int*);
/**
 * Print the packet queue entries.
 * Author: Nicholas
 **/
void sr_print_pq(struct sr_pq *);
/**
 * Send all packets in the queue.
 * Author: Nicholas
 **/
void sr_send_packets(struct sr_instance*, struct sr_pq *, char*, unsigned char [ETHER_ADDR_LEN]);
/**
 * Convert a MAC address to a nicely formated string.
 * Author: Nicholas
 **/
char *strmac(unsigned char [ETHER_ADDR_LEN]);
/**
 * Convert an IP address to a buffered string.
 * Author: Nicholas
 **/
char *strip(uint32_t);
/**
 * Send ARP requests and ICMP unreachable errors for queued packets.
 * Author: Nicholas
 **/
void sr_update_pq(struct sr_instance*, struct sr_pq*, char*, uint32_t);

#endif