#ifndef CLICK_RFC2507C_HH
#define CLICK_RFC2507C_HH
#include <click/element.hh>
#include <click/hashmap.hh>
#include <click/glue.hh>
#include <click/ipflowid.hh>
#include <clicknet/ip.h>
#include <clicknet/tcp.h>
CLICK_DECLS

/* =c
 * RFC2507Comp
 *
 * =s tcp
 * RFC2507 IPv4/TCP header compressor.
 *
 * =d
 * Input packets need to be IPv4 (no ether header &c).
 * It's OK if they're not TCP.
 * 
 * How to specify various kinds of output? There is not really
 * a useful general standard. Perhaps emit each different format
 * of output on a different output() and let further modules
 * sort it out. Then we wouldn't be AGNOSTIC...
 *
 * =a
 * RFC2507Decomp
 */

class RFC2507c : public Element {
public:

  /* used to store context as well as hash key */
  struct tcpip {
    click_ip _ip;
    click_tcp _tcp;
    operator bool() const { return(_ip.ip_src.s_addr != 0); }
    tcpip() { _ip.ip_src.s_addr = 0; }
    operator IPFlowID() const;
  };
  
  RFC2507c();
  ~RFC2507c();

  const char *class_name() const		{ return "RFC2507Comp"; }
  const char *port_count() const		{ return PORTS_1_1; }
  const char *processing() const		{ return AGNOSTIC; }

  Packet *simple_action(Packet *);

private:
  /* constants specified in the RFC */
  enum { TCP_SPACE = 15 }; /* max CID value for TCP. 3..255 are legal. */

  /* first byte of packet indicates type */
  enum { PT_OTHER = 0, /* ordinary packet (not compressed, no CID) */
	 PT_FULL_HEADER = 1, /* one byte CID, then full ip/tcp */
	 PT_COMPRESSED_TCP = 2 }; /* CID, compressed packet */
  
  /* per-connection control block, indexed by CID */
  struct ccb {
    struct tcpip _context;
  };
  struct ccb _ccbs[TCP_SPACE];

  /* map packet header ID fields to CID */
  HashMap<IPFlowID, int> _map;

  void make_key(const struct tcpip &from, struct tcpip &to);
  WritablePacket *make_other(Packet *p);
  WritablePacket *make_full(int cid, Packet *p);
  int encode16(int o, int n, char *p, int &i);
  int encode32(int o, int n, char *p, int &i);
  int encodeX(int o, int n, char *p, int &i);
  Packet *make_compressed(int cid, Packet *p);
};

CLICK_ENDDECLS
#endif