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[/] [openrisc/] [trunk/] [rtos/] [freertos-6.1.1/] [Demo/] [Common/] [ethernet/] [lwIP_132/] [src/] [netif/] [ppp/] [vj.h] - Blame information for rev 606

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1 606 jeremybenn
/*
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 * Definitions for tcp compression routines.
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 *
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 * $Id: vj.h 2 2011-07-17 20:13:17Z filepang@gmail.com $
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 *
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 * Copyright (c) 1989 Regents of the University of California.
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms are permitted
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 * provided that the above copyright notice and this paragraph are
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 * duplicated in all such forms and that any documentation,
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 * advertising materials, and other materials related to such
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 * distribution and use acknowledge that the software was developed
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 * by the University of California, Berkeley.  The name of the
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 * University may not be used to endorse or promote products derived
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 * from this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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 *
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 * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
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 * - Initial distribution.
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 */
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#ifndef VJ_H
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#define VJ_H
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#include "vjbsdhdr.h"
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#define MAX_SLOTS 16 /* must be > 2 and < 256 */
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#define MAX_HDR   128
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/*
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 * Compressed packet format:
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 *
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 * The first octet contains the packet type (top 3 bits), TCP
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 * 'push' bit, and flags that indicate which of the 4 TCP sequence
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 * numbers have changed (bottom 5 bits).  The next octet is a
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 * conversation number that associates a saved IP/TCP header with
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 * the compressed packet.  The next two octets are the TCP checksum
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 * from the original datagram.  The next 0 to 15 octets are
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 * sequence number changes, one change per bit set in the header
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 * (there may be no changes and there are two special cases where
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 * the receiver implicitly knows what changed -- see below).
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 *
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 * There are 5 numbers which can change (they are always inserted
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 * in the following order): TCP urgent pointer, window,
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 * acknowlegement, sequence number and IP ID.  (The urgent pointer
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 * is different from the others in that its value is sent, not the
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 * change in value.)  Since typical use of SLIP links is biased
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 * toward small packets (see comments on MTU/MSS below), changes
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 * use a variable length coding with one octet for numbers in the
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 * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the
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 * range 256 - 65535 or 0.  (If the change in sequence number or
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 * ack is more than 65535, an uncompressed packet is sent.)
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 */
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/*
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 * Packet types (must not conflict with IP protocol version)
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 *
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 * The top nibble of the first octet is the packet type.  There are
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 * three possible types: IP (not proto TCP or tcp with one of the
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 * control flags set); uncompressed TCP (a normal IP/TCP packet but
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 * with the 8-bit protocol field replaced by an 8-bit connection id --
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 * this type of packet syncs the sender & receiver); and compressed
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 * TCP (described above).
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 *
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 * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and
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 * is logically part of the 4-bit "changes" field that follows.  Top
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 * three bits are actual packet type.  For backward compatibility
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 * and in the interest of conserving bits, numbers are chosen so the
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 * IP protocol version number (4) which normally appears in this nibble
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 * means "IP packet".
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 */
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/* packet types */
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#define TYPE_IP               0x40
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#define TYPE_UNCOMPRESSED_TCP 0x70
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#define TYPE_COMPRESSED_TCP   0x80
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#define TYPE_ERROR            0x00
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/* Bits in first octet of compressed packet */
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#define NEW_C 0x40 /* flag bits for what changed in a packet */
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#define NEW_I 0x20
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#define NEW_S 0x08
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#define NEW_A 0x04
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#define NEW_W 0x02
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#define NEW_U 0x01
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/* reserved, special-case values of above */
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#define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */
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#define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */
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#define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)
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#define TCP_PUSH_BIT 0x10
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/*
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 * "state" data for each active tcp conversation on the wire.  This is
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 * basically a copy of the entire IP/TCP header from the last packet
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 * we saw from the conversation together with a small identifier
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 * the transmit & receive ends of the line use to locate saved header.
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 */
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struct cstate {
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  struct cstate *cs_next; /* next most recently used state (xmit only) */
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  u_short cs_hlen;        /* size of hdr (receive only) */
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  u_char cs_id;           /* connection # associated with this state */
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  u_char cs_filler;
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  union {
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    char csu_hdr[MAX_HDR];
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    struct ip csu_ip;     /* ip/tcp hdr from most recent packet */
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  } vjcs_u;
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};
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#define cs_ip vjcs_u.csu_ip
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#define cs_hdr vjcs_u.csu_hdr
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struct vjstat {
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  unsigned long vjs_packets;        /* outbound packets */
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  unsigned long vjs_compressed;     /* outbound compressed packets */
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  unsigned long vjs_searches;       /* searches for connection state */
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  unsigned long vjs_misses;         /* times couldn't find conn. state */
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  unsigned long vjs_uncompressedin; /* inbound uncompressed packets */
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  unsigned long vjs_compressedin;   /* inbound compressed packets */
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  unsigned long vjs_errorin;        /* inbound unknown type packets */
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  unsigned long vjs_tossed;         /* inbound packets tossed because of error */
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};
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/*
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 * all the state data for one serial line (we need one of these per line).
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 */
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struct vjcompress {
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  struct cstate *last_cs;          /* most recently used tstate */
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  u_char last_recv;                /* last rcvd conn. id */
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  u_char last_xmit;                /* last sent conn. id */
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  u_short flags;
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  u_char maxSlotIndex;
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  u_char compressSlot;             /* Flag indicating OK to compress slot ID. */
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#if LINK_STATS
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  struct vjstat stats;
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#endif
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  struct cstate tstate[MAX_SLOTS]; /* xmit connection states */
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  struct cstate rstate[MAX_SLOTS]; /* receive connection states */
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};
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/* flag values */
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#define VJF_TOSS 1U /* tossing rcvd frames because of input err */
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extern void  vj_compress_init    (struct vjcompress *comp);
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extern u_int vj_compress_tcp     (struct vjcompress *comp, struct pbuf *pb);
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extern void  vj_uncompress_err   (struct vjcompress *comp);
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extern int   vj_uncompress_uncomp(struct pbuf *nb, struct vjcompress *comp);
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extern int   vj_uncompress_tcp   (struct pbuf **nb, struct vjcompress *comp);
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#endif /* VJ_H */

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