Adam Green / Mbed 2 deprecated WeatherStation

Web server based weather station using Sparkfun Weather Meters.

Dependencies:   FatFileSystem mbed WeatherMeters SDFileSystem

NetStack/lwip/netif/ppp/vj.h@0:616601bde9fb, 2012-02-23 (annotated)

Committer:
AdamGreen
Date:
Thu Feb 23 21:38:39 2012 +0000
Revision:
0:616601bde9fb

        

        
Who changed what in which revision?

        

            
                
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/*





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 * Definitions for tcp compression routines.





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 *





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 * $Id: vj.h,v 1.7 2010/02/22 17:52:09 goldsimon Exp $





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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 "lwip/ip.h"





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#include "lwip/tcp_impl.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_hdr 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 */