You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
183 lines
6.6 KiB
183 lines
6.6 KiB
#ifndef _SLHC_H
|
|
#define _SLHC_H
|
|
/*
|
|
* Definitions for tcp compression routines.
|
|
*
|
|
* $Header: slcompress.h,v 1.10 89/12/31 08:53:02 van Exp $
|
|
*
|
|
* Copyright (c) 1989 Regents of the University of California.
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms are permitted
|
|
* provided that the above copyright notice and this paragraph are
|
|
* duplicated in all such forms and that any documentation,
|
|
* advertising materials, and other materials related to such
|
|
* distribution and use acknowledge that the software was developed
|
|
* by the University of California, Berkeley. The name of the
|
|
* University may not be used to endorse or promote products derived
|
|
* from this software without specific prior written permission.
|
|
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
|
|
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
|
|
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
|
|
*
|
|
* Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
|
|
* - Initial distribution.
|
|
*
|
|
*
|
|
* modified for KA9Q Internet Software Package by
|
|
* Katie Stevens (dkstevens@ucdavis.edu)
|
|
* University of California, Davis
|
|
* Computing Services
|
|
* - 01-31-90 initial adaptation
|
|
*
|
|
* - Feb 1991 Bill_Simpson@um.cc.umich.edu
|
|
* variable number of conversation slots
|
|
* allow zero or one slots
|
|
* separate routines
|
|
* status display
|
|
*/
|
|
|
|
/*
|
|
* Compressed packet format:
|
|
*
|
|
* The first octet contains the packet type (top 3 bits), TCP
|
|
* 'push' bit, and flags that indicate which of the 4 TCP sequence
|
|
* numbers have changed (bottom 5 bits). The next octet is a
|
|
* conversation number that associates a saved IP/TCP header with
|
|
* the compressed packet. The next two octets are the TCP checksum
|
|
* from the original datagram. The next 0 to 15 octets are
|
|
* sequence number changes, one change per bit set in the header
|
|
* (there may be no changes and there are two special cases where
|
|
* the receiver implicitly knows what changed -- see below).
|
|
*
|
|
* There are 5 numbers which can change (they are always inserted
|
|
* in the following order): TCP urgent pointer, window,
|
|
* acknowledgment, sequence number and IP ID. (The urgent pointer
|
|
* is different from the others in that its value is sent, not the
|
|
* change in value.) Since typical use of SLIP links is biased
|
|
* toward small packets (see comments on MTU/MSS below), changes
|
|
* use a variable length coding with one octet for numbers in the
|
|
* range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the
|
|
* range 256 - 65535 or 0. (If the change in sequence number or
|
|
* ack is more than 65535, an uncompressed packet is sent.)
|
|
*/
|
|
|
|
/*
|
|
* Packet types (must not conflict with IP protocol version)
|
|
*
|
|
* The top nibble of the first octet is the packet type. There are
|
|
* three possible types: IP (not proto TCP or tcp with one of the
|
|
* control flags set); uncompressed TCP (a normal IP/TCP packet but
|
|
* with the 8-bit protocol field replaced by an 8-bit connection id --
|
|
* this type of packet syncs the sender & receiver); and compressed
|
|
* TCP (described above).
|
|
*
|
|
* LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and
|
|
* is logically part of the 4-bit "changes" field that follows. Top
|
|
* three bits are actual packet type. For backward compatibility
|
|
* and in the interest of conserving bits, numbers are chosen so the
|
|
* IP protocol version number (4) which normally appears in this nibble
|
|
* means "IP packet".
|
|
*/
|
|
|
|
|
|
#include <linux/ip.h>
|
|
#include <linux/tcp.h>
|
|
|
|
/* SLIP compression masks for len/vers byte */
|
|
#define SL_TYPE_IP 0x40
|
|
#define SL_TYPE_UNCOMPRESSED_TCP 0x70
|
|
#define SL_TYPE_COMPRESSED_TCP 0x80
|
|
#define SL_TYPE_ERROR 0x00
|
|
|
|
/* Bits in first octet of compressed packet */
|
|
#define NEW_C 0x40 /* flag bits for what changed in a packet */
|
|
#define NEW_I 0x20
|
|
#define NEW_S 0x08
|
|
#define NEW_A 0x04
|
|
#define NEW_W 0x02
|
|
#define NEW_U 0x01
|
|
|
|
/* reserved, special-case values of above */
|
|
#define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */
|
|
#define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */
|
|
#define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)
|
|
|
|
#define TCP_PUSH_BIT 0x10
|
|
|
|
/*
|
|
* data type and sizes conversion assumptions:
|
|
*
|
|
* VJ code KA9Q style generic
|
|
* u_char byte_t unsigned char 8 bits
|
|
* u_short int16 unsigned short 16 bits
|
|
* u_int int16 unsigned short 16 bits
|
|
* u_long unsigned long unsigned long 32 bits
|
|
* int int32 long 32 bits
|
|
*/
|
|
|
|
typedef __u8 byte_t;
|
|
typedef __u32 int32;
|
|
|
|
/*
|
|
* "state" data for each active tcp conversation on the wire. This is
|
|
* basically a copy of the entire IP/TCP header from the last packet
|
|
* we saw from the conversation together with a small identifier
|
|
* the transmit & receive ends of the line use to locate saved header.
|
|
*/
|
|
struct cstate {
|
|
byte_t cs_this; /* connection id number (xmit) */
|
|
struct cstate *next; /* next in ring (xmit) */
|
|
struct iphdr cs_ip; /* ip/tcp hdr from most recent packet */
|
|
struct tcphdr cs_tcp;
|
|
unsigned char cs_ipopt[64];
|
|
unsigned char cs_tcpopt[64];
|
|
int cs_hsize;
|
|
};
|
|
#define NULLSLSTATE (struct cstate *)0
|
|
|
|
/*
|
|
* all the state data for one serial line (we need one of these per line).
|
|
*/
|
|
struct slcompress {
|
|
struct cstate *tstate; /* transmit connection states (array)*/
|
|
struct cstate *rstate; /* receive connection states (array)*/
|
|
|
|
byte_t tslot_limit; /* highest transmit slot id (0-l)*/
|
|
byte_t rslot_limit; /* highest receive slot id (0-l)*/
|
|
|
|
byte_t xmit_oldest; /* oldest xmit in ring */
|
|
byte_t xmit_current; /* most recent xmit id */
|
|
byte_t recv_current; /* most recent rcvd id */
|
|
|
|
byte_t flags;
|
|
#define SLF_TOSS 0x01 /* tossing rcvd frames until id received */
|
|
|
|
int32 sls_o_nontcp; /* outbound non-TCP packets */
|
|
int32 sls_o_tcp; /* outbound TCP packets */
|
|
int32 sls_o_uncompressed; /* outbound uncompressed packets */
|
|
int32 sls_o_compressed; /* outbound compressed packets */
|
|
int32 sls_o_searches; /* searches for connection state */
|
|
int32 sls_o_misses; /* times couldn't find conn. state */
|
|
|
|
int32 sls_i_uncompressed; /* inbound uncompressed packets */
|
|
int32 sls_i_compressed; /* inbound compressed packets */
|
|
int32 sls_i_error; /* inbound error packets */
|
|
int32 sls_i_tossed; /* inbound packets tossed because of error */
|
|
|
|
int32 sls_i_runt;
|
|
int32 sls_i_badcheck;
|
|
};
|
|
#define NULLSLCOMPR (struct slcompress *)0
|
|
|
|
/* In slhc.c: */
|
|
struct slcompress *slhc_init(int rslots, int tslots);
|
|
void slhc_free(struct slcompress *comp);
|
|
|
|
int slhc_compress(struct slcompress *comp, unsigned char *icp, int isize,
|
|
unsigned char *ocp, unsigned char **cpp, int compress_cid);
|
|
int slhc_uncompress(struct slcompress *comp, unsigned char *icp, int isize);
|
|
int slhc_remember(struct slcompress *comp, unsigned char *icp, int isize);
|
|
int slhc_toss(struct slcompress *comp);
|
|
|
|
#endif /* _SLHC_H */
|
|
|