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Diffstat (limited to 'include/net/slhc_vj.h')
| -rw-r--r-- | include/net/slhc_vj.h | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/include/net/slhc_vj.h b/include/net/slhc_vj.h new file mode 100644 index 000000000..8716d5942 --- /dev/null +++ b/include/net/slhc_vj.h @@ -0,0 +1,183 @@ +#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 */ |