| #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 */ |
