| #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 */ |