RFC1144: add slhc code from linux kernel
SLHC is an Implementation of RFC1144 TCP/IP header compression. We will need RFC1144 compression to compress GPRS TCP/IP traffic. The implementation pushed with this commit was taken from: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git commit 29b4817d4018df78086157ea3a55c1d9424a7cfc Change-Id: Ied69c143678dc4a64cecc671f5c4dfebe19d8519
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#ifndef _SLHC_H
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#define _SLHC_H
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/*
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* Definitions for tcp compression routines.
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*
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* $Header: slcompress.h,v 1.10 89/12/31 08:53:02 van 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 MERCHANTABILITY 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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*
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* modified for KA9Q Internet Software Package by
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* Katie Stevens (dkstevens@ucdavis.edu)
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* University of California, Davis
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* Computing Services
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* - 01-31-90 initial adaptation
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*
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* - Feb 1991 Bill_Simpson@um.cc.umich.edu
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* variable number of conversation slots
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* allow zero or one slots
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* separate routines
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* status display
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*/
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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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* acknowledgment, 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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#include <linux/ip.h>
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#include <linux/tcp.h>
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/* SLIP compression masks for len/vers byte */
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#define SL_TYPE_IP 0x40
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#define SL_TYPE_UNCOMPRESSED_TCP 0x70
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#define SL_TYPE_COMPRESSED_TCP 0x80
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#define SL_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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* data type and sizes conversion assumptions:
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*
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* VJ code KA9Q style generic
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* u_char byte_t unsigned char 8 bits
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* u_short int16 unsigned short 16 bits
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* u_int int16 unsigned short 16 bits
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* u_long unsigned long unsigned long 32 bits
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* int int32 long 32 bits
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*/
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typedef __u8 byte_t;
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typedef __u32 int32;
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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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byte_t cs_this; /* connection id number (xmit) */
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struct cstate *next; /* next in ring (xmit) */
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struct iphdr cs_ip; /* ip/tcp hdr from most recent packet */
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struct tcphdr cs_tcp;
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unsigned char cs_ipopt[64];
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unsigned char cs_tcpopt[64];
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int cs_hsize;
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};
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#define NULLSLSTATE (struct cstate *)0
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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 slcompress {
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struct cstate *tstate; /* transmit connection states (array)*/
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struct cstate *rstate; /* receive connection states (array)*/
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byte_t tslot_limit; /* highest transmit slot id (0-l)*/
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byte_t rslot_limit; /* highest receive slot id (0-l)*/
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byte_t xmit_oldest; /* oldest xmit in ring */
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byte_t xmit_current; /* most recent xmit id */
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byte_t recv_current; /* most recent rcvd id */
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byte_t flags;
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#define SLF_TOSS 0x01 /* tossing rcvd frames until id received */
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int32 sls_o_nontcp; /* outbound non-TCP packets */
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int32 sls_o_tcp; /* outbound TCP packets */
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int32 sls_o_uncompressed; /* outbound uncompressed packets */
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int32 sls_o_compressed; /* outbound compressed packets */
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int32 sls_o_searches; /* searches for connection state */
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int32 sls_o_misses; /* times couldn't find conn. state */
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int32 sls_i_uncompressed; /* inbound uncompressed packets */
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int32 sls_i_compressed; /* inbound compressed packets */
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int32 sls_i_error; /* inbound error packets */
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int32 sls_i_tossed; /* inbound packets tossed because of error */
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int32 sls_i_runt;
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int32 sls_i_badcheck;
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};
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#define NULLSLCOMPR (struct slcompress *)0
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/* In slhc.c: */
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struct slcompress *slhc_init(int rslots, int tslots);
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void slhc_free(struct slcompress *comp);
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int slhc_compress(struct slcompress *comp, unsigned char *icp, int isize,
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unsigned char *ocp, unsigned char **cpp, int compress_cid);
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int slhc_uncompress(struct slcompress *comp, unsigned char *icp, int isize);
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int slhc_remember(struct slcompress *comp, unsigned char *icp, int isize);
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int slhc_toss(struct slcompress *comp);
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#endif /* _SLHC_H */
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/*
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* Routines to compress and uncompress tcp packets (for transmission
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* over low speed serial lines).
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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 MERCHANTABILITY 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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*
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* modified for KA9Q Internet Software Package by
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* Katie Stevens (dkstevens@ucdavis.edu)
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* University of California, Davis
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* Computing Services
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* - 01-31-90 initial adaptation (from 1.19)
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* PPP.05 02-15-90 [ks]
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* PPP.08 05-02-90 [ks] use PPP protocol field to signal compression
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* PPP.15 09-90 [ks] improve mbuf handling
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* PPP.16 11-02 [karn] substantially rewritten to use NOS facilities
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*
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* - Feb 1991 Bill_Simpson@um.cc.umich.edu
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* variable number of conversation slots
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* allow zero or one slots
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* separate routines
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* status display
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* - Jul 1994 Dmitry Gorodchanin
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* Fixes for memory leaks.
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* - Oct 1994 Dmitry Gorodchanin
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* Modularization.
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* - Jan 1995 Bjorn Ekwall
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* Use ip_fast_csum from ip.h
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* - July 1995 Christos A. Polyzols
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* Spotted bug in tcp option checking
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*
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*
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* This module is a difficult issue. It's clearly inet code but it's also clearly
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* driver code belonging close to PPP and SLIP
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/string.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <net/slhc_vj.h>
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#ifdef CONFIG_INET
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/* Entire module is for IP only */
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#include <linux/mm.h>
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#include <linux/socket.h>
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#include <linux/sockios.h>
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#include <linux/termios.h>
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#include <linux/in.h>
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#include <linux/fcntl.h>
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#include <linux/inet.h>
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#include <linux/netdevice.h>
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#include <net/ip.h>
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#include <net/protocol.h>
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#include <net/icmp.h>
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#include <net/tcp.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <linux/timer.h>
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#include <asm/uaccess.h>
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#include <net/checksum.h>
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#include <asm/unaligned.h>
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static unsigned char *encode(unsigned char *cp, unsigned short n);
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static long decode(unsigned char **cpp);
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static unsigned char * put16(unsigned char *cp, unsigned short x);
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static unsigned short pull16(unsigned char **cpp);
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/* Allocate compression data structure
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* slots must be in range 0 to 255 (zero meaning no compression)
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* Returns pointer to structure or ERR_PTR() on error.
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*/
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struct slcompress *
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slhc_init(int rslots, int tslots)
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{
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register short i;
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register struct cstate *ts;
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struct slcompress *comp;
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if (rslots < 0 || rslots > 255 || tslots < 0 || tslots > 255)
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return ERR_PTR(-EINVAL);
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comp = kzalloc(sizeof(struct slcompress), GFP_KERNEL);
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if (! comp)
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goto out_fail;
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if (rslots > 0) {
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size_t rsize = rslots * sizeof(struct cstate);
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comp->rstate = kzalloc(rsize, GFP_KERNEL);
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if (! comp->rstate)
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goto out_free;
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comp->rslot_limit = rslots - 1;
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}
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if (tslots > 0) {
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size_t tsize = tslots * sizeof(struct cstate);
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comp->tstate = kzalloc(tsize, GFP_KERNEL);
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if (! comp->tstate)
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goto out_free2;
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comp->tslot_limit = tslots - 1;
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}
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comp->xmit_oldest = 0;
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comp->xmit_current = 255;
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comp->recv_current = 255;
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/*
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* don't accept any packets with implicit index until we get
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* one with an explicit index. Otherwise the uncompress code
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* will try to use connection 255, which is almost certainly
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* out of range
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*/
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comp->flags |= SLF_TOSS;
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if ( tslots > 0 ) {
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ts = comp->tstate;
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for(i = comp->tslot_limit; i > 0; --i){
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ts[i].cs_this = i;
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ts[i].next = &(ts[i - 1]);
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}
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ts[0].next = &(ts[comp->tslot_limit]);
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ts[0].cs_this = 0;
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}
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return comp;
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out_free2:
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kfree(comp->rstate);
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out_free:
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kfree(comp);
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out_fail:
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return ERR_PTR(-ENOMEM);
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}
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/* Free a compression data structure */
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void
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slhc_free(struct slcompress *comp)
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{
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if ( comp == NULLSLCOMPR )
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return;
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if ( comp->tstate != NULLSLSTATE )
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kfree( comp->tstate );
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if ( comp->rstate != NULLSLSTATE )
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kfree( comp->rstate );
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kfree( comp );
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}
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/* Put a short in host order into a char array in network order */
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static inline unsigned char *
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put16(unsigned char *cp, unsigned short x)
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{
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*cp++ = x >> 8;
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*cp++ = x;
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return cp;
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}
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/* Encode a number */
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static unsigned char *
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encode(unsigned char *cp, unsigned short n)
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{
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if(n >= 256 || n == 0){
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*cp++ = 0;
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cp = put16(cp,n);
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} else {
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*cp++ = n;
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}
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return cp;
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}
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/* Pull a 16-bit integer in host order from buffer in network byte order */
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static unsigned short
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pull16(unsigned char **cpp)
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{
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short rval;
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rval = *(*cpp)++;
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rval <<= 8;
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rval |= *(*cpp)++;
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return rval;
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}
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/* Decode a number */
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static long
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decode(unsigned char **cpp)
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{
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register int x;
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x = *(*cpp)++;
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if(x == 0){
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return pull16(cpp) & 0xffff; /* pull16 returns -1 on error */
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} else {
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return x & 0xff; /* -1 if PULLCHAR returned error */
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}
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}
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/*
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* icp and isize are the original packet.
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* ocp is a place to put a copy if necessary.
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* cpp is initially a pointer to icp. If the copy is used,
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* change it to ocp.
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*/
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int
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slhc_compress(struct slcompress *comp, unsigned char *icp, int isize,
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unsigned char *ocp, unsigned char **cpp, int compress_cid)
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{
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register struct cstate *ocs = &(comp->tstate[comp->xmit_oldest]);
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register struct cstate *lcs = ocs;
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register struct cstate *cs = lcs->next;
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register unsigned long deltaS, deltaA;
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register short changes = 0;
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int hlen;
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unsigned char new_seq[16];
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register unsigned char *cp = new_seq;
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struct iphdr *ip;
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struct tcphdr *th, *oth;
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__sum16 csum;
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/*
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* Don't play with runt packets.
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*/
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if(isize<sizeof(struct iphdr))
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return isize;
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ip = (struct iphdr *) icp;
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/* Bail if this packet isn't TCP, or is an IP fragment */
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if (ip->protocol != IPPROTO_TCP || (ntohs(ip->frag_off) & 0x3fff)) {
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/* Send as regular IP */
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if(ip->protocol != IPPROTO_TCP)
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comp->sls_o_nontcp++;
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else
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comp->sls_o_tcp++;
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return isize;
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}
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/* Extract TCP header */
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th = (struct tcphdr *)(((unsigned char *)ip) + ip->ihl*4);
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hlen = ip->ihl*4 + th->doff*4;
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/* Bail if the TCP packet isn't `compressible' (i.e., ACK isn't set or
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* some other control bit is set). Also uncompressible if
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* it's a runt.
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*/
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if(hlen > isize || th->syn || th->fin || th->rst ||
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! (th->ack)){
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/* TCP connection stuff; send as regular IP */
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comp->sls_o_tcp++;
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return isize;
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}
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/*
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* Packet is compressible -- we're going to send either a
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* COMPRESSED_TCP or UNCOMPRESSED_TCP packet. Either way,
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* we need to locate (or create) the connection state.
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*
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* States are kept in a circularly linked list with
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* xmit_oldest pointing to the end of the list. The
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* list is kept in lru order by moving a state to the
|
||||
* head of the list whenever it is referenced. Since
|
||||
* the list is short and, empirically, the connection
|
||||
* we want is almost always near the front, we locate
|
||||
* states via linear search. If we don't find a state
|
||||
* for the datagram, the oldest state is (re-)used.
|
||||
*/
|
||||
for ( ; ; ) {
|
||||
if( ip->saddr == cs->cs_ip.saddr
|
||||
&& ip->daddr == cs->cs_ip.daddr
|
||||
&& th->source == cs->cs_tcp.source
|
||||
&& th->dest == cs->cs_tcp.dest)
|
||||
goto found;
|
||||
|
||||
/* if current equal oldest, at end of list */
|
||||
if ( cs == ocs )
|
||||
break;
|
||||
lcs = cs;
|
||||
cs = cs->next;
|
||||
comp->sls_o_searches++;
|
||||
}
|
||||
/*
|
||||
* Didn't find it -- re-use oldest cstate. Send an
|
||||
* uncompressed packet that tells the other side what
|
||||
* connection number we're using for this conversation.
|
||||
*
|
||||
* Note that since the state list is circular, the oldest
|
||||
* state points to the newest and we only need to set
|
||||
* xmit_oldest to update the lru linkage.
|
||||
*/
|
||||
comp->sls_o_misses++;
|
||||
comp->xmit_oldest = lcs->cs_this;
|
||||
goto uncompressed;
|
||||
|
||||
found:
|
||||
/*
|
||||
* Found it -- move to the front on the connection list.
|
||||
*/
|
||||
if(lcs == ocs) {
|
||||
/* found at most recently used */
|
||||
} else if (cs == ocs) {
|
||||
/* found at least recently used */
|
||||
comp->xmit_oldest = lcs->cs_this;
|
||||
} else {
|
||||
/* more than 2 elements */
|
||||
lcs->next = cs->next;
|
||||
cs->next = ocs->next;
|
||||
ocs->next = cs;
|
||||
}
|
||||
|
||||
/*
|
||||
* Make sure that only what we expect to change changed.
|
||||
* Check the following:
|
||||
* IP protocol version, header length & type of service.
|
||||
* The "Don't fragment" bit.
|
||||
* The time-to-live field.
|
||||
* The TCP header length.
|
||||
* IP options, if any.
|
||||
* TCP options, if any.
|
||||
* If any of these things are different between the previous &
|
||||
* current datagram, we send the current datagram `uncompressed'.
|
||||
*/
|
||||
oth = &cs->cs_tcp;
|
||||
|
||||
if(ip->version != cs->cs_ip.version || ip->ihl != cs->cs_ip.ihl
|
||||
|| ip->tos != cs->cs_ip.tos
|
||||
|| (ip->frag_off & htons(0x4000)) != (cs->cs_ip.frag_off & htons(0x4000))
|
||||
|| ip->ttl != cs->cs_ip.ttl
|
||||
|| th->doff != cs->cs_tcp.doff
|
||||
|| (ip->ihl > 5 && memcmp(ip+1,cs->cs_ipopt,((ip->ihl)-5)*4) != 0)
|
||||
|| (th->doff > 5 && memcmp(th+1,cs->cs_tcpopt,((th->doff)-5)*4) != 0)){
|
||||
goto uncompressed;
|
||||
}
|
||||
|
||||
/*
|
||||
* Figure out which of the changing fields changed. The
|
||||
* receiver expects changes in the order: urgent, window,
|
||||
* ack, seq (the order minimizes the number of temporaries
|
||||
* needed in this section of code).
|
||||
*/
|
||||
if(th->urg){
|
||||
deltaS = ntohs(th->urg_ptr);
|
||||
cp = encode(cp,deltaS);
|
||||
changes |= NEW_U;
|
||||
} else if(th->urg_ptr != oth->urg_ptr){
|
||||
/* argh! URG not set but urp changed -- a sensible
|
||||
* implementation should never do this but RFC793
|
||||
* doesn't prohibit the change so we have to deal
|
||||
* with it. */
|
||||
goto uncompressed;
|
||||
}
|
||||
if((deltaS = ntohs(th->window) - ntohs(oth->window)) != 0){
|
||||
cp = encode(cp,deltaS);
|
||||
changes |= NEW_W;
|
||||
}
|
||||
if((deltaA = ntohl(th->ack_seq) - ntohl(oth->ack_seq)) != 0L){
|
||||
if(deltaA > 0x0000ffff)
|
||||
goto uncompressed;
|
||||
cp = encode(cp,deltaA);
|
||||
changes |= NEW_A;
|
||||
}
|
||||
if((deltaS = ntohl(th->seq) - ntohl(oth->seq)) != 0L){
|
||||
if(deltaS > 0x0000ffff)
|
||||
goto uncompressed;
|
||||
cp = encode(cp,deltaS);
|
||||
changes |= NEW_S;
|
||||
}
|
||||
|
||||
switch(changes){
|
||||
case 0: /* Nothing changed. If this packet contains data and the
|
||||
* last one didn't, this is probably a data packet following
|
||||
* an ack (normal on an interactive connection) and we send
|
||||
* it compressed. Otherwise it's probably a retransmit,
|
||||
* retransmitted ack or window probe. Send it uncompressed
|
||||
* in case the other side missed the compressed version.
|
||||
*/
|
||||
if(ip->tot_len != cs->cs_ip.tot_len &&
|
||||
ntohs(cs->cs_ip.tot_len) == hlen)
|
||||
break;
|
||||
goto uncompressed;
|
||||
case SPECIAL_I:
|
||||
case SPECIAL_D:
|
||||
/* actual changes match one of our special case encodings --
|
||||
* send packet uncompressed.
|
||||
*/
|
||||
goto uncompressed;
|
||||
case NEW_S|NEW_A:
|
||||
if(deltaS == deltaA &&
|
||||
deltaS == ntohs(cs->cs_ip.tot_len) - hlen){
|
||||
/* special case for echoed terminal traffic */
|
||||
changes = SPECIAL_I;
|
||||
cp = new_seq;
|
||||
}
|
||||
break;
|
||||
case NEW_S:
|
||||
if(deltaS == ntohs(cs->cs_ip.tot_len) - hlen){
|
||||
/* special case for data xfer */
|
||||
changes = SPECIAL_D;
|
||||
cp = new_seq;
|
||||
}
|
||||
break;
|
||||
}
|
||||
deltaS = ntohs(ip->id) - ntohs(cs->cs_ip.id);
|
||||
if(deltaS != 1){
|
||||
cp = encode(cp,deltaS);
|
||||
changes |= NEW_I;
|
||||
}
|
||||
if(th->psh)
|
||||
changes |= TCP_PUSH_BIT;
|
||||
/* Grab the cksum before we overwrite it below. Then update our
|
||||
* state with this packet's header.
|
||||
*/
|
||||
csum = th->check;
|
||||
memcpy(&cs->cs_ip,ip,20);
|
||||
memcpy(&cs->cs_tcp,th,20);
|
||||
/* We want to use the original packet as our compressed packet.
|
||||
* (cp - new_seq) is the number of bytes we need for compressed
|
||||
* sequence numbers. In addition we need one byte for the change
|
||||
* mask, one for the connection id and two for the tcp checksum.
|
||||
* So, (cp - new_seq) + 4 bytes of header are needed.
|
||||
*/
|
||||
deltaS = cp - new_seq;
|
||||
if(compress_cid == 0 || comp->xmit_current != cs->cs_this){
|
||||
cp = ocp;
|
||||
*cpp = ocp;
|
||||
*cp++ = changes | NEW_C;
|
||||
*cp++ = cs->cs_this;
|
||||
comp->xmit_current = cs->cs_this;
|
||||
} else {
|
||||
cp = ocp;
|
||||
*cpp = ocp;
|
||||
*cp++ = changes;
|
||||
}
|
||||
*(__sum16 *)cp = csum;
|
||||
cp += 2;
|
||||
/* deltaS is now the size of the change section of the compressed header */
|
||||
memcpy(cp,new_seq,deltaS); /* Write list of deltas */
|
||||
memcpy(cp+deltaS,icp+hlen,isize-hlen);
|
||||
comp->sls_o_compressed++;
|
||||
ocp[0] |= SL_TYPE_COMPRESSED_TCP;
|
||||
return isize - hlen + deltaS + (cp - ocp);
|
||||
|
||||
/* Update connection state cs & send uncompressed packet (i.e.,
|
||||
* a regular ip/tcp packet but with the 'conversation id' we hope
|
||||
* to use on future compressed packets in the protocol field).
|
||||
*/
|
||||
uncompressed:
|
||||
memcpy(&cs->cs_ip,ip,20);
|
||||
memcpy(&cs->cs_tcp,th,20);
|
||||
if (ip->ihl > 5)
|
||||
memcpy(cs->cs_ipopt, ip+1, ((ip->ihl) - 5) * 4);
|
||||
if (th->doff > 5)
|
||||
memcpy(cs->cs_tcpopt, th+1, ((th->doff) - 5) * 4);
|
||||
comp->xmit_current = cs->cs_this;
|
||||
comp->sls_o_uncompressed++;
|
||||
memcpy(ocp, icp, isize);
|
||||
*cpp = ocp;
|
||||
ocp[9] = cs->cs_this;
|
||||
ocp[0] |= SL_TYPE_UNCOMPRESSED_TCP;
|
||||
return isize;
|
||||
}
|
||||
|
||||
|
||||
int
|
||||
slhc_uncompress(struct slcompress *comp, unsigned char *icp, int isize)
|
||||
{
|
||||
register int changes;
|
||||
long x;
|
||||
register struct tcphdr *thp;
|
||||
register struct iphdr *ip;
|
||||
register struct cstate *cs;
|
||||
int len, hdrlen;
|
||||
unsigned char *cp = icp;
|
||||
|
||||
/* We've got a compressed packet; read the change byte */
|
||||
comp->sls_i_compressed++;
|
||||
if(isize < 3){
|
||||
comp->sls_i_error++;
|
||||
return 0;
|
||||
}
|
||||
changes = *cp++;
|
||||
if(changes & NEW_C){
|
||||
/* Make sure the state index is in range, then grab the state.
|
||||
* If we have a good state index, clear the 'discard' flag.
|
||||
*/
|
||||
x = *cp++; /* Read conn index */
|
||||
if(x < 0 || x > comp->rslot_limit)
|
||||
goto bad;
|
||||
|
||||
comp->flags &=~ SLF_TOSS;
|
||||
comp->recv_current = x;
|
||||
} else {
|
||||
/* this packet has an implicit state index. If we've
|
||||
* had a line error since the last time we got an
|
||||
* explicit state index, we have to toss the packet. */
|
||||
if(comp->flags & SLF_TOSS){
|
||||
comp->sls_i_tossed++;
|
||||
return 0;
|
||||
}
|
||||
}
|
||||
cs = &comp->rstate[comp->recv_current];
|
||||
thp = &cs->cs_tcp;
|
||||
ip = &cs->cs_ip;
|
||||
|
||||
thp->check = *(__sum16 *)cp;
|
||||
cp += 2;
|
||||
|
||||
thp->psh = (changes & TCP_PUSH_BIT) ? 1 : 0;
|
||||
/*
|
||||
* we can use the same number for the length of the saved header and
|
||||
* the current one, because the packet wouldn't have been sent
|
||||
* as compressed unless the options were the same as the previous one
|
||||
*/
|
||||
|
||||
hdrlen = ip->ihl * 4 + thp->doff * 4;
|
||||
|
||||
switch(changes & SPECIALS_MASK){
|
||||
case SPECIAL_I: /* Echoed terminal traffic */
|
||||
{
|
||||
register short i;
|
||||
i = ntohs(ip->tot_len) - hdrlen;
|
||||
thp->ack_seq = htonl( ntohl(thp->ack_seq) + i);
|
||||
thp->seq = htonl( ntohl(thp->seq) + i);
|
||||
}
|
||||
break;
|
||||
|
||||
case SPECIAL_D: /* Unidirectional data */
|
||||
thp->seq = htonl( ntohl(thp->seq) +
|
||||
ntohs(ip->tot_len) - hdrlen);
|
||||
break;
|
||||
|
||||
default:
|
||||
if(changes & NEW_U){
|
||||
thp->urg = 1;
|
||||
if((x = decode(&cp)) == -1) {
|
||||
goto bad;
|
||||
}
|
||||
thp->urg_ptr = htons(x);
|
||||
} else
|
||||
thp->urg = 0;
|
||||
if(changes & NEW_W){
|
||||
if((x = decode(&cp)) == -1) {
|
||||
goto bad;
|
||||
}
|
||||
thp->window = htons( ntohs(thp->window) + x);
|
||||
}
|
||||
if(changes & NEW_A){
|
||||
if((x = decode(&cp)) == -1) {
|
||||
goto bad;
|
||||
}
|
||||
thp->ack_seq = htonl( ntohl(thp->ack_seq) + x);
|
||||
}
|
||||
if(changes & NEW_S){
|
||||
if((x = decode(&cp)) == -1) {
|
||||
goto bad;
|
||||
}
|
||||
thp->seq = htonl( ntohl(thp->seq) + x);
|
||||
}
|
||||
break;
|
||||
}
|
||||
if(changes & NEW_I){
|
||||
if((x = decode(&cp)) == -1) {
|
||||
goto bad;
|
||||
}
|
||||
ip->id = htons (ntohs (ip->id) + x);
|
||||
} else
|
||||
ip->id = htons (ntohs (ip->id) + 1);
|
||||
|
||||
/*
|
||||
* At this point, cp points to the first byte of data in the
|
||||
* packet. Put the reconstructed TCP and IP headers back on the
|
||||
* packet. Recalculate IP checksum (but not TCP checksum).
|
||||
*/
|
||||
|
||||
len = isize - (cp - icp);
|
||||
if (len < 0)
|
||||
goto bad;
|
||||
len += hdrlen;
|
||||
ip->tot_len = htons(len);
|
||||
ip->check = 0;
|
||||
|
||||
memmove(icp + hdrlen, cp, len - hdrlen);
|
||||
|
||||
cp = icp;
|
||||
memcpy(cp, ip, 20);
|
||||
cp += 20;
|
||||
|
||||
if (ip->ihl > 5) {
|
||||
memcpy(cp, cs->cs_ipopt, (ip->ihl - 5) * 4);
|
||||
cp += (ip->ihl - 5) * 4;
|
||||
}
|
||||
|
||||
put_unaligned(ip_fast_csum(icp, ip->ihl),
|
||||
&((struct iphdr *)icp)->check);
|
||||
|
||||
memcpy(cp, thp, 20);
|
||||
cp += 20;
|
||||
|
||||
if (thp->doff > 5) {
|
||||
memcpy(cp, cs->cs_tcpopt, ((thp->doff) - 5) * 4);
|
||||
cp += ((thp->doff) - 5) * 4;
|
||||
}
|
||||
|
||||
return len;
|
||||
bad:
|
||||
comp->sls_i_error++;
|
||||
return slhc_toss( comp );
|
||||
}
|
||||
|
||||
|
||||
int
|
||||
slhc_remember(struct slcompress *comp, unsigned char *icp, int isize)
|
||||
{
|
||||
register struct cstate *cs;
|
||||
unsigned ihl;
|
||||
|
||||
unsigned char index;
|
||||
|
||||
if(isize < 20) {
|
||||
/* The packet is shorter than a legal IP header */
|
||||
comp->sls_i_runt++;
|
||||
return slhc_toss( comp );
|
||||
}
|
||||
/* Peek at the IP header's IHL field to find its length */
|
||||
ihl = icp[0] & 0xf;
|
||||
if(ihl < 20 / 4){
|
||||
/* The IP header length field is too small */
|
||||
comp->sls_i_runt++;
|
||||
return slhc_toss( comp );
|
||||
}
|
||||
index = icp[9];
|
||||
icp[9] = IPPROTO_TCP;
|
||||
|
||||
if (ip_fast_csum(icp, ihl)) {
|
||||
/* Bad IP header checksum; discard */
|
||||
comp->sls_i_badcheck++;
|
||||
return slhc_toss( comp );
|
||||
}
|
||||
if(index > comp->rslot_limit) {
|
||||
comp->sls_i_error++;
|
||||
return slhc_toss(comp);
|
||||
}
|
||||
|
||||
/* Update local state */
|
||||
cs = &comp->rstate[comp->recv_current = index];
|
||||
comp->flags &=~ SLF_TOSS;
|
||||
memcpy(&cs->cs_ip,icp,20);
|
||||
memcpy(&cs->cs_tcp,icp + ihl*4,20);
|
||||
if (ihl > 5)
|
||||
memcpy(cs->cs_ipopt, icp + sizeof(struct iphdr), (ihl - 5) * 4);
|
||||
if (cs->cs_tcp.doff > 5)
|
||||
memcpy(cs->cs_tcpopt, icp + ihl*4 + sizeof(struct tcphdr), (cs->cs_tcp.doff - 5) * 4);
|
||||
cs->cs_hsize = ihl*2 + cs->cs_tcp.doff*2;
|
||||
/* Put headers back on packet
|
||||
* Neither header checksum is recalculated
|
||||
*/
|
||||
comp->sls_i_uncompressed++;
|
||||
return isize;
|
||||
}
|
||||
|
||||
int
|
||||
slhc_toss(struct slcompress *comp)
|
||||
{
|
||||
if ( comp == NULLSLCOMPR )
|
||||
return 0;
|
||||
|
||||
comp->flags |= SLF_TOSS;
|
||||
return 0;
|
||||
}
|
||||
|
||||
#else /* CONFIG_INET */
|
||||
|
||||
int
|
||||
slhc_toss(struct slcompress *comp)
|
||||
{
|
||||
printk(KERN_DEBUG "Called IP function on non IP-system: slhc_toss");
|
||||
return -EINVAL;
|
||||
}
|
||||
int
|
||||
slhc_uncompress(struct slcompress *comp, unsigned char *icp, int isize)
|
||||
{
|
||||
printk(KERN_DEBUG "Called IP function on non IP-system: slhc_uncompress");
|
||||
return -EINVAL;
|
||||
}
|
||||
int
|
||||
slhc_compress(struct slcompress *comp, unsigned char *icp, int isize,
|
||||
unsigned char *ocp, unsigned char **cpp, int compress_cid)
|
||||
{
|
||||
printk(KERN_DEBUG "Called IP function on non IP-system: slhc_compress");
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
int
|
||||
slhc_remember(struct slcompress *comp, unsigned char *icp, int isize)
|
||||
{
|
||||
printk(KERN_DEBUG "Called IP function on non IP-system: slhc_remember");
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
void
|
||||
slhc_free(struct slcompress *comp)
|
||||
{
|
||||
printk(KERN_DEBUG "Called IP function on non IP-system: slhc_free");
|
||||
}
|
||||
struct slcompress *
|
||||
slhc_init(int rslots, int tslots)
|
||||
{
|
||||
printk(KERN_DEBUG "Called IP function on non IP-system: slhc_init");
|
||||
return NULL;
|
||||
}
|
||||
|
||||
#endif /* CONFIG_INET */
|
||||
|
||||
/* VJ header compression */
|
||||
EXPORT_SYMBOL(slhc_init);
|
||||
EXPORT_SYMBOL(slhc_free);
|
||||
EXPORT_SYMBOL(slhc_remember);
|
||||
EXPORT_SYMBOL(slhc_compress);
|
||||
EXPORT_SYMBOL(slhc_uncompress);
|
||||
EXPORT_SYMBOL(slhc_toss);
|
||||
|
||||
MODULE_LICENSE("Dual BSD/GPL");
|
||||
Loading…
Reference in New Issue