linux 2.0.x kernels have broken header files. It is silly to be so

tightly coupled to kernel headers (since the 2.2 ones work with 2.0
as well), so I'm checking in include/net.

1 files changed, 148 insertions, 0 deletions

diff --git a/include/net/slcompress.h b/include/net/slcompress.h
new file mode 100644
index 000000000..658edb7f8
--- /dev/null
+++ b/include/net/slcompress.h
@@ -0,0 +1,148 @@
+/*
+ * Definitions for tcp compression routines.
+ *
+ * $Id: slcompress.h,v 1.1 2001/01/16 10:03:48 andersen 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 MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ *	Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
+ *	- Initial distribution.
+ */
+
+#ifndef _SLCOMPRESS_H_
+#define _SLCOMPRESS_H_
+
+#define MAX_STATES 16		/* must be > 2 and < 256 */
+#define MAX_HDR MLEN		/* XXX 4bsd-ism: should really be 128 */
+
+/*
+ * 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,
+ * acknowlegement, 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".
+ */
+
+/* packet types */
+#define TYPE_IP 0x40
+#define TYPE_UNCOMPRESSED_TCP 0x70
+#define TYPE_COMPRESSED_TCP 0x80
+#define 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
+
+
+/*
+ * "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 {
+	struct cstate *cs_next;	/* next most recently used cstate (xmit only) */
+	u_short cs_hlen;	/* size of hdr (receive only) */
+	u_char cs_id;		/* connection # associated with this state */
+	u_char cs_filler;
+	union {
+		char csu_hdr[MAX_HDR];
+		struct ip csu_ip;	/* ip/tcp hdr from most recent packet */
+	} slcs_u;
+};
+#define cs_ip slcs_u.csu_ip
+#define cs_hdr slcs_u.csu_hdr
+
+/*
+ * all the state data for one serial line (we need one of these
+ * per line).
+ */
+struct slcompress {
+	struct cstate *last_cs;	/* most recently used tstate */
+	u_char last_recv;	/* last rcvd conn. id */
+	u_char last_xmit;	/* last sent conn. id */
+	u_short flags;
+#ifndef SL_NO_STATS
+	int sls_packets;	/* outbound packets */
+	int sls_compressed;	/* outbound compressed packets */
+	int sls_searches;	/* searches for connection state */
+	int sls_misses;		/* times couldn't find conn. state */
+	int sls_uncompressedin;	/* inbound uncompressed packets */
+	int sls_compressedin;	/* inbound compressed packets */
+	int sls_errorin;	/* inbound unknown type packets */
+	int sls_tossed;		/* inbound packets tossed because of error */
+#endif
+	struct cstate tstate[MAX_STATES];	/* xmit connection states */
+	struct cstate rstate[MAX_STATES];	/* receive connection states */
+};
+/* flag values */
+#define SLF_TOSS 1		/* tossing rcvd frames because of input err */
+
+void	sl_compress_init __P((struct slcompress *));
+void	sl_compress_setup __P((struct slcompress *, int));
+u_int	sl_compress_tcp __P((struct mbuf *,
+	    struct ip *, struct slcompress *, int));
+int	sl_uncompress_tcp __P((u_char **, int, u_int, struct slcompress *));
+int	sl_uncompress_tcp_core __P((u_char *, int, int, u_int,
+	    struct slcompress *, u_char **, u_int *));
+
+#endif /* _SLCOMPRESS_H_ */