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authorNeels Hofmeyr <nhofmeyr@sysmocom.de>2017-07-13 02:55:56 +0200
committerNeels Hofmeyr <nhofmeyr@sysmocom.de>2017-07-13 02:55:56 +0200
commit27badcf1b6c9a571eb4eaa7e4724e1b69feee286 (patch)
tree17b97034dd2dcc01f2e51c6769cdeeeffd9b8fc2
parent246388085b81b2979ba8753787acda4127155f59 (diff)
undelete slhc.h
-rw-r--r--include/openbsc/slhc.h187
1 files changed, 187 insertions, 0 deletions
diff --git a/include/openbsc/slhc.h b/include/openbsc/slhc.h
new file mode 100644
index 00000000..cd5a47cf
--- /dev/null
+++ b/include/openbsc/slhc.h
@@ -0,0 +1,187 @@
+#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(const void *ctx, 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);
+
+void slhc_i_status(struct slcompress *comp);
+void slhc_o_status(struct slcompress *comp);
+
+#endif /* _SLHC_H */