slip: Move the SLIP drivers

Move the Serial Line Internet Protocol (SLIP) drivers into
drivers/net/slip/ and make the necessary Kconfig and Makefile
changes.

Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Alan Cox <alan@linux.intel.com>

1 files changed, 742 insertions, 0 deletions

diff --git a/drivers/net/slip/slhc.c b/drivers/net/slip/slhc.c
new file mode 100644
index 000000000000..0a0a6643cf3a
--- /dev/null
+++ b/drivers/net/slip/slhc.c
@@ -0,0 +1,742 @@
+/*
+ * Routines to compress and uncompress tcp packets (for transmission
+ * over low speed serial lines).
+ *
+ * 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 (from 1.19)
+ *      PPP.05  02-15-90 [ks]
+ *      PPP.08  05-02-90 [ks]   use PPP protocol field to signal compression
+ *      PPP.15  09-90    [ks]   improve mbuf handling
+ *      PPP.16  11-02    [karn] substantially rewritten to use NOS facilities
+ *
+ *      - Feb 1991      Bill_Simpson@um.cc.umich.edu
+ *                      variable number of conversation slots
+ *                      allow zero or one slots
+ *                      separate routines
+ *                      status display
+ *      - Jul 1994      Dmitry Gorodchanin
+ *                      Fixes for memory leaks.
+ *      - Oct 1994      Dmitry Gorodchanin
+ *                      Modularization.
+ *      - Jan 1995      Bjorn Ekwall
+ *                      Use ip_fast_csum from ip.h
+ *      - July 1995     Christos A. Polyzols
+ *                      Spotted bug in tcp option checking
+ *
+ *
+ *      This module is a difficult issue. It's clearly inet code but it's also clearly
+ *      driver code belonging close to PPP and SLIP
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <net/slhc_vj.h>
+
+#ifdef CONFIG_INET
+/* Entire module is for IP only */
+#include <linux/mm.h>
+#include <linux/socket.h>
+#include <linux/sockios.h>
+#include <linux/termios.h>
+#include <linux/in.h>
+#include <linux/fcntl.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <net/ip.h>
+#include <net/protocol.h>
+#include <net/icmp.h>
+#include <net/tcp.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <linux/timer.h>
+#include <asm/system.h>
+#include <asm/uaccess.h>
+#include <net/checksum.h>
+#include <asm/unaligned.h>
+
+static unsigned char *encode(unsigned char *cp, unsigned short n);
+static long decode(unsigned char **cpp);
+static unsigned char * put16(unsigned char *cp, unsigned short x);
+static unsigned short pull16(unsigned char **cpp);
+
+/* Initialize compression data structure
+ *      slots must be in range 0 to 255 (zero meaning no compression)
+ */
+struct slcompress *
+slhc_init(int rslots, int tslots)
+{
+        register short i;
+        register struct cstate *ts;
+        struct slcompress *comp;
+
+        comp = kzalloc(sizeof(struct slcompress), GFP_KERNEL);
+        if (! comp)
+                goto out_fail;
+
+        if ( rslots > 0  &&  rslots < 256 ) {
+                size_t rsize = rslots * sizeof(struct cstate);
+                comp->rstate = kzalloc(rsize, GFP_KERNEL);
+                if (! comp->rstate)
+                        goto out_free;
+                comp->rslot_limit = rslots - 1;
+        }
+
+        if ( tslots > 0  &&  tslots < 256 ) {
+                size_t tsize = tslots * sizeof(struct cstate);
+                comp->tstate = kzalloc(tsize, GFP_KERNEL);
+                if (! comp->tstate)
+                        goto out_free2;
+                comp->tslot_limit = tslots - 1;
+        }
+
+        comp->xmit_oldest = 0;
+        comp->xmit_current = 255;
+        comp->recv_current = 255;
+        /*
+         * don't accept any packets with implicit index until we get
+         * one with an explicit index.  Otherwise the uncompress code
+         * will try to use connection 255, which is almost certainly
+         * out of range
+         */
+        comp->flags |= SLF_TOSS;
+
+        if ( tslots > 0 ) {
+                ts = comp->tstate;
+                for(i = comp->tslot_limit; i > 0; --i){
+                        ts[i].cs_this = i;
+                        ts[i].next = &(ts[i - 1]);
+                }
+                ts[0].next = &(ts[comp->tslot_limit]);
+                ts[0].cs_this = 0;
+        }
+        return comp;
+
+out_free2:
+        kfree(comp->rstate);
+out_free:
+        kfree(comp);
+out_fail:
+        return NULL;
+}
+
+
+/* Free a compression data structure */
+void
+slhc_free(struct slcompress *comp)
+{
+        if ( comp == NULLSLCOMPR )
+                return;
+
+        if ( comp->tstate != NULLSLSTATE )
+                kfree( comp->tstate );
+
+        if ( comp->rstate != NULLSLSTATE )
+                kfree( comp->rstate );
+
+        kfree( comp );
+}
+
+
+/* Put a short in host order into a char array in network order */
+static inline unsigned char *
+put16(unsigned char *cp, unsigned short x)
+{
+        *cp++ = x >> 8;
+        *cp++ = x;
+
+        return cp;
+}
+
+
+/* Encode a number */
+static unsigned char *
+encode(unsigned char *cp, unsigned short n)
+{
+        if(n >= 256 || n == 0){
+                *cp++ = 0;
+                cp = put16(cp,n);
+        } else {
+                *cp++ = n;
+        }
+        return cp;
+}
+
+/* Pull a 16-bit integer in host order from buffer in network byte order */
+static unsigned short
+pull16(unsigned char **cpp)
+{
+        short rval;
+
+        rval = *(*cpp)++;
+        rval <<= 8;
+        rval |= *(*cpp)++;
+        return rval;
+}
+
+/* Decode a number */
+static long
+decode(unsigned char **cpp)
+{
+        register int x;
+
+        x = *(*cpp)++;
+        if(x == 0){
+                return pull16(cpp) & 0xffff;    /* pull16 returns -1 on error */
+        } else {
+                return x & 0xff;                /* -1 if PULLCHAR returned error */
+        }
+}
+
+/*
+ * icp and isize are the original packet.
+ * ocp is a place to put a copy if necessary.
+ * cpp is initially a pointer to icp.  If the copy is used,
+ *    change it to ocp.
+ */
+
+int
+slhc_compress(struct slcompress *comp, unsigned char *icp, int isize,
+        unsigned char *ocp, unsigned char **cpp, int compress_cid)
+{
+        register struct cstate *ocs = &(comp->tstate[comp->xmit_oldest]);
+        register struct cstate *lcs = ocs;
+        register struct cstate *cs = lcs->next;
+        register unsigned long deltaS, deltaA;
+        register short changes = 0;
+        int hlen;
+        unsigned char new_seq[16];
+        register unsigned char *cp = new_seq;
+        struct iphdr *ip;
+        struct tcphdr *th, *oth;
+        __sum16 csum;
+
+
+        /*
+         *      Don't play with runt packets.
+         */
+
+        if(isize<sizeof(struct iphdr))
+                return isize;
+
+        ip = (struct iphdr *) icp;
+
+        /* Bail if this packet isn't TCP, or is an IP fragment */
+        if (ip->protocol != IPPROTO_TCP || (ntohs(ip->frag_off) & 0x3fff)) {
+                /* Send as regular IP */
+                if(ip->protocol != IPPROTO_TCP)
+                        comp->sls_o_nontcp++;
+                else
+                        comp->sls_o_tcp++;
+                return isize;
+        }
+        /* Extract TCP header */
+
+        th = (struct tcphdr *)(((unsigned char *)ip) + ip->ihl*4);
+        hlen = ip->ihl*4 + th->doff*4;
+
+        /*  Bail if the TCP packet isn't `compressible' (i.e., ACK isn't set or
+         *  some other control bit is set). Also uncompressible if
+         *  it's a runt.
+         */
+        if(hlen > isize || th->syn || th->fin || th->rst ||
+            ! (th->ack)){
+                /* TCP connection stuff; send as regular IP */
+                comp->sls_o_tcp++;
+                return isize;
+        }
+        /*
+         * Packet is compressible -- we're going to send either a
+         * COMPRESSED_TCP or UNCOMPRESSED_TCP packet.  Either way,
+         * we need to locate (or create) the connection state.
+         *
+         * States are kept in a circularly linked list with
+         * xmit_oldest pointing to the end of the list.  The
+         * 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;
+                break;
+        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");