diff options
Diffstat (limited to 'drivers/net/slip/slhc.c')
| -rw-r--r-- | drivers/net/slip/slhc.c | 755 |
1 files changed, 755 insertions, 0 deletions
diff --git a/drivers/net/slip/slhc.c b/drivers/net/slip/slhc.c new file mode 100644 index 000000000..ba93bab94 --- /dev/null +++ b/drivers/net/slip/slhc.c @@ -0,0 +1,755 @@ +/* + * 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 <linux/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); + +/* Allocate compression data structure + * slots must be in range 0 to 255 (zero meaning no compression) + * Returns pointer to structure or ERR_PTR() on error. + */ +struct slcompress * +slhc_init(int rslots, int tslots) +{ + short i; + struct cstate *ts; + struct slcompress *comp; + + if (rslots < 0 || rslots > 255 || tslots < 0 || tslots > 255) + return ERR_PTR(-EINVAL); + + comp = kzalloc(sizeof(struct slcompress), GFP_KERNEL); + if (! comp) + goto out_fail; + + if (rslots > 0) { + 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) { + 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 ERR_PTR(-ENOMEM); +} + + +/* Free a compression data structure */ +void +slhc_free(struct slcompress *comp) +{ + if ( IS_ERR_OR_NULL(comp) ) + 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) +{ + 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) +{ + struct cstate *ocs = &(comp->tstate[comp->xmit_oldest]); + struct cstate *lcs = ocs; + struct cstate *cs = lcs->next; + unsigned long deltaS, deltaA; + short changes = 0; + int nlen, hlen; + unsigned char new_seq[16]; + 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; + if (ip->version != 4 || ip->ihl < 5) + return isize; + + /* 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; + } + nlen = ip->ihl * 4; + if (isize < nlen + sizeof(*th)) + return isize; + + th = (struct tcphdr *)(icp + nlen); + if (th->doff < sizeof(struct tcphdr) / 4) + return isize; + hlen = nlen + 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; + 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) +{ + int changes; + long x; + struct tcphdr *thp; + struct iphdr *ip; + 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; + + /* Check if the cstate is initialized */ + if (!comp->rstate[x].initialized) + 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 */ + { + 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) +{ + 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; + cs->initialized = true; + /* 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"); |