diff options
Diffstat (limited to 'c/src/libnetworking/net/pppcompress.c')
| -rw-r--r-- | c/src/libnetworking/net/pppcompress.c | 593 |
1 files changed, 593 insertions, 0 deletions
diff --git a/c/src/libnetworking/net/pppcompress.c b/c/src/libnetworking/net/pppcompress.c new file mode 100644 index 0000000000..aebe441fd3 --- /dev/null +++ b/c/src/libnetworking/net/pppcompress.c @@ -0,0 +1,593 @@ +/*- + * Copyright (c) 1989 The Regents of the University of California. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * @(#)slcompress.c 7.7 (Berkeley) 5/7/91 + */ + +/* + * Routines to compress and uncompess tcp packets (for transmission + * over low speed serial lines. + * + * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989: + * - Initial distribution. + * + * $Id$ + */ + +#include <sys/types.h> +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/mbuf.h> +#include <sys/socket.h> +#include <sys/socketvar.h> + +#include <netinet/in.h> +#include <netinet/in_systm.h> +#include <netinet/ip.h> +#include <netinet/tcp.h> + +#include <net/pppcompress.h> + +#ifndef SL_NO_STATS +#define INCR(counter) ++comp->counter; +#else +#define INCR(counter) +#endif + +#define BCMP(p1, p2, n) bcmp((char *)(p1), (char *)(p2), (int)(n)) +#define BCOPY(p1, p2, n) bcopy((char *)(p1), (char *)(p2), (int)(n)) +#ifndef KERNEL +#define ovbcopy bcopy +#endif + +void +vj_compress_init(comp, max_state) + struct vjcompress *comp; + int max_state; +{ + register u_int i; + register struct cstate *tstate = comp->tstate; + + if ((unsigned) max_state > MAX_STATES - 1) + max_state = MAX_STATES - 1; + bzero((char *)comp, sizeof(*comp)); + for (i = max_state; i > 0; --i) { + tstate[i].cs_id = i; + tstate[i].cs_next = &tstate[i - 1]; + } + tstate[0].cs_next = &tstate[max_state]; + tstate[0].cs_id = 0; + comp->last_cs = &tstate[0]; + comp->last_recv = 255; + comp->last_xmit = 255; + comp->flags = SLF_TOSS; +} + + +/* ENCODE encodes a number that is known to be non-zero. ENCODEZ + * checks for zero (since zero has to be encoded in the long, 3 byte + * form). + */ +#define ENCODE(n) { \ + if ((u_short)(n) >= 256) { \ + *cp++ = 0; \ + cp[1] = (n); \ + cp[0] = (n) >> 8; \ + cp += 2; \ + } else { \ + *cp++ = (n); \ + } \ +} +#define ENCODEZ(n) { \ + if ((u_short)(n) >= 256 || (u_short)(n) == 0) { \ + *cp++ = 0; \ + cp[1] = (n); \ + cp[0] = (n) >> 8; \ + cp += 2; \ + } else { \ + *cp++ = (n); \ + } \ +} + +#define DECODEL(f) { \ + if (*cp == 0) {\ + (f) = htonl(ntohl(f) + ((cp[1] << 8) | cp[2])); \ + cp += 3; \ + } else { \ + (f) = htonl(ntohl(f) + (u_long)*cp++); \ + } \ +} + +#define DECODES(f) { \ + if (*cp == 0) {\ + (f) = htons(ntohs(f) + ((cp[1] << 8) | cp[2])); \ + cp += 3; \ + } else { \ + (f) = htons(ntohs(f) + (u_long)*cp++); \ + } \ +} + +#define DECODEU(f) { \ + if (*cp == 0) {\ + (f) = htons((cp[1] << 8) | cp[2]); \ + cp += 3; \ + } else { \ + (f) = htons((u_long)*cp++); \ + } \ +} + +u_int +vj_compress_tcp(m, ip, comp, compress_cid) + struct mbuf *m; + register struct ip *ip; + struct vjcompress *comp; + int compress_cid; +{ + register struct cstate *cs = comp->last_cs->cs_next; + register u_int hlen = ip->ip_hl; + register struct tcphdr *oth; + register struct tcphdr *th; + register u_int deltaS, deltaA; + register u_int changes = 0; + u_char new_seq[16]; + register u_char *cp = new_seq; + + /* + * Bail if this is an IP fragment or if the TCP packet isn't + * `compressible' (i.e., ACK isn't set or some other control bit is + * set). (We assume that the caller has already made sure the + * packet is IP proto TCP). + */ + if ((ip->ip_off & htons(0x3fff)) || m->m_len < 40) + return (TYPE_IP); + + th = (struct tcphdr *)&((int *)ip)[hlen]; + if ((th->th_flags & (TH_SYN|TH_FIN|TH_RST|TH_ACK)) != TH_ACK) + return (TYPE_IP); + /* + * 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. Special case the + * most recently used connection since it's most likely to be used + * again & we don't have to do any reordering if it's used. + */ + INCR(sls_packets) + if (ip->ip_src.s_addr != cs->cs_ip.ip_src.s_addr || + ip->ip_dst.s_addr != cs->cs_ip.ip_dst.s_addr || + *(int *)th != ((int *)&cs->cs_ip)[cs->cs_ip.ip_hl]) { + /* + * Wasn't the first -- search for it. + * + * States are kept in a circularly linked list with + * last_cs 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. + */ + register struct cstate *lcs; + register struct cstate *lastcs = comp->last_cs; + + do { + lcs = cs; cs = cs->cs_next; + INCR(sls_searches) + if (ip->ip_src.s_addr == cs->cs_ip.ip_src.s_addr + && ip->ip_dst.s_addr == cs->cs_ip.ip_dst.s_addr + && *(int *)th == ((int *)&cs->cs_ip)[cs->cs_ip.ip_hl]) + goto found; + } while (cs != lastcs); + + /* + * 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 + * last_cs to update the lru linkage. + */ + INCR(sls_misses) + comp->last_cs = lcs; + hlen += th->th_off; + hlen <<= 2; + goto uncompressed; + + found: + /* + * Found it -- move to the front on the connection list. + */ + if (cs == lastcs) + comp->last_cs = lcs; + else { + lcs->cs_next = cs->cs_next; + cs->cs_next = lastcs->cs_next; + lastcs->cs_next = cs; + } + } + + /* + * Make sure that only what we expect to change changed. The first + * line of the `if' checks the IP protocol version, header length & + * type of service. The 2nd line checks the "Don't fragment" bit. + * The 3rd line checks the time-to-live and protocol (the protocol + * check is unnecessary but costless). The 4th line checks the TCP + * header length. The 5th line checks IP options, if any. The 6th + * line checks TCP options, if any. If any of these things are + * different between the previous & current datagram, we send the + * current datagram `uncompressed'. + */ + oth = (struct tcphdr *)&((int *)&cs->cs_ip)[hlen]; + deltaS = hlen; + hlen += th->th_off; + hlen <<= 2; + + if (((u_short *)ip)[0] != ((u_short *)&cs->cs_ip)[0] || + ((u_short *)ip)[3] != ((u_short *)&cs->cs_ip)[3] || + ((u_short *)ip)[4] != ((u_short *)&cs->cs_ip)[4] || + th->th_off != oth->th_off || + (deltaS > 5 && + BCMP(ip + 1, &cs->cs_ip + 1, (deltaS - 5) << 2)) || + (th->th_off > 5 && + BCMP(th + 1, oth + 1, (th->th_off - 5) << 2))) + 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->th_flags & TH_URG) { + deltaS = ntohs(th->th_urp); + ENCODEZ(deltaS); + changes |= NEW_U; + } else if (th->th_urp != oth->th_urp) + /* 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 = (u_short)(ntohs(th->th_win) - ntohs(oth->th_win)))) { + ENCODE(deltaS); + changes |= NEW_W; + } + + if ((deltaA = ntohl(th->th_ack) - ntohl(oth->th_ack))) { + if (deltaA > 0xffff) + goto uncompressed; + ENCODE(deltaA); + changes |= NEW_A; + } + + if ((deltaS = ntohl(th->th_seq) - ntohl(oth->th_seq))) { + if (deltaS > 0xffff) + goto uncompressed; + ENCODE(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->ip_len != cs->cs_ip.ip_len && + ntohs(cs->cs_ip.ip_len) == hlen) + break; + + /* (fall through) */ + + 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.ip_len) - hlen) { + /* special case for echoed terminal traffic */ + changes = SPECIAL_I; + cp = new_seq; + } + break; + + case NEW_S: + if (deltaS == ntohs(cs->cs_ip.ip_len) - hlen) { + /* special case for data xfer */ + changes = SPECIAL_D; + cp = new_seq; + } + break; + } + + deltaS = ntohs(ip->ip_id) - ntohs(cs->cs_ip.ip_id); + if (deltaS != 1) { + ENCODEZ(deltaS); + changes |= NEW_I; + } + if (th->th_flags & TH_PUSH) + changes |= TCP_PUSH_BIT; + /* + * Grab the cksum before we overwrite it below. Then update our + * state with this packet's header. + */ + deltaA = ntohs(th->th_sum); + BCOPY(ip, &cs->cs_ip, hlen); + + /* + * 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. hlen is how + * many bytes of the original packet to toss so subtract the two to + * get the new packet size. + */ + deltaS = cp - new_seq; + cp = (u_char *)ip; + if (compress_cid == 0 || comp->last_xmit != cs->cs_id) { + comp->last_xmit = cs->cs_id; + hlen -= deltaS + 4; + cp += hlen; + *cp++ = changes | NEW_C; + *cp++ = cs->cs_id; + } else { + hlen -= deltaS + 3; + cp += hlen; + *cp++ = changes; + } + m->m_len -= hlen; + m->m_data += hlen; + *cp++ = deltaA >> 8; + *cp++ = deltaA; + BCOPY(new_seq, cp, deltaS); + INCR(sls_compressed) + return (TYPE_COMPRESSED_TCP); + + /* + * Update connection state cs & send uncompressed packet ('uncompressed' + * means a regular ip/tcp packet but with the 'conversation id' we hope + * to use on future compressed packets in the protocol field). + */ +uncompressed: + BCOPY(ip, &cs->cs_ip, hlen); + ip->ip_p = cs->cs_id; + comp->last_xmit = cs->cs_id; + return (TYPE_UNCOMPRESSED_TCP); +} + + +int +vj_uncompress_tcp(bufp, len, type, comp) + u_char **bufp; + int len; + u_int type; + struct vjcompress *comp; +{ + u_char *hdr, *cp; + int hlen, vjlen; + + cp = bufp? *bufp: NULL; + vjlen = vj_uncompress_tcp_core(cp, len, len, type, comp, &hdr, &hlen); + if (vjlen < 0) + return (0); /* error */ + if (vjlen == 0) + return (len); /* was uncompressed already */ + + cp += vjlen; + len -= vjlen; + + /* + * At this point, cp points to the first byte of data in the + * packet. If we're not aligned on a 4-byte boundary, copy the + * data down so the ip & tcp headers will be aligned. Then back up + * cp by the tcp/ip header length to make room for the reconstructed + * header (we assume the packet we were handed has enough space to + * prepend 128 bytes of header). + */ + if ((int)cp & 3) { + if (len > 0) + (void) ovbcopy(cp, (caddr_t)((int)cp &~ 3), len); + cp = (u_char *)((int)cp &~ 3); + } + cp -= hlen; + len += hlen; + BCOPY(hdr, cp, hlen); + + *bufp = cp; + return (len); +} + +/* + * Uncompress a packet of total length total_len. The first buflen + * bytes are at buf; this must include the entire (compressed or + * uncompressed) TCP/IP header. This procedure returns the length + * of the VJ header, with a pointer to the uncompressed IP header + * in *hdrp and its length in *hlenp. + */ +int +vj_uncompress_tcp_core(buf, buflen, total_len, type, comp, hdrp, hlenp) + u_char *buf; + int buflen, total_len; + u_int type; + struct vjcompress *comp; + u_char **hdrp; + u_int *hlenp; +{ + register u_char *cp; + register u_int hlen, changes; + register struct tcphdr *th; + register struct cstate *cs; + register struct ip *ip; + register u_short *bp; + register u_int vjlen; + + switch (type) { + + case TYPE_UNCOMPRESSED_TCP: + ip = (struct ip *) buf; + if (ip->ip_p >= MAX_STATES) + goto bad; + cs = &comp->rstate[comp->last_recv = ip->ip_p]; + comp->flags &=~ SLF_TOSS; + ip->ip_p = IPPROTO_TCP; + /* + * Calculate the size of the TCP/IP header and make sure that + * we don't overflow the space we have available for it. + */ + hlen = ip->ip_hl << 2; + if (hlen + sizeof(struct tcphdr) > buflen) + goto bad; + hlen += ((struct tcphdr *)&((char *)ip)[hlen])->th_off << 2; + if (hlen > MAX_HDR || hlen > buflen) + goto bad; + BCOPY(ip, &cs->cs_ip, hlen); + cs->cs_hlen = hlen; + INCR(sls_uncompressedin) + *hdrp = (u_char *) &cs->cs_ip; + *hlenp = hlen; + return (0); + + default: + goto bad; + + case TYPE_COMPRESSED_TCP: + break; + } + /* We've got a compressed packet. */ + INCR(sls_compressedin) + cp = buf; + 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. */ + if (*cp >= MAX_STATES) + goto bad; + + comp->flags &=~ SLF_TOSS; + comp->last_recv = *cp++; + } 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) { + INCR(sls_tossed) + return (-1); + } + } + cs = &comp->rstate[comp->last_recv]; + hlen = cs->cs_ip.ip_hl << 2; + th = (struct tcphdr *)&((u_char *)&cs->cs_ip)[hlen]; + th->th_sum = htons((*cp << 8) | cp[1]); + cp += 2; + if (changes & TCP_PUSH_BIT) + th->th_flags |= TH_PUSH; + else + th->th_flags &=~ TH_PUSH; + + switch (changes & SPECIALS_MASK) { + case SPECIAL_I: + { + register u_int i = ntohs(cs->cs_ip.ip_len) - cs->cs_hlen; + th->th_ack = htonl(ntohl(th->th_ack) + i); + th->th_seq = htonl(ntohl(th->th_seq) + i); + } + break; + + case SPECIAL_D: + th->th_seq = htonl(ntohl(th->th_seq) + ntohs(cs->cs_ip.ip_len) + - cs->cs_hlen); + break; + + default: + if (changes & NEW_U) { + th->th_flags |= TH_URG; + DECODEU(th->th_urp) + } else + th->th_flags &=~ TH_URG; + if (changes & NEW_W) + DECODES(th->th_win) + if (changes & NEW_A) + DECODEL(th->th_ack) + if (changes & NEW_S) + DECODEL(th->th_seq) + break; + } + if (changes & NEW_I) { + DECODES(cs->cs_ip.ip_id) + } else + cs->cs_ip.ip_id = htons(ntohs(cs->cs_ip.ip_id) + 1); + + /* + * At this point, cp points to the first byte of data in the + * packet. Fill in the IP total length and update the IP + * header checksum. + */ + vjlen = cp - buf; + buflen -= vjlen; + if (buflen < 0) + /* we must have dropped some characters (crc should detect + * this but the old slip framing won't) */ + goto bad; + + total_len += cs->cs_hlen - vjlen; + cs->cs_ip.ip_len = htons(total_len); + + /* recompute the ip header checksum */ + bp = (u_short *) &cs->cs_ip; + cs->cs_ip.ip_sum = 0; + for (changes = 0; hlen > 0; hlen -= 2) + changes += *bp++; + changes = (changes & 0xffff) + (changes >> 16); + changes = (changes & 0xffff) + (changes >> 16); + cs->cs_ip.ip_sum = ~ changes; + + *hdrp = (u_char *) &cs->cs_ip; + *hlenp = cs->cs_hlen; + return vjlen; + +bad: + comp->flags |= SLF_TOSS; + INCR(sls_errorin) + return (-1); +} |