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Diffstat (limited to 'src/slcompress.c')
| -rw-r--r-- | src/slcompress.c | 605 |
1 files changed, 605 insertions, 0 deletions
diff --git a/src/slcompress.c b/src/slcompress.c new file mode 100644 index 0000000..ef421c0 --- /dev/null +++ b/src/slcompress.c @@ -0,0 +1,605 @@ +/*- + * Copyright (c) 1989, 1993, 1994 + * 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. 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 8.2 (Berkeley) 4/16/94 + */ + +/* + * 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. + * + * $FreeBSD: src/usr.sbin/ppp/slcompress.c,v 1.39.26.1 2010/12/21 17:10:29 kensmith Exp $ + */ + +#include <sys/param.h> +#include <netinet/in_systm.h> +#include <netinet/in.h> +#include <netinet/tcp.h> +#include <netinet/ip.h> +#include <sys/socket.h> +#include <sys/un.h> + +#include <stdarg.h> +#include <stdio.h> +#include <string.h> +#include <termios.h> + +#include "layer.h" +#include "defs.h" +#include "command.h" +#include "mbuf.h" +#include "log.h" +#include "slcompress.h" +#include "descriptor.h" +#include "prompt.h" +#include "timer.h" +#include "fsm.h" +#include "throughput.h" +#include "iplist.h" +#include "lqr.h" +#include "hdlc.h" +#include "ncpaddr.h" +#include "ipcp.h" +#include "filter.h" +#include "lcp.h" +#include "ccp.h" +#include "link.h" +#include "mp.h" +#ifndef NORADIUS +#include "radius.h" +#endif +#include "ipv6cp.h" +#include "ncp.h" +#include "bundle.h" + +void +sl_compress_init(struct slcompress *comp, int max_state) +{ + register u_int i; + register struct cstate *tstate = comp->tstate; + + memset(comp, '\0', 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 32-bit, 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_int32_t)*cp++); \ + } \ +} + +#define DECODES(f) { \ + if (*cp == 0) {\ + (f) = htons(ntohs(f) + ((cp[1] << 8) | cp[2])); \ + cp += 3; \ + } else { \ + (f) = htons(ntohs(f) + (u_int32_t)*cp++); \ + } \ +} + +#define DECODEU(f) { \ + if (*cp == 0) {\ + (f) = htons((cp[1] << 8) | cp[2]); \ + cp += 3; \ + } else { \ + (f) = htons((u_int32_t)*cp++); \ + } \ +} + + +u_char +sl_compress_tcp(struct mbuf * m, + struct ip * ip, + struct slcompress *comp, + struct slstat *slstat, + 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) { + log_Printf(LogDEBUG, "??? 1 ip_off = %x, m_len = %lu\n", + ip->ip_off, (unsigned long)m->m_len); + log_DumpBp(LogDEBUG, "", m); + return (TYPE_IP); + } + th = (struct tcphdr *) & ((int *) ip)[hlen]; + if ((th->th_flags & (TH_SYN | TH_FIN | TH_RST | TH_ACK)) != TH_ACK) { + log_Printf(LogDEBUG, "??? 2 th_flags = %x\n", th->th_flags); + log_DumpBp(LogDEBUG, "", m); + 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. + */ + slstat->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; + slstat->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. + */ + slstat->sls_misses++; + comp->last_cs = lcs; +#define THOFFSET(th) (th->th_off) + hlen += th->th_off; + hlen <<= 2; + if (hlen > m->m_len) + return (TYPE_IP); + 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 (hlen > m->m_len) + return (TYPE_IP); + + 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] || + THOFFSET(th) != THOFFSET(oth) || + (deltaS > 5 && + memcmp(ip + 1, &cs->cs_ip + 1, (deltaS - 5) << 2)) || + (THOFFSET(th) > 5 && + memcmp(th + 1, oth + 1, (THOFFSET(th) - 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; + } + deltaS = (u_short) (ntohs(th->th_win) - ntohs(oth->th_win)); + if (deltaS) { + ENCODE(deltaS); + changes |= NEW_W; + } + deltaA = ntohl(th->th_ack) - ntohl(oth->th_ack); + if (deltaA) { + if (deltaA > 0xffff) { + goto uncompressed; + } + ENCODE(deltaA); + changes |= NEW_A; + } + deltaS = ntohl(th->th_seq) - ntohl(oth->th_seq); + if (deltaS) { + 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; + + /* FALLTHROUGH */ + + 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); + memcpy(&cs->cs_ip, 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; + + /* + * Since fastq traffic can jump ahead of the background traffic, we don't + * know what order packets will go on the line. In this case, we always + * send a "new" connection id so the receiver state stays synchronized. + */ + if (comp->last_xmit == cs->cs_id && compress_cid) { + hlen -= deltaS + 3; + cp += hlen; + *cp++ = changes; + } else { + comp->last_xmit = cs->cs_id; + hlen -= deltaS + 4; + cp += hlen; + *cp++ = changes | NEW_C; + *cp++ = cs->cs_id; + } + m->m_len -= hlen; + m->m_offset += hlen; + *cp++ = deltaA >> 8; + *cp++ = deltaA; + memcpy(cp, new_seq, deltaS); + slstat->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: + memcpy(&cs->cs_ip, ip, hlen); + ip->ip_p = cs->cs_id; + comp->last_xmit = cs->cs_id; + return (TYPE_UNCOMPRESSED_TCP); +} + + +int +sl_uncompress_tcp(u_char ** bufp, int len, u_int type, struct slcompress *comp, + struct slstat *slstat, int max_state) +{ + register u_char *cp; + register u_int hlen, changes; + register struct tcphdr *th; + register struct cstate *cs; + register struct ip *ip; + u_short *bp; + + switch (type) { + + case TYPE_UNCOMPRESSED_TCP: + ip = (struct ip *) * bufp; + if (ip->ip_p > max_state) + 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 ((int)(hlen + sizeof(struct tcphdr)) > len) + goto bad; + th = (struct tcphdr *) & ((char *) ip)[hlen]; + hlen += THOFFSET(th) << 2; + if (hlen > MAX_HDR) + goto bad; + memcpy(&cs->cs_ip, ip, hlen); + cs->cs_hlen = hlen; + slstat->sls_uncompressedin++; + return (len); + + default: + goto bad; + + case TYPE_COMPRESSED_TCP: + break; + } + + /* We've got a compressed packet. */ + slstat->sls_compressedin++; + cp = *bufp; + changes = *cp++; + log_Printf(LogDEBUG, "compressed: changes = %02x\n", changes); + + 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_state || comp->last_recv == 255) + 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) { + slstat->sls_tossed++; + return (0); + } + } + 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) { + log_Printf(LogDEBUG, "NEW_S: %02x, %02x, %02x\n", + *cp, cp[1], cp[2]); + 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); + + log_Printf(LogDEBUG, "Uncompress: id = %04x, seq = %08lx\n", + cs->cs_ip.ip_id, (u_long)ntohl(th->th_seq)); + + /* + * At this point, cp points to the first byte of data in the packet. + * 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). Adjust the length to account + * for the new header & fill in the IP total length. + */ + len -= (cp - *bufp); + if (len < 0) + /* + * we must have dropped some characters (crc should detect this but the + * old slip framing won't) + */ + goto bad; + + *bufp = cp - cs->cs_hlen; + len += cs->cs_hlen; + cs->cs_ip.ip_len = htons(len); + + /* recompute the ip header checksum */ + cs->cs_ip.ip_sum = 0; + bp = (u_short *)&cs->cs_ip; + 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; + + /* And copy the result into our buffer */ + memcpy(*bufp, &cs->cs_ip, cs->cs_hlen); + + return (len); +bad: + comp->flags |= SLF_TOSS; + slstat->sls_errorin++; + return (0); +} + +int +sl_Show(struct cmdargs const *arg) +{ + prompt_Printf(arg->prompt, "VJ compression statistics:\n"); + prompt_Printf(arg->prompt, " Out: %d (compress) / %d (total)", + arg->bundle->ncp.ipcp.vj.slstat.sls_compressed, + arg->bundle->ncp.ipcp.vj.slstat.sls_packets); + prompt_Printf(arg->prompt, " %d (miss) / %d (search)\n", + arg->bundle->ncp.ipcp.vj.slstat.sls_misses, + arg->bundle->ncp.ipcp.vj.slstat.sls_searches); + prompt_Printf(arg->prompt, " In: %d (compress), %d (uncompress)", + arg->bundle->ncp.ipcp.vj.slstat.sls_compressedin, + arg->bundle->ncp.ipcp.vj.slstat.sls_uncompressedin); + prompt_Printf(arg->prompt, " %d (error), %d (tossed)\n", + arg->bundle->ncp.ipcp.vj.slstat.sls_errorin, + arg->bundle->ncp.ipcp.vj.slstat.sls_tossed); + return 0; +} |