ref: c00c60d327168c25e56077c8310cf2380833e9be
dir: /sys/src/cmd/ip/ppp/mppc.c/
#include <u.h>
#include <libc.h>
#include <libsec.h>
#include <ip.h>
#include <auth.h>
#include "ppp.h"
enum {
HistorySize= 8*1024,
Cminmatch = 3, /* sintest match possible */
Chshift = 4, /* nice compromise between space & time */
Cnhash = 1<<(Chshift*Cminmatch),
HMASK = Cnhash-1,
};
typedef struct Carena Carena;
struct Carena
{
uchar *pos; /* current place, also amount of history filled */
uchar buf[HistorySize];
};
typedef struct Cstate Cstate;
struct Cstate
{
QLock;
int count;
int reset; /* compressor has been reset */
int front; /* move to begining of history */
ulong sreg; /* output shift reg */
int bits; /* number of bits in sreg */
Block *b; /* output block */
/*
* state for hashing compressor
*/
Carena arenas[2];
Carena *hist;
Carena *ohist;
ulong hash[Cnhash];
int h;
ulong me;
ulong split;
int encrypt;
uchar startkey[16];
uchar key[16];
RC4state rc4key;
};
typedef struct Uncstate Uncstate;
struct Uncstate
{
int count; /* packet count - detects missing packets */
int resetid; /* id of reset requests */
uchar his[HistorySize];
int indx; /* current indx in history */
int size; /* current history size */
uchar startkey[16];
uchar key[16];
RC4state rc4key;
};
/* packet flags */
enum {
Preset= (1<<15), /* reset history */
Pfront= (1<<14), /* move packet to front of history */
Pcompress= (1<<13), /* packet is compressed */
Pencrypt= (1<<12), /* packet is encrypted */
};
enum {
Lit7, /* seven bit literal */
Lit8, /* eight bit literal */
Off6, /* six bit offset */
Off8, /* eight bit offset */
Off13, /* thirteen bit offset */
};
/* decode first four bits */
int decode[16] = {
Lit7,
Lit7,
Lit7,
Lit7,
Lit7,
Lit7,
Lit7,
Lit7,
Lit8,
Lit8,
Lit8,
Lit8,
Off13,
Off13,
Off8,
Off6,
};
static void *compinit(PPP*);
static Block* comp(PPP*, ushort, Block*, int*);
static void comp2(Cstate*, uchar*, int);
static Block *compresetreq(void*, Block*);
static void compfini(void*);
static void complit(Cstate*, int);
static void compcopy(Cstate*, int, int);
static void compout(Cstate*, ulong, int);
static void compfront(Cstate*);
static void hashcheck(Cstate*);
static void compreset(Cstate*);
static int hashit(uchar*);
static void *uncinit(PPP*);
static Block* uncomp(PPP*, Block*, int *protop, Block**);
static Block *uncomp2(Uncstate *s, Block*, ushort);
static void uncfini(void*);
static void uncresetack(void*, Block*);
static int ipcheck(uchar*, int);
static void hischeck(Uncstate*);
static void setkey(uchar *key, uchar *startkey);
Comptype cmppc = {
compinit,
comp,
compresetreq,
compfini
};
Uncomptype uncmppc = {
uncinit,
uncomp,
uncresetack,
uncfini
};
static void *
compinit(PPP *ppp)
{
Cstate *cs;
cs = mallocz(sizeof(Cstate), 1);
cs->hist = &cs->arenas[0];
cs->ohist = &cs->arenas[1];
compreset(cs);
/*
* make reset clear the hash table
*/
cs->me = ~0;
compreset(cs);
cs->reset = 0;
if(ppp->sendencrypted) {
cs->encrypt = 1;
memmove(cs->startkey, ppp->key, 16);
memmove(cs->key, ppp->key, 16);
setkey(cs->key, cs->startkey);
setupRC4state(&cs->rc4key, cs->key, 16);
}
return cs;
}
static void
compfini(void *as)
{
Cstate *cs;
cs = as;
free(cs);
}
static Block*
comp(PPP *ppp, ushort proto, Block *b, int *protop)
{
Cstate *s;
int n, n2;
ushort count;
s = ppp->cstate;
*protop = 0;
qlock(s);
/* put protocol into b */
b->rptr -= 2;
if(b->rptr < b->base)
sysfatal("mppc: not enough header in block");
b->rptr[0] = proto>>8;
b->rptr[1] = proto;
n = BLEN(b);
s->bits = 0;
s->b = allocb(n*9/8+20);
s->b->wptr += 2; /* leave room for mppc header */
comp2(s, b->rptr, n);
/* flush sreg */
if(s->bits)
*s->b->wptr++ = s->sreg<<(8-s->bits);
if(s->b->wptr > s->b->lim)
sysfatal("mppc: comp: output block overflowed");
n2 = BLEN(s->b);
if(n2 > n-2 && !s->encrypt) {
/* expened and not excrypting so send as a regular packet */
//netlog("mppc: comp: expanded\n");
compreset(s);
freeb(s->b);
b->rptr += 2;
qunlock(s);
*protop = proto;
return b;
}
count = s->count++;
s->count &= 0xfff;
if(s->front)
count |= Pfront;
if(s->reset)
count |= Preset;
s->reset = 0;
s->front = 0;
if(n2 > n) {
//netlog("mppc: comp: expanded\n");
freeb(s->b);
/* make room for count */
compreset(s);
b->rptr -= 2;
} else {
freeb(b);
b = s->b;
count |= Pcompress;
}
s->b = nil;
if(s->encrypt) {
count |= Pencrypt;
if((count&0xff) == 0xff) {
//netlog("mppc: comp: changing key\n");
setkey(s->key, s->startkey);
setupRC4state(&s->rc4key, s->key, 16);
rc4(&s->rc4key, s->key, 16);
setupRC4state(&s->rc4key, s->key, 16);
} else if(count&Preset)
setupRC4state(&s->rc4key, s->key, 16);
rc4(&s->rc4key, b->rptr+2, BLEN(b)-2);
//netlog("mppc: encrypt %ux\n", count);
}
b->rptr[0] = count>>8;
b->rptr[1] = count;
qunlock(s);
*protop = Pcdata;
return b;
}
static Block *
compresetreq(void *as, Block *b)
{
Cstate *cs;
cs = as;
netlog("mppc: comp: reset request\n");
qlock(cs);
compreset(cs);
qunlock(cs);
freeb(b);
return nil;
}
static void
comp2(Cstate *cs, uchar *p, int n)
{
Carena *hist, *ohist;
ulong *hash, me, split, you, last;
uchar *s, *t, *et, *buf, *obuf, *pos, *opos;
int i, h, m;
/*
* check for wrap
*/
if(cs->me + n < cs->me)
compreset(cs);
if(cs->hist->pos + n > cs->hist->buf + HistorySize)
compfront(cs);
hist = cs->hist;
ohist = cs->ohist;
hash = cs->hash;
me = cs->me;
split = cs->split;
memmove(hist->pos, p, n);
p = hist->pos;
hist->pos = pos = p + n;
m = Cminmatch;
if(m > n)
m = n;
h = cs->h;
for(i = 0; i < m; i++) {
h = (((h)<<Chshift) ^ p[i]) & HMASK;
last = me + (i - (Cminmatch-1));
if(last >= split && last != me)
hash[h] = last;
}
buf = hist->buf - split;
obuf = ohist->buf + HistorySize - split;
opos = ohist->pos;
while(p < pos) {
you = hash[h];
if(you < split) {
if(me - you >= HistorySize)
t = opos;
else
t = obuf + you;
et = opos;
} else {
t = buf + you;
et = pos;
}
m = pos - p;
if(m < et - t)
et = t + m;
for(s = p; t < et; t++) {
if(*s != *t)
break;
s++;
}
m = s - p;
if(m < Cminmatch) {
complit(cs, *p);
s = p + 1;
} else
compcopy(cs, me - you, m);
for(; p != s; p++) {
if(p + Cminmatch <= pos) {
hash[h] = me;
if(p + Cminmatch < pos)
h = (((h)<<Chshift) ^ p[Cminmatch]) & HMASK;
}
me++;
}
}
cs->h = h;
cs->me = me;
}
static void
compfront(Cstate *cs)
{
Carena *th;
cs->front = 1;
th = cs->ohist;
cs->ohist = cs->hist;
cs->hist = th;
cs->hist->pos = cs->hist->buf;
cs->h = 0;
cs->me = cs->split + HistorySize;
cs->split = cs->me;
}
static void
compreset(Cstate *cs)
{
ulong me;
cs->reset = 1;
me = cs->me;
if(me + 2 * HistorySize < me){
me = 0;
memset(cs->hash, 0, sizeof(cs->hash));
}
cs->me = me + 2 * HistorySize;
cs->split = cs->me;
cs->hist->pos = cs->hist->buf;
cs->ohist->pos = cs->ohist->buf;
}
static void
complit(Cstate *s, int c)
{
if(c&0x80)
compout(s, 0x100|(c&0x7f), 9);
else
compout(s, c, 8);
}
static void
compcopy(Cstate *s, int off, int len)
{
int i;
ulong mask;
if(off<64)
compout(s, 0x3c0|off, 10);
else if(off<320)
compout(s, 0xe00|(off-64), 12);
else
compout(s, 0xc000|(off-320), 16);
if(len < 3)
sysfatal("compcopy: bad len: %d", len);
if(len == 3)
compout(s, 0, 1);
else {
for(i=3; (1<<i) <= len; i++)
;
mask = (1<<(i-1))-1;
compout(s, (((1<<(i-2))-1)<<i) | len&mask, (i-1)<<1);
}
}
static void
compout(Cstate *s, ulong data, int bits)
{
ulong sreg;
sreg = s->sreg;
sreg <<= bits;
sreg |= data;
bits += s->bits;
while(bits >= 8) {
*s->b->wptr++ = sreg>>(bits-8);
bits -= 8;
}
s->sreg = sreg;
s->bits = bits;
}
void
printkey(uchar *key)
{
char buf[200], *p;
int i;
p = buf;
for(i=0; i<16; i++)
p += sprint(p, "%.2ux ", key[i]);
//netlog("key = %s\n", buf);
}
static void *
uncinit(PPP *ppp)
{
Uncstate *s;
s = mallocz(sizeof(Uncstate), 1);
s->count = 0xfff; /* count of non existant last packet */
memmove(s->startkey, ppp->key, 16);
memmove(s->key, ppp->key, 16);
setkey(s->key, s->startkey);
setupRC4state(&s->rc4key, s->key, 16);
return s;
}
static Block*
uncomp(PPP *ppp, Block *b, int *protop, Block **r)
{
Uncstate *s;
ushort proto;
ushort count;
Lcpmsg *m;
*r = nil;
*protop = 0;
s = ppp->uncstate;
if(BLEN(b) < 2){
syslog(0, "ppp", ": mppc: short packet");
freeb(b);
return nil;
}
count = nhgets(b->rptr);
b->rptr += 2;
b = uncomp2(s, b, count);
if(b == nil) {
//netlog("ppp: mppc: reset request\n");
/* return reset request packet */
*r = alloclcp(Lresetreq, s->resetid++, 4, &m);
hnputs(m->len, 4);
*protop = 0;
return nil;
}
if(BLEN(b) < 2){
syslog(0, "ppp", ": mppc: short packet");
freeb(b);
*protop = 0;
return nil;
}
proto = nhgets(b->rptr);
b->rptr += 2;
/*
if(proto == 0x21)
if(!ipcheck(b->rptr, BLEN(b)))
hischeck(s);
*/
*protop = proto;
return b;
}
#define NEXTBYTE sreg = (sreg<<8) | *p++; n--; bits += 8
int maxoff;
static Block*
uncomp2(Uncstate *s, Block *b, ushort count)
{
int ecount, n, bits, off, len, ones;
ulong sreg;
int t;
uchar *p, c, *hp, *hs, *he, *hq;
if(count&Preset) {
//netlog("mppc reset\n");
s->indx = 0;
s->size = 0;
setupRC4state(&s->rc4key, s->key, 16);
} else {
ecount = (s->count+1)&0xfff;
if((count&0xfff) != ecount) {
netlog("******* bad count - got %ux expected %ux\n", count&0xfff, ecount);
freeb(b);
return nil;
}
if(count&Pfront) {
s->indx = 0;
/* netlog("ppp: mppc: frount flag set\n"); */
}
}
/* update key */
n = (((count+1)>>8)&0xf) - (((s->count+1)>>8)&0xf);
if(n < 0)
n += 16;
//netlog("mppc count = %ux oldcount %ux n = %d\n", count, s->count, n);
if(n < 0 || n > 1) {
syslog(0, "ppp", ": mppc bad count %ux, %ux", count, s->count);
freeb(b);
return nil;
}
if(n == 1) {
setkey(s->key, s->startkey);
setupRC4state(&s->rc4key, s->key, 16);
rc4(&s->rc4key, s->key, 16);
setupRC4state(&s->rc4key, s->key, 16);
}
s->count = count;
n = BLEN(b);
p = b->rptr;
if(count & Pencrypt) {
//netlog("mppc unencrypt count = %ux\n", count);
rc4(&s->rc4key, p, n);
}
if(!(count & Pcompress)) {
//netlog("uncompress blen = %d\n", BLEN(b));
return b;
}
bits = 0;
sreg = 0;
hs = s->his; /* history start */
hp = hs+s->indx; /* write pointer in history */
he = hs+sizeof(s->his); /* hsitory end */
for(;;) {
if(bits<4) {
if(n==0) goto Done;
NEXTBYTE;
}
t = decode[(sreg>>(bits-4))&0xf];
switch(t) {
default:
sysfatal("mppc: bad decode!");
case Lit7:
bits -= 1;
if(bits<7) {
if(n==0) goto Done;
NEXTBYTE;
}
c = (sreg>>(bits-7))&0x7f;
bits -= 7;
if(hp >= he) goto His;
*hp++ = c;
/* netlog("\tlit7 %.2ux\n", c); */
continue;
case Lit8:
bits -= 2;
if(bits<7) {
if(n==0) goto Eof;
NEXTBYTE;
}
c = 0x80 | ((sreg>>(bits-7))&0x7f);
bits -= 7;
if(hp >= he) goto His;
*hp++ = c;
/* netlog("\tlit8 %.2ux\n", c); */
continue;
case Off6:
bits -= 4;
if(bits<6) {
if(n==0) goto Eof;
NEXTBYTE;
}
off = (sreg>>(bits-6))&0x3f;
bits -= 6;
break;
case Off8:
bits -= 4;
if(bits<8) {
if(n==0) goto Eof;
NEXTBYTE;
}
off = ((sreg>>(bits-8))&0xff)+64;
bits -= 8;
break;
case Off13:
bits -= 3;
while(bits<13) {
if(n==0) goto Eof;
NEXTBYTE;
}
off = ((sreg>>(bits-13))&0x1fff)+320;
bits -= 13;
/* netlog("\toff=%d bits = %d sreg = %ux t = %x\n", off, bits, sreg, t); */
break;
}
for(ones=0;;ones++) {
if(bits == 0) {
if(n==0) goto Eof;
NEXTBYTE;
}
bits--;
if(!(sreg&(1<<bits)))
break;
}
if(ones>11) {
netlog("ppp: mppc: bad length %d\n", ones);
freeb(b);
return nil;
}
if(ones == 0) {
len = 3;
} else {
ones++;
while(bits<ones) {
if(n==0) goto Eof;
NEXTBYTE;
}
len = (1<<ones) | ((sreg>>(bits-ones))&((1<<ones)-1));
bits -= ones;
}
hq = hp-off;
if(hq < hs) {
hq += sizeof(s->his);
if(hq-hs+len > s->size)
goto His;
}
if(hp+len > he) goto His;
while(len) {
*hp++ = *hq++;
len--;
}
}
Done:
freeb(b);
/* build up return block */
hq = hs+s->indx;
len = hp-hq;
b = allocb(len);
memmove(b->wptr, hq, len);
b->wptr += len;
netlog("ppp: mppc: len %d bits = %d n=%d\n", len, bits, n);
s->indx += len;
if(s->indx > s->size)
s->size = s->indx;
return b;
Eof:
netlog("*****unexpected end of data\n");
freeb(b);
return nil;
His:
netlog("*****bad history\n");
freeb(b);
return nil;
}
static void
uncresetack(void*, Block*)
{
}
static void
uncfini(void *as)
{
Uncstate *s;
s = as;
free(s);
}
static void
setkey(uchar *key, uchar *startkey)
{
uchar pad[40];
SHAstate *s;
uchar digest[SHA1dlen];
s = sha1(startkey, 16, nil, nil);
memset(pad, 0, 40);
sha1(pad, 40, nil, s);
sha1(key, 16, nil, s);
memset(pad, 0xf2, 40);
sha1(pad, 40, digest, s);
memmove(key, digest, 16);
}
/* code to check if IP packet looks good */
typedef struct Iphdr Iphdr;
struct Iphdr
{
uchar vihl; /* Version and header length */
uchar tos; /* Type of service */
uchar length[2]; /* packet length */
uchar id[2]; /* Identification */
uchar frag[2]; /* Fragment information */
uchar ttl; /* Time to live */
uchar proto; /* Protocol */
uchar cksum[2]; /* Header checksum */
uchar src[4]; /* Ip source */
uchar dst[4]; /* Ip destination */
};
enum
{
QMAX = 64*1024-1,
IP_TCPPROTO = 6,
TCP_IPLEN = 8,
TCP_PHDRSIZE = 12,
TCP_HDRSIZE = 20,
TCP_PKT = TCP_IPLEN+TCP_PHDRSIZE,
};
enum
{
UDP_PHDRSIZE = 12,
UDP_HDRSIZE = 20,
UDP_IPHDR = 8,
IP_UDPPROTO = 17,
UDP_USEAD = 12,
UDP_RELSIZE = 16,
Udprxms = 200,
Udptickms = 100,
Udpmaxxmit = 10,
};
typedef struct UDPhdr UDPhdr;
struct UDPhdr
{
/* ip header */
uchar vihl; /* Version and header length */
uchar tos; /* Type of service */
uchar length[2]; /* packet length */
uchar id[2]; /* Identification */
uchar frag[2]; /* Fragment information */
uchar Unused;
uchar udpproto; /* Protocol */
uchar udpplen[2]; /* Header plus data length */
uchar udpsrc[4]; /* Ip source */
uchar udpdst[4]; /* Ip destination */
/* udp header */
uchar udpsport[2]; /* Source port */
uchar udpdport[2]; /* Destination port */
uchar udplen[2]; /* data length */
uchar udpcksum[2]; /* Checksum */
};
typedef struct TCPhdr TCPhdr;
struct TCPhdr
{
uchar vihl; /* Version and header length */
uchar tos; /* Type of service */
uchar length[2]; /* packet length */
uchar id[2]; /* Identification */
uchar frag[2]; /* Fragment information */
uchar Unused;
uchar proto;
uchar tcplen[2];
uchar tcpsrc[4];
uchar tcpdst[4];
uchar tcpsport[2];
uchar tcpdport[2];
uchar tcpseq[4];
uchar tcpack[4];
uchar tcpflag[2];
uchar tcpwin[2];
uchar tcpcksum[2];
uchar tcpurg[2];
/* Options segment */
uchar tcpopt[2];
uchar tcpmss[2];
};
static void
hischeck(Uncstate *s)
{
uchar *p;
Iphdr *iph;
int len;
p = s->his;
netlog("***** history check\n");
while(p < s->his+s->size) {
if(p[0] != 0 || p[1] != 0x21) {
netlog("***** unknown protocol\n");
return;
}
p += 2;
netlog("off = %zd ", p-s->his);
iph = (Iphdr*)p;
len = nhgets(iph->length);
ipcheck(p, len);
p += len;
}
}
static int
ipcheck(uchar *p, int len)
{
Iphdr *iph;
TCPhdr *tcph;
ushort length;
UDPhdr *uh;
Block *bp;
ushort cksum;
int good;
bp = allocb(len);
memmove(bp->wptr, p, len);
bp->wptr += len;
good = 1;
iph = (Iphdr *)(bp->rptr);
/* netlog("ppp: mppc: ipcheck %I %I len %d proto %d\n", iph->src, iph->dst, BLEN(bp), iph->proto); */
if(len != nhgets(iph->length)) {
netlog("***** bad length! %d %d\n", len, nhgets(iph->length));
good = 0;
}
cksum = ipcsum(&iph->vihl);
if(cksum) {
netlog("***** IP proto cksum!!! %I %ux\n", iph->src, cksum);
good = 0;
}
switch(iph->proto) {
default:
break;
case IP_TCPPROTO:
tcph = (TCPhdr*)(bp->rptr);
length = nhgets(tcph->length);
tcph->Unused = 0;
hnputs(tcph->tcplen, length-TCP_PKT);
cksum = ptclcsum(bp, TCP_IPLEN, length-TCP_IPLEN);
if(cksum) {
netlog("***** bad tcp proto cksum %ux!!!\n", cksum);
good = 0;
}
break;
case IP_UDPPROTO:
uh = (UDPhdr*)(bp->rptr);
/* Put back pseudo header for checksum */
uh->Unused = 0;
len = nhgets(uh->udplen);
hnputs(uh->udpplen, len);
if(nhgets(uh->udpcksum)) {
cksum = ptclcsum(bp, UDP_IPHDR, len+UDP_PHDRSIZE);
if(cksum) {
netlog("***** udp: proto cksum!!! %I %ux\n", uh->udpsrc, cksum);
good = 0;
}
}
break;
}
freeb(bp);
return good;
}