ref: 88b386a4a15654bcc9d34a534812f1ec9c77e069
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->sendkey, 16); memmove(cs->key, cs->startkey, 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->recvkey, 16); memmove(s->key, s->startkey, 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)) 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); } void getasymkey(uchar *key, uchar *masterkey, int send, int server) { uchar digest[SHA1dlen]; uchar pad[40]; SHAstate *s; char *m; s = sha1(masterkey, 16, nil, nil); memset(pad, 0, 40); sha1(pad, 40, nil, s); if(send ^ server) m = "On the client side, this is the send key; on the server side, it is the receive key."; else m = "On the client side, this is the receive key; on the server side, it is the send key."; sha1((uchar*)m, 84, nil, s); memset(pad, 0xf2, 40); sha1(pad, 40, digest, s); memmove(key, digest, 16); } 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; }