ref: 6fa3e08412c49a188e2abe7d9ee54cd1f37a85f5
dir: /sys/src/cmd/ip/pptp.c/
/* * Point-to-point Tunneling Protocol (PPTP) * See RFC 2637, pptpd.c */ #include <u.h> #include <libc.h> #include <bio.h> #include <ip.h> #include <thread.h> int ack; int alarmed; int ctlechotime; int ctlfd; int ctlrcvtime; int debug; int grefd; uchar localip[IPaddrlen]; int localwin; char *keyspec; int now; char *pppnetmntpt; int pid; Channel *pidchan; int pppfd; int primary; int rack; Channel *rdchan; int rdexpect; int remid; uchar remoteip[IPaddrlen]; int remwin; int rseq; int seq; char tcpdir[40]; Channel *tickchan; int topppfd; int aread(int, int, void*, int); int catchalarm(void*, char*); void dumpctlpkt(uchar*); void getaddrs(void); void *emalloc(long); void ewrite(int, void*, int); void myfatal(char*, ...); #pragma varargck argpos myfatal 1 int pptp(char*); void pushppp(int); void recordack(int); int schedack(int, uchar*, int); void waitacks(void); void usage(void) { fprint(2, "usage: ip/pptp [-Pd] [-k keyspec] [-x pppnetmntpt] [-w window] server\n"); exits("usage"); } void threadmain(int argc, char **argv) { int fd; ARGBEGIN{ case 'P': primary = 1; break; case 'd': debug++; break; case 'k': keyspec = EARGF(usage()); break; case 'w': localwin = atoi(EARGF(usage())); break; case 'x': pppnetmntpt = EARGF(usage()); break; default: usage(); }ARGEND if(argc != 1) usage(); fmtinstall('E', eipfmt); fmtinstall('I', eipfmt); rfork(RFNOTEG); atnotify(catchalarm, 1); fd = pptp(argv[0]); pushppp(fd); exits(nil); } int catchalarm(void *a, char *msg) { USED(a); if(strstr(msg, "alarm")){ alarmed = 1; return 1; } if(debug) fprint(2, "note rcved: %s\n", msg); return 0; } enum { Stack = 8192, PptpProto = 0x0100, Magic = 0x1a2b3c4d, Window = 16, /* default window size */ Timeout = 60, /* timeout in seconds for control channel */ Pktsize = 2000, /* maximum packet size */ Tick = 500, /* tick length in milliseconds */ Sendtimeout = 4, /* in ticks */ Servertimeout = 5*60*1000/Tick, Echointerval = 60*1000/Tick, }; enum { Syncframe = 0x1, Asyncframe = 0x2, Analog = 0x1, Digital = 0x2, Version = 0x100, }; enum { Tstart = 1, Rstart = 2, Tstop = 3, Rstop = 4, Techo = 5, Recho = 6, Tcallout = 7, Rcallout = 8, Tcallreq = 9, Rcallreq = 10, Acallcon = 11, Tcallclear = 12, Acalldis = 13, Awaninfo = 14, Alinkinfo = 15, }; void recho(uchar *in) { uchar out[20]; if(nhgets(in) < 16) return; memset(out, 0, sizeof out); hnputs(out, sizeof out); hnputs(out+2, 1); hnputl(out+4, Magic); hnputs(out+8, Recho); memmove(out+12, in+12, 4); out[16] = 1; ewrite(ctlfd, out, sizeof out); } void sendecho(void) { uchar out[16]; ctlechotime = now; memset(out, 0, sizeof out); hnputs(out, sizeof out); hnputs(out+2, 1); hnputl(out+4, Magic); hnputs(out+8, Techo); ewrite(ctlfd, out, sizeof out); } void pptpctlproc(void*) { uchar pkt[1600], *p; int len; for(;;){ if(readn(ctlfd, pkt, 2) != 2) myfatal("pptpread: %r"); len = nhgets(pkt); if(len < 12 || len+2 >= sizeof pkt) myfatal("pptpread: bad length %d", len); if(readn(ctlfd, pkt+2, len-2) != len-2) myfatal("pptpread: %r"); if(nhgetl(pkt+4) != Magic) myfatal("pptpread bad magic"); if(nhgets(pkt+2) != 1) myfatal("pptpread bad message type"); if(debug) dumpctlpkt(pkt); ctlrcvtime = now; switch(nhgets(pkt+8)){ case Tstart: case Tstop: case Tcallout: case Tcallreq: case Tcallclear: case Acallcon: case Acalldis: case Awaninfo: myfatal("unexpected msg type %d", nhgets(pkt+8)); case Techo: recho(pkt); break; case Recho: break; case Rstart: case Rstop: case Rcallout: case Rcallreq: if(rdexpect != nhgets(pkt+8)) continue; p = emalloc(len); memmove(p, pkt, len); sendp(rdchan, p); break; case Alinkinfo: myfatal("cannot change ppp params on the fly"); } } } enum { Seqnum = 0x1000, Acknum = 0x0080, GrePPP = 0x880B, }; void grereadproc(void*) { int datoff, flags, len, n, pass; uchar pkt[1600]; uchar src[IPaddrlen], dst[IPaddrlen]; rfork(RFFDG); close(pppfd); sendul(pidchan, getpid()); while((n = read(grefd, pkt, sizeof pkt)) > 0){ if(n == sizeof pkt) myfatal("gre pkt buffer too small"); if(n < 16){ if(debug) fprint(2, "small pkt len %d ignored\n", n); continue; } v4tov6(src, pkt); v4tov6(dst, pkt+4); if(ipcmp(src, remoteip) != 0 || ipcmp(dst, localip) != 0) myfatal("%I: gre read bad address src=%I dst=%I", remoteip, src, dst); if(nhgets(pkt+10) != GrePPP) myfatal("%I: gre read bad protocol 0x%x", remoteip, nhgets(pkt+10)); flags = nhgets(pkt+8); if((flags&0xEF7F) != 0x2001){ if(debug) fprint(2, "bad flags in gre hdr 0x%x\n", flags); continue; } datoff = 8+8; pass = 0; len = nhgets(pkt+8+4); if(len > n-datoff){ fprint(2, "bad payload length %d > %d\n", len, n-datoff); continue; } if(flags&Seqnum) datoff += 4; if(flags&Acknum){ recordack(nhgetl(pkt+datoff)); datoff += 4; } if(flags&Seqnum) pass = schedack(nhgetl(pkt+8+8), pkt+datoff, len); if(debug) fprint(2, "got gre callid %d len %d flag 0x%x pass %d seq %d rseq %d\n", nhgets(pkt+8+6), len, flags, pass, nhgetl(pkt+8+8), rseq); } threadexits(nil); } void pppreadproc(void*) { int n, myrseq; uchar pkt[1600]; enum { Hdr = 8+16, }; rfork(RFFDG); close(pppfd); sendul(pidchan, getpid()); while((n = read(topppfd, pkt+Hdr, sizeof pkt-Hdr)) > 0){ if(n == sizeof pkt-Hdr) myfatal("ppp pkt buffer too small"); v6tov4(pkt+0, localip); v6tov4(pkt+4, remoteip); hnputs(pkt+8, 0x2001 | Seqnum | Acknum); hnputs(pkt+10, GrePPP); hnputs(pkt+12, n); hnputs(pkt+14, remid); hnputl(pkt+16, ++seq); myrseq = rseq; hnputl(pkt+20, myrseq); rack = myrseq; if(debug) fprint(2, "wrote gre callid %d len %d flag 0x%x seq %d rseq %d\n", nhgets(pkt+8+6), n, nhgets(pkt+8), nhgetl(pkt+16), nhgetl(pkt+20)); if(write(grefd, pkt, n+Hdr) != n+Hdr) myfatal("gre write: %r"); waitacks(); } threadexits(nil); } void sendack(void) { int myrseq; uchar pkt[20]; v6tov4(pkt+0, localip); v6tov4(pkt+4, remoteip); hnputs(pkt+8, 0x2001 | Acknum); hnputs(pkt+10, GrePPP); hnputs(pkt+12, 0); hnputs(pkt+14, remid); myrseq = rseq; rack = myrseq; hnputs(pkt+16, myrseq); if(write(grefd, pkt, sizeof pkt) != sizeof pkt) myfatal("gre write: %r"); } int schedack(int n, uchar *dat, int len) { static uchar sdat[1600]; static int srseq, slen; if(n-rseq <= 0){ fprint(2, "skipping pkt %d len %d, have %d\n", n, len, rseq); return 0; } /* missed one pkt, maybe a swap happened, save pkt */ if(n==rseq+2){ memmove(sdat, dat, len); slen = len; srseq = n; return 0; } if(n-rseq > 1){ if(slen && srseq == n-1){ fprint(2, "reswapped pkts %d and %d\n", srseq, n); write(topppfd, sdat, slen); slen = 0; }else fprint(2, "missed pkts %d-%d, got %d len %d\n", rseq+1, n-1, n, len); } write(topppfd, dat, len); rseq = n; /* send ack if we haven't recently */ if((int)(rseq-rack) > (localwin>>1)) sendack(); return 1; } void gretimeoutproc(void*) { for(;;){ sleep(Tick); now++; nbsendul(tickchan, now); if(now - ctlrcvtime > Servertimeout) myfatal("server timeout"); if(now - ctlechotime > Echointerval) sendecho(); } } void recordack(int n) { ack = n; } void waitacks(void) { /* int start; start = now; while(seq-ack > remwin && now-start < Sendtimeout){ print("seq %d ack %d remwin %d now %d start %d\n", seq, ack, remwin, now, start); recvul(tickchan); } */ } void tstart(void) { char *name; uchar pkt[200], *rpkt; memset(pkt, 0, sizeof pkt); hnputs(pkt+0, 156); hnputs(pkt+2, 1); hnputl(pkt+4, Magic); hnputs(pkt+8, Tstart); hnputs(pkt+12, PptpProto); hnputl(pkt+16, 1); hnputl(pkt+20, 1); hnputs(pkt+24, 1); name = sysname(); if(name == nil) name = "gnot"; strcpy((char*)pkt+28, name); strcpy((char*)pkt+92, "plan 9"); if(debug) dumpctlpkt(pkt); rdexpect = Rstart; ewrite(ctlfd, pkt, 156); rpkt = recvp(rdchan); if(rpkt == nil) myfatal("recvp: %r"); if(nhgets(rpkt) != 156) myfatal("Rstart wrong length %d != 156", nhgets(rpkt)); if(rpkt[14] != 1) myfatal("Rstart error %d", rpkt[15]); free(rpkt); } void tcallout(void) { uchar pkt[200], *rpkt; pid = getpid(); memset(pkt, 0, sizeof pkt); hnputs(pkt+0, 168); hnputs(pkt+2, 1); hnputl(pkt+4, Magic); hnputs(pkt+8, Tcallout); hnputl(pkt+16, 56000); hnputl(pkt+20, 768000); hnputl(pkt+24, 3); hnputl(pkt+28, 3); if(localwin == 0) localwin = Window; hnputs(pkt+32, localwin); if(debug) dumpctlpkt(pkt); rdexpect = Rcallout; ewrite(ctlfd, pkt, 168); rpkt = recvp(rdchan); if(rpkt == nil) myfatal("recvp: %r"); if(nhgets(rpkt) != 32) myfatal("Rcallreq wrong length %d != 32", nhgets(rpkt)); if(rpkt[16] != 1) myfatal("Rcallreq error %d", rpkt[17]); remid = nhgets(pkt+12); remwin = nhgets(pkt+24); free(rpkt); } /* void tcallreq(void) { uchar pkt[200], *rpkt; pid = getpid(); memset(pkt, 0, sizeof pkt); hnputs(pkt+0, 220); hnputs(pkt+2, 1); hnputl(pkt+4, Magic); hnputs(pkt+8, Tcallreq); if(debug) dumpctlpkt(pkt); rdexpect = Rcallreq; ewrite(ctlfd, pkt, 220); rpkt = recvp(rdchan); if(rpkt == nil) myfatal("recvp: %r"); if(nhgets(rpkt) != 24) myfatal("Rcallreq wrong length %d != 24", nhgets(rpkt)); if(rpkt[16] != 1) myfatal("Rcallreq error %d", rpkt[17]); remid = nhgets(pkt+12); remwin = nhgets(pkt+18); free(rpkt); } void acallcon(void) { uchar pkt[200]; memset(pkt, 0, sizeof pkt); hnputs(pkt+0, 28); hnputs(pkt+2, 1); hnputl(pkt+4, Magic); hnputs(pkt+8, Acallcon); hnputs(pkt+12, remid); if(localwin == 0) localwin = Window; hnputs(pkt+20, localwin); hnputl(pkt+24, 1); if(debug) dumpctlpkt(pkt); ewrite(ctlfd, pkt, 28); } */ int pptp(char *addr) { int p[2]; char greaddr[128]; addr = netmkaddr(addr, "net", "pptp"); ctlfd = dial(addr, nil, tcpdir, nil); if(ctlfd < 0) myfatal("dial %s: %r", addr); getaddrs(); rdchan = chancreate(sizeof(void*), 0); proccreate(pptpctlproc, nil, Stack); tstart(); tcallout(); if(pipe(p) < 0) myfatal("pipe: %r"); pppfd = p[0]; topppfd = p[1]; strcpy(greaddr, tcpdir); *strrchr(greaddr, '/') = '\0'; sprint(strrchr(greaddr, '/')+1, "gre!%I!%d", remoteip, GrePPP); print("local %I remote %I gre %s remid %d remwin %d\n", localip, remoteip, greaddr, remid, remwin); grefd = dial(greaddr, nil, nil, nil); if(grefd < 0) myfatal("dial gre: %r"); tickchan = chancreate(sizeof(int), 0); proccreate(gretimeoutproc, nil, Stack); pidchan = chancreate(sizeof(int), 0); proccreate(grereadproc, nil, Stack); recvul(pidchan); proccreate(pppreadproc, nil, Stack); recvul(pidchan); close(topppfd); return pppfd; } void pushppp(int fd) { char *argv[16]; int argc; argc = 0; argv[argc++] = "/bin/ip/ppp"; argv[argc++] = "-C"; argv[argc++] = "-m1450"; if(debug) argv[argc++] = "-d"; if(primary) argv[argc++] = "-P"; if(pppnetmntpt){ argv[argc++] = "-x"; argv[argc++] = pppnetmntpt; } if(keyspec){ argv[argc++] = "-k"; argv[argc++] = keyspec; } argv[argc] = nil; switch(fork()){ case -1: myfatal("fork: %r"); default: return; case 0: dup(fd, 0); dup(fd, 1); exec(argv[0], argv); myfatal("exec: %r"); } } int aread(int timeout, int fd, void *buf, int nbuf) { int n; alarmed = 0; alarm(timeout); n = read(fd, buf, nbuf); alarm(0); if(alarmed) return -1; if(n < 0) myfatal("read: %r"); if(n == 0) myfatal("short read"); return n; } void ewrite(int fd, void *buf, int nbuf) { char e[ERRMAX], path[64]; if(write(fd, buf, nbuf) != nbuf){ rerrstr(e, sizeof e); strcpy(path, "unknown"); fd2path(fd, path, sizeof path); myfatal("write %d to %s: %s", nbuf, path, e); } } void* emalloc(long n) { void *v; v = malloc(n); if(v == nil) myfatal("out of memory"); return v; } int thread(void(*f)(void*), void *a) { int pid; pid=rfork(RFNOWAIT|RFMEM|RFPROC); if(pid < 0) myfatal("rfork: %r"); if(pid != 0) return pid; (*f)(a); _exits(nil); return 0; // never reaches here } void dumpctlpkt(uchar *pkt) { fprint(2, "pkt len %d mtype %d cookie 0x%.8ux type %d\n", nhgets(pkt), nhgets(pkt+2), nhgetl(pkt+4), nhgets(pkt+8)); switch(nhgets(pkt+8)){ default: fprint(2, "\tunknown type\n"); break; case Tstart: fprint(2, "\tTstart proto %d framing %d bearer %d maxchan %d firmware %d\n", nhgets(pkt+12), nhgetl(pkt+16), nhgetl(pkt+20), nhgets(pkt+24), nhgets(pkt+26)); fprint(2, "\thost %.64s\n", (char*)pkt+28); fprint(2, "\tvendor %.64s\n", (char*)pkt+92); break; case Rstart: fprint(2, "\tRstart proto %d res %d err %d framing %d bearer %d maxchan %d firmware %d\n", nhgets(pkt+12), pkt[14], pkt[15], nhgetl(pkt+16), nhgetl(pkt+20), nhgets(pkt+24), nhgets(pkt+26)); fprint(2, "\thost %.64s\n", (char*)pkt+28); fprint(2, "\tvendor %.64s\n", (char*)pkt+92); break; case Tstop: fprint(2, "\tTstop reason %d\n", pkt[12]); break; case Rstop: fprint(2, "\tRstop res %d err %d\n", pkt[12], pkt[13]); break; case Techo: fprint(2, "\tTecho id %.8ux\n", nhgetl(pkt+12)); break; case Recho: fprint(2, "\tRecho id %.8ux res %d err %d\n", nhgetl(pkt+12), pkt[16], pkt[17]); break; case Tcallout: fprint(2, "\tTcallout id %d serno %d bps %d-%d\n", nhgets(pkt+12), nhgets(pkt+14), nhgetl(pkt+16), nhgetl(pkt+20)); fprint(2, "\tbearer 0x%x framing 0x%x recvwin %d delay %d\n", nhgetl(pkt+24), nhgetl(pkt+28), nhgets(pkt+32), nhgets(pkt+34)); fprint(2, "\tphone len %d num %.64s\n", nhgets(pkt+36), (char*)pkt+40); fprint(2, "\tsubaddr %.64s\n", (char*)pkt+104); break; case Rcallout: fprint(2, "\tRcallout id %d peerid %d res %d err %d cause %d\n", nhgets(pkt+12), nhgets(pkt+14), pkt[16], pkt[17], nhgets(pkt+18)); fprint(2, "\tconnect %d recvwin %d delay %d chan 0x%.8ux\n", nhgetl(pkt+20), nhgets(pkt+24), nhgets(pkt+26), nhgetl(pkt+28)); break; case Tcallreq: fprint(2, "\tTcallreq id %d serno %d bearer 0x%x id 0x%x\n", nhgets(pkt+12), nhgets(pkt+14), nhgetl(pkt+16), nhgetl(pkt+20)); fprint(2, "\tdialed len %d num %.64s\n", nhgets(pkt+24), (char*)pkt+28); fprint(2, "\tdialing len %d num %.64s\n", nhgets(pkt+26), (char*)pkt+92); fprint(2, "\tsubaddr %.64s\n", (char*)pkt+156); break; case Rcallreq: fprint(2, "\tRcallout id %d peerid %d res %d err %d recvwin %d delay %d\n", nhgets(pkt+12), nhgets(pkt+14), pkt[16], pkt[17], nhgets(pkt+18), nhgets(pkt+20)); break; case Acallcon: fprint(2, "\tAcallcon peerid %d connect %d recvwin %d delay %d framing 0x%x\n", nhgets(pkt+12), nhgetl(pkt+16), nhgets(pkt+20), nhgets(pkt+22), nhgetl(pkt+24)); break; case Tcallclear: fprint(2, "\tTcallclear callid %d\n", nhgets(pkt+12)); break; case Acalldis: fprint(2, "\tAcalldis callid %d res %d err %d cause %d\n", nhgets(pkt+12), pkt[14], pkt[15], nhgets(pkt+16)); fprint(2, "\tstats %.128s\n", (char*)pkt+20); break; case Awaninfo: fprint(2, "\tAwaninfo peerid %d\n", nhgets(pkt+12)); fprint(2, "\tcrc errors %d\n", nhgetl(pkt+16)); fprint(2, "\tframe errors %d\n", nhgetl(pkt+20)); fprint(2, "\thardware overruns %d\n", nhgetl(pkt+24)); fprint(2, "\tbuffer overruns %d\n", nhgetl(pkt+28)); fprint(2, "\ttime-out errors %d\n", nhgetl(pkt+32)); fprint(2, "\talignment errors %d\n", nhgetl(pkt+36)); break; case Alinkinfo: fprint(2, "\tAlinkinfo peerid %d sendaccm 0x%ux recvaccm 0x%ux\n", nhgets(pkt+12), nhgetl(pkt+16), nhgetl(pkt+20)); break; } } void getaddrs(void) { char buf[128]; int fd, n; sprint(buf, "%s/local", tcpdir); if((fd = open(buf, OREAD)) < 0) myfatal("could not open %s: %r", buf); if((n = read(fd, buf, sizeof(buf))) < 0) myfatal("could not read %s: %r", buf); buf[n] = 0; parseip(localip, buf); close(fd); sprint(buf, "%s/remote", tcpdir); if((fd = open(buf, OREAD)) < 0) myfatal("could not open %s: %r", buf); if((n = read(fd, buf, sizeof(buf))) < 0) myfatal("could not read %s: %r", buf); buf[n] = 0; parseip(remoteip, buf); close(fd); } void myfatal(char *fmt, ...) { char sbuf[512]; va_list arg; uchar buf[16]; memset(buf, 0, sizeof(buf)); hnputs(buf+0, sizeof(buf)); /* length */ hnputs(buf+2, 1); /* message type */ hnputl(buf+4, Magic); /* magic */ hnputs(buf+8, Tstop); /* op */ buf[12] = 3; /* local shutdown */ write(ctlfd, buf, sizeof(buf)); va_start(arg, fmt); vseprint(sbuf, sbuf+sizeof(sbuf), fmt, arg); va_end(arg); fprint(2, "fatal: %s\n", sbuf); threadexitsall(nil); }