ppp.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

		if(c->state == Cauthok) {
			setphase(ppp, Pnet);
		} else {
			/* restart chapp negotiation */
			chapinit(ppp);
		}
		
		break;
	case Csuccess:
		netlog("ppp: chap succeeded\n");
		break;
	case Cfailure:
		netlog("ppp: chap failed\n");
		break;
	default:
		syslog(0, LOG, "chap code %d?\n", m->code);
		break;
	}
	qunlock(ppp);
	freeb(b);
}

static void
putpaprequest(PPP *ppp)
{
	Block *b;
	Lcpmsg *m;
	Chap *c;
	int len, nlen, slen;

	getauth(ppp);

	c = ppp->chap;
	c->id++;
	netlog("PPP: pap: send authreq %d %s %s\n", c->id, ppp->chapname, "****");

	nlen = strlen(ppp->chapname);
	slen = strlen(ppp->secret);
	len = 4 + 1 + nlen + 1 + slen;
	b = alloclcp(Pauthreq, c->id, len, &m);

	*b->wptr++ = nlen;
	memmove(b->wptr, ppp->chapname, nlen);
	b->wptr += nlen;
	*b->wptr++ = slen;
	memmove(b->wptr, ppp->secret, slen);
	b->wptr += slen;
	hnputs(m->len, len);

	putframe(ppp, Ppasswd, b);
	freeb(b);
}

static void
papinit(PPP *ppp)
{
	ppp->chap->id = 0;
	putpaprequest(ppp);
}

static void
getpap(PPP *ppp, Block *b)
{
	Lcpmsg *m;
	int len;

	m = (Lcpmsg*)b->rptr;
	len = 4;
	if(BLEN(b) < 4 || BLEN(b) < (len = nhgets(m->len))){
		syslog(0, LOG, "short pap message (%ld < %d)", BLEN(b), len);
		freeb(b);
		return;
	}
	if(len < sizeof(Lcpmsg))
		m->data[0] = 0;

	qlock(ppp);
	switch(m->code){
	case Pauthreq:
		netlog("PPP: pap auth request, not supported\n");
		break;
	case Pauthack:
		if(ppp->phase == Pauth
		&& ppp->chap->proto == APpasswd
		&& m->id <= ppp-> chap->id){
			netlog("PPP: pap succeeded\n");
			setphase(ppp, Pnet);
		}
		break;
	case Pauthnak:
		if(ppp->phase == Pauth
		&& ppp->chap->proto == APpasswd
		&& m->id <= ppp-> chap->id){
			netlog("PPP: pap failed (%d:%.*s)\n",
				m->data[0], m->data[0], (char*)m->data+1);
			terminate(ppp, 0);
		}
		break;
	default:
		netlog("PPP: unknown pap messsage %d\n", m->code);
	}
	qunlock(ppp);
	freeb(b);
}

static void
printopts(Pstate *p, Block *b, int send)
{
	Lcpmsg *m;	
	Lcpopt *o;
	int proto, x, period;
	uchar *cp;
	char *code, *dir;

	m = (Lcpmsg*)b->rptr;
	switch(m->code) {
	default: code = "<unknown>"; break;
	case Lconfreq: code = "confrequest"; break;
	case Lconfack: code = "confack"; break;
	case Lconfnak: code = "confnak"; break;
	case Lconfrej: code = "confreject"; break;
	}

	if(send)
		dir = "send";
	else
		dir = "recv";

	netlog("ppp: %s %s: id=%d\n", dir, code, m->id);

	for(cp = m->data; cp < b->wptr; cp += o->len){
		o = (Lcpopt*)cp;
		if(cp + o->len > b->wptr){
			netlog("\tbad option length %ux\n", o->type);
			return;
		}

		switch(p->proto){
		case Plcp:
			switch(o->type){
			default:
				netlog("\tunknown %d len=%d\n", o->type, o->len);
				break;
			case Omtu:
				netlog("\tmtu = %d\n", nhgets(o->data));
				break;
			case Octlmap:
				netlog("\tctlmap = %ux\n", nhgetl(o->data));
				break;
			case Oauth:
				netlog("\tauth = %ux", nhgetl(o->data));
				proto = nhgets(o->data);
				switch(proto) {
				default:
					netlog("unknown auth proto %d\n", proto);
					break;
				case Ppasswd:
					netlog("password\n");
					break;
				case Pchap:
					netlog("chap %ux\n", o->data[2]);
					break;
				}
				break;
			case Oquality:
				proto = nhgets(o->data);
				switch(proto) {
				default:
					netlog("\tunknown quality proto %d\n", proto);
					break;
				case Plqm:
					x = nhgetl(o->data+2)*10;
					period = (x+Period-1)/Period;
					netlog("\tlqm period = %d\n", period);
					break;
				}
			case Omagic:
				netlog("\tmagic = %ux\n", nhgetl(o->data));
				break;
			case Opc:
				netlog("\tprotocol compress\n");
				break;
			case Oac:
				netlog("\taddr compress\n");
				break;
			}
			break;
		case Pccp:
			switch(o->type){
			default:
				netlog("\tunknown %d len=%d\n", o->type, o->len);
				break;
			case Ocoui:	
				netlog("\tOUI\n");
				break;
			case Ocstac:
				netlog("\tstac LZS\n");
				break;
			case Ocmppc:	
				netlog("\tMicrosoft PPC len=%d %ux\n", o->len, nhgetl(o->data));
				break;
			case Octhwack:	
				netlog("\tThwack\n");
				break;
			}
			break;
		case Pecp:
			switch(o->type){
			default:
				netlog("\tunknown %d len=%d\n", o->type, o->len);
				break;
			case Oeoui:	
				netlog("\tOUI\n");
				break;
			case Oedese:
				netlog("\tDES\n");
				break;
			}
			break;
		case Pipcp:
			switch(o->type){
			default:
				netlog("\tunknown %d len=%d\n", o->type, o->len);
				break;
			case Oipaddrs:	
				netlog("\tip addrs - deprecated\n");
				break;
			case Oipcompress:
				netlog("\tip compress\n");
				break;
			case Oipaddr:	
				netlog("\tip addr %V\n", o->data);
				break;
			case Oipdns:	
				netlog("\tdns addr %V\n", o->data);
				break;
			case Oipwins:	
				netlog("\twins addr %V\n", o->data);
				break;
			case Oipdns2:	
				netlog("\tdns2 addr %V\n", o->data);
				break;
			case Oipwins2:	
				netlog("\twins2 addr %V\n", o->data);
				break;
			}
			break;
		}
	}
}

static void
sendtermreq(PPP *ppp, Pstate *p)
{
	Block *b;
	Lcpmsg *m;

	p->termid = ++(p->id);
	b = alloclcp(Ltermreq, p->termid, 4, &m);
	hnputs(m->len, 4);
	putframe(ppp, p->proto, b);
	freeb(b);
	newstate(ppp, p, Sclosing);
}

static void
sendechoreq(PPP *ppp, Pstate *p)
{
	Block *b;
	Lcpmsg *m;

	p->termid = ++(p->id);
	b = alloclcp(Lechoreq, p->id, 4, &m);
	hnputs(m->len, 4);
	putframe(ppp, p->proto, b);
	freeb(b);
}

enum
{
	CtrlD	= 0x4,
	CtrlE	= 0x5,
	CtrlO	= 0xf,
	Cr	= 13,
	View	= 0x80,
};

int conndone;

static void
xfer(int fd)
{
	int i, n;
	uchar xbuf[128];

	for(;;) {
		n = read(fd, xbuf, sizeof(xbuf));
		if(n < 0)
			break;
		if(conndone)
			break;
		for(i = 0; i < n; i++)
			if(xbuf[i] == Cr)
				xbuf[i] = ' ';
		write(1, xbuf, n);
	}
	close(fd);
}

static int
readcr(int fd, char *buf, int nbuf)
{
	char c;
	int n, tot;

	tot = 0;
	while((n=read(fd, &c, 1)) == 1){
		if(c == '\n'){
			buf[tot] = 0;
			return tot;
		}
		buf[tot++] = c;
		if(tot == nbuf)
			sysfatal("line too long in readcr");
	}
	return n;
}

static void
connect(int fd, int cfd)
{
	int n, ctl;
	char xbuf[128];

	if (chatfile) {
		int chatfd, lineno, nb;
		char *buf, *p, *s, response[128];
		Dir *dir;

		if ((chatfd = open(chatfile, OREAD)) < 0)
			sysfatal("cannot open %s: %r", chatfile);

		if ((dir = dirfstat(chatfd)) == nil)
			sysfatal("cannot fstat %s: %r",chatfile);

		buf = (char *)malloc(dir->length + 1);
		assert(buf);

		if ((nb = read(chatfd, buf, dir->length)) < 0)
			sysfatal("cannot read chatfile %s: %r", chatfile);
		assert(nb == dir->length);
		buf[dir->length] = '\0';
		free(dir);
		close(chatfd);

		p = buf;
		lineno = 0;
		for(;;) {
			char *_args[3];

			if ((s = strchr(p, '\n')) == nil)
				break;
			*s++ = '\0';
		
			lineno++;

			if (*p == '#') {
				p = s; 
				continue;
			}

			if (tokenize(p, _args, 3) != 2)
				sysfatal("invalid line %d (line expected: 'send' 'expect')", 
						lineno);

			if (debug)
				print("sending %s, expecting %s\n", _args[0], _args[1]);

			if(strlen(_args[0])){
				nb = fprint(fd, "%s\r", _args[0]);
				assert(nb > 0);
			}

			if (strlen(_args[1]) > 0) {
				if ((nb = readcr(fd, response, sizeof response-1)) < 0)
					sysfatal("cannot read response from: %r");

				if (debug)
					print("response %s\n", response);

				if (nb == 0)
					sysfatal("eof on input?\n");

				if (cistrstr(response, _args[1]) == nil)
					sysfatal("expected %s, got %s\n", _args[1], response);
			}
			p = s;
		}
		free(buf);
		return;
	}

	print("Connect to file system now, type ctrl-d when done.\n");
	print("...(Use the view or down arrow key to send a break)\n");
	print("...(Use ctrl-e to set even parity or ctrl-o for odd)\n");

	ctl = open("/dev/consctl", OWRITE);
	if(ctl < 0)
		sysfatal("opening consctl");
	fprint(ctl, "rawon");

	fd = dup(fd, -1);
	conndone = 0;
	switch(rfork(RFPROC|RFMEM|RFNOWAIT)){
	case -1:
		sysfatal("forking xfer");
	case 0:
		xfer(fd);
		_exits(nil);
	}

	for(;;){
		read(0, xbuf, 1);
		switch(xbuf[0]&0xff) {
		case CtrlD:	/* done */
			conndone = 1;
			close(ctl);
			print("\n");
			return;
		case CtrlE:	/* set even parity */
			fprint(cfd, "pe");
			break;
		case CtrlO:	/* set odd parity */
			fprint(cfd, "po");
			break;
		case View:	/* send a break */
			fprint(cfd, "k500");
			break;
		default:
			n = write(fd, xbuf, 1);
			if(n < 0) {
				errstr(xbuf, sizeof(xbuf));
				conndone = 1;
				close(ctl);
				print("[remote write error (%s)]\n", xbuf);
				return;
			}
		}
	}
}

int interactive;

void
usage(void)
{
	fprint(2, "usage: ppp [-cCdfPSu] [-b baud] [-k keyspec] [-m mtu] [-p dev] [-s username] [-x netmntpt] [-t modemcmd] [local-addr [remote-addr]]\n");
	exits("usage");
}

void
main(int argc, char **argv)
{
	int mtu, baud, framing, user, mediain, mediaout, cfd;
	Ipaddr ipaddr, remip;
	char *dev, *modemcmd;
	char net[128];
	PPP *ppp;
	char buf[128];

	rfork(RFREND|RFNOTEG|RFNAMEG);

	fmtinstall('I', eipfmt);
	fmtinstall('V', eipfmt);
	fmtinstall('E', eipfmt);

	dev = nil;

	invalidate(ipaddr);
	invalidate(remip);

	mtu = Defmtu;
	baud = 0;
	framing = 0;
	setnetmtpt(net, sizeof(net), nil);
	user = 0;
	modemcmd = nil;

	ARGBEGIN{
	case 'b':
		baud = atoi(EARGF(usage()));
		if(baud < 0)
			baud = 0;
		break;
	case 'c':
		nocompress = 1;
		break;
	case 'C':
		noipcompress = 1;
		break;
	case 'd':
		debug++;
		break;
	case 'f':
		framing = 1;
		break;
	case 'F':
		pppframing = 0;
		break;
	case 'k':
		keyspec = EARGF(usage());
		break;
	case 'm':
		mtu = atoi(EARGF(usage()));
		if(mtu < Minmtu)
			mtu = Minmtu;
		if(mtu > Maxmtu)
			mtu = Maxmtu;
		break;
	case 'M':
		chatfile = EARGF(usage());
		break;
	case 'p':
		dev = EARGF(usage());
		break;
	case 'P':
		primary = 1;
		break;
	case 'S':
		server = 1;
		break;
	case 't':
		modemcmd = EARGF(usage());
		break;
	case 'u':
		user = 1;
		break;
	case 'x':
		setnetmtpt(net, sizeof net, EARGF(usage()));
		break;
	default:
		fprint(2, "unknown option %c\n", ARGC());
		usage();
	}ARGEND;

	switch(argc){
	case 2:
		parseip(remip, argv[1]);
	case 1:
		parseip(ipaddr, argv[0]);
	case 0:
		break;
	default:
		usage();
	}

	nip = nipifcs(net);
	if(nip == 0 && !server)
		primary = 1;

	if(dev != nil){
		mediain = open(dev, ORDWR);
		if(mediain < 0){
			if(strchr(dev, '!')){
				if((mediain = dial(dev, 0, 0, &cfd)) == -1){
					fprint(2, "ppp: couldn't dial %s: %r\n", dev);
					exits(dev);
				}
			} else {
				fprint(2, "ppp: couldn't open %s\n", dev);
				exits(dev);
			}
		} else {
			snprint(buf, sizeof buf, "%sctl", dev);
			cfd = open(buf, ORDWR);
		}
		if(cfd > 0){
			if(baud)
				fprint(cfd, "b%d", baud);
			fprint(cfd, "m1");	/* cts/rts flow control (and fifo's) on */
			fprint(cfd, "q64000");	/* increase q size to 64k */
			fprint(cfd, "n1");	/* nonblocking writes on */
			fprint(cfd, "r1");	/* rts on */
			fprint(cfd, "d1");	/* dtr on */
			fprint(cfd, "c1");	/* dcdhup on */
			if(user || chatfile)
				connect(mediain, cfd);
			close(cfd);
		} else {
			if(user || chatfile)
				connect(mediain, -1);
		}
		mediaout = mediain;
	} else {
		mediain = open("/fd/0", OREAD);
		if(mediain < 0){
			fprint(2, "ppp: couldn't open /fd/0\n");
			exits("/fd/0");
		}
		mediaout = open("/fd/1", OWRITE);
		if(mediaout < 0){
			fprint(2, "ppp: couldn't open /fd/0\n");
			exits("/fd/1");
		}
	}

	if(modemcmd != nil && mediaout >= 0)
		fprint(mediaout, "%s\r", modemcmd);

	ppp = mallocz(sizeof(*ppp), 1);
	pppopen(ppp, mediain, mediaout, net, ipaddr, remip, mtu, framing);

	/* wait until ip is configured */
	rendezvous((void*)Rmagic, 0);

	if(primary){
		/* create a /net/ndb entry */
		putndb(ppp, net);
	}

	exits(0);
}

void
netlog(char *fmt, ...)
{
	va_list arg;
	char *m;
	static long start;
	long now;

	if(debug == 0)
		return;

	now = time(0);
	if(start == 0)
		start = now;

	va_start(arg, fmt);
	m = vsmprint(fmt, arg);
	fprint(2, "%ld %s", now-start, m);
	free(m);
	va_end(arg);
}

/*
 *  return non-zero if this is a valid v4 address
 */
static int
validv4(Ipaddr addr)
{
	return memcmp(addr, v4prefix, IPv4off) == 0 && memcmp(addr, v4prefix, IPaddrlen) != 0;
}

static void
invalidate(Ipaddr addr)
{
	ipmove(addr, IPnoaddr);
}

/*
 *  return number of networks
 */
static int
nipifcs(char *net)
{
	static Ipifc *ifc;
	Ipifc *nifc;
	Iplifc *lifc;
	int n;

	n = 0;
	ifc = readipifc(net, ifc, -1);
	for(nifc = ifc; nifc != nil; nifc = nifc->next)
		for(lifc = ifc->lifc; lifc != nil; lifc = lifc->next)
			n++;
	return n;
}

/*
 *   make an ndb entry and put it into /net/ndb for the servers to see
 */
static void
putndb(PPP *ppp, char *net)
{
	char buf[1024];
	char file[64];
	char *p, *e;
	int fd;

	e = buf + sizeof(buf);
	p = buf;
	p = seprint(p, e, "ip=%I ipmask=255.255.255.255 ipgw=%I\n", ppp->local,
			ppp->remote);
	if(validv4(ppp->dns[0]))
		p = seprint(p, e, "\tdns=%I\n", ppp->dns[0]);
	if(validv4(ppp->dns[1]))
		p = seprint(p, e, "\tdns=%I\n", ppp->dns[1]);
	if(validv4(ppp->wins[0]))
		p = seprint(p, e, "\twins=%I\n", ppp->wins[0]);
	if(validv4(ppp->wins[1]))
		p = seprint(p, e, "\twins=%I\n", ppp->wins[1]);
	seprint(file, file+sizeof file, "%s/ndb", net);
	fd = open(file, OWRITE);
	if(fd < 0)
		return;
	write(fd, buf, p-buf);
	close(fd);
	seprint(file, file+sizeof file, "%s/cs", net);
	fd = open(file, OWRITE);
	write(fd, "refresh", 7);
	close(fd);
	seprint(file, file+sizeof file, "%s/dns", net);
	fd = open(file, OWRITE);
	write(fd, "refresh", 7);
	close(fd);
}

static void
getauth(PPP *ppp)
{
	UserPasswd *up;

	if(*ppp->chapname)
		return;

	up = auth_getuserpasswd(auth_getkey,"proto=pass service=ppp %s", keyspec);
	if(up != nil){
		strcpy(ppp->chapname, up->user);
		strcpy(ppp->secret, up->passwd);
	}		
}