ip/ipconfig: initial dhcpv6 support, clean default-routes and /net/ndb on remove

This adds a very basic (probably wrong) DHCPv6 client,
to handle the "managed"-flag in IPv6 router solicitations.

We add -U option to pass the DHCPv6 client id as well as
an -s flag to manually add a dns server (because ppp
is going to call ipconfig to handle all the configuration
and write-back to /net/ndb in the future).

Have the remove command also remove default routes and
/net/ndb entries. (needed by ppp).

1 files changed, 233 insertions, 0 deletions

diff --git a/sys/src/cmd/ip/ipconfig/dhcpv6.c b/sys/src/cmd/ip/ipconfig/dhcpv6.c
new file mode 100644
index 000000000..ba31fb1e3
--- /dev/null
+++ b/sys/src/cmd/ip/ipconfig/dhcpv6.c
@@ -0,0 +1,233 @@
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+#include <ip.h>
+#include <ndb.h>
+#include "ipconfig.h"
+
+enum {
+	SOLICIT	= 1,
+	ADVERTISE,
+	REQUEST,
+	CONFIRM,
+	RENEW,
+	REBIND,
+	REPLY,
+	RELEASE,
+	DECLINE,
+	RECONFIGURE,
+	INFOREQ,
+	RELAYFORW,
+	RELAYREPL,
+};
+
+static uchar v6dhcpservers[IPaddrlen] = {
+	0xff, 0x02, 0, 0,
+	0, 0, 0, 0,
+	0, 0, 0, 0,
+	0, 1, 0, 2,
+};
+
+static uchar sid[256];
+static int sidlen;
+
+static int
+openlisten(void)
+{
+	int n, fd, cfd;
+	char data[128], devdir[40];
+
+	sprint(data, "%s/udp!%I!546", conf.mpoint, conf.lladdr);
+	for (n = 0; (cfd = announce(data, devdir)) < 0; n++) {
+		if(!noconfig)
+			sysfatal("can't announce for dhcp: %r");
+
+		/* might be another client - wait and try again */
+		warning("can't announce %s: %r", data);
+		sleep(jitter());
+		if(n > 10)
+			return -1;
+	}
+
+	if(fprint(cfd, "headers") < 0)
+		sysfatal("can't set header mode: %r");
+
+	fprint(cfd, "ignoreadvice");
+
+	sprint(data, "%s/data", devdir);
+	fd = open(data, ORDWR);
+	if(fd < 0)
+		sysfatal("open %s: %r", data);
+	close(cfd);
+	return fd;
+}
+
+static int
+transaction(int fd, int type, int timeout)
+{
+	union {
+		Udphdr;
+		uchar	buf[4096];
+	} ipkt, opkt;
+
+	uchar *p, *e, *x;
+	int tra, opt, len, sleepfor;
+
+	tra = lrand() & 0xFFFFFF;
+
+	ipmove(opkt.laddr, conf.lladdr);
+	ipmove(opkt.raddr, v6dhcpservers);
+	ipmove(opkt.ifcaddr, conf.lladdr);
+	hnputs(opkt.lport, 546);
+	hnputs(opkt.rport, 547);
+
+	p = opkt.buf + Udphdrsize;
+
+	*p++ = type;
+	*p++ = tra >> 16;
+	*p++ = tra >> 8;
+	*p++ = tra >> 0;
+
+	/* client identifier */
+	*p++ = 0x00; *p++ = 0x01;
+	/* len */
+	*p++ = conf.duidlen >> 8;
+	*p++ = conf.duidlen;
+	memmove(p, conf.duid, conf.duidlen);
+	p += conf.duidlen;
+
+	/* IA for non-temporary address */
+	len = 12;
+	if(validip(conf.laddr))
+		len += 4 + IPaddrlen + 2*4;
+	*p++ = 0x00; *p++ = 0x03;
+	*p++ = len >> 8;
+	*p++ = len;
+	/* IAID */
+	*p++ = 0x00; *p++ = 0x00; *p++ = 0x00; *p++ = 0x01;
+	/* T1, T2 */
+	*p++ = 0x00; *p++ = 0x00; *p++ = 0x00; *p++ = 0x00;
+	*p++ = 0x00; *p++ = 0x00; *p++ = 0x00; *p++ = 0x00;
+	if(len > 12){
+		*p++ = 0x00; *p++ = 0x05;
+		*p++ = 0x00; *p++ = IPaddrlen + 2*4;
+		memmove(p, conf.laddr, IPaddrlen);
+		p += IPaddrlen;
+		memset(p, 0xFF, 2*4);
+		p += 2*4;
+	}
+
+	/* Option Request */
+	*p++ = 0x00; *p++ = 0x06;
+	*p++ = 0x00; *p++ = 0x02;
+	*p++ = 0x00; *p++ = 0x17;	/* DNS servers */
+
+	if(sidlen > 0){
+		*p++ = 0x00; *p++ = 0x02;
+		/* len */
+		*p++ = sidlen >> 8;
+		*p++ = sidlen;;
+		memmove(p, sid, sidlen);
+		p += sidlen;
+	}
+
+	len = -1;
+	for(sleepfor = 500; timeout > 0; sleepfor <<= 1){
+		DEBUG("sending dhcpv6 request %x", opkt.buf[Udphdrsize]);
+
+		alarm(sleepfor);
+		if(len < 0)
+			write(fd, opkt.buf, p - opkt.buf);
+
+		len = read(fd, ipkt.buf, sizeof(ipkt.buf));
+		timeout += alarm(0);
+		timeout -= sleepfor;
+		if(len == 0)
+			break;
+
+		if(len < Udphdrsize+4)
+			continue;
+		if(ipkt.buf[Udphdrsize+1] != ((tra>>16)&0xFF)
+		|| ipkt.buf[Udphdrsize+2] != ((tra>>8)&0xFF)
+		|| ipkt.buf[Udphdrsize+3] != ((tra>>0)&0xFF))
+			continue;
+
+		DEBUG("got dhcpv6 reply %x from %I on %I", ipkt.buf[Udphdrsize+0], ipkt.raddr, ipkt.ifcaddr);
+
+		type |= (int)ipkt.buf[Udphdrsize+0]<<8;
+		switch(type){
+		case ADVERTISE << 8 | SOLICIT:
+		case REPLY << 8 | REQUEST:
+			goto Response;
+		default:
+			return -1;
+		}
+	}
+	return -1;
+
+Response:
+	for(p = ipkt.buf + Udphdrsize + 4, e = ipkt.buf + len; p < e; p = x) {
+		if (p+4 > e)
+			return -1;
+
+		opt = (int)p[0] << 8 | p[1];
+		len = (int)p[2] << 8 | p[3];
+		p += 4;
+		x = p+len;
+		if (x > e)
+			return -1;
+
+		DEBUG("got dhcpv6 option %x: [%d] %.*H", opt, len, len, p);
+
+		switch(opt){
+		case 0x01:		/* client identifier */
+			continue;
+		case 0x02:		/* server identifier */
+			if(len < 1 || len > sizeof(sid))
+				break;
+			sidlen = len;
+			memmove(sid, p, sidlen);
+			continue;
+		case 0x03:		/* IA for non-temporary address */
+			if(p+12+4+IPaddrlen+2*4 > x)
+				break;
+			/* skip IAID, T1, T2 */
+			p += 12;
+			/* IA Addresss */
+			if(p[0] != 0x00 || p[1] != 0x05
+			|| p[2] != 0x00 || p[3] != IPaddrlen+2*4)
+				break;
+			p += 4;
+			memset(conf.mask, 0xFF, IPaddrlen);
+			memmove(conf.laddr, p, IPaddrlen);
+			continue;
+		case 0x17:	/* dns servers */
+			if(len % IPaddrlen)
+				break;
+			addaddrs(conf.dns, sizeof(conf.dns), p, len);
+			continue;
+		default:
+			DEBUG("unknown dhcpv6 option %x", opt);
+			continue;
+		}
+		warning("dhcpv6: malformed option %x: [%d] %.*H", opt, len, len, x-len);
+	}
+
+	return 0;
+}
+
+void
+dhcpv6query(void)
+{
+	int fd;
+
+	fd = openlisten();
+	if(transaction(fd, SOLICIT, 5000) < 0)
+		goto out;
+	if(!validip(conf.laddr))
+		goto out;
+	if(transaction(fd, REQUEST, 10000) < 0)
+		goto out;
+out:
+	close(fd);
+}