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ip/dhcp6d: work arround non-ethernet based client duid

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in ndb, we use the ethernet mac to identify the client.
in dhcpv6, there is just a uniqueue device id that
might even be generated randomly. to find the ethernet
address of a client, check the duid type and only use
it when the dudid is of type 1 (link layer) or 3 (link
layer address + time) and the link layer address type
is 1 (ethernet). otherwise, assume the source ip is
a link local address and extract it from that.

this hack works for thinkpad t495, which uses random
uuid based client duid.
This commit is contained in:
cinap_lenrek 2020-03-31 21:57:53 +02:00
parent 480ce0314e
commit d3512f60df
1 changed files with 31 additions and 4 deletions
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35
sys/src/cmd/ip/dhcp6d.c
View file

@ -31,7 +31,8 @@ struct Req
Udphdr *udp;
Ipifc *ifc;
uchar mac[Eaddrlen];
int ncid;
uchar cid[256];
uchar ips[IPaddrlen*8];
int nips;
@ -236,6 +237,31 @@ lookupips(uchar *ip, int n, Ndb *db, uchar mac[Eaddrlen])
return r;
}
static uchar*
clientea(Req *r)
{
static uchar ea[Eaddrlen];
u32int type;
uchar *ip;
if(r->ncid >= 4+Eaddrlen){
type = r->cid[0]<<24 | r->cid[1]<<16 | r->cid[2]<<8 | r->cid[3];
switch(type){
case 0x00010001:
case 0x00030001:
return r->cid + r->ncid - Eaddrlen;
}
}
ip = r->udp->raddr;
ea[0] = ip[8] ^ 2;
ea[1] = ip[9];
ea[2] = ip[10];
ea[3] = ip[13];
ea[4] = ip[14];
ea[5] = ip[15];
return ea;
}
static void
clearotab(void)
{
@ -387,7 +413,7 @@ main(int argc, char *argv[])
if((r->db = opendb()) == nil)
continue;
r->nips = lookupips(r->ips, sizeof(r->ips), r->db, r->mac)/IPaddrlen;
r->nips = lookupips(r->ips, sizeof(r->ips), r->db, clientea(r))/IPaddrlen;
if(debug){
for(i=0; i<r->nips; i++)
fprint(2, "ip=%I\n", r->ips+i*IPaddrlen);
@ -411,10 +437,11 @@ oclientid(uchar *w, int n, Otab*, Req *r)
if((p = gettlv(1, &len, r->req.p, r->req.e)) == nil)
return -1;
if(len < 4+4+Eaddrlen || n < len)
if(len > sizeof(r->cid) || n < len)
return -1;
memmove(r->mac, p+len-Eaddrlen, Eaddrlen);
memmove(w, p, len);
memmove(r->cid, p, len);
r->ncid = len;
return len;
}