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dhcpv6: Fix REPLY messages with NotOnLink status code

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The NotOnLink status code needs to be appended to the existing IA
content, because if we omit the requested addresses in the reply,
ISC's dhclient handles it as a NoAddrsAvail response.

Also fix length accounting (we would send a bunch of zeroes after
the IA otherwise), and print an informational message with the
requested address, if it's not appropriate for the link.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Stefano Brivio 2021-04-21 17:15:23 +02:00
parent 61fa05c7c0
commit faff133629
1 changed files with 19 additions and 9 deletions
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28
dhcpv6.c
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@ -299,6 +299,7 @@ static struct opt_hdr *dhcpv6_ia_notonlink(struct opt_hdr *o, size_t len,
struct in6_addr *addr)
{
struct opt_hdr *ia, *ia_addr;
char buf[INET6_ADDRSTRLEN];
struct in6_addr *req_addr;
size_t __len;
int ia_type;
@ -309,7 +310,7 @@ ia_ta:
ia = o;
while ((ia = dhcpv6_opt(ia, ia_type, &__len))) {
size_t ia_len = ntohs(ia->l) - sizeof(struct opt_hdr);
size_t ia_len = ntohs(ia->l);
if (ia_len > __len)
return NULL;
@ -328,8 +329,13 @@ ia_ta:
struct opt_ia_addr *next;
req_addr = (struct in6_addr *)(ia_addr + 1);
if (memcmp(addr, req_addr, sizeof(*addr)))
if (memcmp(addr, req_addr, sizeof(*addr))) {
info("DHCPv6: requested address %s not on link",
inet_ntop(AF_INET6, req_addr,
buf, sizeof(buf)));
return ia;
}
next = (struct opt_ia_addr *)ia_addr + 1;
ia_addr = (struct opt_hdr *)next;
@ -412,17 +418,21 @@ int dhcpv6(struct ctx *c, struct ethhdr *eh, size_t len)
if ((bad_ia = dhcpv6_ia_notonlink((struct opt_hdr *)(mh + 1),
mlen, &c->addr6))) {
n = OPT_IA_NA ? sizeof(struct opt_ia_na) :
sizeof(struct opt_ia_ta);
memcpy(&resp_not_on_link.var, bad_ia, n);
info("DHCPv6: received CONFIRM with inappropriate IA,"
" sending NotOnLink status in REPLY");
memcpy(&resp_not_on_link.var + n, &sc_not_on_link,
n = ntohs(bad_ia->l) + sizeof(struct opt_hdr);
bad_ia->l = htons(n - sizeof(struct opt_hdr) +
sizeof(sc_not_on_link));
memcpy(resp_not_on_link.var, bad_ia, n);
memcpy(resp_not_on_link.var + n, &sc_not_on_link,
sizeof(sc_not_on_link));
n += sizeof(sc_not_on_link);
memcpy(&resp_not_on_link.var + n, client_id,
sizeof(struct opt_hdr) + client_id->l);
n += sizeof(struct opt_hdr) + client_id->l;
memcpy(resp_not_on_link.var + n, client_id,
sizeof(struct opt_hdr) + ntohs(client_id->l));
n += sizeof(struct opt_hdr) + ntohs(client_id->l);
n = offsetof(struct resp_not_on_link_t, var) + n;
resp_not_on_link.uh.len = htons(n);