Better sanity for working out if our SLA id overflows the PD length + interface id.

diff --git a/dhcp6.c b/dhcp6.c
index 1291e2ddc144ed1545c6063b5d2f5fa106c271ec..e5a384f7f2e5d3000d90404f634520a88a3058b1 100644 (file)
--- a/dhcp6.c
+++ b/dhcp6.c
@@ -1333,7 +1333,7 @@ dhcp6_delegate_addr(struct interface *ifp, const struct ipv6_addr *prefix,
 {
        struct dhcp6_state *state;
        struct ipv6_addr *a, *ap;
-       int b, i, l;
+       int b, i, l, pl, hl;
        const uint8_t *p;
        char iabuf[INET6_ADDRSTRLEN];
        const char *ia;
@@ -1341,9 +1341,11 @@ dhcp6_delegate_addr(struct interface *ifp, const struct ipv6_addr *prefix,
        state = D6_STATE(ifp);
 
        l = prefix->prefix_len + sla->sla_len;
-       if (l < 0 || l > 128) {
-               syslog(LOG_ERR, "%s: invalid prefix length (%d + %d = %d)",
-                   ifs->name, prefix->prefix_len, sla->sla_len, l);
+       hl= (ifp->hwlen * 8) + (2 * 8); /* 2 magic bytes for ethernet */
+       pl = l + hl;
+       if (pl < 0 || pl > 128) {
+               syslog(LOG_ERR, "%s: invalid prefix length (%d + %d + %d = %d)",
+                   ifs->name, prefix->prefix_len, sla->sla_len, hl, pl);
                return NULL;
        }
 
@@ -1377,7 +1379,7 @@ dhcp6_delegate_addr(struct interface *ifp, const struct ipv6_addr *prefix,
        for (i = 0, b = prefix->prefix_len; b > 0; b -= 8, i++)
                a->prefix.s6_addr[i] = prefix->prefix.s6_addr[i];
        p = &sla->sla[3];
-       i = (128 - 64) / 8;
+       i = (128 - hl) / 8;
        for (b = sla->sla_len; b > 7; b -= 8, p--)
                a->prefix.s6_addr[--i] = *p;
        if (b)