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Avoid RA code trampling on DHCPv6 messages.

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Calling lease_update_file() _can_ result in a call to  periodic_ra()

Since both the DHCPv6 and RA subsystems use the same packet buffer
this can overwrite the DHCPv6 packet. To avoid this we ensure the
DHCPv6 packet has been sent before calling lease_update_file().
This commit is contained in:
Simon Kelley
2019-12-20 18:19:20 +00:00
parent 9e732445cf
commit 18a6bdd541
1 changed files with 22 additions and 13 deletions
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35
src/dhcp6.c
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@@ -135,7 +135,14 @@ void dhcp6_packet(time_t now)
if (!indextoname(daemon->dhcp6fd, if_index, ifr.ifr_name))
return;
if ((port = relay_reply6(&from, sz, ifr.ifr_name)) == 0)
if ((port = relay_reply6(&from, sz, ifr.ifr_name)) != 0)
{
from.sin6_port = htons(port);
while (retry_send(sendto(daemon->dhcp6fd, daemon->outpacket.iov_base,
save_counter(-1), 0, (struct sockaddr *)&from,
sizeof(from))));
}
else
{
struct dhcp_bridge *bridge, *alias;
@@ -233,21 +240,23 @@ void dhcp6_packet(time_t now)
port = dhcp6_reply(parm.current, if_index, ifr.ifr_name, &parm.fallback,
&parm.ll_addr, &parm.ula_addr, sz, &from.sin6_addr, now);
/* The port in the source address of the original request should
be correct, but at least once client sends from the server port,
so we explicitly send to the client port to a client, and the
server port to a relay. */
if (port != 0)
{
from.sin6_port = htons(port);
while (retry_send(sendto(daemon->dhcp6fd, daemon->outpacket.iov_base,
save_counter(-1), 0, (struct sockaddr *)&from,
sizeof(from))));
}
/* These need to be called _after_ we send DHCPv6 packet, since lease_update_file()
may trigger sending an RA packet, which overwrites our buffer. */
lease_update_file(now);
lease_update_dns(0);
}
/* The port in the source address of the original request should
be correct, but at least once client sends from the server port,
so we explicitly send to the client port to a client, and the
server port to a relay. */
if (port != 0)
{
from.sin6_port = htons(port);
while (retry_send(sendto(daemon->dhcp6fd, daemon->outpacket.iov_base,
save_counter(-1), 0, (struct sockaddr *)&from,
sizeof(from))));
}
}
void get_client_mac(struct in6_addr *client, int iface, unsigned char *mac, unsigned int *maclenp, unsigned int *mactypep, time_t now)