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dhcp/nettools: don't trim the "expiry" timestamp to 32 bit

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The "expiry" is the Unix timestamp when the lease expires.
This is not at all a useful parameter, in particular because
the system's clock can be reset. Instead, we should expose
the lease receive time stamp (in CLOCK_BOOTTIME), and the lease
lifetime.

Anyway. So, we somehow need to express infinite lifetimes. Previously,
we would use the special value 4294967295 (2^32-1). However, that value
does not seem so great, because it's also the Unix timestamp of
2106-02-07T06:28:15+0000. While that is quite far in the future, it's
a valid timestamp still. Of course, the code worked around that by never
setting a timestamp larger than 4294967295-1, but it still limits the
range of what we can expose.

Note that for the lifetime "dhcp_lease_time", we do express infinity
with 4294967295. That's fine, it also does not contradict what we
receive in the DHCP lease on the wire because the lifetime there is
expressed by a 32 bit integer.

Instead, for the "expiry" timestamp, don't perform such triming.
The expiry timestamp is just the start timestamp plus the lease
lifetime. If that is larger than 2106-02-07, so be it.
On the other hand, express infinity by omitting the "expiry" field.
This commit is contained in:
Thomas Haller
2019-09-23 16:14:05 +02:00
parent 42026f9fb3
commit a8d46492b3
1 changed files with 8 additions and 9 deletions
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17
src/dhcp/nm-dhcp-nettools.c
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@@ -372,7 +372,7 @@ lease_parse_address (NDhcp4ClientLease *lease,
*/
if (nettools_lifetime == G_MAXUINT64) {
a_lifetime = NM_PLATFORM_LIFETIME_PERMANENT;
a_expiry = NM_PLATFORM_LIFETIME_PERMANENT;
a_expiry = -1;
} else {
gint64 ts_time = time (NULL);
@@ -383,10 +383,7 @@ lease_parse_address (NDhcp4ClientLease *lease,
else if (a_lifetime > NM_PLATFORM_LIFETIME_PERMANENT)
a_lifetime = NM_PLATFORM_LIFETIME_PERMANENT - 1;
if (ts_time > NM_PLATFORM_LIFETIME_PERMANENT - a_lifetime)
a_expiry = NM_PLATFORM_LIFETIME_PERMANENT - 1;
else
a_expiry = ts_time + a_lifetime;
a_expiry = ts_time + a_lifetime;
}
if (!lease_get_in_addr (lease, NM_DHCP_OPTION_DHCP4_SUBNET_MASK, &a_netmask)) {
@@ -411,10 +408,12 @@ lease_parse_address (NDhcp4ClientLease *lease,
NM_DHCP_OPTION_DHCP4_IP_ADDRESS_LEASE_TIME,
(guint64) a_lifetime);
nm_dhcp_option_add_option_u64 (options,
_nm_dhcp_option_dhcp4_options,
NM_DHCP_OPTION_DHCP4_NM_EXPIRY,
(guint64) a_expiry);
if (a_expiry != -1) {
nm_dhcp_option_add_option_u64 (options,
_nm_dhcp_option_dhcp4_options,
NM_DHCP_OPTION_DHCP4_NM_EXPIRY,
(guint64) a_expiry);
}
n_dhcp4_client_lease_get_siaddr (lease, &a_next_server);