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device: set a per-device default MTU on activation

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In absence of an explicit MTU (either via user configuration, PPP or
DHCP), set a default MTU on activation that depends on the device type.

We only want to do that on the very first call to _commit_mtu(). Later
calls (for example in response to new DHCP leases) skip over this step.

This means, on activation the MTU will always be reset to a sensible
value instead of preserving whatever was left from a previous
configuration.

This does not cover setting the MTU from the VPN plugin :(
This commit is contained in:
Thomas Haller
2017-01-16 12:18:51 +01:00
parent 1e67c7ac0b
commit 22e8af6242
1 changed files with 25 additions and 5 deletions
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30
src/devices/nm-device.c
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@@ -310,7 +310,9 @@ typedef struct _NMDevicePrivate {
guint32 mtu_initial;
guint32 ip6_mtu_initial;
bool up; /* IFF_UP */
bool mtu_initialized:1;
bool up:1; /* IFF_UP */
/* Generic DHCP stuff */
guint32 dhcp_timeout;
@@ -2573,6 +2575,7 @@ realize_start_setup (NMDevice *self, const NMPlatformLink *plink)
/* Balanced by a thaw in nm_device_realize_finish() */
g_object_freeze_notify (G_OBJECT (self));
priv->mtu_initialized = FALSE;
priv->mtu_initial = 0;
priv->ip6_mtu_initial = 0;
priv->ip6_mtu = 0;
@@ -6625,10 +6628,9 @@ _commit_mtu (NMDevice *self, const NMIP4Config *config)
gboolean mtu_is_user_config = FALSE;
guint32 mtu = 0;
/* preferably, get the MTU from explict user-configuration. If that fails,
* look at the current @config (which contains MTUs from DHCP/PPP.
*
* Finally, assume no MTU change. */
/* preferably, get the MTU from explict user-configuration.
* Only if that fails, look at the current @config (which contains
* MTUs from DHCP/PPP) or maybe fallback to a device-specific MTU. */
if (NM_DEVICE_GET_CLASS (self)->get_configured_mtu)
mtu = NM_DEVICE_GET_CLASS (self)->get_configured_mtu (self, &mtu_is_user_config);
@@ -6640,10 +6642,27 @@ _commit_mtu (NMDevice *self, const NMIP4Config *config)
mtu_desired = nm_ip4_config_get_mtu (config);
else
mtu_desired = 0;
if (!mtu_desired && !priv->mtu_initialized) {
/* there is no MTU specified, and this is the first commit of the MTU.
* Reset a per-device MTU default, as returned from get_configured_mtu().
*
* The device might choose not to return a default MTU via get_configured_mtu()
* to suppress this behavior. */
mtu_desired = mtu;
}
}
}
ip6_mtu = priv->ip6_mtu;
if (!ip6_mtu && !priv->mtu_initialized) {
/* initially, if the IPv6 MTU is not specified, grow it as large as the
* link MTU @mtu_desired. Only exception is, if @mtu_desired is so small
* to disable IPv6. */
if (mtu_desired >= 1280)
ip6_mtu = mtu_desired;
}
priv->mtu_initialized = TRUE;
if (!ip6_mtu && !mtu_desired)
return;
@@ -11455,6 +11474,7 @@ nm_device_cleanup (NMDevice *self, NMDeviceStateReason reason, CleanupType clean
NM_DEVICE_GET_CLASS (self)->deactivate_reset_hw_addr (self);
}
priv->mtu_initialized = FALSE;
if (priv->mtu_initial || priv->ip6_mtu_initial) {
ifindex = nm_device_get_ip_ifindex (self);