[WIP] Linux: set broadcast flag by default for ipvlan interfaces. #33
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rsmarples
requested changes
Apr 23, 2021
|
Please remember to change the documentation as well! |
rsmarples
reviewed
Apr 24, 2021
rsmarples
reviewed
Apr 24, 2021
rsmarples
reviewed
Apr 24, 2021
rsmarples
reviewed
Apr 24, 2021
|
I squashed the commits into one patch. So far, this sets broadcast. I might have a solution for setting unique IAIDs soon. |
Linux ipvlan interfaces share a MAC address with their siblings and parent physical interface. Before they are assigned an IP address, these virtual interfaces do not receive DHCP OFFER unicast messages because the ipvlan driver does not know to pass them to the virtual interface yet by IP. This chicken-and-egg problem is resolved with two changes: In this patch, we set the broadcast flag for an interface if it belongs to the ipvlan driver, as detected via SIOCETHTOOL ETHTOOL_GDRVINFO. (closes #32) A forthcoming patch will automatically modify the DHCP IAID for ipvlan interfaces so that they do not conflict with the parent (lower/physical) interface IAID. For now, dhcpcd will display a warning log message when conflicting IAID (same MAC address) interfaces are active. (A minor grammar correction is included free of charge.)
rsmarples
reviewed
Apr 25, 2021
Differentiate between ioctl error and zero-length driver name in if_get_driver.
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The patch uses ethtool's
SIOCETHTOOLioctlto obtain the driver name of the interface, and turns on the broadcast flag by default when it detects anipvlaninterface. This does not yet differentiate between L2, L3, or L3S mode.@rsmarples we can use this
ethtoolmethod to detect most other device types, likebridgeandtuntap, without reading/sys. I might refactor those after this is cleaned up.TODO:
ipvlaninterfaces do not generate an IAID conflict:ipvlan0: IAID conflicts with one assigned to eth0Fixes #32