dhcp: send DHCPRELEASE with the client IP addr as ciaddr - #1279
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The dhcp IPAM plugin sends DHCPRELEASE packets with 0.0.0.0 as the IP source address instead of the client's assigned IP. This violates RFC 2131 section 4.4.4 and causes DHCP servers (e.g. dnsmasq) to silently ignore the release. Leases are never freed — they only expire via timeout. By using the `nclient4.WithUnicast()` option, the client will stop using a raw packet socket which constructs IP headers with 0.0.0.0 as the source. Using src IP 0.0.0.0 is appropriate for DHCPDISCOVER (no address assigned yet) but wrong for DHCPRELEASE. Signed-off-by: Miguel Duarte Barroso <mdbarroso@redhat.com>
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Tested this fix manually and it is working as expected - CNI DEL with DHCP IPAM sends the DHCPRELEASE msg w/ the proper source IP address, and in turn, dnsmasq actually processes the packet and releases the DHCP lease. |
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The dhcp IPAM plugin sends DHCPRELEASE packets with 0.0.0.0 as the IP source address instead of the client's assigned IP.
This violates RFC 2131 section 4.4.4 (quote below) and causes DHCP servers (e.g. dnsmasq) to silently ignore the release. Leases are never freed - they only expire via timeout.
By using the
nclient4.WithUnicast()option to create theDHCPClient, the client will send unicast msgs.Fixes: #1278