[libvirt] [PATCH 0/9] add DHCP snooping support to nwfilter

The following series of patches replaces IP address learning in network filtering with DHCP snooping. The existing address learning capability does not provide security since it relies on addresses used in initial packets sent by the guest to determine an IP address. A spoofing guest can simply arrange to send packets using the target address early on. With DHCP snooping, only addresses acknowledged by a DHCP server can be used by the guest, and only for the given lease time if the address lease is not renewed. The patches also add support for multiple IP addresses per interface. The split: p1 -add return & continue support Add support for "return" and "continue" in filters. p2 -fix ARP input checks Fix a bug that breaks correct use of ARP by overfiltering. p3 -add MAC check; split ARP intp ARPMAC and ARPIP Support for multiple IP addresses in ARP checks, and allow for multiple MAC addresses in the future. p4 -set default protocol policy to "DROP"; edit filters Change default protocol policy to "DROP", rather than adding explicit "DROP" rules at the end of all of them. This is for multiple address support. p5 -optional "modify" (don't use temp, generate placeholder rules) Add support to dynamically add and remove filters without re-installing an entire chain. p6 -addRules Add support for adding new rules to a chain incrementally. Remove support was already there. p7 -ChangeVar support Add support to change chains that have a matching variable substitution to either add or delete rules with the given variable value (e.g., "IP") p8 -add DHCP snooping The DHCP snooping code itself. p9 -delete learnipaddr Clean up remaining learnipaddr infrastructure.