dhcp: allow suppressing default gateway from lease result - #1276
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locker95 wants to merge 2 commits into
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dhcp: allow suppressing default gateway from lease result#1276locker95 wants to merge 2 commits into
locker95 wants to merge 2 commits into
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Some DHCP servers send a router option even when the client did not
request it (skipDefault only affects the parameter request list). With
Multus secondary attachments that installs a second default route and
breaks pod networking.
Add an ipam.suppress list; when it includes "gateway", clear
IPConfig.Gateway and drop default routes (0.0.0.0/0, ::/0) from the
result while keeping non-default routes such as option 121 classless
static routes.
Example:
"ipam": { "type": "dhcp", "suppress": ["gateway"] }
Fixes containernetworking#1208
Signed-off-by: Dean Chen <862469039@qq.com>
nonamedreturns fails CI on the suppress helper. Signed-off-by: Dean Chen <862469039@qq.com>
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Summary
When Multus (or similar) attaches a secondary interface with the dhcp IPAM plugin, a DHCP-provided default gateway is written into the CNI result. That becomes a second default route in the pod and often breaks connectivity. Multus documents this failure mode, and
skipDefaultonly changes the DHCP parameter request list — many servers still send option 3 (routers) unsolicited.This adds an
ipam.suppresslist. With"suppress": ["gateway"]:IPConfig.Gatewayis left empty0.0.0.0/0,::/0) are dropped fromRoutesThis is intentionally narrower than the abandoned
discardDhcpRoutesapproach in #701, which dropped all DHCP routes (maintainers called that out).Example
{ "type": "macvlan", "master": "eth1", "mode": "bridge", "ipam": { "type": "dhcp", "suppress": ["gateway"] } }request/skipDefaultremain unchanged for clients that want to avoid requesting the router option;suppresscovers servers that send it anyway.Test plan
parseSuppress,isDefaultRoute,filterDefaultRoutesgo test ./plugins/ipam/dhcp/(package needs netns/root; pure helpers compile withGOOS=linux)Fixes #1208