feat(endpoint): add DirectAddrFilter to drop direct address candidates - #4397
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ifdario wants to merge 5 commits into
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feat(endpoint): add DirectAddrFilter to drop direct address candidates#4397ifdario wants to merge 5 commits into
ifdario wants to merge 5 commits into
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Add `Builder::direct_addr_filter`, taking a `DirectAddrFilter` trait object (`Arc<dyn>`, mirroring `PathSelector`), consulted in the magicsock's `update_direct_addresses` before the direct addresses are stored. A rejected address is never stored, published via Address Lookup, or offered as a holepunch / NAT-traversal candidate. This lets an application exclude the address of a virtual interface (e.g. a VPN overlay bound on a TUN device) from the candidate set while still binding to the unspecified address for normal multi-homing. `addr_filter` only filters published data; this filters the underlying candidate set, so it also covers in-band NAT-traversal.
5 tasks
Add a blanket `impl DirectAddrFilter for Vec<IpNet>` so whole CIDR ranges can be excluded without implementing the trait, plus `Builder::exclude_direct_addrs` as a convenience wrapper over it for the common case (e.g. dropping a VPN overlay bound on a TUN device).
Collaborator
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For the random observer: this is linked to #4399 and we need to decide which approach is best. |
Author
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I think they fill different needs |
`exclude_direct_addrs` now wraps a private `ExcludeNets` newtype instead of a public `impl DirectAddrFilter for Vec<IpNet>`, which kept a trait impl on a foreign type out of the public API. `IpNet` is re-exported from `iroh::endpoint` so callers do not need a matching `ipnet` of their own, and `ipnet::*` joins the accepted non-1.0 crates in `allowed_external_types` (the check fails on the `exclude_direct_addrs` signature otherwise). Also documents the filter as covering the whole candidate set rather than just local interface addresses, borrows it instead of cloning the `Arc` on every update, and imports `DirectAddrFilter` instead of naming it inline.
GrizzlT
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Aug 31, 2026
Use iroh's new `Builder::direct_addr_filter` to keep rayfish overlay addresses (100.64.0.0/10, 200::/7) out of the gathered direct-address set, so a mesh IP bound on the TUN is never advertised, published, or offered as a holepunch / NAT-traversal candidate. Previously the overlay IP leaked into the candidate set and peers dialed it, looping the underlay back through the tunnel (a flapping path that fell back to relay latency). Pins iroh (and iroh-base/-dns/-relay) to the fork branch carrying the API, upstream PR n0-computer/iroh#4397.
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Description
Adds
Builder::direct_addr_filterto drop addresses from the endpoint's directaddress candidates. A dropped address is not stored, published, or used for
holepunching / NAT-traversal.
This lets an app exclude a virtual interface's address (e.g. a VPN overlay on a
TUN device) that would otherwise be advertised and dialed by peers, looping the
underlay back into the tunnel.
addr_filteronly covers published data; this runson the candidate set before
store_direct_addresses, so it also covers in-bandNAT-traversal.
DirectAddrFiltertrait (keeps(&self, ip) -> bool), modelled onPathSelector.Builder::direct_addr_filter, stored onOptions/Socket, applied inupdate_direct_addresses.Breaking Changes
None. Optional, defaults to off.
Notes & open questions
Applied at the final gate so it covers all sources (local, QAD, portmap, config).
Could be scoped to local-interface addresses instead if preferred.
Change checklist
proposed change and wrote an as clear and concise description as
they could.
intented effect.