This is an alternative for #27407 with a solution based on gencodec.
With the PR, one can now configure like this:
```
# config.toml
[Node.P2P]
NAT = "extip:33.33.33.33"
```
```shell
$ geth --config config.toml
...
INFO [01-17|16:37:31.436] Started P2P networking self=enode://2290...ab@33.33.33.33:30303
```
Closes#23210
# Context
When deploying Geth in Kubernetes with ReplicaSets, we encountered two
DNS-related issues affecting node connectivity. First, during startup,
Geth tries to resolve DNS names for static nodes too early in the config
unmarshaling phase. If peer nodes aren't ready yet (which is common in
Kubernetes rolling deployments), this causes an immediate failure:
```
INFO [11-26|10:03:42.816] Starting Geth on Ethereum mainnet...
INFO [11-26|10:03:42.817] Bumping default cache on mainnet provided=1024 updated=4096
Fatal: config.toml, line 81: (p2p.Config.StaticNodes) lookup idontexist.geth.node: no such host
```
The second issue comes up when pods get rescheduled to different nodes -
their IPs change but peers keep using the initially resolved IP, never
updating the DNS mapping.
This PR adds proper DNS support for enode:// URLs by deferring resolution
to connection time. It also handles DNS failures gracefully instead of failing
fatally during startup, making it work better in container environments where
IPs are dynamic and peers come and go during rollouts.
---------
Co-authored-by: Felix Lange <fjl@twurst.com>
This fixes an issue where the disconnect message was not wrapped in a list.
The specification requires it to be a list like any other message.
In order to remain compatible with legacy geth versions, we now accept both
encodings when parsing a disconnect message.
---------
Co-authored-by: Felix Lange <fjl@twurst.com>
This PR modifies how the metrics library handles `Enabled`: previously,
the package `init` decided whether to serve real metrics or just
dummy-types.
This has several drawbacks:
- During pkg init, we need to determine whether metrics are enabled or
not. So we first hacked in a check if certain geth-specific
commandline-flags were enabled. Then we added a similar check for
geth-env-vars. Then we almost added a very elaborate check for
toml-config-file, plus toml parsing.
- Using "real" types and dummy types interchangeably means that
everything is hidden behind interfaces. This has a performance penalty,
and also it just adds a lot of code.
This PR removes the interface stuff, uses concrete types, and allows for
the setting of Enabled to happen later. It is still assumed that
`metrics.Enable()` is invoked early on.
The somewhat 'heavy' operations, such as ticking meters and exp-decay,
now checks the enable-flag to prevent resource leak.
The change may be large, but it's mostly pretty trivial, and from the
last time I gutted the metrics, I ensured that we have fairly good test
coverage.
---------
Co-authored-by: Felix Lange <fjl@twurst.com>
Changelog: https://golangci-lint.run/product/changelog/#1610
Removes `exportloopref` (no longer needed), replaces it with
`copyloopvar` which is basically the opposite.
Also adds:
- `durationcheck`
- `gocheckcompilerdirectives`
- `reassign`
- `mirror`
- `tenv`
---------
Co-authored-by: Marius van der Wijden <m.vanderwijden@live.de>
