update consts and add discrete types for enums

[thaJeztah]

document IPVS netlink constants and use explicit values

Replace iota-based constant definitions with explicit values matching
the Linux kernel's IPVS generic netlink interface.

Add comments identifying the corresponding kernel constants and links
to their definitions in the Linux UAPI headers.

This makes it easier to verify the values against the kernel and
prevents accidental changes to protocol values when constants are
added or reordered.

define a distinct type for IPVS netlink commands

Introduce an ipvsCmd type for IPVS generic netlink commands and
update the command helpers to use it.

This groups the command constants under a distinct type, allowing
linters such as exhaustive to detect missing cases in switches and
providing stronger type checking.

Keep the generic netlink request helper accepting uint8, as it is
also used for commands outside the IPVS family.

define distinct types for IPVS netlink attributes

Introduce dedicated types for IPVS command, service, destination,
and statistics attributes, using int as the underlying type to
match the netlink package's API.

Update the encoding and decoding paths to use these types, with
explicit conversions at the netlink API boundaries.

This improves type safety and allows linters such as exhaustive
to detect missing attribute cases in switch statements.

The attribute values and wire format remain unchanged.

deduplicate IPVS forwarding method constants

Use the ConnFwd* constants as the canonical names for IPVS
forwarding methods, and deprecate the duplicate ConnectionFlag*
constants while retaining them as aliases for compatibility.

Update internal references to use ConnFwd* and document their
corresponding Linux kernel definitions.

Simplify lookupFwMethod by returning string literals directly
instead of indexing into a separate slice, and handle the
previously missing LocalNode and Bypass methods.

document IPVS scheduler name constants

Add a reference to the Linux kernel's IPVS scheduler implementations
to clarify where the scheduler names originate.

Unlike the netlink attributes and forwarding flags, these names
are registered as strings by the individual kernel schedulers,
rather than defined as UAPI constants.

use unix address family constants directly

Replace nl.FAMILY_* constants with their corresponding unix.AF_*
constants.

The netlink package aliases these constants to the Linux address
family values, so using golang.org/x/sys/unix directly avoids an
unnecessary layer of indirection and makes their origin explicit.

[Copilot]

🟢 Approval recommended

The type-safety changes preserve protocol values and consistently update all affected call sites.

0 open findings

What changed in this PR

Introduces type-safe IPVS netlink enums while preserving existing wire values.

Changes:

• Replaces iota constants with documented kernel values.
• Adds distinct command and attribute types.
• Converts typed values at netlink API boundaries.

File	Description
constants_linux.go	Defines documented, typed netlink constants.
netlink_linux.go	Applies typed constants in encoding and decoding.

🧠 Review effort: Balanced

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[Copilot]

🟡 Changes recommended

Several linked UAPI enum members are omitted, undermining the intended exhaustive checking.

1 open finding

• Add missing IPVS service STATS64 attribute · New

🧠 Review effort: Balanced

[thaJeztah]

Yup; back-filling missing ones is on my list for a follow-up. This PR is just cleaning up the current definitions and correlating them with the upstream (Linux kernel)