[omrzk]

VLAN and bridge VLAN protocol attributes are network-endian, but the drivers used native-endian integers with byte-swapped constants. This produces 00 81 instead of 81 00 for 802.1Q on s390x, and decoding a kernel response does not recognize the protocol.

Use canonical EtherType constants (0x8100/0x88a8) and network byte order for these payloads, preserving the surrounding native-endian attributes. Also make the four bridge raw fixtures native-endian so they can run on s390x; these reproduce the failures in #292.

The exported constants' numeric values change; callers using the named constants retain the intended protocol and wire bytes on little-endian hosts. Callers using the previous byte-swapped numeric literals should use the named constants.

Validation: the new regression fails on the original code and passes with the fix for both VLAN drivers, both protocols and both byte orders. Full native go test -race -shuffle=on -cover ./..., full Linux/s390x fixture suite under qemu-user, go vet ./..., go build -tags=gofuzz ./..., and golangci-lint 2.15.0 pass. No privileged live interface creation was run; this host has no effective capabilities.

Fixes #292.

[omrzk]

The Go 1.25 vulnerability job fails while installing govulncheck, before scanning this code: golang.org/x/vuln@v1.9.0 requires go >= 1.26.0 (running go 1.25.14; GOTOOLCHAIN=local). The workflow installs govulncheck@latest and is unchanged from master 9498c7a; this PR changes neither the workflow nor dependencies.

Both Linux integration jobs and both macOS test jobs pass on Go 1.25/1.26, as do lint and DCO. The Go 1.26 vulnerability job is marked canceled, so the overall workflow is still not green. I have left the VLAN patch focused; the scanner/toolchain compatibility needs a separate CI fix.