Enable golangci-lint

Add a GitHub actions workflow to run golanci-lint.
* Only uses latest Go version to avoid `gofmt` differences.
* Fixup linting issues.
* Ignore misspell `Prefered` as it is used as a public struct variable.
* Disable `unused-parameter` as it produces unecessary warning noise.

Signed-off-by: SuperQ <[email protected]>

.github/workflows/golangci-lint.yml

@@ -0,0 +1,32 @@
+---
+# This action is synced from https://github.com/prometheus/prometheus
+name: golangci-lint
+on:
+  push:
+    paths:
+      - "go.sum"
+      - "go.mod"
+      - "**.go"
+      - "scripts/errcheck_excludes.txt"
+      - ".github/workflows/golangci-lint.yml"
+      - ".golangci.yml"
+  pull_request:
+
+jobs:
+  golangci:
+    name: lint
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - name: install Go
+        uses: actions/setup-go@6edd4406fa81c3da01a34fa6f6343087c207a568 # v3.5.0
+        with:
+          go-version: 1.21.x
+      - name: Install snmp_exporter/generator dependencies
+        run: sudo apt-get update && sudo apt-get -y install libsnmp-dev
+        if: github.repository == 'prometheus/snmp_exporter'
+      - name: Lint
+        uses: golangci/golangci-lint-action@3a919529898de77ec3da873e3063ca4b10e7f5cc # v3.7.0
+        with:
+          version: v1.54.2

.golangci.yml

@@ -0,0 +1,18 @@
+---
+linters:
+  enable:
+    - gofmt
+    - misspell
+    - revive
+
+linters-settings:
+  misspell:
+    ignore-words:
+      # Incorrect spelling used in CacheInfo struct.
+      - Prefered
+  revive:
+    rules:
+      # https://github.com/mgechev/revive/blob/master/RULES_DESCRIPTIONS.md#unused-parameter
+      - name: unused-parameter
+        severity: warning
+        disabled: true

link.go

@@ -165,7 +165,7 @@ func (l *LinkService) Get(index uint32) (LinkMessage, error) {
 // RTM_SETLINK because:
 //   - using RTM_SETLINK is actually an old rtnetlink API, not supporting most
 //     attributes common today
-//   - using RTM_NEWLINK is the prefered way to create AND update links
+//   - using RTM_NEWLINK is the preferred way to create AND update links
 //   - RTM_NEWLINK is backward compatible to RTM_SETLINK
 func (l *LinkService) Set(req *LinkMessage) error {
 	flags := netlink.Request | netlink.Acknowledge

rtnl/addr.go

@@ -12,7 +12,6 @@ import (
 //
 //	iface, _ := net.InterfaceByName("lo")
 //	conn.AddrAdd(iface, rtnl.MustParseAddr("127.0.0.1/8"))
-//
 func (c *Conn) AddrAdd(ifc *net.Interface, addr *net.IPNet) error {
 	af, err := addrFamily(addr.IP)
 	if err != nil {
@@ -43,7 +42,6 @@ func (c *Conn) AddrAdd(ifc *net.Interface, addr *net.IPNet) error {
 //
 //	iface, _ := net.InterfaceByName("lo")
 //	conn.AddrDel(iface, rtnl.MustParseAddr("127.0.0.1/8"))
-//
 func (c *Conn) AddrDel(ifc *net.Interface, addr *net.IPNet) error {
 	af, err := addrFamily(addr.IP)
 	if err != nil {
@@ -79,7 +77,6 @@ func (c *Conn) AddrDel(ifc *net.Interface, addr *net.IPNet) error {
 // To retrieve all addresses configured for the system, run:
 //
 //	conn.Addrs(nil, 0)
-//
 func (c *Conn) Addrs(ifc *net.Interface, family int) (out []*net.IPNet, err error) {
 	rx, err := c.Conn.Address.List()
 	if err != nil {
@@ -136,7 +133,6 @@ func ParseAddr(s string) (*net.IPNet, error) {
 //
 //	iface, _ := net.InterfaceByName("enp2s0")
 //	conn.AddrDel(iface, rtnl.MustParseAddr("10.1.1.1/24"))
-//
 func MustParseAddr(s string) *net.IPNet {
 	n, err := ParseAddr(s)
 	if err != nil {

rtnl/conn.go

@@ -12,13 +12,13 @@ type Conn struct {
 }
 
 // Dial the netlink socket. Establishes a new connection. The typical initialisation is:
-// 	conn, err := rtnl.Dial(nil)
+//
+//	conn, err := rtnl.Dial(nil)
 //	if err != nil {
 //		log.Fatal("can't establish netlink connection: ", err)
 //	}
 //	defer conn.Close()
 //	// use conn for your calls
-//
 func Dial(cfg *netlink.Config) (*Conn, error) {
 	conn, err := rtnetlink.Dial(cfg)
 	if err != nil {

rtnl/route.go

@@ -64,7 +64,7 @@ func genRouteMessage(ifc *net.Interface, dst net.IPNet, gw net.IP, options ...Ro
 	return tx, nil
 }
 
-// RouteAdd adds infomation about a network route.
+// RouteAdd adds information about a network route.
 func (c *Conn) RouteAdd(ifc *net.Interface, dst net.IPNet, gw net.IP, options ...RouteOption) (err error) {
 	rm, err := genRouteMessage(ifc, dst, gw, options...)
 	if err != nil {