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// Copyright 2017 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//go:build !noarp
// +build !noarp
package collector
import (
"fmt"
"log/slog"
"github.com/jsimonetti/rtnetlink/v2/rtnl"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/procfs"
"golang.org/x/sys/unix"
"gopkg.in/alecthomas/kingpin.v2"
)
var (
arpDeviceInclude = kingpin.Flag("collector.arp.device-include", "Regexp of arp devices to include (mutually exclusive to device-exclude).").String()
arpDeviceExclude = kingpin.Flag("collector.arp.device-exclude", "Regexp of arp devices to exclude (mutually exclusive to device-include).").String()
arpNetlink = kingpin.Flag("collector.arp.netlink", "Use netlink to gather stats instead of /proc/net/arp.").Default("true").Bool()
)
type arpCollector struct {
fs procfs.FS
deviceFilter deviceFilter
entries *prometheus.Desc
logger *slog.Logger
}
func init() {
registerCollector("arp", defaultEnabled, NewARPCollector)
}
// NewARPCollector returns a new Collector exposing ARP stats.
func NewARPCollector(logger *slog.Logger) (Collector, error) {
fs, err := procfs.NewFS(*procPath)
if err != nil {
return nil, fmt.Errorf("failed to open procfs: %w", err)
}
return &arpCollector{
fs: fs,
deviceFilter: newDeviceFilter(*arpDeviceExclude, *arpDeviceInclude),
entries: prometheus.NewDesc(
prometheus.BuildFQName(namespace, "arp", "entries"),
"ARP entries by device",
[]string{"device"}, nil,
),
logger: logger,
}, nil
}
func getTotalArpEntries(deviceEntries []procfs.ARPEntry) map[string]uint32 {
entries := make(map[string]uint32)
for _, device := range deviceEntries {
entries[device.Device]++
}
return entries
}
func getTotalArpEntriesRTNL() (map[string]uint32, error) {
conn, err := rtnl.Dial(nil)
if err != nil {
return nil, err
}
defer conn.Close()
// Neighbors will also contain IPv6 neighbors, but since this is purely an ARP collector,
// restrict to AF_INET.
neighbors, err := conn.Neighbours(nil, unix.AF_INET)
if err != nil {
return nil, err
}
// Map of interface name to ARP neighbor count.
entries := make(map[string]uint32)
for _, n := range neighbors {
// Skip entries which have state NUD_NOARP to conform to output of /proc/net/arp.
if n.State&unix.NUD_NOARP == 0 {
entries[n.Interface.Name]++
}
}
return entries, nil
}
func (c *arpCollector) Update(ch chan<- prometheus.Metric) error {
var enumeratedEntry map[string]uint32
if *arpNetlink {
var err error
enumeratedEntry, err = getTotalArpEntriesRTNL()
if err != nil {
return fmt.Errorf("could not get ARP entries: %w", err)
}
} else {
entries, err := c.fs.GatherARPEntries()
if err != nil {
return fmt.Errorf("could not get ARP entries: %w", err)
}
enumeratedEntry = getTotalArpEntries(entries)
}
for device, entryCount := range enumeratedEntry {
if c.deviceFilter.ignored(device) {
continue
}
ch <- prometheus.MustNewConstMetric(
c.entries, prometheus.GaugeValue, float64(entryCount), device)
}
return nil
}
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