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// Copyright 2019 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.
package procfs
import (
"fmt"
"io/ioutil"
"net"
"strings"
)
// ARPEntry contains a single row of the columnar data represented in
// /proc/net/arp.
type ARPEntry struct {
// IP address
IPAddr net.IP
// MAC address
HWAddr net.HardwareAddr
// Name of the device
Device string
}
// GatherARPEntries retrieves all the ARP entries, parse the relevant columns,
// and then return a slice of ARPEntry's.
func (fs FS) GatherARPEntries() ([]ARPEntry, error) {
data, err := ioutil.ReadFile(fs.proc.Path("net/arp"))
if err != nil {
return nil, fmt.Errorf("error reading arp %q: %w", fs.proc.Path("net/arp"), err)
}
return parseARPEntries(data)
}
func parseARPEntries(data []byte) ([]ARPEntry, error) {
lines := strings.Split(string(data), "\n")
entries := make([]ARPEntry, 0)
var err error
const (
expectedDataWidth = 6
expectedHeaderWidth = 9
)
for _, line := range lines {
columns := strings.Fields(line)
width := len(columns)
if width == expectedHeaderWidth || width == 0 {
continue
} else if width == expectedDataWidth {
entry, err := parseARPEntry(columns)
if err != nil {
return []ARPEntry{}, fmt.Errorf("failed to parse ARP entry: %w", err)
}
entries = append(entries, entry)
} else {
return []ARPEntry{}, fmt.Errorf("%d columns were detected, but %d were expected", width, expectedDataWidth)
}
}
return entries, err
}
func parseARPEntry(columns []string) (ARPEntry, error) {
ip := net.ParseIP(columns[0])
mac := net.HardwareAddr(columns[3])
entry := ARPEntry{
IPAddr: ip,
HWAddr: mac,
Device: columns[5],
}
return entry, nil
}
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