116 lines
2.9 KiB
Go
116 lines
2.9 KiB
Go
// Copyright 2019 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package procfs
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import (
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"fmt"
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"net"
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"os"
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"strconv"
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"strings"
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)
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// Learned from include/uapi/linux/if_arp.h.
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const (
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// completed entry (ha valid).
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ATFComplete = 0x02
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// permanent entry.
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ATFPermanent = 0x04
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// Publish entry.
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ATFPublish = 0x08
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// Has requested trailers.
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ATFUseTrailers = 0x10
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// Obsoleted: Want to use a netmask (only for proxy entries).
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ATFNetmask = 0x20
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// Don't answer this addresses.
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ATFDontPublish = 0x40
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)
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// ARPEntry contains a single row of the columnar data represented in
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// /proc/net/arp.
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type ARPEntry struct {
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// IP address
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IPAddr net.IP
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// MAC address
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HWAddr net.HardwareAddr
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// Name of the device
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Device string
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// Flags
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Flags byte
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}
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// GatherARPEntries retrieves all the ARP entries, parse the relevant columns,
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// and then return a slice of ARPEntry's.
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func (fs FS) GatherARPEntries() ([]ARPEntry, error) {
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data, err := os.ReadFile(fs.proc.Path("net/arp"))
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if err != nil {
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return nil, fmt.Errorf("error reading arp %q: %w", fs.proc.Path("net/arp"), err)
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}
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return parseARPEntries(data)
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}
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func parseARPEntries(data []byte) ([]ARPEntry, error) {
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lines := strings.Split(string(data), "\n")
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entries := make([]ARPEntry, 0)
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var err error
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const (
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expectedDataWidth = 6
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expectedHeaderWidth = 9
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)
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for _, line := range lines {
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columns := strings.Fields(line)
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width := len(columns)
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if width == expectedHeaderWidth || width == 0 {
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continue
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} else if width == expectedDataWidth {
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entry, err := parseARPEntry(columns)
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if err != nil {
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return []ARPEntry{}, fmt.Errorf("failed to parse ARP entry: %w", err)
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}
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entries = append(entries, entry)
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} else {
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return []ARPEntry{}, fmt.Errorf("%d columns were detected, but %d were expected", width, expectedDataWidth)
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}
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}
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return entries, err
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}
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func parseARPEntry(columns []string) (ARPEntry, error) {
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entry := ARPEntry{Device: columns[5]}
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ip := net.ParseIP(columns[0])
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entry.IPAddr = ip
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if mac, err := net.ParseMAC(columns[3]); err == nil {
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entry.HWAddr = mac
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} else {
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return ARPEntry{}, err
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}
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if flags, err := strconv.ParseUint(columns[2], 0, 8); err == nil {
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entry.Flags = byte(flags)
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} else {
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return ARPEntry{}, err
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}
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return entry, nil
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}
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// IsComplete returns true if ARP entry is marked with complete flag.
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func (entry *ARPEntry) IsComplete() bool {
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return entry.Flags&ATFComplete != 0
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}
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