75 lines
1.4 KiB
Go
75 lines
1.4 KiB
Go
//go:build darwin || freebsd
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package arpdb
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import (
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"bufio"
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"net"
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"net/netip"
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"strings"
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"sync"
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"github.com/AdguardTeam/golibs/log"
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)
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func newARPDB() (arp *cmdARPDB) {
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return &cmdARPDB{
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parse: parseArpA,
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ns: &neighs{
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mu: &sync.RWMutex{},
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ns: make([]Neighbor, 0),
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},
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cmd: "arp",
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// Use -n flag to avoid resolving the hostnames of the neighbors. By
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// default ARP attempts to resolve the hostnames via DNS. See man 8
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// arp.
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//
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// See also https://github.com/AdguardTeam/AdGuardHome/issues/3157.
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args: []string{"-a", "-n"},
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}
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}
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// parseArpA parses the output of the "arp -a -n" command on macOS and FreeBSD.
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// The expected input format:
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//
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// host.name (192.168.0.1) at ff:ff:ff:ff:ff:ff on en0 ifscope [ethernet]
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func parseArpA(sc *bufio.Scanner, lenHint int) (ns []Neighbor) {
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ns = make([]Neighbor, 0, lenHint)
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for sc.Scan() {
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ln := sc.Text()
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fields := strings.Fields(ln)
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if len(fields) < 4 {
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continue
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}
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ipStr := fields[1]
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if len(ipStr) < 2 {
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continue
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}
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ip, err := netip.ParseAddr(ipStr[1 : len(ipStr)-1])
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if err != nil {
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log.Debug("arpdb: parsing arp output: ip: %s", err)
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continue
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}
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hwStr := fields[3]
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mac, err := net.ParseMAC(hwStr)
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if err != nil {
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log.Debug("arpdb: parsing arp output: mac: %s", err)
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continue
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}
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ns = append(ns, Neighbor{
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IP: ip,
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MAC: mac,
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Name: validatedHostname(fields[0]),
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})
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}
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return ns
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}
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