//go:build linux package aghnet import ( "bufio" "fmt" "io/fs" "net" "net/netip" "strings" "sync" "github.com/AdguardTeam/AdGuardHome/internal/aghos" "github.com/AdguardTeam/golibs/log" "github.com/AdguardTeam/golibs/netutil" "github.com/AdguardTeam/golibs/stringutil" ) func newARPDB() (arp *arpdbs) { // Use the common storage among the implementations. ns := &neighs{ mu: &sync.RWMutex{}, ns: make([]Neighbor, 0), } var parseF parseNeighsFunc if aghos.IsOpenWrt() { parseF = parseArpAWrt } else { parseF = parseArpA } return newARPDBs( // Try /proc/net/arp first. &fsysARPDB{ ns: ns, fsys: rootDirFS, filename: "proc/net/arp", }, // Then, try "arp -a -n". &cmdARPDB{ parse: parseF, ns: ns, cmd: "arp", // Use -n flag to avoid resolving the hostnames of the neighbors. // By default ARP attempts to resolve the hostnames via DNS. See // man 8 arp. // // See also https://github.com/AdguardTeam/AdGuardHome/issues/3157. args: []string{"-a", "-n"}, }, // Finally, try "ip neigh". &cmdARPDB{ parse: parseIPNeigh, ns: ns, cmd: "ip", args: []string{"neigh"}, }, ) } // fsysARPDB accesses the ARP cache file to update the database. type fsysARPDB struct { ns *neighs fsys fs.FS filename string } // type check var _ ARPDB = (*fsysARPDB)(nil) // Refresh implements the ARPDB interface for *fsysARPDB. func (arp *fsysARPDB) Refresh() (err error) { var f fs.File f, err = arp.fsys.Open(arp.filename) if err != nil { return fmt.Errorf("opening %q: %w", arp.filename, err) } sc := bufio.NewScanner(f) // Skip the header. if !sc.Scan() { return nil } else if err = sc.Err(); err != nil { return err } ns := make([]Neighbor, 0, arp.ns.len()) for sc.Scan() { ln := sc.Text() fields := stringutil.SplitTrimmed(ln, " ") if len(fields) != 6 { continue } n := Neighbor{} n.IP, err = netip.ParseAddr(fields[0]) if err != nil || n.IP.IsUnspecified() { continue } else if n.MAC, err = net.ParseMAC(fields[3]); err != nil { continue } ns = append(ns, n) } arp.ns.reset(ns) return nil } // Neighbors implements the ARPDB interface for *fsysARPDB. func (arp *fsysARPDB) Neighbors() (ns []Neighbor) { return arp.ns.clone() } // parseArpAWrt parses the output of the "arp -a -n" command on OpenWrt. The // expected input format: // // IP address HW type Flags HW address Mask Device // 192.168.11.98 0x1 0x2 5a:92:df:a9:7e:28 * wan func parseArpAWrt(sc *bufio.Scanner, lenHint int) (ns []Neighbor) { if !sc.Scan() { // Skip the header. return } ns = make([]Neighbor, 0, lenHint) for sc.Scan() { ln := sc.Text() fields := strings.Fields(ln) if len(fields) < 4 { continue } n := Neighbor{} ip, err := netip.ParseAddr(fields[0]) if err != nil || n.IP.IsUnspecified() { log.Debug("arpdb: parsing arp output: ip: %s", err) continue } else { n.IP = ip } hwStr := fields[3] mac, err := net.ParseMAC(hwStr) if err != nil { log.Debug("arpdb: parsing arp output: mac: %s", err) continue } else { n.MAC = mac } ns = append(ns, n) } return ns } // parseArpA parses the output of the "arp -a -n" command on Linux. The // expected input format: // // hostname (192.168.1.1) at ab:cd:ef:ab:cd:ef [ether] on enp0s3 func parseArpA(sc *bufio.Scanner, lenHint int) (ns []Neighbor) { ns = make([]Neighbor, 0, lenHint) for sc.Scan() { ln := sc.Text() fields := strings.Fields(ln) if len(fields) < 4 { continue } n := Neighbor{} if ipStr := fields[1]; len(ipStr) < 2 { continue } else if ip, err := netip.ParseAddr(ipStr[1 : len(ipStr)-1]); err != nil { log.Debug("arpdb: parsing arp output: ip: %s", err) continue } else { n.IP = ip } hwStr := fields[3] if mac, err := net.ParseMAC(hwStr); err != nil { log.Debug("arpdb: parsing arp output: mac: %s", err) continue } else { n.MAC = mac } host := fields[0] if verr := netutil.ValidateDomainName(host); verr != nil { log.Debug("arpdb: parsing arp output: host: %s", verr) } else { n.Name = host } ns = append(ns, n) } return ns } // parseIPNeigh parses the output of the "ip neigh" command on Linux. The // expected input format: // // 192.168.1.1 dev enp0s3 lladdr ab:cd:ef:ab:cd:ef REACHABLE func parseIPNeigh(sc *bufio.Scanner, lenHint int) (ns []Neighbor) { ns = make([]Neighbor, 0, lenHint) for sc.Scan() { ln := sc.Text() fields := strings.Fields(ln) if len(fields) < 5 { continue } n := Neighbor{} ip, err := netip.ParseAddr(fields[0]) if err != nil { log.Debug("arpdb: parsing arp output: ip: %s", err) continue } else { n.IP = ip } mac, err := net.ParseMAC(fields[4]) if err != nil { log.Debug("arpdb: parsing arp output: mac: %s", err) continue } else { n.MAC = mac } ns = append(ns, n) } return ns }