+/*
+NNCP -- Node to Node copy, utilities for store-and-forward data exchange
+Copyright (C) 2016-2021 Sergey Matveev <stargrave@stargrave.org>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, version 3 of the License.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package nncp
+
+import (
+ "bytes"
+ "encoding/hex"
+ "fmt"
+ "net"
+ "sync"
+ "time"
+
+ xdr "github.com/davecgh/go-xdr/xdr2"
+)
+
+const (
+ MCDPort = 5400
+)
+
+type MCD struct {
+ Magic [8]byte
+ Sender *NodeId
+}
+
+type MCDAddr struct {
+ Addr net.UDPAddr
+ lastSeen time.Time
+}
+
+var (
+ MagicNNCPDv1 [8]byte = [8]byte{'N', 'N', 'C', 'P', 'D', 0, 0, 1}
+
+ mcdIP = net.ParseIP("ff02::1")
+ mcdAddrLifetime = 2 * time.Minute
+
+ mcdPktSize int
+ MCDAddrs map[NodeId][]*MCDAddr
+ MCDAddrsM sync.RWMutex
+)
+
+func init() {
+ nodeId := new(NodeId)
+ var buf bytes.Buffer
+ mcd := MCD{Sender: nodeId}
+ if _, err := xdr.Marshal(&buf, mcd); err != nil {
+ panic(err)
+ }
+ mcdPktSize = buf.Len()
+
+ MCDAddrs = make(map[NodeId][]*MCDAddr)
+ go func() {
+ for {
+ time.Sleep(time.Minute)
+ MCDAddrsM.Lock()
+ now := time.Now()
+ for nodeId, addrs := range MCDAddrs {
+ addrsAlive := make([]*MCDAddr, 0, len(addrs))
+ for _, addr := range addrs {
+ if !addr.lastSeen.Add(mcdAddrLifetime).Before(now) {
+ addrsAlive = append(addrsAlive, addr)
+ }
+ }
+ MCDAddrs[nodeId] = addrsAlive
+ }
+ MCDAddrsM.Unlock()
+ }
+ }()
+}
+
+func (ctx *Ctx) MCDRx(ifiName string) error {
+ ifi, err := net.InterfaceByName(ifiName)
+ if err != nil {
+ return err
+ }
+ addr := &net.UDPAddr{IP: mcdIP, Port: MCDPort, Zone: ifiName}
+ conn, err := net.ListenMulticastUDP("udp", ifi, addr)
+ if err != nil {
+ return err
+ }
+ go func() {
+ buf := make([]byte, mcdPktSize)
+ var n int
+ var mcd MCD
+ ListenCycle:
+ for {
+ les := LEs{{"If", ifiName}}
+ n, addr, err = conn.ReadFromUDP(buf)
+ if err != nil {
+ ctx.LogE("mcd", les, err, func(les LEs) string {
+ return fmt.Sprintf("MCD Rx %s/%d", ifiName, MCDPort)
+ })
+ continue
+ }
+ if n != mcdPktSize {
+ ctx.LogD("mcd", les, func(les LEs) string {
+ return fmt.Sprintf(
+ "MCD Rx %s/%d: got packet with invalid size",
+ ifiName, MCDPort,
+ )
+ })
+ continue
+ }
+ _, err = xdr.Unmarshal(bytes.NewReader(buf[:n]), &mcd)
+ if err != nil {
+ ctx.LogD("mcd", les, func(les LEs) string {
+ return fmt.Sprintf(
+ "MCD Rx %s/%d: can not unmarshal: %s",
+ ifiName, MCDPort, err,
+ )
+ })
+ continue
+ }
+ if mcd.Magic != MagicNNCPDv1 {
+ ctx.LogD("mcd", les, func(les LEs) string {
+ return fmt.Sprintf(
+ "MCD Rx %s/%d: unexpected magic: %s",
+ ifiName, MCDPort, hex.EncodeToString(mcd.Magic[:]),
+ )
+ })
+ continue
+ }
+ node, known := ctx.Neigh[*mcd.Sender]
+ if known {
+ les = append(les, LE{"Node", node.Id})
+ ctx.LogD("mcd", les, func(les LEs) string {
+ return fmt.Sprintf(
+ "MCD Rx %s/%d: %s: node %s",
+ ifiName, MCDPort, addr, node.Name,
+ )
+ })
+ } else {
+ ctx.LogD("mcd", les, func(les LEs) string {
+ return fmt.Sprintf(
+ "MCD Rx %s/%d: %s: unknown node %s",
+ ifiName, MCDPort, addr, node.Id.String(),
+ )
+ })
+ continue
+ }
+ MCDAddrsM.RLock()
+ for _, mcdAddr := range MCDAddrs[*mcd.Sender] {
+ if mcdAddr.Addr.IP.Equal(addr.IP) &&
+ mcdAddr.Addr.Port == addr.Port &&
+ mcdAddr.Addr.Zone == addr.Zone {
+ mcdAddr.lastSeen = time.Now()
+ MCDAddrsM.RUnlock()
+ continue ListenCycle
+ }
+ }
+ MCDAddrsM.RUnlock()
+ MCDAddrsM.Lock()
+ MCDAddrs[*mcd.Sender] = append(
+ MCDAddrs[*mcd.Sender],
+ &MCDAddr{Addr: *addr, lastSeen: time.Now()},
+ )
+ MCDAddrsM.Unlock()
+ ctx.LogI("mcd-add", les, func(les LEs) string {
+ return fmt.Sprintf("MCD discovered %s's address: %s", node.Name, addr)
+ })
+ }
+ }()
+ return nil
+}
+
+func (ctx *Ctx) MCDTx(ifiName string, port int, interval time.Duration) error {
+ conn, err := net.DialUDP("udp",
+ &net.UDPAddr{Port: port, Zone: ifiName},
+ &net.UDPAddr{IP: mcdIP, Port: MCDPort, Zone: ifiName},
+ )
+ if err != nil {
+ return err
+ }
+ var buf bytes.Buffer
+ mcd := MCD{Magic: MagicNNCPDv1, Sender: ctx.Self.Id}
+ if _, err := xdr.Marshal(&buf, mcd); err != nil {
+ panic(err)
+ }
+ if interval == 0 {
+ _, err = conn.Write(buf.Bytes())
+ return err
+ }
+ go func() {
+ les := LEs{{"If", ifiName}}
+ for {
+ ctx.LogD("mcd", les, func(les LEs) string {
+ return fmt.Sprintf(
+ "MCD Tx %s/%d/%d",
+ ifiName, MCDPort, port,
+ )
+ })
+ _, err = conn.Write(buf.Bytes())
+ if err != nil {
+ ctx.LogE("mcd", les, err, func(les LEs) string {
+ return fmt.Sprintf("MCD on %s/%d/%d", ifiName, MCDPort, port)
+ })
+ }
+ time.Sleep(interval)
+ }
+ }()
+ return nil
+}