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backend.go
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backend.go
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package gateway
import (
"encoding/base64"
"encoding/json"
"fmt"
"io/ioutil"
"net"
"regexp"
"sync"
"time"
"github.com/pkg/errors"
log "github.com/sirupsen/logrus"
"github.com/brocaar/lora-gateway-bridge/internal/gateway/semtech"
"github.com/brocaar/loraserver/api/gw"
"github.com/brocaar/lorawan"
)
// errors
var (
errGatewayDoesNotExist = errors.New("gateway does not exist")
)
// gatewayCleanupDuration contains the duration after which the gateway is
// cleaned up from the registry after no activity
var gatewayCleanupDuration = -1 * time.Minute
// loRaDataRateRegex contains a regexp for parsing the data-rate string.
var loRaDataRateRegex = regexp.MustCompile(`SF(\d+)BW(\d+)`)
// udpPacket represents a raw UDP packet.
type udpPacket struct {
addr *net.UDPAddr
data []byte
}
// gateway contains a connection and meta-data for a gateway connection.
type gateway struct {
addr *net.UDPAddr
lastSeen time.Time
protocolVersion uint8
}
// gateways contains the gateways registry.
type gateways struct {
sync.RWMutex
gateways map[lorawan.EUI64]gateway
onNew func(lorawan.EUI64) error
onDelete func(lorawan.EUI64) error
}
// get returns the gateway object for the given MAC.
func (c *gateways) get(mac lorawan.EUI64) (gateway, error) {
defer c.RUnlock()
c.RLock()
gw, ok := c.gateways[mac]
if !ok {
return gw, errGatewayDoesNotExist
}
return gw, nil
}
// set creates or updates the gateway for the given MAC.
func (c *gateways) set(mac lorawan.EUI64, gw gateway) error {
defer c.Unlock()
c.Lock()
_, ok := c.gateways[mac]
if !ok && c.onNew != nil {
gatewayEventCounter("register_gateway")
if err := c.onNew(mac); err != nil {
return err
}
}
c.gateways[mac] = gw
return nil
}
// cleanup removes inactive gateways from the registry.
func (c *gateways) cleanup() error {
defer c.Unlock()
c.Lock()
for mac := range c.gateways {
if c.gateways[mac].lastSeen.Before(time.Now().Add(gatewayCleanupDuration)) {
if c.onDelete != nil {
gatewayEventCounter("unregister_gateway")
if err := c.onDelete(mac); err != nil {
return err
}
}
delete(c.gateways, mac)
}
}
return nil
}
// Backend implements a Semtech packet-forwarder gateway backend.
type Backend struct {
conn *net.UDPConn
txAckChan chan gw.TXAck // received TX ACKs
rxChan chan gw.RXPacketBytes // received uplink frames
statsChan chan gw.GatewayStatsPacket // received gateway stats
udpSendChan chan udpPacket
closed bool
gateways gateways
configurations []semtech.PFConfiguration
wg sync.WaitGroup
skipCRCCheck bool
}
// NewBackend creates a new backend.
func NewBackend(bind string, onNew func(lorawan.EUI64) error, onDelete func(lorawan.EUI64) error, skipCRCCheck bool, configurations []semtech.PFConfiguration) (*Backend, error) {
addr, err := net.ResolveUDPAddr("udp", bind)
if err != nil {
return nil, err
}
log.WithField("addr", addr).Info("gateway: starting gateway udp listener")
conn, err := net.ListenUDP("udp", addr)
if err != nil {
return nil, err
}
b := &Backend{
skipCRCCheck: skipCRCCheck,
conn: conn,
txAckChan: make(chan gw.TXAck),
rxChan: make(chan gw.RXPacketBytes),
statsChan: make(chan gw.GatewayStatsPacket),
udpSendChan: make(chan udpPacket),
gateways: gateways{
gateways: make(map[lorawan.EUI64]gateway),
onNew: onNew,
onDelete: onDelete,
},
configurations: configurations,
}
go func() {
for {
if err := b.gateways.cleanup(); err != nil {
log.Errorf("gateway: gateways cleanup failed: %s", err)
}
time.Sleep(time.Minute)
}
}()
go func() {
b.wg.Add(1)
err := b.readPackets()
if !b.closed {
log.Error(err)
}
b.wg.Done()
}()
go func() {
b.wg.Add(1)
err := b.sendPackets()
if !b.closed {
log.Error(err)
}
b.wg.Done()
}()
return b, nil
}
// Close closes the backend.
func (b *Backend) Close() error {
log.Info("gateway: closing gateway backend")
b.closed = true
close(b.udpSendChan)
if err := b.conn.Close(); err != nil {
return err
}
log.Info("gateway: handling last packets")
b.wg.Wait()
return nil
}
// ApplyConfiguration applies the given configuration.
func (b *Backend) ApplyConfiguration(config gw.GatewayConfigPacket) error {
return gatewayConfigHandleTimer(func() error {
var found bool
for i, c := range b.configurations {
if c.MAC != config.MAC {
continue
}
found = true
gwConfig, err := getGatewayConfig(config)
if err != nil {
return errors.Wrap(err, "get gateway config error")
}
baseConfig, err := loadConfigFile(c.BaseFile)
if err != nil {
return errors.Wrap(err, "load config file error")
}
if err = mergeConfig(c.MAC, baseConfig, gwConfig); err != nil {
return errors.Wrap(err, "merge config error")
}
// generate config json
bb, err := json.Marshal(baseConfig)
if err != nil {
return errors.Wrap(err, "marshal json error")
}
// write new config file to disk
if err = ioutil.WriteFile(c.OutputFile, bb, 0644); err != nil {
return errors.Wrap(err, "write config file errror")
}
log.WithFields(log.Fields{
"mac": config.MAC,
"file": c.OutputFile,
}).Info("gateway: new configuration file written")
// invoke restart command
if err = invokePFRestart(c.RestartCommand); err != nil {
return errors.Wrap(err, "invoke packet-forwarder restart error")
}
log.WithFields(log.Fields{
"mac": config.MAC,
"cmd": c.RestartCommand,
}).Info("gateway: packet-forwarder restart command invoked")
b.configurations[i].Version = config.Version
}
if !found {
log.WithField("mac", config.MAC).Warning("gateway: configuration was not applied, gateway is not configured for managed configuration")
}
return nil
})
}
// RXPacketChan returns the channel containing the received RX packets.
func (b *Backend) RXPacketChan() chan gw.RXPacketBytes {
return b.rxChan
}
// StatsChan returns the channel containing the received gateway stats.
func (b *Backend) StatsChan() chan gw.GatewayStatsPacket {
return b.statsChan
}
// TXAckChan returns the channel containing the TX acknowledgements
// (or errors).
func (b *Backend) TXAckChan() chan gw.TXAck {
return b.txAckChan
}
// Send sends the given packet to the gateway.
func (b *Backend) Send(txPacket gw.TXPacketBytes) error {
gw, err := b.gateways.get(txPacket.TXInfo.MAC)
if err != nil {
return err
}
txpk, err := newTXPKFromTXPacket(txPacket)
if err != nil {
return err
}
pullResp := PullRespPacket{
RandomToken: txPacket.Token,
ProtocolVersion: gw.protocolVersion,
Payload: PullRespPayload{
TXPK: txpk,
},
}
bytes, err := pullResp.MarshalBinary()
if err != nil {
return fmt.Errorf("gateway: json marshall PullRespPacket error: %s", err)
}
b.udpSendChan <- udpPacket{
data: bytes,
addr: gw.addr,
}
return nil
}
func (b *Backend) readPackets() error {
buf := make([]byte, 65507) // max udp data size
for {
i, addr, err := b.conn.ReadFromUDP(buf)
if err != nil {
if b.closed {
return nil
}
log.WithError(err).Error("gateway: read from udp error")
continue
}
data := make([]byte, i)
copy(data, buf[:i])
go func(data []byte) {
if err := b.handlePacket(addr, data); err != nil {
log.WithFields(log.Fields{
"data_base64": base64.StdEncoding.EncodeToString(data),
"addr": addr,
}).Errorf("gateway: could not handle packet: %s", err)
}
}(data)
}
}
func (b *Backend) sendPackets() error {
for p := range b.udpSendChan {
pt, err := GetPacketType(p.data)
if err != nil {
log.WithFields(log.Fields{
"addr": p.addr,
"data_base64": base64.StdEncoding.EncodeToString(p.data),
}).Error("gateway: unknown packet type")
continue
}
log.WithFields(log.Fields{
"addr": p.addr,
"type": pt,
"protocol_version": p.data[0],
}).Debug("gateway: sending udp packet to gateway")
err = gatewayWriteUDPTimer(pt.String(), func() error {
_, err := b.conn.WriteToUDP(p.data, p.addr)
return err
})
if err != nil {
log.WithFields(log.Fields{
"addr": p.addr,
"type": pt,
"protocol_version": p.data[0],
}).WithError(err).Error("gateway: write to udp error")
}
}
return nil
}
func (b *Backend) handlePacket(addr *net.UDPAddr, data []byte) error {
pt, err := GetPacketType(data)
if err != nil {
return err
}
log.WithFields(log.Fields{
"addr": addr,
"type": pt,
"protocol_version": data[0],
}).Debug("gateway: received udp packet from gateway")
return gatewayHandleTimer(pt.String(), func() error {
switch pt {
case PushData:
return b.handlePushData(addr, data)
case PullData:
return b.handlePullData(addr, data)
case TXACK:
return b.handleTXACK(addr, data)
default:
return fmt.Errorf("gateway: unknown packet type: %s", pt)
}
})
}
func (b *Backend) handlePullData(addr *net.UDPAddr, data []byte) error {
var p PullDataPacket
if err := p.UnmarshalBinary(data); err != nil {
return err
}
ack := PullACKPacket{
ProtocolVersion: p.ProtocolVersion,
RandomToken: p.RandomToken,
}
bytes, err := ack.MarshalBinary()
if err != nil {
return err
}
err = b.gateways.set(p.GatewayMAC, gateway{
addr: addr,
lastSeen: time.Now().UTC(),
protocolVersion: p.ProtocolVersion,
})
if err != nil {
return err
}
b.udpSendChan <- udpPacket{
addr: addr,
data: bytes,
}
return nil
}
func (b *Backend) handlePushData(addr *net.UDPAddr, data []byte) error {
var p PushDataPacket
if err := p.UnmarshalBinary(data); err != nil {
return err
}
// ack the packet
ack := PushACKPacket{
ProtocolVersion: p.ProtocolVersion,
RandomToken: p.RandomToken,
}
bytes, err := ack.MarshalBinary()
if err != nil {
return err
}
b.udpSendChan <- udpPacket{
addr: addr,
data: bytes,
}
// gateway stats
if p.Payload.Stat != nil {
b.handleStat(addr, p.GatewayMAC, *p.Payload.Stat)
}
// rx packets
for _, rxpk := range p.Payload.RXPK {
if err := b.handleRXPacket(addr, p.GatewayMAC, rxpk); err != nil {
return err
}
}
return nil
}
func (b *Backend) handleStat(addr *net.UDPAddr, mac lorawan.EUI64, stat Stat) {
gwStats := newGatewayStatsPacket(mac, stat)
log.WithFields(log.Fields{
"addr": addr,
"mac": mac,
}).Info("gateway: stat packet received")
if addr.IP.IsLoopback() {
ip, err := getOutboundIP()
if err != nil {
log.WithError(err).Error("gateway: get outbound ip error")
} else {
gwStats.CustomData["ip"] = ip.String()
}
} else {
gwStats.CustomData["ip"] = addr.IP.String()
}
// set configuration version, if available
for _, c := range b.configurations {
if gwStats.MAC == c.MAC {
gwStats.ConfigVersion = c.Version
}
}
b.statsChan <- gwStats
}
func (b *Backend) handleRXPacket(addr *net.UDPAddr, mac lorawan.EUI64, rxpk RXPK) error {
logFields := log.Fields{
"addr": addr,
"mac": mac,
"data": rxpk.Data,
}
log.WithFields(logFields).Info("gateway: rxpk packet received")
// decode packet(s)
rxPackets, err := newRXPacketsFromRXPK(mac, rxpk)
if err != nil {
return err
}
for i := range rxPackets {
// check CRC
if !b.skipCRCCheck && rxPackets[i].RXInfo.CRCStatus != 1 {
log.WithFields(logFields).Warningf("gateway: invalid packet CRC: %d", rxPackets[i].RXInfo.CRCStatus)
return errors.New("gateway: invalid CRC")
}
b.rxChan <- rxPackets[i]
}
return nil
}
func (b *Backend) handleTXACK(addr *net.UDPAddr, data []byte) error {
var p TXACKPacket
if err := p.UnmarshalBinary(data); err != nil {
return err
}
if p.Payload != nil {
txAck := newTXAckFromTXPKACK(p.GatewayMAC, p.RandomToken, p.Payload.TXPKACK)
b.txAckChan <- txAck
} else {
b.txAckChan <- gw.TXAck{
MAC: p.GatewayMAC,
Token: p.RandomToken,
}
}
return nil
}
func getOutboundIP() (net.IP, error) {
// this does not actually connect to 8.8.8.8, unless the connection is
// used to send UDP frames
conn, err := net.Dial("udp", "8.8.8.8:80")
if err != nil {
return nil, err
}
defer conn.Close()
localAddr := conn.LocalAddr().(*net.UDPAddr)
return localAddr.IP, nil
}