144 lines
2.5 KiB
Go
144 lines
2.5 KiB
Go
package main
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import (
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"encoding/json"
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"log"
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"net"
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"reflect"
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"strings"
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"time"
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)
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const (
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// default multicast group used by announced
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MultiCastGroup string = "ff02:0:0:0:0:0:2:1001"
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// default udp port used by announced
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Port string = "1001"
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// maximum receivable size
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MaxDataGramSize int = 8192
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)
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type Response struct {
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Address net.UDPAddr
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Raw []byte
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}
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type Collector struct {
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collectType string
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connection *net.UDPConn // UDP socket
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queue chan *Response // received responses
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}
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func NewCollector(collectType string) *Collector {
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// Parse address
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addr, err := net.ResolveUDPAddr("udp", "[::]:0")
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if err != nil {
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log.Panic(err)
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}
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// Open socket
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conn, err := net.ListenUDP("udp", addr)
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if err != nil {
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log.Panic(err)
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}
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conn.SetReadBuffer(MaxDataGramSize)
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collector := &Collector{
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collectType: collectType,
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connection: conn,
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queue: make(chan *Response, 400),
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}
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go collector.sendOnce()
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go collector.sender()
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go collector.receiver()
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go collector.parser()
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return collector
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}
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func (coll *Collector) Close() {
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coll.connection.Close()
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close(coll.queue)
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}
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func (coll *Collector) sendOnce() {
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coll.sendPacket(net.JoinHostPort(MultiCastGroup,Port))
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}
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func (coll *Collector) sendPacket(address string) {
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addr, err := net.ResolveUDPAddr("udp", address)
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if err != nil {
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log.Panic(err)
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}
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coll.connection.WriteToUDP([]byte(coll.collectType), addr)
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}
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func (coll *Collector) sender() {
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c := time.Tick(collectInterval)
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for range c {
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// TODO break condition
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coll.sendOnce()
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}
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}
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func (coll *Collector) parser() {
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for obj := range coll.queue {
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coll.parse(obj)
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}
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}
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// Parses a response
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func (coll *Collector) parse(res *Response) {
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var result map[string]interface{}
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json.Unmarshal(res.Raw, &result)
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nodeId, _ := result["node_id"].(string)
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if nodeId == "" {
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log.Println("unable to parse node_id")
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return
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}
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node := nodes.get(nodeId)
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// Set result
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elem := reflect.ValueOf(node).Elem()
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field := elem.FieldByName(strings.Title(coll.collectType))
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log.Println(field)
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log.Println(result)
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if !reflect.DeepEqual(field,result){
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nodeserver.SendAll(node)
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}
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field.Set(reflect.ValueOf(result))
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}
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func (coll *Collector) receiver() {
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buf := make([]byte, MaxDataGramSize)
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for {
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n, src, err := coll.connection.ReadFromUDP(buf)
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if err != nil {
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log.Println("ReadFromUDP failed:", err)
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return
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}
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raw := make([]byte, n)
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copy(raw, buf)
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coll.queue <- &Response{
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Address: *src,
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Raw: raw,
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}
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log.Println("received", coll.collectType, "from", src)
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}
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}
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