Ejemplo n.º 1
0
Archivo: server.go Proyecto: rht/ipget
// parsePacket is used to parse an incoming packet
func (s *Server) parsePacket(packet []byte, from net.Addr) error {
	var msg dns.Msg
	if err := msg.Unpack(packet); err != nil {
		log.Printf("[ERR] mdns: Failed to unpack packet: %v", err)
		return err
	}
	return s.handleQuery(&msg, from)
}
Ejemplo n.º 2
0
Archivo: client.go Proyecto: rht/ipget
// sendQuery is used to multicast a query out
func (c *client) sendQuery(q *dns.Msg) error {
	buf, err := q.Pack()
	if err != nil {
		return err
	}
	if c.ipv4UnicastConn != nil {
		c.ipv4UnicastConn.WriteToUDP(buf, ipv4Addr)
	}
	if c.ipv6UnicastConn != nil {
		c.ipv6UnicastConn.WriteToUDP(buf, ipv6Addr)
	}
	return nil
}
Ejemplo n.º 3
0
Archivo: server.go Proyecto: rht/ipget
// sendResponse is used to send a response packet
func (s *Server) sendResponse(resp *dns.Msg, from net.Addr, unicast bool) error {
	// TODO(reddaly): Respect the unicast argument, and allow sending responses
	// over multicast.
	buf, err := resp.Pack()
	if err != nil {
		return err
	}

	// Determine the socket to send from
	addr := from.(*net.UDPAddr)
	if addr.IP.To4() != nil {
		_, err = s.ipv4List.WriteToUDP(buf, addr)
		return err
	} else {
		_, err = s.ipv6List.WriteToUDP(buf, addr)
		return err
	}
}
Ejemplo n.º 4
0
Archivo: client.go Proyecto: rht/ipget
// recv is used to receive until we get a shutdown
func (c *client) recv(l *net.UDPConn, msgCh chan *dns.Msg) {
	if l == nil {
		return
	}
	buf := make([]byte, 65536)
	for !c.closed {
		n, err := l.Read(buf)
		if err != nil {
			log.Printf("[ERR] mdns: Failed to read packet: %v", err)
			continue
		}
		msg := new(dns.Msg)
		if err := msg.Unpack(buf[:n]); err != nil {
			log.Printf("[ERR] mdns: Failed to unpack packet: %v", err)
			continue
		}
		select {
		case msgCh <- msg:
		case <-c.closedCh:
			return
		}
	}
}
Ejemplo n.º 5
0
Archivo: client.go Proyecto: rht/ipget
// query is used to perform a lookup and stream results
func (c *client) query(params *QueryParam) error {
	// Create the service name
	serviceAddr := fmt.Sprintf("%s.%s.", trimDot(params.Service), trimDot(params.Domain))

	// Start listening for response packets
	msgCh := make(chan *dns.Msg, 32)
	go c.recv(c.ipv4UnicastConn, msgCh)
	go c.recv(c.ipv6UnicastConn, msgCh)
	go c.recv(c.ipv4MulticastConn, msgCh)
	go c.recv(c.ipv6MulticastConn, msgCh)

	// Send the query
	m := new(dns.Msg)
	m.SetQuestion(serviceAddr, dns.TypePTR)
	// RFC 6762, section 18.12.  Repurposing of Top Bit of qclass in Question
	// Section
	//
	// In the Question Section of a Multicast DNS query, the top bit of the qclass
	// field is used to indicate that unicast responses are preferred for this
	// particular question.  (See Section 5.4.)
	if params.WantUnicastResponse {
		m.Question[0].Qclass |= 1 << 15
	}
	m.RecursionDesired = false
	if err := c.sendQuery(m); err != nil {
		return err
	}

	// Map the in-progress responses
	inprogress := make(map[string]*ServiceEntry)

	// Listen until we reach the timeout
	finish := time.After(params.Timeout)
	for {
		select {
		case resp := <-msgCh:
			var inp *ServiceEntry
			for _, answer := range append(resp.Answer, resp.Extra...) {
				// TODO(reddaly): Check that response corresponds to serviceAddr?
				switch rr := answer.(type) {
				case *dns.PTR:
					// Create new entry for this
					inp = ensureName(inprogress, rr.Ptr)

				case *dns.SRV:
					// Check for a target mismatch
					if rr.Target != rr.Hdr.Name {
						alias(inprogress, rr.Hdr.Name, rr.Target)
					}

					// Get the port
					inp = ensureName(inprogress, rr.Hdr.Name)
					inp.Host = rr.Target
					inp.Port = int(rr.Port)

				case *dns.TXT:
					// Pull out the txt
					inp = ensureName(inprogress, rr.Hdr.Name)
					inp.Info = strings.Join(rr.Txt, "|")
					inp.hasTXT = true

				case *dns.A:
					// Pull out the IP
					inp = ensureName(inprogress, rr.Hdr.Name)
					inp.Addr = rr.A // @Deprecated
					inp.AddrV4 = rr.A

				case *dns.AAAA:
					// Pull out the IP
					inp = ensureName(inprogress, rr.Hdr.Name)
					inp.Addr = rr.AAAA // @Deprecated
					inp.AddrV6 = rr.AAAA
				}
			}

			if inp == nil {
				continue
			}

			// Check if this entry is complete
			if inp.complete() {
				if inp.sent {
					continue
				}
				inp.sent = true
				select {
				case params.Entries <- inp:
				default:
				}
			} else {
				// Fire off a node specific query
				m := new(dns.Msg)
				m.SetQuestion(inp.Name, dns.TypePTR)
				m.RecursionDesired = false
				if err := c.sendQuery(m); err != nil {
					log.Printf("[ERR] mdns: Failed to query instance %s: %v", inp.Name, err)
				}
			}
		case <-finish:
			return nil
		}
	}
}