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Use undirected broadcast and WriteTo (fixes #75)

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This commit is contained in:
Jakob Borg 2014-03-03 15:28:10 +01:00
parent 5d8f0f835e
commit ba59e0d3f0
1 changed files with 67 additions and 51 deletions
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118
discover/discover.go
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@ -80,24 +80,75 @@ func (d *Discoverer) sendAnnouncements() {
var errCounter = 0
var err error
remote := &net.UDPAddr{
IP: net.IP{255, 255, 255, 255},
Port: AnnouncementPort,
}
for errCounter < maxErrors {
for _, ipStr := range allBroadcasts() {
var addrStr = ipStr + ":21025"
intfs, err := net.Interfaces()
if err != nil {
log.Printf("discover/listInterfaces: %v; no local announcements", err)
return
}
remote, err := net.ResolveUDPAddr("udp4", addrStr)
if err != nil {
log.Printf("discover/external: %v; no external announcements", err)
return
}
for _, intf := range intfs {
if intf.Flags&(net.FlagBroadcast|net.FlagLoopback) == net.FlagBroadcast {
addrs, err := intf.Addrs()
if err != nil {
log.Println("discover/listAddrs: warning:", err)
errCounter++
continue
}
if Debug {
log.Println("send announcement -> ", remote)
}
_, _, err = d.conn.WriteMsgUDP(buf, nil, remote)
if err != nil {
log.Println("discover/write: warning:", err)
errCounter++
} else {
var srcAddr string
for _, addr := range addrs {
if strings.Contains(addr.String(), ".") {
// Found an IPv4 adress
parts := strings.Split(addr.String(), "/")
srcAddr = parts[0]
break
}
}
if len(srcAddr) == 0 {
if Debug {
log.Println("discover: debug: no source address found on interface", intf.Name)
}
continue
}
iaddr, err := net.ResolveUDPAddr("udp4", srcAddr+":0")
if err != nil {
log.Println("discover/resolve: warning:", err)
errCounter++
continue
}
conn, err := net.ListenUDP("udp4", iaddr)
if err != nil {
log.Println("discover/listen: warning:", err)
errCounter++
continue
}
if Debug {
log.Println("discover: debug: send announcement from", conn.LocalAddr(), "to", remote, "on", intf.Name)
}
_, err = conn.WriteTo(buf, remote)
if err != nil {
// Some interfaces don't seem to support broadcast even though the flags claims they do, i.e. vmnet
conn.Close()
if Debug {
log.Println("discover/write: debug:", err)
}
errCounter++
continue
}
conn.Close()
errCounter = 0
}
}
@ -125,7 +176,7 @@ func (d *Discoverer) sendExtAnnouncements() {
if Debug {
log.Println("send announcement -> ", remote)
}
_, _, err = d.conn.WriteMsgUDP(buf, nil, remote)
_, err = d.conn.WriteTo(buf, remote)
if err != nil {
log.Println("discover/write: warning:", err)
errCounter++
@ -289,38 +340,3 @@ func ipStr(ip []byte) string {
}
return strings.Join(ss, s)
}
func allBroadcasts() []string {
var bcasts = make(map[string]bool)
addrs, err := net.InterfaceAddrs()
if err != nil {
return nil
}
for _, addr := range addrs {
switch {
case strings.HasPrefix(addr.String(), "127."):
// Ignore v4 localhost
case strings.Contains(addr.String(), ":"):
// Ignore all v6, because we need link local multicast there which I haven't implemented
default:
if in, ok := addr.(*net.IPNet); ok {
il := len(in.IP) - 1
ml := len(in.Mask) - 1
for i := range in.Mask {
in.IP[il-i] = in.IP[il-i] | ^in.Mask[ml-i]
}
parts := strings.Split(in.String(), "/")
bcasts[parts[0]] = true
}
}
}
var l []string
for ip := range bcasts {
l = append(l, ip)
}
return l
}