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|
package main
import (
"net"
"time"
"github.com/jedisct1/dlog"
)
func NetProbe(proxy *Proxy, address string, timeout int) error {
if len(address) <= 0 || timeout == 0 {
return nil
}
if captivePortalHandler, err := ColdStart(proxy); err == nil {
if captivePortalHandler != nil {
defer captivePortalHandler.Stop()
}
} else {
dlog.Critical(err)
}
remoteUDPAddr, err := net.ResolveUDPAddr("udp", address)
if err != nil {
return err
}
retried := false
if timeout < 0 {
timeout = MaxTimeout
} else {
timeout = Min(MaxTimeout, timeout)
}
for tries := timeout; tries > 0; tries-- {
pc, err := net.DialUDP("udp", nil, remoteUDPAddr)
if err == nil {
// Write at least 1 byte. This ensures that sockets are ready to use for writing.
// Windows specific: during the system startup, sockets can be created but the underlying buffers may not be setup yet. If this is the case
// Write fails with WSAENOBUFS: "An operation on a socket could not be performed because the system lacked sufficient buffer space or because a queue was full"
_, err = pc.Write([]byte{0})
}
if err != nil {
if !retried {
retried = true
dlog.Notice("Network not available yet -- waiting...")
}
dlog.Debug(err)
time.Sleep(1 * time.Second)
continue
}
pc.Close()
dlog.Notice("Network connectivity detected")
return nil
}
dlog.Error("Timeout while waiting for network connectivity")
return nil
}
|
