Hi all,
As part of an Azure Event Hub field gateway project I'm working on I was doing some testing and noticed I could reliably lock the device/network stack up.
I was checking how my AMQP Net Lite code reacted when network connectivity was lost, Initially I though it was my code (as it was unlikely to be an AMQP Net Lite issue) but now I think it might be something in the IP stack.
To try and isolate the problem I built a small application which does an HTTP request as this was the simplest repro I could come up with
My Netduino 3 Wifi reliably connects to the Wireless Access Point in my office, then waits for an IP address and starts making http requests.
If I pull the LAN cable out of the back of the WAP the requests fail as expected
HTTP Status:200 : OK
HTTP Status:200 : OK
A first chance exception of type 'System.Net.Sockets.SocketException' occurred in Netduino.IP.LinkLayers.CC3100
A first chance exception of type 'System.Net.WebException' occurred in System.Http.dll
A first chance exception of type 'System.Net.WebException' occurred in System.Http.dll
...
Then when I plug the cable back in, the HTTP requests start working again
A first chance exception of type 'System.Net.Sockets.SocketException' occurred in Netduino.IP.LinkLayers.CC3100
A first chance exception of type 'System.Net.WebException' occurred in System.Http.dll
A first chance exception of type 'System.Net.WebException' occurred in System.Http.dll
HTTP Status:200 : OK
HTTP Status:200 : OK
...
So far so good, but if I power down the WAP the requests fail as expected and the WLAN connectivity LED on the N3 goes yellow.
HTTP Status:200 : OK
HTTP Status:200 : OK
HTTP Status:200 : OK
NetworkChange_NetworkAvailabilityChanged False
A first chance exception of type 'System.Net.Sockets.SocketException' occurred in Netduino.IP.LinkLayers.CC3100
A first chance exception of type 'System.Net.WebException' occurred in System.Http.dll
A first chance exception of type 'System.Net.WebException' occurred in System.Http.dll
...
If I power the WAP back up, after a while the WLAN connectivity LED on the N3 goes Green. There is a network connectivity change notification but when the next HTTP request is initiated the devices hangs
A first chance exception of type 'System.Net.Sockets.SocketException' occurred in Netduino.IP.LinkLayers.CC3100
A first chance exception of type 'System.Net.WebException' occurred in System.Http.dll
A first chance exception of type 'System.Net.WebException' occurred in System.Http.dll
NetworkChange_NetworkAvailabilityChanged True
A first chance exception of type 'System.Net.Sockets.SocketException' occurred in Netduino.IP.LinkLayers.CC3100
A first chance exception of type 'System.Net.WebException' occurred in System.Http.dll
A first chance exception of type 'System.Net.WebException' occurred in System.Http.dll
The code is attached for those who want to follow along at home
Any suggestions as to why and how I can work around this?
@KiwiBryn
blog.devmobile.co.nz
public static void Main()
{
// Wait for Network address if DHCP
NetworkInterface networkInterface = NetworkInterface.GetAllNetworkInterfaces()[0];
if (networkInterface.IsDhcpEnabled)
{
Debug.Print(" Waiting for DHCP IP address");
while (NetworkInterface.GetAllNetworkInterfaces()[0].IPAddress == IPAddress.Any.ToString())
{
Debug.Print(" .");
Thread.Sleep(250);
}
}
// Display network config for debugging
Debug.Print("Network configuration");
Debug.Print(" Network interface type : " + networkInterface.NetworkInterfaceType.ToString());
Debug.Print(" MAC Address : " + BytesToHexString(networkInterface.PhysicalAddress));
Debug.Print(" DHCP enabled : " + networkInterface.IsDhcpEnabled.ToString());
Debug.Print(" Dynamic DNS enabled : " + networkInterface.IsDynamicDnsEnabled.ToString());
Debug.Print(" IP Address : " + networkInterface.IPAddress.ToString());
Debug.Print(" Subnet Mask : " + networkInterface.SubnetMask.ToString());
Debug.Print(" Gateway : " + networkInterface.GatewayAddress.ToString());
foreach (string dnsAddress in networkInterface.DnsAddresses)
{
Debug.Print(" DNS Server : " + dnsAddress.ToString());
}
NetworkChange.NetworkAvailabilityChanged += NetworkChange_NetworkAvailabilityChanged;
NetworkChange.NetworkAddressChanged += NetworkChange_NetworkAddressChanged;
while (true)
{
try
{
//WebProxy proxy = new WebProxy("10.0.0.37", 8888);
using (HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://www.bing.com"))
{
//request.Proxy = proxy;
request.Method = "GET";
request.ContentType = "text/html; charset=utf-8";
request.KeepAlive = false;
using (var response = (HttpWebResponse)request.GetResponse())
{
Debug.Print("HTTP Status:" + response.StatusCode + " : " + response.StatusDescription);
}
}
}
catch (Exception ex)
{
Debug.Print(ex.Message);
}
Thread.Sleep(1000);
}
}
static void NetworkChange_NetworkAvailabilityChanged(object sender, NetworkAvailabilityEventArgs e)
{
Debug.Print(" NetworkChange_NetworkAvailabilityChanged " + e.IsAvailable);
}
static void NetworkChange_NetworkAddressChanged(object sender, EventArgs e)
{
NetworkInterface networkInterface = NetworkInterface.GetAllNetworkInterfaces()[0];
Debug.Print("NetworkChange_NetworkAddressChanged " + networkInterface.IPAddress);
}
Attached Files
-
Program.cs 3.98KB
20 downloads
Answered
