Android Question LAN Ip only ever returns 127.0.0.0

Falcon · Oct 19, 2020

Hi Guys,

I am trying to get the IP Address assigned to my device for my local wifi network, but all I ever get is 127.0.0.0 even though I can see my device is connected to the wifi if I look in my device's android settings.

I use this code:

B4X:

Dim Sock as ServerSocket
Sock.Initialize(0,"")
Dim IP as string = Sock.GetMyWifiIP

Any ideas?

Thanks in advance,
Jacques.

Erel · Oct 20, 2020

Tip: this is one of the few cases where you don't need to initialize the object.

Is this a real device? Which device?

Falcon · Oct 20, 2020

Hi Erel,

Thanks for the reply.
My device is real, it is a Xiaomi Redmi Note 7 cellphone running Android Version 9.

I removed the 'Initialize' line of code, but I still get 127.0.0.0

Here is my Manifest (if it will help you):

B4X:

AddManifestText(
<uses-sdk android:minSdkVersion="5" android:targetSdkVersion="28"/>
<supports-screens android:largeScreens="true" 
    android:normalScreens="true" 
    android:smallScreens="true" 
    android:anyDensity="true"/>)
SetApplicationAttribute(android:icon, "@drawable/icon")
SetApplicationAttribute(android:label, "$LABEL$")
CreateResourceFromFile(Macro, Themes.LightTheme)
AddPermission(android.permission.ACCESS_NETWORK_STATE)
AddPermission(android.permission.ACCESS_WIFI_STATE)
AddPermission(android.permission.ACCESS_FINE_LOCATION)
AddPermission(android.permission.CHANGE_WIFI_STATE)
AddPermission(android.permission.INTERNET)
AddPermission(android.permission.WAKE_LOCK)

Regards,
Jacques.

Erel · Oct 20, 2020

Do you see any ip address in the device setting?

Falcon · Oct 20, 2020

Erel if I go to on the phone to Settings --> About Phone --> All Specs --> Status the phone has an assigned IP Address of 10.0.0.8 and I have a Wi-fi Mac Address also.
The phone is also showing in the router as connected.

agraham · Oct 20, 2020

Do you have B4A-Bridge installed? If so what IP address does it show and does it work? If not you could download it and try it.

Falcon · Oct 20, 2020

Yes I have B4A Bridge installed, it shows 10.0.0.8, and yes it does work, it is what I use for my development all the time.

agraham · Oct 20, 2020

I've had a quick look at the B4A_Bridge source code

B4A-Bridge source code

B4A-Bridge is made of two components. One component is running on the device and the other is embedded in the IDE. The device side is the server side. It waits for connections and when a connection is established it handles the "action" messages. The code itself is made of a simple activity...

www.b4x.com

B4A-Bridge uses ServerSocket.GetMyWifiIP, it doesn't even bother to Initialize it as it only uses it to get the IP address, so it seems to be working OK there.

agraham · Oct 20, 2020

I've just noticed in post #3 that you have manually added a lot of permissions to your manifest. That is not needed, B4A will add most permissions if a library needs them. B4A-Bridge has none of those you have added in its manifest, try removing them. You can see the permissions added by B4A by pressing the List Permissions button at the bottom of the Log pane.

Falcon · Oct 20, 2020

Hmmm that's interesting Agraham since that is exactly what I am doing as you know
Oh well I guess I must just keep on trying.

By the way, while I am speaking to yourself & erel, I would like a simple way to connect my android app to a pc on my local LAN.
I want to have a server program listening on this PC which I will create in VB.Net. I would just basically like to send simple plain text commands to the pc.

What is the way you would reccommend I could achieve this?

Thanks for all the help so far, much appreciated!

agraham · Oct 20, 2020

Falcon said:
What is the way you would reccommend I could achieve this?

If you are willing to use B4J there is a ready made cross-platform example from Erel that you could probably build on here

[B4X] Cross platform chat layout example

Example of implementing a chat layout. It is based on xCustomListView. The text is created with a hidden BBCodeView (BCTextEngine) and the bubble is drawn with BitmapCreator. Extracting the image from BBCodeView is not trivial. See the code. The code is implemented in the Chat class which is...

www.b4x.com

Have you seen my permission post above?

Falcon · Oct 20, 2020

Ahh I just saw your last reply, I removed 'android.permission.CHANGE_WIFI_STATE' from the manifest and now I get the IP! Thank you so much Agraham!

Erel · Oct 21, 2020

Falcon said:
I removed 'android.permission.CHANGE_WIFI_STATE' from the manifest and now I get the IP

I must say that I don't see how it can cause this. I have a feeling that something else was the problem. Once it working, try to add the permission and see if it changes anything.

Falcon · Oct 21, 2020

Hi Erel,

The weird thing is now all of a sudden if I don't add that permission my app crashes when I try to connect to Wifi!
So at the moment I am forced to add it, but in doing so again I end up with 127.0.0.0

drgottjr · Oct 21, 2020

FWIW, on my pixel 3a, os 11, b4a 10.2, sdk 29, jdk1.8.0_211 i get my wifi address with op's 3 lines of code with or without change_wifi_state permission. manifest permissions are only those generated by the server socket in the network library.

in addition, GetMyWifiIp method in network library makes a call to wifimanager.getConnectionInfo(). according to android docs, ACCESS_FINE_LOCATION is required. this permission appears in op's manifest, but not in mine (objects folder). and yet the test returns the same wifi address shown in my system settings.

canalrun · Oct 21, 2020

I had this problem years ago.

I found that I could not get the IP address of the device in the same routine that I initialized the ServerSocket.

My solution was to get the IP address in the Phone Events ConnectivityChanged event.

Falcon · Oct 21, 2020

Thank you for all the replies guys, much appreciated.

Canalrun I am a noob with B4A development as you may have gathered, how do I get the IP Address from the ConnectivityChanged event? ?

So far I have this (In my Class Module):

B4X:

Sub Class_Globals
      Private PE As PhoneEvents
End Sub

Public Sub Initialize(Activity As Activity,strEventName As String)
     PE.Initialize("PE")
End Sub

Sub PE_ConnectivityChanged (NetworkType As String, State As String, Intent As Intent)
      'No clue what to put here to get IP???
End Sub

canalrun · Oct 21, 2020

Here is some code that is quite a few years old. There is some extraneous stuff, but I've highlighted the important code.
NetSvr is type ServerSocket
pe is type PhoneEvents

Whoops! It looks like highlighting doesn't work inside a code block. The stuff between (B) and (/B) is supposed to be highlighted.

B4X:

Sub Service_Create
  'start listening for wifi connections
  [B]NetSvr.Initialize(NetPort, "NetSvr")[/B]

  Try
    NetSvr.Listen
  Catch
      Log("NetSvr.Listen: " & LastException.Message)
  End Try

  [B]pe.Initialize("pe")
  pe_ConnectivityChanged("", "", Null)[/B]

  UDPSoc.Initialize("UDPSvr", UDPPort, 128)

  BCAddr = Utl.GetBroadcastAddress

'  Log("BCAddr: " & BCAddr)

  mConnections.Initialize
  bConnecting = False

  MyIP = "N/A"
End Sub

Sub pe_ConnectivityChanged(NetworkType As String, State As String, Intent As Intent)
'  Log("ConnectivityChanged: " & NetworkType & ", "  & "State" & ", " & Intent.ExtrasToString)

  ' MyIP = NetSvr.GetMyWifiIP
  [B]MyIP = NetSvr.GetMyIP[/B]

  UpdateUI
End Sub

Android Question LAN Ip only ever returns 127.0.0.0

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