iOS Question New post (UDPSocket.send returns "error sending data: 13")

RaymondHung

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When I use UDPSocket, it returns "error sending data: 13", do u know what is the problem?
I using B4i 6.5 and IOS 12.4.8, Hope you can help, Thanks.
B4X: 
Sub Process_Globals
        Dim UDPSocket1 As UDPSocket
End Sub

Private Sub Application_Start (Nav As NavigationController)   
    UDPSocket1.Initialize("UDP", 30303, 8000)
End Sub

Public Sub DiscoverIP
    Dim Packet As UDPPacket
    Dim data() As Byte
    Dim strCmd As String = "Discovery"
    
    data = strCmd.GetBytes("UTF8")
    Packet.Initialize(data, "255.255.255.255", 30303)
    UDPSocket1.send(Packet)   
End Sub
 
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walterf25

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Have you looked at this thread?

UDPSocket.send returns "error sending data: 13"

I'm trying to use the code shown below to send my ip address to the broadcast address of the local wifi router. Note that receiving data using UDPSocket works OK. Only when sending do I get error 13. It's odd that this error is not trapped with try/catch. This same code works fine on Android...
www.b4x.com

Walter
 
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OliverA

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My guess: 255.255.255.255 is an invalid IP address. That's a network mask, not a broadcast address.
 
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Semen Matusovskiy

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1) Check firewall settings. Maybe a port is closed.
2) Packet.Initialize(data, "255.255.255.255", 30303)
Use UDPSocket1.GetBroadcastAddress instead of "255.255.255.255"
3) UDPSocket1.send(Packet)
Replace to UDPSocket1.SendBroadcast (Packet)
4) It seems to me it's necessary to make a delay after UDPSocket.Initialize, for example, Sleep (1).
 
Last edited:
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drgottjr

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it's not been mentioned, but io error 13 is permission denied. you're doing something the system doesn't like. generally, everybody can send a broadcast, so i'd be looking at a port issue. also, not clear who's sending the packet.
 
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OliverA

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RaymondHung said:
Packet.Initialize(data, "255.255.255.255", 30303)
Click to expand...
Semen Matusovskiy said:
2) Packet.Initialize(data, "255.255.255.255", 30303)
Click to expand...
drgottjr said:
it's not been mentioned, but io error 13 is permission denied. you're doing something the system doesn't like. generally, everybody can send a broadcast, so i'd be looking at a port issue. also, not clear who's sending the packet.
Click to expand...
255.255.255.255 is not a valid broadcast address. This issue needs to be resolved first before one can continue with this issue, since fixing this issue (using a correct broadcast address) may fix the issue at hand (io error 13). Please see this Wikipedia entry on how to determine the broadcast address for a network: https://en.wikipedia.org/wiki/Broadcast_address.

Note:
 
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RaymondHung

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Thank you very much for your help. After I revised it with your comments,
"error sending data: 13" did not appear, but no response was received in
UDPSocket1_PacketArrived. I use the same settings in B4A and Windows and it works normally.
I test UDPSocket1.GetBroadcastAddress = 127.0.0.1
 
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RaymondHung

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Longtime User
Sorry everyone, I made a mistake on the name, it should be "UDP_PacketArrived". Now it works normally.
B4X: 
Sub Process_Globals
        Dim UDPSocket1 As UDPSocket
End Sub

Private Sub Application_Start (Nav As NavigationController)   
    UDPSocket1.Initialize("UDP", 30303, 8000)
End Sub

Public Sub DiscoverIP
    Dim Packet As UDPPacket
    Dim data() As Byte
    Dim strCmd As String = "Discovery"
    
    data = strCmd.GetBytes("UTF8")
    Packet.Initialize(data, "255.255.255.255", 30303)
    UDPSocket1.SendBroadcast(Packet)
End Sub

Sub UDP_PacketArrived(Packet As UDPPacket)
    Dim msg, IP, mac, otif As String
    
    IP = Packet.HostAddress
    msg = BytesToString(Packet.Data, Packet.Offset, Packet.Length, "UTF-8")
                  



End Sub
 
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