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Rek
Level 7

UDP Broadcasts

Hi all, I'm trying to send a UDP broadcast on the local network in order to discover my server. I wrote a udp client/server in c, and it works. Now, I'm trying to convert the client to brighscript, but I can't get it working. It seems that the server never receives any packets. Right now I've stripped the code down to just sending the packet. I then watch the server output to see if the packet is received -- it never is.

Here's the code I'm using:

function Discover()
SEND_PORT = "8881"
KEY_SEND = "SeCrEt"

msgPort = CreateObject("roMessagePort")
sendSock = CreateObject("roDatagramSocket")
sendSock.SetMessagePort(msgPort)


sendAddr = CreateObject("roSocketAddress")
sendAddr.setAddress("255.255.255.255:"+SEND_PORT)

sendSock.setSendToAddress(sendAddr)
sendSock.setBroadcast(true)
sendSock.notifyReadable(true)

data = CreateObject("roByteArray")
data.FromAsciiString(KEY_SEND)

' Sanity Check
?"Data count: "+data.Count().tostr()

sendSock.send(data, 0, data.Count())

' Check error
if sendSock.eAgain()
?"E_AGAIN"
return false
else if sendSock.eAlready()
?"E_ALREADY"
return false
else if sendSock.eDestAddrReq()
?"E_DEST_ADDR_REQ"
return false
else if sendSock.eHostUnreach()
?"E_HOST_UNREACH"
return false
else if sendSock.eInProgress()
?"E_IN_PROGRESS"
return false
else if sendSock.eOk()
?"E_OK"

else if sendSock.eSuccess()
?"E_SUCCESS"

else if sendSock.eWouldBlock()
?"E_WOULD_BLOCK"
return false
end if

continue:
while true
event = wait(1000, msgPort)
if event = invalid
?"Recevieved invalid event"
goto continue
end if

if type(event) <> "roSocketEvent"
?"Received unknown type"
goto continue
end if

?"Message: " + event.GetMessage()
end while
end function


Can anyone see the problem? Any help would be greatly appreciated. Cheers!
0 Kudos
7 REPLIES 7\
Rek
Level 7

Re: UDP Broadcasts

Update: I've changed the sendToAddress to the network broadcast address, and that seems to work. Changing it to 255.255.255.255 is what breaks it. Any ideas why this is happening? Or alternative approaches?

Here's the updated code:

function Discover()
SEND_PORT = "8881"
KEY_SEND = "SeCrEt"

msgPort = CreateObject("roMessagePort")
sock = CreateObject("roDatagramSocket")
sock.SetMessagePort(msgPort)

addr = CreateObject("roSocketAddress")
addr.setAddress("0.0.0.0:8882")
sock.setAddress(addr)

sendAddr = CreateObject("roSocketAddress")
sendAddr.setAddress("192.168.128.255:"+SEND_PORT)

sock.setSendToAddress(sendAddr)
sock.setBroadcast(true)
sock.notifyReadable(true)

data = CreateObject("roByteArray")
data.FromAsciiString(KEY_SEND)

' Sanity Check
?"Data count: "+data.Count().tostr()

sock.send(data, 0, data.Count())

' Check error
if sock.eAgain()
?"E_AGAIN"
return false
else if sock.eAlready()
?"E_ALREADY"
return false
else if sock.eDestAddrReq()
?"E_DEST_ADDR_REQ"
return false
else if sock.eHostUnreach()
?"E_HOST_UNREACH"
return false
else if sock.eInProgress()
?"E_IN_PROGRESS"
return false
else if sock.eOk()
?"E_OK"

else if sock.eSuccess()
?"E_SUCCESS"

else if sock.eWouldBlock()
?"E_WOULD_BLOCK"
return false
end if

continue:
while true
event = wait(10000, msgPort)
if event = invalid
?"Recevieved invalid event (Timeout)"
goto continue
end if

if type(event) <> "roSocketEvent"
?"Received unknown type"
goto continue

end if

if event.GetSocketID() = sock.GetID()
if sock.isReadable()
message = sock.receiveStr(68)
?"Message: "+message
end if
end if
end while
end function


Cheers!
0 Kudos
Rek
Level 7

Re: UDP Broadcasts

Can I access the subnet mask? That would let me get the network broadcast address myself...
0 Kudos
Rek
Level 7

Re: UDP Broadcasts

Anyone?
0 Kudos
Rek
Level 7

Re: UDP Broadcasts

Can any of the roku dev's pitch in with some thoughts? How can I send a UDP broadcast to the LAN? I'm really stuck on this one.
0 Kudos
RokuMarkn
Level 8

Re: UDP Broadcasts

Right now we don't have a good solution for this. You could try this workaround:

look at the local address and guess:
a. the /24 (sub)network
b. the natural network implied by the non-routable address.

We hope to provide a better way to do this in a future release.

--Mark
0 Kudos
Rek
Level 7

Re: UDP Broadcasts

"RokuMarkn" wrote:
Right now we don't have a good solution for this. You could try this workaround:

look at the local address and guess:
a. the /24 (sub)network
b. the natural network implied by the non-routable address.

We hope to provide a better way to do this in a future release.

--Mark

Ah, I see. Ok, well I'll explore using multicasting instead then. Cheers Smiley Happy
0 Kudos
malort
Level 7

Re: UDP Broadcasts

Any chance this made the cut? It would be great to obtain the subnet as part of roDeviceInfo.GetConnectionInfo, but any access would be appreciated.

"RokuMarkn" wrote:
Right now we don't have a good solution for this. You could try this workaround:

look at the local address and guess:
a. the /24 (sub)network
b. the natural network implied by the non-routable address.

We hope to provide a better way to do this in a future release.

--Mark
0 Kudos