Hello Udo, thanks for your detailed reply. I am going to try your suggestions and report back afterwards. Not sure though if I get to try it before next weekend.
The address I am sending to is definitely a multi-cast address (as defined in the SSDP spec). But what makes me wonder is why the minimal NodeJS example works in both cases without modifications (regular router/accesspoint + camera accesspoint) and the Pharo one only receives data in the first case. But maybe there is something happening behind the curtains in NodeJS when it comes to multi-cast addresses. Thanks, Manfred On Mon, May 18, 2015 at 11:29 PM, Udo Schneider < udo.schnei...@homeaddress.de> wrote: > Hi Manfred, > > I just stumbled over the IP address you are using (239.255.255.250). If I > remember correctly this is a IPv4 Class D Multicast address. > (224.0.0.0-239.255.255.255). > > So if you want to transmit datagrams to this IP address or recieve > datagrams sent to this multicast groups you have to set appropriate IP > Options. > > You can set this options using Socket>>#setOption:value: and read them > using Socket>>#getOption:. Please note that both methods expect the option > to set as a name - not as constant. E.g. > > socket setOption: 'IP_MULTICAST_IF' value: multicastInterface. > > If I do remember correctly you have to set the following options for > sending/receiving: > > Sending: > IP_MULTICAST_IF > (IP_MULTICAST_LOOP) > (IP_MULTICAST_TTL) > > Sending should AFAIK work w/o setting any option - although > IP_MULTICAST_IF is highly recommended. > > Receiving: > (SO_REUSEADDR) > IP_ADD_MEMBERSHIP > (IP_DROP_MEMBERSHIP) > > Receiving only works if you joined the multicast group previously. So I > assume that you need to do something like this (not tested). > > imrMultiaddr := #[239 255 255 250]. > imrInterface := #[0 0 0 0]. > ipMreq := imrMultiaddr , imrInterface. > socket setOption: 'MEMBERSHIP' value: ipMreq. > > Hope this helps. > > CU, > > Udo > > > > On 18/05/15 16:34, Manfred Kröhnert wrote: > >> Hi Sven, >> >> On Mon, May 18, 2015 at 4:14 PM, Sven Van Caekenberghe >> <s...@stfx.eu >> <mailto:s...@stfx.eu>> wrote: >> >> >> > On 18 May 2015, at 15:47, Manfred Kröhnert >> <mkroehner...@googlemail.com >> <mailto:mkroehner...@googlemail.com>> wrote: >> > >> > Hi, >> > apparently I am missing something else. >> > >> > I can find devices when connected to a 'regular' LAN. >> > >> > However, I have a camera that creates a Wifi accesspoint and >> makes itself discoverable via SSDP. >> > Once I connect to this accesspoint my computer gets a valid IP >> address assigned and the NodeJS code is able to discover the device. >> > Unfortunately, the Pharo snippet I posted before does not give me >> any results and hangs in Socket>>waitForDataIfClosed: . >> > >> > Any further ideas? >> >> Are you sure you restarted the image and your code after switching >> networks ? >> >> >> I did not check this before. >> But I just downloaded a fresh 40613 image with PharoLauncher and started >> it after connecting to the camera accesspoint. >> The code snippet freezes there as well. >> >> Manfred >> > > > >
