> On 19 May 2015, at 10:30, Udo Schneider <udo.schnei...@homeaddress.de> wrote: > > Hi Sven, > > you got me :-) > > I had this as a package sometime ago for my own purposes (mDNS). So I knew it > does work and how to do it. It's just I can't find that damned package > anymore...
Did you look in all your package caches ? > > I do think making all this cross platform could be a bit harder, we'll see. > It's not that hard. The socket API is the same on all supported platforms. No > surprises on *nix based OS. The only exception is Windows where the API is > the same but where you might run into some packet drops due to strange > personal FW products and "value-add" NDIS drivers for NICs. The situation has > gotten much better though since Windows Vista/7 are using multicast for some > of their services out of the box. > > I will recreate it though. Should I simply publish a package or add this as a > slice? Thanks a lot, Udo, a good multicast example would be super cool. If it is just a small example, like one class, maybe it could be added to the image, in which case it should indeed be a slice. If it is larger and more application/framework oriented, then maybe a standalone package is more interesting. We try to keep the image as modular as possible. This route would be a bit more work for you, but might make more sense if you also see it possibly growing in the future. > Best Regards, > > Udo > > > On 19/05/15 10:20, Sven Van Caekenberghe wrote: >> Hi Udo, >> >> It would be good if some of this knowledge could be added inside the image, >> as class comment or methods comments. Even better would be an example >> combined with a unit test, like UDPSocketEchoTest and TCPSocketEchoTest - >> the unit test would then actively ensure this functionality is protected. >> >> I do think making all this cross platform could be a bit harder, we'll see. >> >> Sven >> >>> On 19 May 2015, at 00:17, Udo Schneider <udo.schnei...@homeaddress.de> >>> wrote: >>> >>> This should have been 'IP_ADD_MEMBERSHIP' of course: >>> >>> imrMultiaddr := #[239 255 255 250]. >>> imrInterface := #[0 0 0 0]. >>> ipMreq := imrMultiaddr , imrInterface. >>> socket setOption: 'IP_ADD_MEMBERSHIP' value: ipMreq. >>> >>> >>> The "server" could be something like this (execute in first playground). I >>> used another IP address (#[239 255 255 251]) because #[239 255 255 250] >>> might already be part of the multicast group because of other processes and >>> this shows the "whole" process of subscribing to a multicast group: >>> >>> [ >>> | udpSocket | >>> udpSocket := Socket newUDP. >>> udpSocket setPort: 1900. >>> imrMultiaddr := #[239 255 255 251]. >>> imrInterface := #[0 0 0 0]. >>> ipMreq := imrMultiaddr , imrInterface. >>> udpSocket setOption: 'IP_ADD_MEMBERSHIP' value: ipMreq. >>> udpSocket setOption: 'IP_MULTICAST_LOOP' value: 1. >>> "udpSocket setOption: 'SO_REUSEADDR' value: 1." >>> udpSocket waitForData. >>> buffer := ByteArray new: 256. >>> data := udpSocket receiveUDPDataInto: buffer. >>> bytesRead := data at: 1. >>> sender := data at: 2. >>> senderPort := data at: 3. >>> more := data at: 4. >>> result := buffer copyFrom: 1 to: bytesRead. >>> udpSocket closeAndDestroy. >>> result asString inspect. >>> ] fork. >>> >>> >>> >>> The "client" (execute in different playground): >>> | message udpSocket | >>> message := String crlf join: #( >>> 'M-SEARCH * HTTP/1.1' >>> 'HOST:239.255.255.250:1900' >>> 'MAN:"ssdp:discover' >>> 'ST:ssdp:all' >>> 'MX:1' >>> ''). >>> >>> udpSocket := Socket newUDP. >>> udpSocket sendData: message toHost: #[239 255 255 251] port: 1900. >>> (udpSocket waitForSendDoneFor: 5). >>> udpSocket closeAndDestroy. >>> >>> Hope this helps. >>> >>> CU, >>> >>> Udo >>> >>> >>> >>> >>> >>> >>> On 18/05/15 23:29, Udo Schneider 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 >>>> >>>> >>>> >>>> >>> >>> >>> >> >> >> > > >
