> Hi, > > On Mon, Mar 09, 2020 at 09:25:08PM -0300, Victhor Foster wrote: >> I have resumed work on this project, and I decided to implement a few >> changes. I abandoned the socat approach and came up with a different >> implementation, modifying the linux-wpan example programs. >> > > aha, which one? > I based my programs off the af_packet_rx and af_packet_tx examples. >> I made two programs, one that receives packets from a wpan interface >> and outputs them to a UDP port, while the other program receives >> packets from a UDP port and sends them to a wpan interface. It seems >> to work well enough, but there's a problem with my approach. >> > > You telling me something about UDP to a wpan interface. This makes no > sense except you also building some IP layer in user space. > Sorry for the misunderstanding, I'll try to explain it better. This is the data flow currently: [GNU Radio]--UDP socket-->[program 1]--raw wpan socket-->[wpan0] [GNU Radio]<--UDP socket--[program 2]<--raw wpan socket--[wpan0] (wpan0 is a hwsim interface) So the UDP socket is used only to transfer L2 packets to and from GNU Radio, which is where the PHY is implemented. This is like a SoftMAC-type radio, except the PHY is a userspace application, and not a piece of hardware. I'm trying to move L2 packets between my application and the wpan interface. >> I need to get outgoing packets from the wpan interface. Is there a way >> to filter packets coming through a raw socket, such that only outgoing >> packets come out of the socket? >> > > Now you saying something about RAW sockets, what kind of raw sockets? > Raw wpan sockets. Although I'm using ETH_P_ALL as the protocol, as the ETH_P_IEEE802154 protocol type does not output outgoing packets. >> Right now, I'm not filtering for outgoing packets, so when packets are >> received through my program and sent to the wpan interface, the same >> packets come out of the interface, as there's no filtering being done, >> causing a loop. >> >> I tried using the sll_pkttype field in the raw socket structure, but >> all packets received by the socket have the same value, so it's not >> useful, unfortunately. >> > > No, it smells for me you want to do something with traffic control and > egress path. True. In the meantime, I have been working on a possible solution for my problem, having the program that sends packets from the wpan interface to my GNU Radio application do the following checks: - Source MAC or short address is equal to the wpan interface's - Destination MAC or short address is not equal to that of the wpan interface - Destination MAC or short address is equal to the broadcast address I think this should avoid causing a loop. I haven't finished implementing these features yet, so I don't know if they will be effective. It's not the same as having proper flow control, though. I would need to implement a flow control mechanism to avoid this problem, I think. > - Alex
