Module capsules_extra::net::udp::udp_send

This file contains the definition and implementation for a virtualized UDP sending interface. The UDPSender trait provides an interface for kernel capsules to send a UDP packet, and the UDPSendClient trait is implemented by upper layer clients to allow them to receive send_done callbacks once transmission has completed. In order to virtualize between both apps and kernel capsules, this file uses a MuxUdpSender which treats the userspace UDP driver as a kernel capsule with a special capability that allows it to bind to arbitrary ports. Therefore the correctness of port binding / packet transmission/delivery is also dependent on the port binding logic in the driver being correct. The MuxUdpSender acts as a FIFO queue for transmitted packets, with each capsule being allowed a single outstanding / unsent packet at a time. Because the userspace driver is viewed by the MuxUdpSender as being a single capsule, the userspace driver must queue app packets on its own, as it can only pass a single packet to the MuxUdpSender queue at a time.

Structs

• MuxUdpSender
• UDPSendStruct
  This is a specific instantiation of the UDPSender trait. Note that this struct contains a reference to an IP6Sender which it forwards packets to (and receives callbacks from).

Traits

• UDPSendClient
  The send_done function in this trait is invoked after the UDPSender has completed sending the requested packet. Note that the UDPSender::set_client method must be called to set the client.
• UDPSender
  This trait represents the bulk of the UDP functionality. The two variants of sending a packet (either via the send_to or send methods) represent whether the caller wants to construct a custom UDPHeader or not. Calling send_to tells the UDP layer to construct a default UDPHeader and forward the payload to the respective destination and port.