Struct Relay

pub struct Relay { /* private fields */ }

A Relay forwards PacketRcs between PacketDevices, optionally enforcing a bandwidth limit on the rate at which we forward PacketRcs between devices.

The Relay is considered the “active” part of the PacketRc forwarding process: it initiates PacketRc forwarding and internally schedules tasks to ensure that PacketRcs are continually forwarded over time without exceeding the configured RateLimit.

An Ipv4Addr associated with a source PacketDevice object is supplied when creating a Relay. This Ipv4Addr is only meaningful to the extent that the Host understands how to map this Ipv4Addr to the intended PacketDevice when Host::get_packet_device(Ipv4Addr) is called. This source PacketDevice supplies the Relay with a stream of PacketRcs (through its implementation of PacketDevice::pop()) that the Relay will forward to a destination.

Relay::notify() must be called whenever the source PacketDevice changes state from empty to non-empty, to trigger an idle Relay to start forwarding PacketRcs again.

For each PacketRc that needs to be forwarded, the Relay uses the PacketRc’s destination Ipv4Addr to obtain the destination PacketDevice from the Host by calling its Host::get_packet_device(Ipv4Addr) function. The PacketRc is forwarded to the destination through the destination PacketDevice’s implementation of PacketDevice::push().

This design allows the Host to use Host::get_packet_device to define its own routing table.

Note that PacketRcs forwarded between identical source and destination PacketDevices are considered “local” to that device and exempt from any configured RateLimit.

Implementations

impl Relay

pub fn new(rate: RateLimit, src_dev_address: Ipv4Addr) -> Self

Creates a new Relay that will forward PacketRcs following the given RateLimit from the PacketDevice returned by the Host when passing the given src_dev_address to Host::get_packet_device(). The Relay internally schedules tasks as needed to ensure packets continue to be forwarded over time without exceeding the configured RateLimit.

pub fn notify(self: &Arc<Self>, host: &Host)

Notify the relay that its packet source now has packets available for relaying to the packet sink. This must be called when the source changes state from empty to non-empty to signal the relay to resume forwarding.