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66 lines
1.9 KiB
66 lines
1.9 KiB
7 months ago
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.. _module-pw_router:
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---------
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pw_router
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---------
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The ``pw_router`` module provides transport-agnostic classes for routing packets
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over network links.
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Common router interfaces
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========================
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PacketParser
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------------
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To work with arbitrary packet formats, routers require a common interface for
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extracting relevant packet data, such as the destination. This interface is
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``pw::router::PacketParser``, defined in ``pw_router/packet_parser.h``, which
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must be implemented for the packet framing format used by the network.
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Egress
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------
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The Egress class is a virtual interface for sending packet data over a network
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link. Egress implementations provide a single ``SendPacket`` function, which
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takes the raw packet data and transmits it.
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Some common egress implementations are provided upstream in Pigweed.
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StaticRouter
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============
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``pw::router::StaticRouter`` is a router with a static table of address to
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egress mappings. Routes in a static router never change; packets with the same
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address are always sent through the same egress. If links are unavailable,
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packets will be dropped.
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Static routers are suitable for basic networks with persistent links.
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Usage example
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-------------
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.. code-block:: c++
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namespace {
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// Define packet parser and egresses.
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HdlcFrameParser hdlc_parser;
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UartEgress uart_egress;
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BluetoothEgress ble_egress;
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// Define the routing table.
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constexpr pw::router::StaticRouter::Route routes[] = {{1, uart_egress},
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{7, ble_egress}};
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pw::router::StaticRouter router(hdlc_parser, routes);
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} // namespace
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void ProcessPacket(pw::ConstByteSpan packet) {
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router.RoutePacket(packet);
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}
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.. TODO(frolv): Re-enable this when the size report builds.
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.. Size report
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.. -----------
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.. The following size report shows the cost of a ``StaticRouter`` with a simple
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.. ``PacketParser`` implementation and a single route using an ``EgressFunction``.
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.. .. include:: static_router_size
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