263 lines
15 KiB
C++
263 lines
15 KiB
C++
// RHMesh.h
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//
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// Author: Mike McCauley (mikem@airspayce.com)
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// Copyright (C) 2011 Mike McCauley
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// $Id: RHMesh.h,v 1.15 2015/08/13 02:45:47 mikem Exp $
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#ifndef RHMesh_h
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#define RHMesh_h
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#include <RHRouter.h>
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// Types of RHMesh message, used to set msgType in the RHMeshHeader
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#define RH_MESH_MESSAGE_TYPE_APPLICATION 0
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#define RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_REQUEST 1
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#define RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_RESPONSE 2
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#define RH_MESH_MESSAGE_TYPE_ROUTE_FAILURE 3
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// Timeout for address resolution in milliecs
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#define RH_MESH_ARP_TIMEOUT 4000
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/////////////////////////////////////////////////////////////////////
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/// \class RHMesh RHMesh.h <RHMesh.h>
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/// \brief RHRouter subclass for sending addressed, optionally acknowledged datagrams
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/// multi-hop routed across a network, with automatic route discovery
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///
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/// Manager class that extends RHRouter to add automatic route discovery within a mesh of adjacent nodes,
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/// and route signalling.
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///
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/// Unlike RHRouter, RHMesh can be used in networks where the network topology is fluid, or unknown,
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/// or if nodes can mode around or go in or out of service. When a node wants to send a
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/// message to another node, it will automatically discover a route to the destination node and use it.
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/// If the route becomes unavailable, a new route will be discovered.
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///
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/// \par Route Discovery
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///
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/// When a RHMesh mesh node is initialised, it doe not know any routes to any other nodes
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/// (see RHRouter for details on route and the routing table).
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/// When you attempt to send a message with sendtoWait, will first check to see if there is a route to the
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/// destinastion node in the routing tabl;e. If not, it wil initialite 'Route Discovery'.
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/// When a node needs to discover a route to another node, it broadcasts MeshRouteDiscoveryMessage
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/// with a message type of RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_REQUEST.
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/// Any node that receives such a request checks to see if it is a request for a route to itself
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/// (in which case it makes a unicast reply to the originating node with a
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/// MeshRouteDiscoveryMessage
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/// with a message type of RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_RESPONSE)
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/// otherwise it rebroadcasts the request, after adding itself to the list of nodes visited so
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/// far by the request.
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///
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/// If a node receives a RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_REQUEST that already has itself
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/// listed in the visited nodes, it knows it has already seen and rebroadcast this request,
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/// and threfore ignores it. This prevents broadcast storms.
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/// When a node receives a RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_REQUEST it can use the list of
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/// nodes aready visited to deduce routes back towards the originating (requesting node).
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/// This also means that when the destination node of the request is reached, it (and all
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/// the previous nodes the request visited) will have a route back to the originating node.
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/// This means the unicast RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_RESPONSE
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/// reply will be routed successfully back to the original route requester.
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///
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/// The RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_RESPONSE sent back by the destination node contains
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/// the full list of nodes that were visited on the way to the destination.
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/// Therefore, intermediate nodes that route the reply back towards the originating node can use the
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/// node list in the reply to deduce routes to all the nodes between it and the destination node.
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///
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/// Therefore, RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_REQUEST and
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/// RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_RESPONSE together ensure the original requester and all
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/// the intermediate nodes know how to route to the source and destination nodes and every node along the path.
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///
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/// Note that there is a race condition here that can effect routing on multipath routes. For example,
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/// if the route to the destination can traverse several paths, last reply from the destination
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/// will be the one used.
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///
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/// \par Route Failure
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///
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/// RHRouter (and therefore RHMesh) use reliable hop-to-hop delivery of messages using
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/// hop-to-hop acknowledgements, but not end-to-end acknowledgements. When sendtoWait() returns,
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/// you know that the message has been delivered to the next hop, but not if it is (or even if it can be)
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/// delivered to the destination node. If during the course of hop-to-hop routing of a message,
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/// one of the intermediate RHMesh nodes finds it cannot deliver to the next hop
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/// (say due to a lost route or no acknwledgement from the next hop), it replies to the
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/// originator with a unicast MeshRouteFailureMessage RH_MESH_MESSAGE_TYPE_ROUTE_FAILURE message.
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/// Intermediate nodes (on the way beack to the originator)
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/// and the originating node use this message to delete the route to the destination
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/// node of the original message. This means that if a route to a destination becomes unusable
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/// (either because an intermediate node is off the air, or has moved out of range) a new route
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/// will be established the next time a message is to be sent.
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///
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/// \par Message Format
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///
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/// RHMesh uses a number of message formats layered on top of RHRouter:
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/// - MeshApplicationMessage (message type RH_MESH_MESSAGE_TYPE_APPLICATION).
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/// Carries an application layer message for the caller of RHMesh
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/// - MeshRouteDiscoveryMessage (message types RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_REQUEST
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/// and RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_RESPONSE). Carries Route Discovery messages
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/// (broadcast) and replies (unicast).
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/// - MeshRouteFailureMessage (message type RH_MESH_MESSAGE_TYPE_ROUTE_FAILURE) Informs nodes of
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/// route failures.
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///
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/// Part of the Arduino RH library for operating with HopeRF RH compatible transceivers
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/// (see http://www.hoperf.com)
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///
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/// \par Memory
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///
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/// RHMesh programs require significant amount of SRAM, often approaching 2kbytes,
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/// which is beyond or at the limits of some Arduinos and other processors. Programs
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/// with additional software besides basic RHMesh programs may well require even more. If you have insufficient
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/// SRAM for your program, it may result in failure to run, or wierd crashes and other hard to trace behaviour.
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/// In this event you should consider a processor with more SRAM, such as the MotienoMEGA with 16k
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/// (https://lowpowerlab.com/shop/moteinomega) or others.
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///
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/// \par Performance
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/// This class (in the interests of simple implemtenation and low memory use) does not have
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/// message queueing. This means that only one message at a time can be handled. Message transmission
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/// failures can have a severe impact on network performance.
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/// If you need high performance mesh networking under all conditions consider XBee or similar.
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class RHMesh : public RHRouter
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{
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public:
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/// The maximum length permitted for the application payload data in a RHMesh message
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#define RH_MESH_MAX_MESSAGE_LEN (RH_ROUTER_MAX_MESSAGE_LEN - sizeof(RHMesh::MeshMessageHeader))
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/// Structure of the basic RHMesh header.
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typedef struct
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{
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uint8_t msgType; ///< Type of RHMesh message, one of RH_MESH_MESSAGE_TYPE_*
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} MeshMessageHeader;
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/// Signals an application layer message for the caller of RHMesh
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typedef struct
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{
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MeshMessageHeader header; ///< msgType = RH_MESH_MESSAGE_TYPE_APPLICATION
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uint8_t data[RH_MESH_MAX_MESSAGE_LEN]; ///< Application layer payload data
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} MeshApplicationMessage;
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/// Signals a route discovery request or reply (At present only supports physical dest addresses of length 1 octet)
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typedef struct
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{
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MeshMessageHeader header; ///< msgType = RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_*
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uint8_t destlen; ///< Reserved. Must be 1.g
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uint8_t dest; ///< The address of the destination node whose route is being sought
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uint8_t route[RH_MESH_MAX_MESSAGE_LEN - 1]; ///< List of node addresses visited so far. Length is implcit
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} MeshRouteDiscoveryMessage;
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/// Signals a route failure
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typedef struct
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{
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MeshMessageHeader header; ///< msgType = RH_MESH_MESSAGE_TYPE_ROUTE_FAILURE
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uint8_t dest; ///< The address of the destination towards which the route failed
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} MeshRouteFailureMessage;
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/// Constructor.
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/// \param[in] driver The RadioHead driver to use to transport messages.
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/// \param[in] thisAddress The address to assign to this node. Defaults to 0
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RHMesh(RHGenericDriver& driver, uint8_t thisAddress = 0);
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/// Sends a message to the destination node. Initialises the RHRouter message header
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/// (the SOURCE address is set to the address of this node, HOPS to 0) and calls
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/// route() which looks up in the routing table the next hop to deliver to.
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/// If no route is known, initiates route discovery and waits for a reply.
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/// Then sends the message to the next hop
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/// Then waits for an acknowledgement from the next hop
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/// (but not from the destination node (if that is different).
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/// \param [in] buf The application message data
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/// \param [in] len Number of octets in the application message data. 0 is permitted
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/// \param [in] dest The destination node address. If the address is RH_BROADCAST_ADDRESS (255)
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/// the message will be broadcast to all the nearby nodes, but not routed or relayed.
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/// \param [in] flags Optional flags for use by subclasses or application layer,
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/// delivered end-to-end to the dest address. The receiver can recover the flags with recvFromAck().
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/// \return The result code:
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/// - RH_ROUTER_ERROR_NONE Message was routed and delivered to the next hop
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/// (not necessarily to the final dest address)
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/// - RH_ROUTER_ERROR_NO_ROUTE There was no route for dest in the local routing table
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/// - RH_ROUTER_ERROR_UNABLE_TO_DELIVER Not able to deliver to the next hop
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/// (usually because it dod not acknowledge due to being off the air or out of range
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uint8_t sendtoWait(uint8_t* buf, uint8_t len, uint8_t dest, uint8_t flags = 0);
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/// Starts the receiver if it is not running already, processes and possibly routes any received messages
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/// addressed to other nodes
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/// and delivers any messages addressed to this node.
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/// If there is a valid application layer message available for this node (or RH_BROADCAST_ADDRESS),
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/// send an acknowledgement to the last hop
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/// address (blocking until this is complete), then copy the application message payload data
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/// to buf and return true
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/// else return false.
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/// If a message is copied, *len is set to the length..
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/// If from is not NULL, the originator SOURCE address is placed in *source.
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/// If to is not NULL, the DEST address is placed in *dest. This might be this nodes address or
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/// RH_BROADCAST_ADDRESS.
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/// This is the preferred function for getting messages addressed to this node.
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/// If the message is not a broadcast, acknowledge to the sender before returning.
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/// \param[in] buf Location to copy the received message
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/// \param[in,out] len Available space in buf. Set to the actual number of octets copied.
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/// \param[in] source If present and not NULL, the referenced uint8_t will be set to the SOURCE address
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/// \param[in] dest If present and not NULL, the referenced uint8_t will be set to the DEST address
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/// \param[in] id If present and not NULL, the referenced uint8_t will be set to the ID
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/// \param[in] flags If present and not NULL, the referenced uint8_t will be set to the FLAGS
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/// (not just those addressed to this node).
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/// \return true if a valid message was received for this node and copied to buf
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bool recvfromAck(uint8_t* buf, uint8_t* len, uint8_t* source = NULL, uint8_t* dest = NULL, uint8_t* id = NULL, uint8_t* flags = NULL);
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/// Starts the receiver if it is not running already.
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/// Similar to recvfromAck(), this will block until either a valid application layer
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/// message available for this node
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/// or the timeout expires.
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/// \param[in] buf Location to copy the received message
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/// \param[in,out] len Available space in buf. Set to the actual number of octets copied.
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/// \param[in] timeout Maximum time to wait in milliseconds
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/// \param[in] source If present and not NULL, the referenced uint8_t will be set to the SOURCE address
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/// \param[in] dest If present and not NULL, the referenced uint8_t will be set to the DEST address
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/// \param[in] id If present and not NULL, the referenced uint8_t will be set to the ID
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/// \param[in] flags If present and not NULL, the referenced uint8_t will be set to the FLAGS
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/// (not just those addressed to this node).
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/// \return true if a valid message was copied to buf
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bool recvfromAckTimeout(uint8_t* buf, uint8_t* len, uint16_t timeout, uint8_t* source = NULL, uint8_t* dest = NULL, uint8_t* id = NULL, uint8_t* flags = NULL);
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protected:
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/// Internal function that inspects messages being received and adjusts the routing table if necessary.
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/// Called by recvfromAck() immediately after it gets the message from RHReliableDatagram
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/// \param [in] message Pointer to the RHRouter message that was received.
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/// \param [in] messageLen Length of message in octets
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virtual void peekAtMessage(RoutedMessage* message, uint8_t messageLen);
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/// Internal function that inspects messages being received and adjusts the routing table if necessary.
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/// This is virtual, which lets subclasses override or intercept the route() function.
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/// Called by sendtoWait after the message header has been filled in.
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/// \param [in] message Pointer to the RHRouter message to be sent.
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/// \param [in] messageLen Length of message in octets
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virtual uint8_t route(RoutedMessage* message, uint8_t messageLen);
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/// Try to resolve a route for the given address. Blocks while discovering the route
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/// which may take up to 4000 msec.
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/// Virtual so subclasses can override.
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/// \param [in] address The physical address to resolve
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/// \return true if the address was resolved and added to the local routing table
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virtual bool doArp(uint8_t address);
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/// Tests if the given address of length addresslen is indentical to the
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/// physical address of this node.
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/// RHMesh always implements physical addresses as the 1 octet address of the node
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/// given by _thisAddress
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/// Called by recvfromAck() to test whether a RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_REQUEST
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/// is for this node.
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/// Subclasses may want to override to implement more complicated or longer physical addresses
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/// \param [in] address Address of the pyysical addres being tested
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/// \param [in] addresslen Lengthof the address in bytes
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/// \return true if the physical address of this node is identical to address
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virtual bool isPhysicalAddress(uint8_t* address, uint8_t addresslen);
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private:
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/// Temporary message buffer
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static uint8_t _tmpMessage[RH_ROUTER_MAX_MESSAGE_LEN];
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};
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/// @example rf22_mesh_client.pde
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/// @example rf22_mesh_server1.pde
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/// @example rf22_mesh_server2.pde
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/// @example rf22_mesh_server3.pde
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#endif
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