RHMesh.cpp

// RHMesh.cpp
//
// Define addressed datagram
// 
// Part of the Arduino RH library for operating with HopeRF RH compatible transceivers 
// (see http://www.hoperf.com)
// RHDatagram will be received only by the addressed node or all nodes within range if the 
// to address is RH_BROADCAST_ADDRESS
//
// Author: Mike McCauley (mikem@airspayce.com)
// Copyright (C) 2011 Mike McCauley
// $Id: RHMesh.cpp,v 1.12 2020/08/04 09:02:14 mikem Exp $

#include <RHMesh.h>

uint8_t RHMesh::_tmpMessage[RH_ROUTER_MAX_MESSAGE_LEN];

////////////////////////////////////////////////////////////////////
// Constructors
RHMesh::RHMesh(RHGenericDriver& driver, uint8_t thisAddress) 
    : RHRouter(driver, thisAddress)
{
}

////////////////////////////////////////////////////////////////////
// Public methods

////////////////////////////////////////////////////////////////////
// Discovers a route to the destination (if necessary), sends and 
// waits for delivery to the next hop (but not for delivery to the final destination)
uint8_t RHMesh::sendtoWait(uint8_t* buf, uint8_t len, uint8_t address, uint8_t flags)
{
    if (len > RH_MESH_MAX_MESSAGE_LEN)
	return RH_ROUTER_ERROR_INVALID_LENGTH;

    if (address != RH_BROADCAST_ADDRESS)
    {
	RoutingTableEntry* route = getRouteTo(address);
	if (!route && !doArp(address))
	    return RH_ROUTER_ERROR_NO_ROUTE;
    }

    // Now have a route. Contruct an application layer message and send it via that route
    MeshApplicationMessage* a = (MeshApplicationMessage*)&_tmpMessage;
    a->header.msgType = RH_MESH_MESSAGE_TYPE_APPLICATION;
    memcpy(a->data, buf, len);
    return RHRouter::sendtoWait(_tmpMessage, sizeof(RHMesh::MeshMessageHeader) + len, address, flags);
}

////////////////////////////////////////////////////////////////////
bool RHMesh::doArp(uint8_t address)
{
    // Need to discover a route
    // Broadcast a route discovery message with nothing in it
    MeshRouteDiscoveryMessage* p = (MeshRouteDiscoveryMessage*)&_tmpMessage;
    p->header.msgType = RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_REQUEST;
    p->destlen = 1; 
    p->dest = address; // Who we are looking for
    uint8_t error = RHRouter::sendtoWait((uint8_t*)p, sizeof(RHMesh::MeshMessageHeader) + 2, RH_BROADCAST_ADDRESS);
    if (error !=  RH_ROUTER_ERROR_NONE)
	return false;
    
    // Wait for a reply, which will be unicast back to us
    // It will contain the complete route to the destination
    uint8_t messageLen = sizeof(_tmpMessage);
    // FIXME: timeout should be configurable
    unsigned long starttime = millis();
    int32_t timeLeft;
    while ((timeLeft = RH_MESH_ARP_TIMEOUT - (millis() - starttime)) > 0)
    {
	if (waitAvailableTimeout(timeLeft))
	{
	    if (RHRouter::recvfromAck(_tmpMessage, &messageLen))
	    {
		if (   messageLen > 1
		       && p->header.msgType == RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_RESPONSE)
		{
		    // Got a reply, now add the next hop to the dest to the routing table
		    // The first hop taken is the first octet
		    addRouteTo(address, headerFrom());
		    return true;
		}
	    }
	}
	YIELD;
    }
    return false;
}

////////////////////////////////////////////////////////////////////
// Called by RHRouter::recvfromAck whenever a message goes past
void RHMesh::peekAtMessage(RoutedMessage* message, uint8_t messageLen)
{
    MeshMessageHeader* m = (MeshMessageHeader*)message->data;
    if (   messageLen > 1 
	&& m->msgType == RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_RESPONSE)
    {
	// This is a unicast RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_RESPONSE messages 
	// being routed back to the originator here. Want to scrape some routing data out of the response
	// We can find the routes to all the nodes between here and the responding node
	MeshRouteDiscoveryMessage* d = (MeshRouteDiscoveryMessage*)message->data;
	addRouteTo(d->dest, headerFrom());
	uint8_t numRoutes = messageLen - sizeof(RoutedMessageHeader) - sizeof(MeshMessageHeader) - 2;
	uint8_t i;
	// Find us in the list of nodes that were traversed to get to the responding node
	for (i = 0; i < numRoutes; i++)
	    if (d->route[i] == _thisAddress)
		break;
	i++;
	while (i < numRoutes)
	    addRouteTo(d->route[i++], headerFrom());
    }
    else if (   messageLen > 1 
	     && m->msgType == RH_MESH_MESSAGE_TYPE_ROUTE_FAILURE)
    {
	MeshRouteFailureMessage* d = (MeshRouteFailureMessage*)message->data;
	deleteRouteTo(d->dest);
    }
}

////////////////////////////////////////////////////////////////////
// This is called when a message is to be delivered to the next hop
uint8_t RHMesh::route(RoutedMessage* message, uint8_t messageLen)
{
    uint8_t from = headerFrom(); // Might get clobbered during call to superclass route()
    uint8_t ret = RHRouter::route(message, messageLen);
    if (   ret == RH_ROUTER_ERROR_NO_ROUTE
	|| ret == RH_ROUTER_ERROR_UNABLE_TO_DELIVER)
    {
	// Cant deliver to the next hop. Delete the route
	deleteRouteTo(message->header.dest);
	if (message->header.source != _thisAddress)
	{
	    // This is being proxied, so tell the originator about it
	    MeshRouteFailureMessage* p = (MeshRouteFailureMessage*)&_tmpMessage;
	    p->header.msgType = RH_MESH_MESSAGE_TYPE_ROUTE_FAILURE;
	    p->dest = message->header.dest; // Who you were trying to deliver to
	    // Make sure there is a route back towards whoever sent the original message
	    addRouteTo(message->header.source, from);
	    ret = RHRouter::sendtoWait((uint8_t*)p, sizeof(RHMesh::MeshMessageHeader) + 1, message->header.source);
	}
    }
    return ret;
}

////////////////////////////////////////////////////////////////////
// Subclasses may want to override
bool RHMesh::isPhysicalAddress(uint8_t* address, uint8_t addresslen)
{
    // Can only handle physical addresses 1 octet long, which is the physical node address
    return addresslen == 1 && address[0] == _thisAddress;
}

////////////////////////////////////////////////////////////////////
bool RHMesh::recvfromAck(uint8_t* buf, uint8_t* len, uint8_t* source, uint8_t* dest, uint8_t* id, uint8_t* flags, uint8_t* hops)
{     
    uint8_t tmpMessageLen = sizeof(_tmpMessage);
    uint8_t _source;
    uint8_t _dest;
    uint8_t _id;
    uint8_t _flags;
    uint8_t _hops;
    if (RHRouter::recvfromAck(_tmpMessage, &tmpMessageLen, &_source, &_dest, &_id, &_flags, &_hops))
    {
	MeshMessageHeader* p = (MeshMessageHeader*)&_tmpMessage;

	if (   tmpMessageLen >= 1 
	    && p->msgType == RH_MESH_MESSAGE_TYPE_APPLICATION)
	{
	    MeshApplicationMessage* a = (MeshApplicationMessage*)p;
	    // Handle application layer messages, presumably for our caller
	    if (source) *source = _source;
	    if (dest)   *dest   = _dest;
	    if (id)     *id     = _id;
	    if (flags)  *flags  = _flags;
	    if (hops)   *hops   = _hops;
	    uint8_t msgLen = tmpMessageLen - sizeof(MeshMessageHeader);
	    if (*len > msgLen)
		*len = msgLen;
	    memcpy(buf, a->data, *len);
	    
	    return true;
	}
	else if (   _dest == RH_BROADCAST_ADDRESS 
		 && tmpMessageLen > 1 
		 && p->msgType == RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_REQUEST)
	{
	    MeshRouteDiscoveryMessage* d = (MeshRouteDiscoveryMessage*)p;
	    // Handle Route discovery requests
	    // Message is an array of node addresses the route request has already passed through
	    // If it originally came from us, ignore it
	    if (_source == _thisAddress)
		return false;
	    
	    uint8_t numRoutes = tmpMessageLen - sizeof(MeshMessageHeader) - 2;
	    uint8_t i;
	    // Are we already mentioned?
	    for (i = 0; i < numRoutes; i++)
		if (d->route[i] == _thisAddress)
		    return false; // Already been through us. Discard
	    
	        
            addRouteTo(_source, headerFrom()); // The originator needs to be added regardless of node type

	    // Hasnt been past us yet, record routes back to the earlier nodes
            // No need to waste memory if we are not participating in routing
            if (_isa_router)
            {
	        for (i = 0; i < numRoutes; i++)
		    addRouteTo(d->route[i], headerFrom());
            }

	    if (isPhysicalAddress(&d->dest, d->destlen))
	    {
		// This route discovery is for us. Unicast the whole route back to the originator
		// as a RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_RESPONSE
		// We are certain to have a route there, because we just got it
		d->header.msgType = RH_MESH_MESSAGE_TYPE_ROUTE_DISCOVERY_RESPONSE;
		RHRouter::sendtoWait((uint8_t*)d, tmpMessageLen, _source);
	    }
	    else if ((i < _max_hops) && _isa_router)
	    {
		// Its for someone else, rebroadcast it, after adding ourselves to the list
		d->route[numRoutes] = _thisAddress;
		tmpMessageLen++;
		// Have to impersonate the source
		// REVISIT: if this fails what can we do?
		RHRouter::sendtoFromSourceWait(_tmpMessage, tmpMessageLen, RH_BROADCAST_ADDRESS, _source);
	    }
	}
    }
    return false;
}

////////////////////////////////////////////////////////////////////
bool RHMesh::recvfromAckTimeout(uint8_t* buf, uint8_t* len, uint16_t timeout, uint8_t* from, uint8_t* to, uint8_t* id, uint8_t* flags, uint8_t* hops)
{  
    unsigned long starttime = millis();
    int32_t timeLeft;
    while ((timeLeft = timeout - (millis() - starttime)) > 0)
    {
	if (waitAvailableTimeout(timeLeft))
	{
	    if (recvfromAck(buf, len, from, to, id, flags, hops))
		return true;
	    YIELD;
	}
    }
    return false;
}