Diff: RHRouter.h

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+// RHRouter.h
+//
+// Author: Mike McCauley (mikem@airspayce.com)
+// Copyright (C) 2011 Mike McCauley
+// $Id: RHRouter.h,v 1.9 2014/08/10 20:55:17 mikem Exp $
+
+#ifndef RHRouter_h
+#define RHRouter_h
+
+#include <RHReliableDatagram.h>
+
+// Default max number of hops we will route
+#define RH_DEFAULT_MAX_HOPS 30
+
+// The default size of the routing table we keep
+#define RH_ROUTING_TABLE_SIZE 10
+
+// Error codes
+#define RH_ROUTER_ERROR_NONE              0
+#define RH_ROUTER_ERROR_INVALID_LENGTH    1
+#define RH_ROUTER_ERROR_NO_ROUTE          2
+#define RH_ROUTER_ERROR_TIMEOUT           3
+#define RH_ROUTER_ERROR_NO_REPLY          4
+#define RH_ROUTER_ERROR_UNABLE_TO_DELIVER 5
+
+// This size of RH_ROUTER_MAX_MESSAGE_LEN is OK for Arduino Mega, but too big for
+// Duemilanova. Size of 50 works with the sample router programs on Duemilanova.
+#define RH_ROUTER_MAX_MESSAGE_LEN (RH_MAX_MESSAGE_LEN - sizeof(RHRouter::RoutedMessageHeader))
+//#define RH_ROUTER_MAX_MESSAGE_LEN 50
+
+// These allow us to define a simulated network topology for testing purposes
+// See RHRouter.cpp for details
+//#define RH_TEST_NETWORK 1
+//#define RH_TEST_NETWORK 2
+//#define RH_TEST_NETWORK 3
+//#define RH_TEST_NETWORK 4
+
+/////////////////////////////////////////////////////////////////////
+/// \class RHRouter RHRouter.h <RHRouter.h>
+/// \brief RHReliableDatagram subclass for sending addressed, optionally acknowledged datagrams
+/// multi-hop routed across a network.
+///
+/// Manager class that extends RHReliableDatagram to define addressed messages
+/// That are reliably transmitted and routed across a network. Each message is transmitted reliably 
+/// between each hop in order to get from the source node to the destination node.
+///
+/// With RHRouter, routes are hard wired. This means that each node must have programmed 
+/// in it how to reach each of the other nodes it will be trying to communicate with. 
+/// This means you must specify the next-hop node address for each of the destination nodes, 
+/// using the addRouteTo() function. 
+///
+/// When sendtoWait() is called with a new message to deliver, and the destination address,
+/// RHRouter looks up the next hop node for the destination node. It then uses 
+/// RHReliableDatagram to (reliably) deliver the message to the next hop 
+/// (which is expected also to be running an RHRouter). If that next-hop node is not
+/// the final destination, it will also look up the next hop for the destination node and 
+/// (reliably) deliver the message to the next hop. By this method, messages can be delivered 
+/// across a network of nodes, even if each node cannot hear all of the others in the network.
+/// Each time a message is received for another node and retransmitted to the next hop, 
+/// the HOPS filed in teh header is incremented. If a message is received for routing to another node 
+/// which has exceed the routers max_hops, the message wioll be dropped and ignored. 
+/// This helps prevent infinite routing loops.
+///
+/// RHRouter supports messages with a dest of RH_BROADCAST_ADDRESS. Such messages are not routed, 
+/// and are broadcast (once) to all nodes within range.
+///
+/// The recvfromAck() function is responsible not just for receiving and delivering 
+/// messages addressed to this node (or RH_BROADCAST_ADDRESS), but 
+/// it is also responsible for routing other message to their next hop. This means that it is important to 
+/// call recvfromAck() or recvfromAckTimeout() frequently in your main loop. recvfromAck() will return 
+/// false if it receives a message but it is not for this node.
+///
+/// RHRouter does not provide reliable end-to-end delivery, but uses reliable hop-to-hop delivery. 
+/// If a message is unable to be delivered to an end node during to a delivery failure between 2 hops, 
+/// the source node will not be told about it.
+///
+/// Note: This class is most useful for networks of nodes that are essentially static 
+/// (i.e. the nodes dont move around), and for which the 
+/// routing never changes. If that is not the case for your proposed network, see RHMesh instead.
+///
+/// \par The Routing Table
+///
+/// The routing table is a local table in RHRouter that holds the information about the next hop node 
+/// address for each destination address you may want to send a message to. It is your responsibility 
+/// to make sure every node in an RHRouter network has been configured with a unique address and the 
+/// routing information so that messages are correctly routed across the network from source node to 
+/// destination node. This is usually done once in setup() by calling addRouteTo(). 
+/// The hardwired routing will in general be different on each node, and will depend on the physical 
+/// topololgy of the network.
+/// You can also use addRouteTo() to change a route and 
+/// deleteRouteTo() to delete a route at run time. Youcan also clear the entire routing table
+///
+/// The Routing Table has limited capacity for entries (defined by RH_ROUTING_TABLE_SIZE, which is 10)
+/// if more than RH_ROUTING_TABLE_SIZE are added, the oldest (first) one will be removed by calling 
+/// retireOldestRoute()
+///
+/// \par Message Format
+///
+/// RHRouter add to the lower level RHReliableDatagram (and even lower level RH) class message formats. 
+/// In those lower level classes, the hop-to-hop message headers are in the RH message headers, 
+/// and are handled automcatically by tyhe RH hardware.
+/// RHRouter and its subclasses add an end-to-end addressing header in the payload of the RH message, 
+/// and before the RHRouter application data.
+/// - 1 octet DEST, the destination node address (ie the address of the final 
+///   destination node for this message)
+/// - 1 octet SOURCE, the source node address (ie the address of the originating node that first sent 
+///   the message).
+/// - 1 octet HOPS, the number of hops this message has traversed so far.
+/// - 1 octet ID, an incrementing message ID for end-to-end message tracking for use by subclasses. 
+///   Not used by RHRouter.
+/// - 1 octet FLAGS, a bitmask for use by subclasses. Not used by RHRouter.
+/// - 0 or more octets DATA, the application payload data. The length of this data is implicit 
+///   in the length of the entire message.
+///
+/// You should be careful to note that there are ID and FLAGS fields in the low level per-hop 
+/// message header too. These are used only for hop-to-hop, and in general will be different to 
+/// the ones at the RHRouter level.
+///
+/// \par Testing
+///
+/// Bench testing of such networks is notoriously difficult, especially simulating limited radio 
+/// connectivity between some nodes.
+/// To assist testing (both during RH development and for your own networks) 
+/// RHRouter.cpp has the ability to 
+/// simulate a number of different small network topologies. Each simulated network supports 4 nodes with 
+/// addresses 1 to 4. It operates by pretending to not hear RH messages from certain other nodes.
+/// You can enable testing with a \#define TEST_NETWORK in RHRouter.h
+/// The sample programs rf22_mesh_* rely on this feature.
+///
+/// Part of the Arduino RH library for operating with HopeRF RH compatible transceivers 
+/// (see http://www.hoperf.com)
+class RHRouter : public RHReliableDatagram
+{
+public:
+
+    /// Defines the structure of the RHRouter message header, used to keep track of end-to-end delivery parameters
+    typedef struct
+    {
+	uint8_t    dest;       ///< Destination node address
+	uint8_t    source;     ///< Originator node address
+	uint8_t    hops;       ///< Hops traversed so far
+	uint8_t    id;         ///< Originator sequence number
+	uint8_t    flags;      ///< Originator flags
+	// Data follows, Length is implicit in the overall message length
+    } RoutedMessageHeader;
+
+    /// Defines the structure of a RHRouter message
+    typedef struct
+    {
+	RoutedMessageHeader header;    ///< end-to-end delivery header
+	uint8_t             data[RH_ROUTER_MAX_MESSAGE_LEN]; ///< Application payload data
+    } RoutedMessage;
+
+    /// Values for the possible states for routes
+    typedef enum
+    {
+	Invalid = 0,           ///< No valid route is known
+	Discovering,           ///< Discovering a route (not currently used)
+	Valid                  ///< Route is valid
+    } RouteState;
+
+    /// Defines an entry in the routing table
+    typedef struct
+    {
+	uint8_t      dest;      ///< Destination node address
+	uint8_t      next_hop;  ///< Send via this next hop address
+	uint8_t      state;     ///< State of this route, one of RouteState
+    } RoutingTableEntry;
+
+    /// Constructor. 
+    /// \param[in] driver The RadioHead driver to use to transport messages.
+    /// \param[in] thisAddress The address to assign to this node. Defaults to 0
+    RHRouter(RHGenericDriver& driver, uint8_t thisAddress = 0);
+
+    /// Initialises this instance and the radio module connected to it.
+    /// Overrides the init() function in RH.
+    /// Sets max_hops to the default of RH_DEFAULT_MAX_HOPS (30)
+    bool init();
+
+    /// Sets the max_hops to the given value
+    /// This controls the maximum number of hops allowed between source and destination nodes
+    /// Messages that are not delivered by the time their HOPS field exceeds max_hops on a 
+    /// routing node will be dropped and ignored.
+    /// \param [in] max_hops The new value for max_hops
+    void setMaxHops(uint8_t max_hops);
+
+    /// Adds a route to the local routing table, or updates it if already present.
+    /// If there is not enough room the oldest (first) route will be deleted by calling retireOldestRoute().
+    /// \param [in] dest The destination node address. RH_BROADCAST_ADDRESS is permitted.
+    /// \param [in] next_hop The address of the next hop to send messages destined for dest
+    /// \param [in] state The satte of the route. Defaults to Valid
+    void addRouteTo(uint8_t dest, uint8_t next_hop, uint8_t state = Valid);
+
+    /// Finds and returns a RoutingTableEntry for the given destination node
+    /// \param [in] dest The desired destination node address.
+    /// \return pointer to a RoutingTableEntry for dest
+    RoutingTableEntry* getRouteTo(uint8_t dest);
+
+    /// Deletes from the local routing table any route for the destination node.
+    /// \param [in] dest The destination node address
+    /// \return true if the route was present
+    bool deleteRouteTo(uint8_t dest);
+
+    /// Deletes the oldest (first) route from the 
+    /// local routing table
+    void retireOldestRoute();
+
+    /// Clears all entries from the 
+    /// local routing table
+    void clearRoutingTable();
+
+    /// If RH_HAVE_SERIAL is defined, this will print out the contents of the local 
+    /// routing table using Serial
+    void printRoutingTable();
+
+    /// Sends a message to the destination node. Initialises the RHRouter message header 
+    /// (the SOURCE address is set to the address of this node, HOPS to 0) and calls 
+    /// route() which looks up in the routing table the next hop to deliver to and sends the 
+    /// message to the next hop. Waits for an acknowledgement from the next hop 
+    /// (but not from the destination node (if that is different).
+    /// \param [in] buf The application message data
+    /// \param [in] len Number of octets in the application message data. 0 is permitted
+    /// \param [in] dest The destination node address
+    /// \param [in] flags Optional flags for use by subclasses or application layer, 
+    ///             delivered end-to-end to the dest address. The receiver can recover the flags with recvFromAck().
+    /// \return The result code:
+    ///         - RH_ROUTER_ERROR_NONE Message was routed and delivered to the next hop 
+    ///           (not necessarily to the final dest address)
+    ///         - RH_ROUTER_ERROR_NO_ROUTE There was no route for dest in the local routing table
+    ///         - RH_ROUTER_ERROR_UNABLE_TO_DELIVER Not able to deliver to the next hop 
+    ///           (usually because it dod not acknowledge due to being off the air or out of range
+    uint8_t sendtoWait(uint8_t* buf, uint8_t len, uint8_t dest, uint8_t flags = 0);
+
+    /// Similar to sendtoWait() above, but spoofs the source address.
+    /// For internal use only during routing
+    /// \param [in] buf The application message data.
+    /// \param [in] len Number of octets in the application message data. 0 is permitted.
+    /// \param [in] dest The destination node address.
+    /// \param [in] source The (fake) originating node address.
+    /// \param [in] flags Optional flags for use by subclasses or application layer, 
+    ///             delivered end-to-end to the dest address. The receiver can recover the flags with recvFromAck().
+    /// \return The result code:
+    ///         - RH_ROUTER_ERROR_NONE Message was routed and deliverd to the next hop 
+    ///           (not necessarily to the final dest address)
+    ///         - RH_ROUTER_ERROR_NO_ROUTE There was no route for dest in the local routing table
+    ///         - RH_ROUTER_ERROR_UNABLE_TO_DELIVER Noyt able to deliver to the next hop 
+    ///           (usually because it dod not acknowledge due to being off the air or out of range
+    uint8_t sendtoFromSourceWait(uint8_t* buf, uint8_t len, uint8_t dest, uint8_t source, uint8_t flags = 0);
+
+    /// Starts the receiver if it is not running already.
+    /// If there is a valid message available for this node (or RH_BROADCAST_ADDRESS), 
+    /// send an acknowledgement to the last hop
+    /// address (blocking until this is complete), then copy the application message payload data
+    /// to buf and return true
+    /// else return false. 
+    /// If a message is copied, *len is set to the length..
+    /// If from is not NULL, the originator SOURCE address is placed in *source.
+    /// If to is not NULL, the DEST address is placed in *dest. This might be this nodes address or 
+    /// RH_BROADCAST_ADDRESS. 
+    /// This is the preferred function for getting messages addressed to this node.
+    /// If the message is not a broadcast, acknowledge to the sender before returning.
+    /// \param[in] buf Location to copy the received message
+    /// \param[in,out] len Available space in buf. Set to the actual number of octets copied.
+    /// \param[in] source If present and not NULL, the referenced uint8_t will be set to the SOURCE address
+    /// \param[in] dest If present and not NULL, the referenced uint8_t will be set to the DEST address
+    /// \param[in] id If present and not NULL, the referenced uint8_t will be set to the ID
+    /// \param[in] flags If present and not NULL, the referenced uint8_t will be set to the FLAGS
+    /// (not just those addressed to this node).
+    /// \return true if a valid message was recvived for this node copied to buf
+    bool recvfromAck(uint8_t* buf, uint8_t* len, uint8_t* source = NULL, uint8_t* dest = NULL, uint8_t* id = NULL, uint8_t* flags = NULL);
+
+    /// Starts the receiver if it is not running already.
+    /// Similar to recvfromAck(), this will block until either a valid message available for this node
+    /// or the timeout expires. 
+    /// \param[in] buf Location to copy the received message
+    /// \param[in,out] len Available space in buf. Set to the actual number of octets copied.
+    /// \param[in] timeout Maximum time to wait in milliseconds
+    /// \param[in] source If present and not NULL, the referenced uint8_t will be set to the SOURCE address
+    /// \param[in] dest If present and not NULL, the referenced uint8_t will be set to the DEST address
+    /// \param[in] id If present and not NULL, the referenced uint8_t will be set to the ID
+    /// \param[in] flags If present and not NULL, the referenced uint8_t will be set to the FLAGS
+    /// (not just those addressed to this node).
+    /// \return true if a valid message was copied to buf
+    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);
+
+protected:
+
+    /// Lets sublasses peek at messages going 
+    /// past before routing or local delivery.
+    /// Called by recvfromAck() immediately after it gets the message from RHReliableDatagram
+    /// \param [in] message Pointer to the RHRouter message that was received.
+    /// \param [in] messageLen Length of message in octets
+    virtual void peekAtMessage(RoutedMessage* message, uint8_t messageLen);
+
+    /// Finds the next-hop route and sends the message via RHReliableDatagram::sendtoWait().
+    /// This is virtual, which lets subclasses override or intercept the route() function.
+    /// Called by sendtoWait after the message header has been filled in.
+    /// \param [in] message Pointer to the RHRouter message to be sent.
+    /// \param [in] messageLen Length of message in octets
+    virtual uint8_t route(RoutedMessage* message, uint8_t messageLen);
+
+    /// Deletes a specific rout entry from therouting table
+    /// \param [in] index The 0 based index of the routing table entry to delete
+    void deleteRoute(uint8_t index);
+
+    /// The last end-to-end sequence number to be used
+    /// Defaults to 0
+    uint8_t _lastE2ESequenceNumber;
+
+    /// The maximum number of hops permitted in routed messages.
+    /// If a routed message would exceed this number of hops it is dropped and ignored.
+    uint8_t              _max_hops;
+
+private:
+
+    /// Temporary mesage buffer
+    static RoutedMessage _tmpMessage;
+
+    /// Local routing table
+    RoutingTableEntry    _routes[RH_ROUTING_TABLE_SIZE];
+};
+
+/// @example rf22_router_client.pde
+/// @example rf22_router_server1.pde
+/// @example rf22_router_server2.pde
+/// @example rf22_router_server3.pde
+#endif
+