RHRouter.h

00001 // RHRouter.h
00002 //
00003 // Author: Mike McCauley (mikem@airspayce.com)
00004 // Copyright (C) 2011 Mike McCauley
00005 // $Id: RHRouter.h,v 1.9 2014/08/10 20:55:17 mikem Exp $
00006 
00007 #ifndef RHRouter_h
00008 #define RHRouter_h
00009 
00010 #include <RHReliableDatagram.h>
00011 
00012 // Default max number of hops we will route
00013 #define RH_DEFAULT_MAX_HOPS 30
00014 
00015 // The default size of the routing table we keep
00016 #define RH_ROUTING_TABLE_SIZE 10
00017 
00018 // Error codes
00019 #define RH_ROUTER_ERROR_NONE              0
00020 #define RH_ROUTER_ERROR_INVALID_LENGTH    1
00021 #define RH_ROUTER_ERROR_NO_ROUTE          2
00022 #define RH_ROUTER_ERROR_TIMEOUT           3
00023 #define RH_ROUTER_ERROR_NO_REPLY          4
00024 #define RH_ROUTER_ERROR_UNABLE_TO_DELIVER 5
00025 
00026 // This size of RH_ROUTER_MAX_MESSAGE_LEN is OK for Arduino Mega, but too big for
00027 // Duemilanova. Size of 50 works with the sample router programs on Duemilanova.
00028 #define RH_ROUTER_MAX_MESSAGE_LEN (RH_MAX_MESSAGE_LEN - sizeof(RHRouter::RoutedMessageHeader))
00029 //#define RH_ROUTER_MAX_MESSAGE_LEN 50
00030 
00031 // These allow us to define a simulated network topology for testing purposes
00032 // See RHRouter.cpp for details
00033 //#define RH_TEST_NETWORK 1
00034 //#define RH_TEST_NETWORK 2
00035 //#define RH_TEST_NETWORK 3
00036 //#define RH_TEST_NETWORK 4
00037 
00038 /////////////////////////////////////////////////////////////////////
00039 /// \class RHRouter RHRouter.h <RHRouter.h>
00040 /// \brief RHReliableDatagram subclass for sending addressed, optionally acknowledged datagrams
00041 /// multi-hop routed across a network.
00042 ///
00043 /// Manager class that extends RHReliableDatagram to define addressed messages
00044 /// That are reliably transmitted and routed across a network. Each message is transmitted reliably 
00045 /// between each hop in order to get from the source node to the destination node.
00046 ///
00047 /// With RHRouter, routes are hard wired. This means that each node must have programmed 
00048 /// in it how to reach each of the other nodes it will be trying to communicate with. 
00049 /// This means you must specify the next-hop node address for each of the destination nodes, 
00050 /// using the addRouteTo() function. 
00051 ///
00052 /// When sendtoWait() is called with a new message to deliver, and the destination address,
00053 /// RHRouter looks up the next hop node for the destination node. It then uses 
00054 /// RHReliableDatagram to (reliably) deliver the message to the next hop 
00055 /// (which is expected also to be running an RHRouter). If that next-hop node is not
00056 /// the final destination, it will also look up the next hop for the destination node and 
00057 /// (reliably) deliver the message to the next hop. By this method, messages can be delivered 
00058 /// across a network of nodes, even if each node cannot hear all of the others in the network.
00059 /// Each time a message is received for another node and retransmitted to the next hop, 
00060 /// the HOPS filed in teh header is incremented. If a message is received for routing to another node 
00061 /// which has exceed the routers max_hops, the message wioll be dropped and ignored. 
00062 /// This helps prevent infinite routing loops.
00063 ///
00064 /// RHRouter supports messages with a dest of RH_BROADCAST_ADDRESS. Such messages are not routed, 
00065 /// and are broadcast (once) to all nodes within range.
00066 ///
00067 /// The recvfromAck() function is responsible not just for receiving and delivering 
00068 /// messages addressed to this node (or RH_BROADCAST_ADDRESS), but 
00069 /// it is also responsible for routing other message to their next hop. This means that it is important to 
00070 /// call recvfromAck() or recvfromAckTimeout() frequently in your main loop. recvfromAck() will return 
00071 /// false if it receives a message but it is not for this node.
00072 ///
00073 /// RHRouter does not provide reliable end-to-end delivery, but uses reliable hop-to-hop delivery. 
00074 /// If a message is unable to be delivered to an end node during to a delivery failure between 2 hops, 
00075 /// the source node will not be told about it.
00076 ///
00077 /// Note: This class is most useful for networks of nodes that are essentially static 
00078 /// (i.e. the nodes dont move around), and for which the 
00079 /// routing never changes. If that is not the case for your proposed network, see RHMesh instead.
00080 ///
00081 /// \par The Routing Table
00082 ///
00083 /// The routing table is a local table in RHRouter that holds the information about the next hop node 
00084 /// address for each destination address you may want to send a message to. It is your responsibility 
00085 /// to make sure every node in an RHRouter network has been configured with a unique address and the 
00086 /// routing information so that messages are correctly routed across the network from source node to 
00087 /// destination node. This is usually done once in setup() by calling addRouteTo(). 
00088 /// The hardwired routing will in general be different on each node, and will depend on the physical 
00089 /// topololgy of the network.
00090 /// You can also use addRouteTo() to change a route and 
00091 /// deleteRouteTo() to delete a route at run time. Youcan also clear the entire routing table
00092 ///
00093 /// The Routing Table has limited capacity for entries (defined by RH_ROUTING_TABLE_SIZE, which is 10)
00094 /// if more than RH_ROUTING_TABLE_SIZE are added, the oldest (first) one will be removed by calling 
00095 /// retireOldestRoute()
00096 ///
00097 /// \par Message Format
00098 ///
00099 /// RHRouter add to the lower level RHReliableDatagram (and even lower level RH) class message formats. 
00100 /// In those lower level classes, the hop-to-hop message headers are in the RH message headers, 
00101 /// and are handled automcatically by tyhe RH hardware.
00102 /// RHRouter and its subclasses add an end-to-end addressing header in the payload of the RH message, 
00103 /// and before the RHRouter application data.
00104 /// - 1 octet DEST, the destination node address (ie the address of the final 
00105 ///   destination node for this message)
00106 /// - 1 octet SOURCE, the source node address (ie the address of the originating node that first sent 
00107 ///   the message).
00108 /// - 1 octet HOPS, the number of hops this message has traversed so far.
00109 /// - 1 octet ID, an incrementing message ID for end-to-end message tracking for use by subclasses. 
00110 ///   Not used by RHRouter.
00111 /// - 1 octet FLAGS, a bitmask for use by subclasses. Not used by RHRouter.
00112 /// - 0 or more octets DATA, the application payload data. The length of this data is implicit 
00113 ///   in the length of the entire message.
00114 ///
00115 /// You should be careful to note that there are ID and FLAGS fields in the low level per-hop 
00116 /// message header too. These are used only for hop-to-hop, and in general will be different to 
00117 /// the ones at the RHRouter level.
00118 ///
00119 /// \par Testing
00120 ///
00121 /// Bench testing of such networks is notoriously difficult, especially simulating limited radio 
00122 /// connectivity between some nodes.
00123 /// To assist testing (both during RH development and for your own networks) 
00124 /// RHRouter.cpp has the ability to 
00125 /// simulate a number of different small network topologies. Each simulated network supports 4 nodes with 
00126 /// addresses 1 to 4. It operates by pretending to not hear RH messages from certain other nodes.
00127 /// You can enable testing with a \#define TEST_NETWORK in RHRouter.h
00128 /// The sample programs rf22_mesh_* rely on this feature.
00129 ///
00130 /// Part of the Arduino RH library for operating with HopeRF RH compatible transceivers 
00131 /// (see http://www.hoperf.com)
00132 class RHRouter : public RHReliableDatagram
00133 {
00134 public:
00135 
00136     /// Defines the structure of the RHRouter message header, used to keep track of end-to-end delivery parameters
00137     typedef struct
00138     {
00139     uint8_t    dest;       ///< Destination node address
00140     uint8_t    source;     ///< Originator node address
00141     uint8_t    hops;       ///< Hops traversed so far
00142     uint8_t    id;         ///< Originator sequence number
00143     uint8_t    flags;      ///< Originator flags
00144     // Data follows, Length is implicit in the overall message length
00145     } RoutedMessageHeader;
00146 
00147     /// Defines the structure of a RHRouter message
00148     typedef struct
00149     {
00150     RoutedMessageHeader header;    ///< end-to-end delivery header
00151     uint8_t             data[RH_ROUTER_MAX_MESSAGE_LEN]; ///< Application payload data
00152     } RoutedMessage;
00153 
00154     /// Values for the possible states for routes
00155     typedef enum
00156     {
00157     Invalid = 0,           ///< No valid route is known
00158     Discovering,           ///< Discovering a route (not currently used)
00159     Valid                  ///< Route is valid
00160     } RouteState;
00161 
00162     /// Defines an entry in the routing table
00163     typedef struct
00164     {
00165     uint8_t      dest;      ///< Destination node address
00166     uint8_t      next_hop;  ///< Send via this next hop address
00167     uint8_t      state;     ///< State of this route, one of RouteState
00168     } RoutingTableEntry;
00169 
00170     /// Constructor. 
00171     /// \param[in] driver The RadioHead driver to use to transport messages.
00172     /// \param[in] thisAddress The address to assign to this node. Defaults to 0
00173     RHRouter(RHGenericDriver& driver, uint8_t thisAddress = 0);
00174 
00175     /// Initialises this instance and the radio module connected to it.
00176     /// Overrides the init() function in RH.
00177     /// Sets max_hops to the default of RH_DEFAULT_MAX_HOPS (30)
00178     bool init();
00179 
00180     /// Sets the max_hops to the given value
00181     /// This controls the maximum number of hops allowed between source and destination nodes
00182     /// Messages that are not delivered by the time their HOPS field exceeds max_hops on a 
00183     /// routing node will be dropped and ignored.
00184     /// \param [in] max_hops The new value for max_hops
00185     void setMaxHops(uint8_t max_hops);
00186 
00187     /// Adds a route to the local routing table, or updates it if already present.
00188     /// If there is not enough room the oldest (first) route will be deleted by calling retireOldestRoute().
00189     /// \param [in] dest The destination node address. RH_BROADCAST_ADDRESS is permitted.
00190     /// \param [in] next_hop The address of the next hop to send messages destined for dest
00191     /// \param [in] state The satte of the route. Defaults to Valid
00192     void addRouteTo(uint8_t dest, uint8_t next_hop, uint8_t state = Valid);
00193 
00194     /// Finds and returns a RoutingTableEntry for the given destination node
00195     /// \param [in] dest The desired destination node address.
00196     /// \return pointer to a RoutingTableEntry for dest
00197     RoutingTableEntry* getRouteTo(uint8_t dest);
00198 
00199     /// Deletes from the local routing table any route for the destination node.
00200     /// \param [in] dest The destination node address
00201     /// \return true if the route was present
00202     bool deleteRouteTo(uint8_t dest);
00203 
00204     /// Deletes the oldest (first) route from the 
00205     /// local routing table
00206     void retireOldestRoute();
00207 
00208     /// Clears all entries from the 
00209     /// local routing table
00210     void clearRoutingTable();
00211 
00212     /// If RH_HAVE_SERIAL is defined, this will print out the contents of the local 
00213     /// routing table using Serial
00214     void printRoutingTable();
00215 
00216     /// Sends a message to the destination node. Initialises the RHRouter message header 
00217     /// (the SOURCE address is set to the address of this node, HOPS to 0) and calls 
00218     /// route() which looks up in the routing table the next hop to deliver to and sends the 
00219     /// message to the next hop. Waits for an acknowledgement from the next hop 
00220     /// (but not from the destination node (if that is different).
00221     /// \param [in] buf The application message data
00222     /// \param [in] len Number of octets in the application message data. 0 is permitted
00223     /// \param [in] dest The destination node address
00224     /// \param [in] flags Optional flags for use by subclasses or application layer, 
00225     ///             delivered end-to-end to the dest address. The receiver can recover the flags with recvFromAck().
00226     /// \return The result code:
00227     ///         - RH_ROUTER_ERROR_NONE Message was routed and delivered to the next hop 
00228     ///           (not necessarily to the final dest address)
00229     ///         - RH_ROUTER_ERROR_NO_ROUTE There was no route for dest in the local routing table
00230     ///         - RH_ROUTER_ERROR_UNABLE_TO_DELIVER Not able to deliver to the next hop 
00231     ///           (usually because it dod not acknowledge due to being off the air or out of range
00232     uint8_t sendtoWait(uint8_t* buf, uint8_t len, uint8_t dest, uint8_t flags = 0);
00233 
00234     /// Similar to sendtoWait() above, but spoofs the source address.
00235     /// For internal use only during routing
00236     /// \param [in] buf The application message data.
00237     /// \param [in] len Number of octets in the application message data. 0 is permitted.
00238     /// \param [in] dest The destination node address.
00239     /// \param [in] source The (fake) originating node address.
00240     /// \param [in] flags Optional flags for use by subclasses or application layer, 
00241     ///             delivered end-to-end to the dest address. The receiver can recover the flags with recvFromAck().
00242     /// \return The result code:
00243     ///         - RH_ROUTER_ERROR_NONE Message was routed and deliverd to the next hop 
00244     ///           (not necessarily to the final dest address)
00245     ///         - RH_ROUTER_ERROR_NO_ROUTE There was no route for dest in the local routing table
00246     ///         - RH_ROUTER_ERROR_UNABLE_TO_DELIVER Noyt able to deliver to the next hop 
00247     ///           (usually because it dod not acknowledge due to being off the air or out of range
00248     uint8_t sendtoFromSourceWait(uint8_t* buf, uint8_t len, uint8_t dest, uint8_t source, uint8_t flags = 0);
00249 
00250     /// Starts the receiver if it is not running already.
00251     /// If there is a valid message available for this node (or RH_BROADCAST_ADDRESS), 
00252     /// send an acknowledgement to the last hop
00253     /// address (blocking until this is complete), then copy the application message payload data
00254     /// to buf and return true
00255     /// else return false. 
00256     /// If a message is copied, *len is set to the length..
00257     /// If from is not NULL, the originator SOURCE address is placed in *source.
00258     /// If to is not NULL, the DEST address is placed in *dest. This might be this nodes address or 
00259     /// RH_BROADCAST_ADDRESS. 
00260     /// This is the preferred function for getting messages addressed to this node.
00261     /// If the message is not a broadcast, acknowledge to the sender before returning.
00262     /// \param[in] buf Location to copy the received message
00263     /// \param[in,out] len Available space in buf. Set to the actual number of octets copied.
00264     /// \param[in] source If present and not NULL, the referenced uint8_t will be set to the SOURCE address
00265     /// \param[in] dest If present and not NULL, the referenced uint8_t will be set to the DEST address
00266     /// \param[in] id If present and not NULL, the referenced uint8_t will be set to the ID
00267     /// \param[in] flags If present and not NULL, the referenced uint8_t will be set to the FLAGS
00268     /// (not just those addressed to this node).
00269     /// \return true if a valid message was recvived for this node copied to buf
00270     bool recvfromAck(uint8_t* buf, uint8_t* len, uint8_t* source = NULL, uint8_t* dest = NULL, uint8_t* id = NULL, uint8_t* flags = NULL);
00271 
00272     /// Starts the receiver if it is not running already.
00273     /// Similar to recvfromAck(), this will block until either a valid message available for this node
00274     /// or the timeout expires. 
00275     /// \param[in] buf Location to copy the received message
00276     /// \param[in,out] len Available space in buf. Set to the actual number of octets copied.
00277     /// \param[in] timeout Maximum time to wait in milliseconds
00278     /// \param[in] source If present and not NULL, the referenced uint8_t will be set to the SOURCE address
00279     /// \param[in] dest If present and not NULL, the referenced uint8_t will be set to the DEST address
00280     /// \param[in] id If present and not NULL, the referenced uint8_t will be set to the ID
00281     /// \param[in] flags If present and not NULL, the referenced uint8_t will be set to the FLAGS
00282     /// (not just those addressed to this node).
00283     /// \return true if a valid message was copied to buf
00284     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);
00285 
00286 protected:
00287 
00288     /// Lets sublasses peek at messages going 
00289     /// past before routing or local delivery.
00290     /// Called by recvfromAck() immediately after it gets the message from RHReliableDatagram
00291     /// \param [in] message Pointer to the RHRouter message that was received.
00292     /// \param [in] messageLen Length of message in octets
00293     virtual void peekAtMessage(RoutedMessage* message, uint8_t messageLen);
00294 
00295     /// Finds the next-hop route and sends the message via RHReliableDatagram::sendtoWait().
00296     /// This is virtual, which lets subclasses override or intercept the route() function.
00297     /// Called by sendtoWait after the message header has been filled in.
00298     /// \param [in] message Pointer to the RHRouter message to be sent.
00299     /// \param [in] messageLen Length of message in octets
00300     virtual uint8_t route(RoutedMessage* message, uint8_t messageLen);
00301 
00302     /// Deletes a specific rout entry from therouting table
00303     /// \param [in] index The 0 based index of the routing table entry to delete
00304     void deleteRoute(uint8_t index);
00305 
00306     /// The last end-to-end sequence number to be used
00307     /// Defaults to 0
00308     uint8_t _lastE2ESequenceNumber;
00309 
00310     /// The maximum number of hops permitted in routed messages.
00311     /// If a routed message would exceed this number of hops it is dropped and ignored.
00312     uint8_t              _max_hops;
00313 
00314 private:
00315 
00316     /// Temporary mesage buffer
00317     static RoutedMessage _tmpMessage;
00318 
00319     /// Local routing table
00320     RoutingTableEntry    _routes[RH_ROUTING_TABLE_SIZE];
00321 };
00322 
00323 /// @example rf22_router_client.pde
00324 /// @example rf22_router_server1.pde
00325 /// @example rf22_router_server2.pde
00326 /// @example rf22_router_server3.pde
00327 #endif
00328