add first cut of mesh naive flooding

src/rf95/FloodingRouter.cpp

@@ -0,0 +1,90 @@
+#include "FloodingRouter.h"
+#include "configuration.h"
+#include "mesh-pb-constants.h"
+
+/// We clear our old flood record five minute after we see the last of it
+#define FLOOD_EXPIRE_TIME (5 * 60 * 1000L)
+
+FloodingRouter::FloodingRouter()
+{
+    recentBroadcasts.reserve(MAX_NUM_NODES); // Prealloc the worst case # of records - to prevent heap fragmentation
+}
+
+/**
+ * Send a packet on a suitable interface.  This routine will
+ * later free() the packet to pool.  This routine is not allowed to stall.
+ * If the txmit queue is full it might return an error
+ */
+ErrorCode FloodingRouter::send(MeshPacket *p)
+{
+    // We update our table of recent broadcasts, even for messages we send
+    wasSeenRecently(p);
+
+    return Router::send(p);
+}
+
+/**
+ * Called from loop()
+ * Handle any packet that is received by an interface on this node.
+ * Note: some packets may merely being passed through this node and will be forwarded elsewhere.
+ *
+ * Note: this method will free the provided packet
+ */
+void FloodingRouter::handleReceived(MeshPacket *p)
+{
+    if (wasSeenRecently(p)) {
+        DEBUG_MSG("Ignoring incoming floodmsg, because we've already seen it\n");
+        packetPool.release(p);
+    } else {
+        if (p->to == NODENUM_BROADCAST && p->id != 0) {
+            DEBUG_MSG("Rebroadcasting received floodmsg to neighbors\n");
+            // FIXME, wait a random delay
+
+            MeshPacket *tosend = packetPool.allocCopy(*p);
+            // Note: we are careful to resend using the original senders node id
+            Router::send(tosend); // We are careful not to call our hooked version of send()
+        }
+
+        // handle the packet as normal
+        Router::handleReceived(p);
+    }
+}
+
+/**
+ * Update recentBroadcasts and return true if we have already seen this packet
+ */
+bool FloodingRouter::wasSeenRecently(const MeshPacket *p)
+{
+    if (p->to != NODENUM_BROADCAST)
+        return false; // Not a broadcast, so we don't care
+
+    if (p->id == 0)
+        return false; // Not a floodable message ID, so we don't care
+
+    uint32_t now = millis();
+    for (int i = 0; i < recentBroadcasts.size();) {
+        BroadcastRecord &r = recentBroadcasts[i];
+
+        if ((now - r.rxTimeMsec) >= FLOOD_EXPIRE_TIME) {
+            DEBUG_MSG("Deleting old recentBroadcast %d\n", i);
+            recentBroadcasts.erase(recentBroadcasts.begin() + i); // delete old record
+        } else {
+            if (r.id == p->id && r.sender == p->from) {
+                // Update the time on this record to now
+                r.rxTimeMsec = now;
+                return true;
+            }
+
+            i++;
+        }
+    }
+
+    // Didn't find an existing record, make one
+    BroadcastRecord r;
+    r.id = p->id;
+    r.sender = p->from;
+    r.rxTimeMsec = now;
+    recentBroadcasts.push_back(r);
+
+    return false;
+}