stub encryptor seems nicely backwards compatible with old devices and apps

src/mesh/Router.cpp

@@ -1,7 +1,11 @@
 #include "Router.h"
+#include "CryptoEngine.h"
+#include "GPS.h"
 #include "configuration.h"
 #include "mesh-pb-constants.h"
 
+CryptoEngine *crypto = new CryptoEngine();
+
 /**
  * Router todo
  *
@@ -44,10 +48,30 @@ void Router::loop()
 /**
  * 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.  
+ * If the txmit queue is full it might return an error.
  */
 ErrorCode Router::send(MeshPacket *p)
 {
+    // If the packet hasn't yet been encrypted, do so now (it might already be encrypted if we are just forwarding it)
+
+    assert(p->which_payload == MeshPacket_encrypted_tag ||
+           p->which_payload == MeshPacket_decoded_tag); // I _think_ all packets should have a payload by now
+
+    // First convert from protobufs to raw bytes
+    if (p->which_payload == MeshPacket_decoded_tag) {
+        static uint8_t bytes[MAX_RHPACKETLEN]; // we have to use a scratch buffer because a union
+
+        size_t numbytes = pb_encode_to_bytes(bytes, sizeof(bytes), SubPacket_fields, &p->decoded);
+
+        assert(numbytes <= MAX_RHPACKETLEN);
+        crypto->encrypt(p->from, p->id, numbytes, bytes);
+
+        // Copy back into the packet and set the variant type
+        memcpy(p->encrypted.bytes, bytes, numbytes);
+        p->encrypted.size = numbytes;
+        p->which_payload = MeshPacket_encrypted_tag;
+    }
+
     if (iface) {
         // DEBUG_MSG("Sending packet via interface fr=0x%x,to=0x%x,id=%d\n", p->from, p->to, p->id);
         return iface->send(p);
@@ -58,8 +82,6 @@ ErrorCode Router::send(MeshPacket *p)
     }
 }
 
-#include "GPS.h"
-
 /**
  * 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.
@@ -70,7 +92,25 @@ void Router::handleReceived(MeshPacket *p)
     // Also, we should set the time from the ISR and it should have msec level resolution
     p->rx_time = getValidTime(); // store the arrival timestamp for the phone
 
-    DEBUG_MSG("Notifying observers of received packet fr=0x%x,to=0x%x,id=%d\n", p->from, p->to, p->id);
-    notifyPacketReceived.notifyObservers(p);
+    assert(p->which_payload ==
+           MeshPacket_encrypted_tag); // I _think_ the only thing that pushes to us is raw devices that just received packets
+
+    // Try to decrypt the packet if we can
+    static uint8_t bytes[MAX_RHPACKETLEN];
+    memcpy(bytes, p->encrypted.bytes,
+           p->encrypted.size); // we have to copy into a scratch buffer, because these bytes are a union with the decoded protobuf
+    crypto->decrypt(p->from, p->id, p->encrypted.size, bytes);
+
+    // Take those raw bytes and convert them back into a well structured protobuf we can understand
+    if (!pb_decode_from_bytes(bytes, p->encrypted.size, SubPacket_fields, &p->decoded)) {
+        DEBUG_MSG("Invalid protobufs in received mesh packet, discarding.\n");
+    } else {
+        // parsing was successful, queue for our recipient
+        p->which_payload = MeshPacket_decoded_tag;
+
+        DEBUG_MSG("Notifying observers of received packet fr=0x%x,to=0x%x,id=%d\n", p->from, p->to, p->id);
+        notifyPacketReceived.notifyObservers(p);
+    }
+
     packetPool.release(p);
 }