ban zero id for pathid; clarity and cleanup

llarp/messages/relay_commit.cpp

@@ -322,6 +322,9 @@ namespace llarp
       self->hop = nullptr;
     }
 
+    // TODO: If decryption has succeeded here but we otherwise don't
+    //       want to or can't accept the path build request, send
+    //       a status message saying as much.
     static void
     HandleDecrypted(llarp_buffer_t* buf,
                     std::shared_ptr< LRCMFrameDecrypt > self)
@@ -344,8 +347,16 @@ namespace llarp
         return;
       }
 
-      info.txID     = self->record.txid;
-      info.rxID     = self->record.rxid;
+      info.txID = self->record.txid;
+      info.rxID = self->record.rxid;
+
+      if(info.txID.IsZero() || info.rxID.IsZero())
+      {
+        llarp::LogError("LRCM refusing zero pathid");
+        self->decrypter = nullptr;
+        return;
+      }
+
       info.upstream = self->record.nextHop;
 
       // generate path key as we are in a worker thread

llarp/path/path.cpp

@@ -31,8 +31,14 @@ namespace llarp
       for(size_t idx = 0; idx < hsz; ++idx)
       {
         hops[idx].rc = h[idx];
-        hops[idx].txID.Randomize();
-        hops[idx].rxID.Randomize();
+        while(hops[idx].txID.IsZero())
+        {
+          hops[idx].txID.Randomize();
+        }
+        while(hops[idx].rxID.IsZero())
+        {
+          hops[idx].rxID.Randomize();
+        }
       }
 
       for(size_t idx = 0; idx < hsz - 1; ++idx)

llarp/router/outbound_message_handler.cpp

@@ -263,14 +263,7 @@ namespace llarp
   void
   OutboundMessageHandler::RemoveEmptyPathQueues()
   {
-    if(not removedPaths.empty())
-    {
-      removedSomePaths = true;
-    }
-    else
-    {
-      removedSomePaths = false;
-    }
+    removedSomePaths = (not removedPaths.empty());
 
     while(not removedPaths.empty())
     {

llarp/router/outbound_message_handler.hpp

@@ -123,7 +123,9 @@ namespace llarp
     ILinkManager *_linkManager;
     std::shared_ptr< Logic > _logic;
 
-    const PathID_t zeroID;
+    // paths cannot have pathid "0", so it can be used as the "pathid"
+    // for non-traffic (control) messages, so they can be prioritized.
+    static const PathID_t zeroID;
   };
 
 }  // namespace llarp