Abstract & simplify logic

llarp/handlers/tun.cpp

@@ -1077,11 +1077,7 @@ namespace llarp
         service::Address addr{};
         for (const auto& [range, exitAddr] : exitEntries)
         {
-          if (
-              // we permit this because it matches our rules and we allow bogons:
-              (range.BogonRange() and range.Contains(dst))
-              // allow because the destination is not a bogon and the mapped range is not a bogon
-              or not IsBogon(dst))
+          if (not IsBogon(dst) or range.BogonContains(dst))
           {
             addr = exitAddr;
           }
@@ -1274,7 +1270,7 @@ namespace llarp
         bool allow = false;
         for (const auto& [range, exitAddr] : mapped)
         {
-          if ((range.BogonRange() and range.Contains(src)) or not IsBogon(src))
+          if (not IsBogon(src) or range.BogonContains(src))
           {
             // allow if this address matches the endpoint we think it should be
             allow = exitAddr == fromAddr;

llarp/net/ip_range.hpp

@@ -52,6 +52,14 @@ namespace llarp
       return IsBogon(addr) or IsBogon(HighestAddr());
     }
 
+    /// return true if we intersect with a bogon range *and* we contain the given address
+    template <typename Addr>
+    bool
+    BogonContains(Addr&& addr) const
+    {
+      return BogonRange() and Contains(std::forward<Addr>(addr));
+    }
+
     /// return the number of bits set in the hostmask
     constexpr int
     HostmaskBits() const