fixup edge case on windows

* add platform detection constexprs
* add quark for platforms without native ipv6 like windows, exit mapping cannot work with ipv6 yet

llarp/constants/platform.hpp

@@ -0,0 +1,65 @@
+#pragma once
+
+/// namespace for platform feature detection constexprs
+namespace llarp::platform
+{
+  ///  are we linux  ?
+  inline constexpr bool is_linux =
+#ifdef __linux__
+      true
+#else
+      false
+#endif
+      ;
+
+  ///  are we freebsd ?
+  inline constexpr bool is_freebsd =
+#ifdef __FreeBSD__
+      true
+#else
+      false
+#endif
+      ;
+
+  /// are we windows ?
+  inline constexpr bool is_windows =
+#ifdef _WIN32
+      true
+#else
+      false
+#endif
+      ;
+
+  /// are we an apple platform ?
+  inline constexpr bool is_apple =
+#ifdef __apple__
+      true
+#else
+      false
+#endif
+      ;
+
+  /// are we an android platform ?
+  inline constexpr bool is_android =
+#ifdef ANDROID
+      true
+#else
+      false
+#endif
+      ;
+
+  /// are we an iphone ?
+  inline constexpr bool is_iphone =
+#ifdef IOS
+      true
+#else
+      false
+#endif
+      ;
+
+  /// are we a mobile phone ?
+  inline constexpr bool is_mobile = is_android or is_iphone;
+
+  /// does this platform support native ipv6 ?
+  inline constexpr bool supports_ipv6 = not is_windows;
+}  // namespace llarp::platform

llarp/rpc/rpc_server.cpp

@@ -1,5 +1,6 @@
 #include "rpc_server.hpp"
 #include <llarp/router/route_poker.hpp>
+#include <llarp/constants/platform.hpp>
 #include <llarp/constants/version.hpp>
 #include <nlohmann/json.hpp>
 #include <llarp/exit/context.hpp>
@@ -432,13 +433,27 @@ namespace llarp::rpc
                 const auto range_itr = obj.find("range");
                 if (range_itr == obj.end())
                 {
-                  range.FromString("::/0");
+                  // platforms without ipv6 support will shit themselves
+                  // here if we give them an exit mapping that is ipv6
+                  if constexpr (platform::supports_ipv6)
+                  {
+                    range.FromString("::/0");
+                  }
+                  else
+                  {
+                    range.FromString("0.0.0.0/0");
+                  }
                 }
                 else if (not range.FromString(range_itr->get<std::string>()))
                 {
                   reply(CreateJSONError("invalid ip range"));
                   return;
                 }
+                if (not platform::supports_ipv6 and not range.IsV4())
+                {
+                  reply(CreateJSONError("ipv6 ranges not supported on this platform"));
+                  return;
+                }
                 std::optional<std::string> token;
                 const auto token_itr = obj.find("token");
                 if (token_itr != obj.end())