add close_reason parameter to quic::Endpoint::close_connection defaulting to emtpy string

llarp/quic/endpoint.cpp

@@ -225,7 +225,8 @@ namespace llarp::quic
   }
 
   void
-  Endpoint::close_connection(Connection& conn, uint64_t code, bool application)
+  Endpoint::close_connection(
+      Connection& conn, uint64_t code, bool application, std::string_view close_reason)
   {
     LogDebug("Closing connection ", conn.base_cid);
     if (!conn.closing)
@@ -245,8 +246,8 @@ namespace llarp::quic
           u8data(conn.conn_buffer),
           conn.conn_buffer.size(),
           code,
-          nullptr,  // reason
+          reinterpret_cast<const uint8_t*>(close_reason.data()),
-          0,        // reason length
+          close_reason.size(),
           get_timestamp());
       if (written <= 0)
       {

llarp/quic/endpoint.hpp

@@ -200,10 +200,16 @@ namespace llarp::quic
     //
     // Takes the iterator to the connection pair from `conns` and optional error parameters: if
     // `application` is false (the default) then we do a hard connection close because of transport
-    // error, if true we do a graceful application close.  For application closes the code is
+    // error, if true we do a graceful application close. `close_reason` can be provided for
-    // application-defined; for hard closes the code should be one of the NGTCP2_*_ERROR values.
+    // propagating reason for close to remote, defaults to empty string. For application closes the
+    // code is application-defined; for hard closes the code should be one of the NGTCP2_*_ERROR
+    // values.
     void
-    close_connection(Connection& conn, uint64_t code = NGTCP2_NO_ERROR, bool application = false);
+    close_connection(
+        Connection& conn,
+        uint64_t code = NGTCP2_NO_ERROR,
+        bool application = false,
+        std::string_view close_reason = ""sv);
 
     /// Puts a connection into draining mode (i.e. after getting a connection close).  This will
     /// keep the connection registered for the recommended 3*Probe Timeout, during which we drop