ircd::net: Add close option to skip shutdown syscall prior to close.

include/ircd/net/close.h

@@ -57,4 +57,10 @@ struct ircd::net::close_opts
 	/// If specified, these socket options will be applied when conducting
 	/// the disconnect (useful for adding an SO_LINGER time etc).
 	const sock_opts *sopts { nullptr };
+
+	/// For portable clean disconnection shutdown(2) might be called prior to
+	/// close(2). Setting this option to dc::RST skips the shutdown(2) when
+	/// the caller deems it unnecessary. At this time it only affects non-SSL
+	/// sockets and in the future we will have io_uring(7) fuse these calls.
+	net::dc shutdown { dc::FIN };
 };

ircd/client.cc

@@ -587,7 +587,13 @@ try
 		loghead(client),
 	};
 
-	client.close(net::dc::SSL_NOTIFY, net::close_ignore);
+	const net::close_opts opts
+	{
+		.type = net::dc::SSL_NOTIFY,
+		.shutdown = net::dc::RST,
+	};
+
+	client.close(opts, net::close_ignore);
 	return false;
 }
 catch(const std::exception &e)

ircd/net.cc

@@ -1775,9 +1775,10 @@ try
 	assert(!fini);
 	log::debug
 	{
-		log, "%s disconnect type:%s user[in:%zu out:%zu]",
+		log, "%s disconnect type:%s shut:%s user[in:%zu out:%zu]",
 		loghead(*this),
 		reflect(opts.type),
+		!ssl? reflect(opts.shutdown): "--"_sv,
 		in.bytes,
 		out.bytes
 	};
@@ -1806,7 +1807,9 @@ try
 			if(!ssl)
 			{
 				// Redirect SSL_NOTIFY to another strategy for non-SSL sockets.
-				sd.shutdown(ip::tcp::socket::shutdown_both);
+				if(opts.shutdown != dc::RST)
+					sd.shutdown(translate(opts.shutdown));
+
 				sd.close();
 				break;
 			}