ircd::net::acceptor: Refactor error and limit handling branches; fix reset.

include/ircd/net/acceptor.h

@@ -63,12 +63,13 @@ struct ircd::net::acceptor
 	// Handshake stack
 	bool handle_sni(SSL &, int &ad);
 	string_view handle_alpn(SSL &, const vector_view<const string_view> &in);
-	void check_handshake_error(const error_code &ec, socket &);
+	void check_handshake_error(const error_code &ec, socket &) const;
 	void handshake(const error_code &, const std::shared_ptr<socket>, const decltype(handshaking)::const_iterator) noexcept;
 
 	// Acceptance stack
 	static bool proffer_default(listener &, const ipport &);
-	bool check_accept_error(const error_code &ec, socket &);
+	bool check_handshake_limit(socket &, const ipport &) const;
+	bool check_accept_error(const error_code &ec, socket &) const;
 	void accept(const error_code &, const std::shared_ptr<socket>) noexcept;
 
 	// Accept next

ircd/net.cc

@@ -1590,46 +1590,30 @@ noexcept try
 	};
 
 	--accepting;
-	if(!check_accept_error(ec, *sock))
+	if(unlikely(!check_accept_error(ec, *sock)))
+	{
+		allow(*this);
+		net::close(*sock, dc::RST, close_ignore);
 		return;
+	}
 
 	const auto &remote
 	{
 		remote_ipport(*sock)
 	};
 
-	// Call the proffer-callback if available. This allows the application
-	// to check whether to allow or deny this remote before the handshake.
-	if(pcb && !pcb(*listener_, remote))
+	if(unlikely(!check_handshake_limit(*sock, remote)))
 	{
+		allow(*this);
 		net::close(*sock, dc::RST, close_ignore);
 		return;
 	}
 
-	if(unlikely(handshaking_count(*this) >= size_t(handshaking_max)))
+	// Call the proffer-callback. This allows the application to check whether
+	// to allow or deny this remote before the handshake, as well as setting
+	// the next accept to shape the kernel's queue.
+	if(!pcb(*listener_, remote))
 	{
-		log::dwarning
-		{
-			log, "%s refusing to handshake %s; exceeds maximum of %zu handshakes.",
-			loghead(*sock),
-			loghead(*this),
-			size_t(handshaking_max),
-		};
-
-		net::close(*sock, dc::RST, close_ignore);
-		return;
-	}
-
-	if(unlikely(handshaking_count(*this, remote) >= size_t(handshaking_max_per_peer)))
-	{
-		log::dwarning
-		{
-			log, "%s refusing to handshake %s; exceeds maximum of %zu handshakes to them.",
-			loghead(*sock),
-			loghead(*this),
-			size_t(handshaking_max_per_peer),
-		};
-
 		net::close(*sock, dc::RST, close_ignore);
 		return;
 	}
@@ -1664,9 +1648,9 @@ catch(const ctx::interrupted &e)
 	thread_local char ecbuf[64];
 	log::debug
 	{
-		log, "%s acceptor interrupted %s %s",
-		loghead(*sock),
+		log, "%s acceptor interrupted %s :%s",
 		loghead(*this),
+		loghead(*sock),
 		string(ecbuf, ec)
 	};
 
@@ -1675,30 +1659,14 @@ catch(const ctx::interrupted &e)
 	assert(!ec_);
 	joining.notify_all();
 }
-catch(const std::system_error &e)
-{
-	assert(bool(sock));
-	log::derror
-	{
-		log, "%s %s in accept(): %s",
-		loghead(*sock),
-		loghead(*this),
-		e.what()
-	};
-
-	error_code ec_;
-	sock->sd.close(ec_);
-	assert(!ec_);
-	joining.notify_all();
-}
 catch(const std::exception &e)
 {
 	assert(bool(sock));
 	log::error
 	{
-		log, "%s %s in accept(): %s",
-		loghead(*sock),
+		log, "%s acceptor error in accept() %s :%s",
 		loghead(*this),
+		loghead(*sock),
 		e.what()
 	};
 
@@ -1715,6 +1683,7 @@ catch(const std::exception &e)
 bool
 ircd::net::acceptor::check_accept_error(const error_code &ec,
                                         socket &sock)
+const
 {
 	using std::errc;
 
@@ -1727,14 +1696,58 @@ ircd::net::acceptor::check_accept_error(const error_code &ec,
 	if(system_category(ec)) switch(ec.value())
 	{
 		case int(errc::operation_canceled):
-			return false;
+			throw ctx::interrupted();
 
 		default:
 			break;
 	}
 
-	throw_system_error(ec);
-	__builtin_unreachable();
+	thread_local char ecbuf[64];
+	log::derror
+	{
+		log, "%s in accept %s :%s",
+		loghead(*this),
+		loghead(sock),
+		string(ecbuf, ec),
+	};
+
+	return false;
+}
+
+/// Checks performed for whether handshaking limits have been reached before
+/// allowing a handshake.
+bool
+ircd::net::acceptor::check_handshake_limit(socket &sock,
+                                           const ipport &remote)
+const
+{
+	if(unlikely(handshaking_count(*this) >= size_t(handshaking_max)))
+	{
+		log::warning
+		{
+			log, "%s refusing to handshake %s; exceeds maximum of %zu handshakes.",
+			loghead(sock),
+			loghead(*this),
+			size_t(handshaking_max),
+		};
+
+		return false;
+	}
+
+	if(unlikely(handshaking_count(*this, remote) >= size_t(handshaking_max_per_peer)))
+	{
+		log::dwarning
+		{
+			log, "%s refusing to handshake %s; exceeds maximum of %zu handshakes to them.",
+			loghead(sock),
+			loghead(*this),
+			size_t(handshaking_max_per_peer),
+		};
+
+		return false;
+	}
+
+	return true;
 }
 
 /// Default proffer callback which accepts this connection and allows the
@@ -1841,6 +1854,7 @@ catch(const std::exception &e)
 void
 ircd::net::acceptor::check_handshake_error(const error_code &ec,
                                            socket &sock)
+const
 {
 	using std::errc;
 

modules/m_listen.cc

@@ -265,6 +265,10 @@ _listener_proffer(net::listener &listener,
 		return false;
 	}
 
+	// Sets the asynchronous handler for the next accept. We can play with
+	// delaying this call under certain conditions to provide flow control.
+	allow(listener);
+
 	if(unlikely(client::map.size() >= size_t(client::settings::max_client)))
 	{
 		log::warning
@@ -288,10 +292,6 @@ _listener_proffer(net::listener &listener,
 		return false;
 	}
 
-	// Sets the asynchronous handler for the next accept. We can play with
-	// delaying this call under certain conditions to provide flow control.
-	allow(listener);
-
 	if(client::count(ipport) >= size_t(client::settings::max_client_per_peer))
 	{
 		log::dwarning