From d20870655aeca0614d9fc315fe5f9893ebdc7aa3 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Thu, 26 Sep 2019 23:55:01 +0300
Subject: [PATCH] Improve error handling

Particularly of asynchronous operations
---
 source/http/client.cpp | 28 +++++++++++++++++++++++-----
 source/http/server.cpp | 30 ++++++++++++++++++++++++------
 source/net/resolve.cpp |  9 +++++++++
 3 files changed, 56 insertions(+), 11 deletions(-)

diff --git a/source/http/client.cpp b/source/http/client.cpp
index da6b25e..e090576 100644
--- a/source/http/client.cpp
+++ b/source/http/client.cpp
@@ -141,23 +141,39 @@ void Client::resolve_failed(unsigned tag, const exception &err)
 		return;
 	resolve_tag = 0;
 
-	signal_socket_error.emit(err);
-
 	delete request;
 	request = 0;
+
+	if(signal_socket_error.empty())
+		throw err;
+	signal_socket_error.emit(err);
 }
 
 void Client::connect_finished(const exception *err)
 {
 	if(err)
 	{
-		signal_socket_error.emit(*err);
-
 		delete request;
 		request = 0;
+
+		if(signal_socket_error.empty())
+			throw *err;
+		signal_socket_error.emit(*err);
 	}
 	else
-		sock->write(request->str());
+	{
+		try
+		{
+			sock->write(request->str());
+		}
+		catch(const exception &e)
+		{
+			if(signal_socket_error.empty())
+				throw;
+			signal_socket_error.emit(e);
+			return;
+		}
+	}
 }
 
 void Client::data_available()
@@ -170,6 +186,8 @@ void Client::data_available()
 	}
 	catch(const exception &e)
 	{
+		if(signal_socket_error.empty())
+			throw;
 		signal_socket_error.emit(e);
 		return;
 	}
diff --git a/source/http/server.cpp b/source/http/server.cpp
index 7caa0f5..f985bf9 100644
--- a/source/http/server.cpp
+++ b/source/http/server.cpp
@@ -92,11 +92,19 @@ void Server::client_data_available(Client &cl)
 			break;
 		}
 
-	char rbuf[4096];
-	unsigned len = cl.sock->read(rbuf, sizeof(rbuf));
-	if(cl.stale)
+	try
+	{
+		char rbuf[4096];
+		unsigned len = cl.sock->read(rbuf, sizeof(rbuf));
+		if(cl.stale)
+			return;
+		cl.in_buf.append(rbuf, len);
+	}
+	catch(const exception &)
+	{
+		cl.stale = true;
 		return;
-	cl.in_buf.append(rbuf, len);
+	}
 
 	RefPtr<Response> response;
 	if(!cl.request)
@@ -133,7 +141,7 @@ void Server::client_data_available(Client &cl)
 	}
 	else
 	{
-		len = cl.request->parse_content(cl.in_buf);
+		unsigned len = cl.request->parse_content(cl.in_buf);
 		cl.in_buf.erase(0, len);
 	}
 
@@ -180,7 +188,17 @@ void Server::send_response(Client &cl, Response &resp)
 {
 	if(cl.keepalive)
 		resp.set_header("Connection", "keep-alive");
-	cl.sock->write(resp.str());
+
+	try
+	{
+		cl.sock->write(resp.str());
+	}
+	catch(const exception &)
+	{
+		cl.stale = true;
+		return;
+	}
+
 	cl.async = false;
 	if(cl.keepalive)
 	{
diff --git a/source/net/resolve.cpp b/source/net/resolve.cpp
index 10e8c65..006f210 100644
--- a/source/net/resolve.cpp
+++ b/source/net/resolve.cpp
@@ -132,7 +132,16 @@ void Resolver::task_done()
 		if(task->addr)
 			signal_address_resolved.emit(task->tag, *task->addr);
 		else if(task->error)
+		{
+			if(signal_resolve_failed.empty())
+			{
+				RefPtr<runtime_error> err = task->error;
+				task->error = 0;
+				thread.pop_complete_task();
+				throw *err;
+			}
 			signal_resolve_failed.emit(task->tag, *task->error);
+		}
 		thread.pop_complete_task();
 	}
 }
-- 
2.45.2