Organize exceptions so it's easy to log errors locally.

src/tawashi_implem/CMakeLists.txt

@@ -25,6 +25,7 @@ add_library(${PROJECT_NAME} STATIC
 	sanitized_utf8.cpp
 	tiger.c
 	error_response.cpp
+	tawashi_exception.cpp
 )
 
 target_include_directories(${PROJECT_NAME}

src/tawashi_implem/error_reasons.hpp

@@ -25,6 +25,7 @@ namespace tawashi {
 		PastieNotSaved,
 		UserFlooding,
 		UnkownReason,
-		RedisDisconnected
+		RedisDisconnected,
+		MissingPostVariable
 	)
 } //namespace tawashi

src/tawashi_implem/error_response.cpp

@@ -49,7 +49,8 @@ namespace tawashi {
 			"Submitted pastie couldn't be saved.",
 			"The pastie was not saved because the client is submitting too many pasties too quickly. Please wait a bit longer and try again.",
 			"An unknown error was raised.",
-			"Unable to connect to Redis."
+			"Unable to connect to Redis.",
+			"Request is missing a POST variable."
 		};
 		constexpr const auto lengths = string_lengths(err_descs);
 		static_assert(err_descs.static_size == lengths.static_size, "Mismatching array sizes between strings and their lengths");

src/tawashi_implem/submit_paste_response.cpp

@@ -24,9 +24,8 @@
 #include "duckhandy/compatibility.h"
 #include "duckhandy/lexical_cast.hpp"
 #include "duckhandy/int_to_string_ary.hpp"
+#include "tawashi_exception.hpp"
 #include <ciso646>
-#include <sstream>
-#include <stdexcept>
 #include <algorithm>
 #include <boost/lexical_cast.hpp>
 #include <cstdint>
@@ -40,9 +39,14 @@ namespace tawashi {
 		const char g_language_key[] = "lang";
 		const char g_duration_key[] = "ttl";
 
-		class MissingPostVarError : public std::runtime_error {
+		class MissingPostVarError : public TawashiException {
 		public:
-			MissingPostVarError (const std::string& parMsg) : std::runtime_error(parMsg) {}
+			explicit MissingPostVarError(const boost::string_ref& parKey) :
+				TawashiException(
+					ErrorReasons::MissingPostVariable,
+					"Error retrieving POST variable \"" + std::string(parKey.begin(), parKey.end()) + "\""
+				)
+			{}
 		};
 
 		template <std::size_t N>
@@ -57,11 +61,8 @@ namespace tawashi {
 		boost::string_ref get_value_from_post (const cgi::PostMapType& parPost, boost::string_ref parKey) {
 			std::string key(parKey.data(), parKey.size());
 			auto post_data_it = parPost.find(key);
-			if (parPost.end() == post_data_it) {
+			if (parPost.end() == post_data_it)
-				std::ostringstream oss;
+				throw MissingPostVarError(parKey);
-				oss << "can't find POST data field \"" << parKey << '"';
-				throw MissingPostVarError(oss.str());
-			}
 			return post_data_it->second;
 		}
 
@@ -104,18 +105,24 @@ namespace tawashi {
 		boost::string_ref pastie;
 		boost::string_ref lang;
 		boost::string_ref duration;
+
+		auto statuslog = spdlog::get("statuslog");
+		assert(statuslog);
+
 		try {
 			pastie = get_value_from_post(post, make_string_ref(g_post_key));
 		}
-		catch (const MissingPostVarError& e) {
+		catch (const TawashiException& e) {
-			m_error_message = e.what();
+			statuslog->error(e.what());
+			error_redirect(500, e.reason());
 			return;
 		}
 		try {
 			lang = get_value_from_post(post, make_string_ref(g_language_key));
 			duration = get_value_from_post(post, make_string_ref(g_duration_key));
 		}
-		catch (const MissingPostVarError&) {
+		catch (const MissingPostVarError& e) {
+			statuslog->info(e.what());
 		}
 
 		const SettingsBag& settings = this->settings();
@@ -145,6 +152,7 @@ namespace tawashi {
 			this->change_type(Response::Location, oss.str());
 		}
 		else {
+			error_redirect(500, ErrorReasons::PastieNotSaved);
 			return;
 		}
 	}

src/tawashi_implem/submit_paste_response.hpp

@@ -39,7 +39,5 @@ namespace tawashi {
 		virtual void on_process() override;
 		boost::optional<std::string> submit_to_redis (const boost::string_ref& parText, uint32_t parExpiry, const boost::string_ref& parLang);
 		void error_redirect (int parCode, ErrorReasons parReason);
-
-		std::string m_error_message;
 	};
 } //namespace tawashi

src/tawashi_implem/tawashi_exception.cpp

@@ -0,0 +1,37 @@
+/* Copyright 2017, Michele Santullo
+ * This file is part of "tawashi".
+ *
+ * "tawashi" is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * "tawashi" is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with "tawashi".  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "tawashi_exception.hpp"
+#include <sstream>
+
+namespace tawashi {
+	namespace {
+		std::string compose_err_message (ErrorReasons parReason, const boost::string_ref& parMessage) {
+			std::ostringstream oss;
+			oss << "Exception with reason " << parReason << ": " << parMessage;
+			return oss.str();
+		}
+	} //unnamed namespace
+
+	TawashiException::TawashiException (ErrorReasons parReason, const boost::string_ref& parMessage) :
+		std::runtime_error(compose_err_message(parReason, parMessage)),
+		m_reason(parReason)
+	{
+	}
+
+	TawashiException::~TawashiException() noexcept = default;
+} //namespace tawashi

src/tawashi_implem/tawashi_exception.hpp

@@ -0,0 +1,35 @@
+/* Copyright 2017, Michele Santullo
+ * This file is part of "tawashi".
+ *
+ * "tawashi" is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * "tawashi" is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with "tawashi".  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+#include "error_reasons.hpp"
+#include <stdexcept>
+#include <string>
+#include <boost/utility/string_ref.hpp>
+
+namespace tawashi {
+	class TawashiException : public std::runtime_error {
+	public:
+		TawashiException (ErrorReasons parReason, const boost::string_ref& parMessage);
+		~TawashiException() noexcept;
+
+		ErrorReasons reason() const { return m_reason; }
+
+	private:
+		ErrorReasons m_reason;
+	};
+} //namespace tawashi