input/qobuz: parse and report message from error responses

src/input/plugins/QobuzErrorParser.cxx

@@ -0,0 +1,101 @@
+/*
+ * Copyright 2003-2018 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program 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 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "QobuzErrorParser.hxx"
+#include "lib/yajl/Callbacks.hxx"
+#include "util/ConstBuffer.hxx"
+#include "util/RuntimeError.hxx"
+
+using Wrapper = Yajl::CallbacksWrapper<QobuzErrorParser>;
+static constexpr yajl_callbacks qobuz_error_parser_callbacks = {
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	nullptr,
+	Wrapper::String,
+	nullptr,
+	Wrapper::MapKey,
+	Wrapper::EndMap,
+	nullptr,
+	nullptr,
+};
+
+QobuzErrorParser::QobuzErrorParser(unsigned _status,
+				   const std::multimap<std::string, std::string> &headers)
+	:status(_status),
+	 parser(&qobuz_error_parser_callbacks, nullptr, this)
+{
+	auto i = headers.find("content-type");
+	if (i == headers.end() || i->second.find("/json") == i->second.npos)
+		throw FormatRuntimeError("Status %u from Qobuz", status);
+}
+
+void
+QobuzErrorParser::OnData(ConstBuffer<void> data)
+{
+	parser.Parse((const unsigned char *)data.data, data.size);
+}
+
+void
+QobuzErrorParser::OnEnd()
+{
+	parser.CompleteParse();
+
+	if (!message.empty())
+		throw FormatRuntimeError("Error from Qobuz: %s",
+					 message.c_str());
+	else
+		throw FormatRuntimeError("Status %u from Qobuz", status);
+}
+
+inline bool
+QobuzErrorParser::String(StringView value) noexcept
+{
+	switch (state) {
+	case State::NONE:
+		break;
+
+	case State::MESSAGE:
+		message.assign(value.data, value.size);
+		break;
+	}
+
+	return true;
+}
+
+inline bool
+QobuzErrorParser::MapKey(StringView value) noexcept
+{
+	if (value.Equals("message"))
+		state = State::MESSAGE;
+	else
+		state = State::NONE;
+
+	return true;
+}
+
+inline bool
+QobuzErrorParser::EndMap() noexcept
+{
+	state = State::NONE;
+
+	return true;
+}