mpd-dbcreate/src/output/plugins/ShoutOutputPlugin.cxx

// SPDX-License-Identifier: GPL-2.0-or-later
// Copyright The Music Player Daemon Project

#include "ShoutOutputPlugin.hxx"
#include "../OutputAPI.hxx"
#include "encoder/EncoderInterface.hxx"
#include "encoder/Configured.hxx"
#include "lib/fmt/RuntimeError.hxx"
#include "util/Domain.hxx"
#include "util/ScopeExit.hxx"
#include "util/StringAPI.hxx"
#include "Log.hxx"

#include <shout/shout.h>

#include <fmt/format.h>

#include <cassert>
#include <memory>
#include <stdexcept>

class ShoutConfig {
	const char *const host;
	const char *const mount;
	const char *const user, *const passwd;
	const char *const name;
	const char *const genre, *const description;
	const char *const url;
	const char *const quality, *const bitrate;

	const unsigned port;

	const unsigned format;
	const unsigned protocol;

#ifdef SHOUT_TLS
	const int tls;
#endif

	const bool is_public;

public:
	ShoutConfig(const ConfigBlock &block, const char *mime_type);

	void Setup(shout_t &connection) const;
};

struct ShoutOutput final : AudioOutput {
	shout_t *shout_conn;

	std::unique_ptr<PreparedEncoder> prepared_encoder;

	const ShoutConfig config;

	Encoder *encoder;

	explicit ShoutOutput(const ConfigBlock &block);
	~ShoutOutput() override;

	ShoutOutput(const ShoutOutput &) = delete;
	ShoutOutput &operator=(const ShoutOutput &) = delete;

	static AudioOutput *Create(EventLoop &event_loop,
				   const ConfigBlock &block);

	void Enable() override;
	void Disable() noexcept override;

	void Open(AudioFormat &audio_format) override;
	void Close() noexcept override;

	[[nodiscard]] std::chrono::steady_clock::duration Delay() const noexcept override;
	void SendTag(const Tag &tag) override;
	std::size_t Play(std::span<const std::byte> src) override;
	void Cancel() noexcept override;
	bool Pause() override;

private:
	void WritePage();
};

static int shout_init_count;

static constexpr Domain shout_output_domain("shout_output");

static const char *
require_block_string(const ConfigBlock &block, const char *name)
{
	const char *value = block.GetBlockValue(name);
	if (value == nullptr)
		throw FmtRuntimeError("no {:?} defined for shout device defined "
				      "at line {}\n", name, block.line);

	return value;
}

static void
ShoutSetAudioInfo(shout_t *shout_conn, const AudioFormat &audio_format)
{
	shout_set_audio_info(shout_conn, SHOUT_AI_CHANNELS,
			     fmt::format_int{static_cast<unsigned>(audio_format.channels)}.c_str());

	shout_set_audio_info(shout_conn, SHOUT_AI_SAMPLERATE,
			     fmt::format_int{audio_format.sample_rate}.c_str());
}

#ifdef SHOUT_TLS

static int
ParseShoutTls(const char *value)
{
	if (value == nullptr)
		return SHOUT_TLS_DISABLED;

	if (StringIsEqual(value, "disabled"))
		return SHOUT_TLS_DISABLED;
	else if (StringIsEqual(value, "auto"))
		return SHOUT_TLS_AUTO;
	else if (StringIsEqual(value, "auto_no_plain"))
		return SHOUT_TLS_AUTO_NO_PLAIN;
	else if (StringIsEqual(value, "rfc2818"))
		return SHOUT_TLS_RFC2818;
	else if (StringIsEqual(value, "rfc2817"))
		return SHOUT_TLS_RFC2817;
	else
		throw FmtRuntimeError("invalid shout TLS option {:?}",
				      value);
}

#endif

static unsigned
ParseShoutFormat(const char *mime_type)
{
	if (StringIsEqual(mime_type, "audio/mpeg"))
		return SHOUT_FORMAT_MP3;
	else
		return SHOUT_FORMAT_OGG;
}

static unsigned
ParseShoutProtocol(const char *value, const char *mime_type)
{
	if (value == nullptr)
		return SHOUT_PROTOCOL_HTTP;

	if (StringIsEqual(value, "shoutcast")) {
		if (!StringIsEqual(mime_type, "audio/mpeg"))
			throw FmtRuntimeError("you cannot stream {:?} to shoutcast, use mp3",
					      mime_type);
		return SHOUT_PROTOCOL_ICY;
	} else if (StringIsEqual(value, "icecast1"))
		return SHOUT_PROTOCOL_XAUDIOCAST;
	else if (StringIsEqual(value, "icecast2"))
		return SHOUT_PROTOCOL_HTTP;
	else
		throw FmtRuntimeError("shout protocol {:?} is not \"shoutcast\" or "
				      "\"icecast1\"or \"icecast2\"",
				      value);
}

inline
ShoutConfig::ShoutConfig(const ConfigBlock &block, const char *mime_type)
	:host(require_block_string(block, "host")),
	 mount(require_block_string(block, "mount")),
	 user(block.GetBlockValue("user", "source")),
	 passwd(require_block_string(block, "password")),
	 name(require_block_string(block, "name")),
	 genre(block.GetBlockValue("genre")),
	 description(block.GetBlockValue("description")),
	 url(block.GetBlockValue("url")),
	 quality(block.GetBlockValue("quality")),
	 bitrate(block.GetBlockValue("bitrate")),
	 port(block.GetBlockValue("port", 0U)),
	 format(ParseShoutFormat(mime_type)),
	 protocol(ParseShoutProtocol(block.GetBlockValue("protocol"),
				     mime_type)),
#ifdef SHOUT_TLS
	 tls(ParseShoutTls(block.GetBlockValue("tls"))),
#endif
	 is_public(block.GetBlockValue("public", false))
{
	if (port == 0)
		throw std::runtime_error("shout port must be configured");
}

ShoutOutput::ShoutOutput(const ConfigBlock &block)
	:AudioOutput(FLAG_PAUSE|FLAG_NEED_FULLY_DEFINED_AUDIO_FORMAT|
		     FLAG_ENABLE_DISABLE),
	 prepared_encoder(CreateConfiguredEncoder(block, true)),
	 config(block, prepared_encoder->GetMimeType())
{
}

ShoutOutput::~ShoutOutput()
{
	shout_init_count--;
	if (shout_init_count == 0)
		shout_shutdown();
}

AudioOutput *
ShoutOutput::Create(EventLoop &, const ConfigBlock &block)
{
	if (shout_init_count == 0)
		shout_init();

	shout_init_count++;

	return new ShoutOutput(block);
}

static void
SetMeta(shout_t &connection, const char *name, const char *value)
{
	if (shout_set_meta(&connection, name, value) != SHOUTERR_SUCCESS)
		throw std::runtime_error(shout_get_error(&connection));
}

static void
SetOptionalMeta(shout_t &connection, const char *name, const char *value)
{
	if (value != nullptr)
		SetMeta(connection, name, value);
}

inline void
ShoutConfig::Setup(shout_t &connection) const
{
	if (shout_set_host(&connection, host) != SHOUTERR_SUCCESS ||
	    shout_set_port(&connection, port) != SHOUTERR_SUCCESS ||
	    shout_set_password(&connection, passwd) != SHOUTERR_SUCCESS ||
	    shout_set_mount(&connection, mount) != SHOUTERR_SUCCESS ||
	    shout_set_user(&connection, user) != SHOUTERR_SUCCESS ||
	    shout_set_public(&connection, is_public) != SHOUTERR_SUCCESS ||
#ifdef SHOUT_USAGE_AUDIO
	    /* since libshout 2.4.3 */
	    shout_set_content_format(&connection, format, SHOUT_USAGE_AUDIO,
				     nullptr) != SHOUTERR_SUCCESS ||
#else
	    shout_set_format(&connection, format) != SHOUTERR_SUCCESS ||
#endif
	    shout_set_protocol(&connection, protocol) != SHOUTERR_SUCCESS ||
#ifdef SHOUT_TLS
	    shout_set_tls(&connection, tls) != SHOUTERR_SUCCESS ||
#endif
	    shout_set_agent(&connection, "MPD") != SHOUTERR_SUCCESS)
		throw std::runtime_error(shout_get_error(&connection));

	SetMeta(connection, SHOUT_META_NAME, name);

	/* optional paramters */

	SetOptionalMeta(connection, SHOUT_META_GENRE, genre);
	SetOptionalMeta(connection, SHOUT_META_DESCRIPTION, description);
	SetOptionalMeta(connection, SHOUT_META_URL, url);

	if (quality != nullptr)
		shout_set_audio_info(&connection, SHOUT_AI_QUALITY, quality);

	if (bitrate != nullptr)
		shout_set_audio_info(&connection, SHOUT_AI_BITRATE, bitrate);
}

void
ShoutOutput::Enable()
{
	shout_conn = shout_new();
	if (shout_conn == nullptr)
		throw std::bad_alloc{};

	try {
		config.Setup(*shout_conn);
	} catch (...) {
		shout_free(shout_conn);
		throw;
	}
}

void
ShoutOutput::Disable() noexcept
{
	shout_free(shout_conn);
}

static void
HandleShoutError(shout_t *shout_conn, int err)
{
	switch (err) {
	case SHOUTERR_SUCCESS:
		break;

	case SHOUTERR_UNCONNECTED:
	case SHOUTERR_SOCKET:
		throw FmtRuntimeError("Lost shout connection to {}:{}: {}",
				      shout_get_host(shout_conn),
				      shout_get_port(shout_conn),
				      shout_get_error(shout_conn));

	default:
		throw FmtRuntimeError("connection to {}:{} error: {}",
				      shout_get_host(shout_conn),
				      shout_get_port(shout_conn),
				      shout_get_error(shout_conn));
	}
}

static void
EncoderToShout(shout_t *shout_conn, Encoder &encoder)
{
	while (true) {
		std::byte buffer[32768];
		const auto e = encoder.Read(std::span{buffer});
		if (e.empty())
			return;

		int err = shout_send(shout_conn,
				     (const unsigned char *)e.data(),
				     e.size());
		HandleShoutError(shout_conn, err);
	}
}

void
ShoutOutput::WritePage()
{
	assert(encoder != nullptr);

	EncoderToShout(shout_conn, *encoder);
}

void
ShoutOutput::Close() noexcept
{
	try {
		encoder->End();
		WritePage();
	} catch (...) {
		/* ignore */
	}

	delete encoder;

	if (shout_get_connected(shout_conn) != SHOUTERR_UNCONNECTED &&
	    shout_close(shout_conn) != SHOUTERR_SUCCESS) {
		FmtWarning(shout_output_domain,
			   "problem closing connection to shout server: {}",
			   shout_get_error(shout_conn));
	}
}

void
ShoutOutput::Cancel() noexcept
{
	/* needs to be implemented for shout */
}

static void
ShoutOpen(shout_t *shout_conn)
{
	switch (shout_open(shout_conn)) {
	case SHOUTERR_SUCCESS:
	case SHOUTERR_CONNECTED:
		break;

	default:
		throw FmtRuntimeError("problem opening connection to shout server {}:{}: {}",
				      shout_get_host(shout_conn),
				      shout_get_port(shout_conn),
				      shout_get_error(shout_conn));
	}
}

void
ShoutOutput::Open(AudioFormat &audio_format)
{
	encoder = prepared_encoder->Open(audio_format);

	try {
		ShoutSetAudioInfo(shout_conn, audio_format);
		ShoutOpen(shout_conn);
		WritePage();
	} catch (...) {
		delete encoder;
		throw;
	}
}

std::chrono::steady_clock::duration
ShoutOutput::Delay() const noexcept
{
	int delay = shout_delay(shout_conn);
	if (delay < 0)
		delay = 0;

	return std::chrono::milliseconds(delay);
}

std::size_t
ShoutOutput::Play(std::span<const std::byte> src)
{
	encoder->Write(src);
	WritePage();
	return src.size();
}

bool
ShoutOutput::Pause()
{
	static std::byte silence[1020];

	encoder->Write(std::span{silence});
	WritePage();

	return true;
}

static std::string
shout_tag_to_metadata(const Tag &tag) noexcept
{
	const char *artist = tag.GetValue(TAG_ARTIST);
	const char *title = tag.GetValue(TAG_TITLE);

	return fmt::format("{} - {}",
			   artist != nullptr ? artist : "",
			   title != nullptr ? title : "");
}

void
ShoutOutput::SendTag(const Tag &tag)
{
	if (encoder->ImplementsTag()) {
		/* encoder plugin supports stream tags */

		encoder->PreTag();
		WritePage();
		encoder->SendTag(tag);
	} else {
		/* no stream tag support: fall back to icy-metadata */

		const auto meta = shout_metadata_new();
		AtScopeExit(meta) { shout_metadata_free(meta); };

		const auto song = shout_tag_to_metadata(tag);

		if (SHOUTERR_SUCCESS != shout_metadata_add(meta, "song", song.c_str()) ||
#ifdef SHOUT_FORMAT_TEXT
		    /* since libshout 2.4.6 */
		    SHOUTERR_SUCCESS != shout_set_metadata_utf8(shout_conn, meta)
#else
		    SHOUTERR_SUCCESS != shout_metadata_add(meta, "charset", "UTF-8") ||
		    SHOUTERR_SUCCESS != shout_set_metadata(shout_conn, meta)
#endif
			) {
			LogWarning(shout_output_domain,
				   "error setting shout metadata");
		}
	}

	WritePage();
}

const struct AudioOutputPlugin shout_output_plugin = {
	"shout",
	nullptr,
	&ShoutOutput::Create,
	nullptr,
};