Added metadata support for Shairplay-sync/Airplay interface

server/streamreader/airplayStream.cpp

@@ -22,16 +22,37 @@
 #include "common/utils.h"
 #include "aixlog.hpp"
 
+#ifdef HAS_EXPAT
+#include "base64.h"
+#endif
 
 using namespace std;
 
+static string hex2str(string input)
+{
+        typedef unsigned char byte;
+        unsigned long x = strtoul(input.c_str(), 0, 16);
+        byte a[] = {byte(x >> 24), byte(x >> 16), byte(x >> 8), byte(x), 0};
+        return string((char *)a);
+}
 
-
+/*
+ * Expat is used in metadata parsing from Shairport-sync.
+ * Without HAS_EXPAT defined no parsing will occur.
+ *
+ * This is currently defined in airplayStream.h, prolly should 
+ * move to Makefile?
+ */
 
 AirplayStream::AirplayStream(PcmListener* pcmListener, const StreamUri& uri) : ProcessStream(pcmListener, uri), port_(5000)
 {
 	logStderr_ = true;
 
+	pipePath_ = "/tmp/shairmeta." + to_string(getpid());
+	cout << "Pipe [" << pipePath_ << "]\n";
+
+	// XXX: Check if pipe exists, delete or throw error
+
 	sampleFormat_ = SampleFormat("44100:16:2");
  	uri_.query["sampleformat"] = sampleFormat_.getFormat();
 
@@ -39,16 +60,85 @@ AirplayStream::AirplayStream(PcmListener* pcmListener, const StreamUri& uri) : P
 
 	string devicename = uri_.getQuery("devicename", "Snapcast");
 	params_wo_port_ = "--name=\"" + devicename + "\" --output=stdout";
+	params_wo_port_ += " --metadata-pipename " + pipePath_;
 	params_ = params_wo_port_ + " --port=" + cpt::to_string(port_);
+
+	pipeReaderThread_ = thread(&AirplayStream::pipeReader, this);
+	pipeReaderThread_.detach();
 }
 
 
 AirplayStream::~AirplayStream()
 {
+	parse(string("</metatags>"));
+	XML_ParserFree(parser_);
+}
+
+int AirplayStream::parse(string line)
+{
+	enum XML_Status result;
+
+	if((result = XML_Parse(parser_, line.c_str(), line.length(), false)) == XML_STATUS_ERROR)
+	{
+		XML_ParserFree(parser_);
+		createParser();
+	}
+	return result;
+}
+
+void AirplayStream::createParser()
+{
+	parser_ = XML_ParserCreate("UTF-8");
+	XML_SetElementHandler(parser_, element_start, element_end);
+	XML_SetCharacterDataHandler(parser_, data);
+	XML_SetUserData(parser_, this);
+
+	// Make an outer element to keep parsing going
+	parse(string("<metatags>"));
+}
+
+void AirplayStream::push()
+{
+	string data = entry_->data;
+	if(entry_->isBase64 && entry_->length > 0)
+		data = base64_decode(data);
+
+	if(entry_->type == "ssnc" && entry_->code == "mdst")
+		jtag_ = json();
+
+	if(entry_->code == "asal") jtag_["ALBUM"]  = data;
+	if(entry_->code == "asar") jtag_["ARTIST"] = data;
+	if(entry_->code == "minm") jtag_["TITLE"]  = data;
+
+	if(entry_->type == "ssnc" && entry_->code == "mden"){
+		//LOG(INFO) << "metadata=" << jtag_.dump(4) << "\n";
+		setMeta(jtag_);
+	}
 }
 
 
-void AirplayStream::initExeAndPath(const std::string& filename)
+void AirplayStream::pipeReader()
+{
+	createParser();
+
+	while(true)
+	{
+		ifstream pipe(pipePath_);
+
+		if(pipe){
+			string line;
+
+			while(getline(pipe, line)){
+				parse(line);
+			}
+		}
+
+		// Wait a little until we try to open it again
+		this_thread::sleep_for(chrono::milliseconds(500));
+	}
+}
+
+void AirplayStream::initExeAndPath(const string& filename)
 {
 	path_ = "";
 	exe_ = findExe(filename);
@@ -86,3 +176,52 @@ void AirplayStream::onStderrMsg(const char* buffer, size_t n)
 	}
 }
 
+#ifdef HAS_EXPAT
+void XMLCALL AirplayStream::element_start(void *userdata, const char *element_name, const char **attr)
+{
+	AirplayStream *self = (AirplayStream *)userdata;
+	string name(element_name);
+
+	self->buf_.assign("");
+	if(name == "item") self->entry_.reset(new TageEntry);
+
+	for(int i = 0; attr[i]; i += 2){
+		string name(attr[i]);
+		string value(attr[i+1]);
+		if(name == "encoding")
+			self->entry_->isBase64 = (value == "base64"); // Quick & dirty..
+	}
+}
+
+void XMLCALL AirplayStream::element_end(void *userdata, const char *element_name)
+{
+	AirplayStream *self = (AirplayStream *)userdata;
+	string name(element_name);
+
+	if(name == "code")
+		self->entry_->code.assign(hex2str(self->buf_));
+
+	else if(name == "type")
+		self->entry_->type.assign(hex2str(self->buf_));
+
+	else if(name == "length")
+		self->entry_->length = strtoul(self->buf_.c_str(), 0, 10);
+
+	else if(name == "data")
+		self->entry_->data = self->buf_;
+
+	else if(name == "item")
+		self->push();
+
+	else if(name == "metatags") ;
+	else cout << "Unknown tag <" << name << ">\n";
+}
+
+void XMLCALL AirplayStream::data(void *userdata, const char *content, int length)
+{
+	AirplayStream *self = (AirplayStream *)userdata;
+	string value(content, (size_t)length);
+	self->buf_.append(value);
+}
+#endif
+