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var url = require('url');
var http = require('http');
require('buffertools');
function extractBoundary(contentType) {
var startIndex = contentType.indexOf('boundary=');
var endIndex = contentType.indexOf(';', startIndex);
if (endIndex == -1) { //boundary is the last option
// some servers, like mjpeg-streamer puts a '\r' character at the end of each line.
if ((endIndex = contentType.indexOf('\r', startIndex)) == -1) {
endIndex = contentType.length;
}
}
return contentType.substring(startIndex + 9, endIndex);
}
var MjpegProxy = exports.MjpegProxy = function(mjpegUrl) {
var self = this;
if (!mjpegUrl) throw new Error('Please provide a source MJPEG URL');
self.mjpegOptions = url.parse(mjpegUrl);
self.audienceResponses = [];
self.newAudienceResponses = [];
self.boundary = null;
self.globalMjpegResponse = null;
self.proxyRequest = function(req, res) {
// There is already another client consuming the MJPEG response
if (self.audienceResponses.length > 0) {
self._newClient(req, res);
} else {
// Send source MJPEG request
var mjpegRequest = http.request(self.mjpegOptions, function(mjpegResponse) {
self.globalMjpegResponse = mjpegResponse;
self.boundary = extractBoundary(mjpegResponse.headers['content-type']);
self._newClient(req, res);
var lastByte1 = null;
var lastByte2 = null;
mjpegResponse.on('data', function(chunk) {
// Fix CRLF issue on iOS 6+: boundary should be preceded by CRLF.
if (lastByte1 != null && lastByte2 != null) {
var oldheader = '--' + self.boundary;
var p = chunk.indexOf(oldheader); // indexOf provided by buffertools
if (p == 0 && !(lastByte2 == 0x0d && lastByte1 == 0x0a) || p > 1 && !(chunk[p - 2] == 0x0d && chunk[p - 1] == 0x0a)) {
var b1 = chunk.slice(0, p);
var b2 = new Buffer('\r\n--' + self.boundary);
var b3 = chunk.slice(p + oldheader.length);
chunk = Buffer.concat([b1, b2, b3]);
}
}
lastByte1 = chunk[chunk.length - 1];
lastByte2 = chunk[chunk.length - 2];
for (var i = self.audienceResponses.length; i--;) {
var res = self.audienceResponses[i];
// First time we push data... lets start at a boundary
if (self.newAudienceResponses.indexOf(res) >= 0) {
var p = chunk.indexOf('--' + self.boundary); // indexOf provided by buffertools
res.write(chunk.slice(p));
self.newAudienceResponses.splice(self.newAudienceResponses.indexOf(res), 1); // remove from new
} else {
res.write(chunk);
}
}
});
mjpegResponse.on('end', function () {
// console.log("...end");
for (var i = self.audienceResponses.length; i--;) {
var res = self.audienceResponses[i];
res.end();
}
});
mjpegResponse.on('close', function () {
// console.log("...close");
});
});
mjpegRequest.on('error', function(e) {
console.log('problem with request: ', e);
});
mjpegRequest.end();
}
}
self._newClient = function(req, res) {
res.writeHead(200, {
'Expires': 'Mon, 01 Jul 1980 00:00:00 GMT',
'Cache-Control': 'no-cache, no-store, must-revalidate',
'Pragma': 'no-cache',
'Content-Type': 'multipart/x-mixed-replace;boundary=' + self.boundary
});
self.audienceResponses.push(res);
self.newAudienceResponses.push(res);
res.socket.on('close', function () {
// console.log('exiting client!');
self.audienceResponses.splice(self.audienceResponses.indexOf(res), 1);
if (self.newAudienceResponses.indexOf(res) >= 0) {
self.newAudienceResponses.splice(self.newAudienceResponses.indexOf(res), 1); // remove from new
}
if (self.audienceResponses.length == 0) {
self.globalMjpegResponse.destroy();
}
});
}
}
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