From bab2d15d6eabaf43c9b06388e87d17358a07680e Mon Sep 17 00:00:00 2001
From: Mike Lang <mikelang3000@gmail.com>
Date: Sun, 9 Dec 2018 17:27:08 -0800
Subject: [PATCH] Initial implementation of the restreamer

Supports serving segments, listing segments for an hour, and generating playlists so it can stream.
---
 restreamer/restreamer/__main__.py     | 14 +++++
 restreamer/restreamer/generate_hls.py | 16 +++++
 restreamer/restreamer/main.py         | 84 +++++++++++++++++++++++++++
 3 files changed, 114 insertions(+)
 create mode 100644 restreamer/restreamer/generate_hls.py
 create mode 100644 restreamer/restreamer/main.py

diff --git a/restreamer/restreamer/__main__.py b/restreamer/restreamer/__main__.py
index e69de29..24935eb 100644
--- a/restreamer/restreamer/__main__.py
+++ b/restreamer/restreamer/__main__.py
@@ -0,0 +1,14 @@
+
+import gevent.monkey
+gevent.monkey.patch_all()
+
+import logging
+
+import argh
+
+from restreamer.main import main
+
+LOG_FORMAT = "[%(asctime)s] %(levelname)8s %(name)s(%(module)s:%(lineno)d): %(message)s"
+
+logging.basicConfig(level=logging.INFO, format=LOG_FORMAT)
+argh.dispatch_command(main)
diff --git a/restreamer/restreamer/generate_hls.py b/restreamer/restreamer/generate_hls.py
new file mode 100644
index 0000000..242b763
--- /dev/null
+++ b/restreamer/restreamer/generate_hls.py
@@ -0,0 +1,16 @@
+
+
+def generate_master(playlists):
+	"""Generate master playlist. Playlists arg should be a map {name: url}.
+	Little validation or encoding is done - please try to keep the names valid
+	without escaping.
+	"""
+	lines = ["#EXTM3U"]
+	for name, url in playlists.items():
+		lines += [
+			# We name each variant with a VIDEO rendition with no url
+			'#EXT-X-MEDIA:TYPE=VIDEO,GROUP-ID="{name}",NAME="{name}",AUTOSELECT=YES,DEFAULT=YES'.format(name=name),
+			'#EXT-X-STREAM-INF:VIDEO="{name}"'.format(name=name),
+			url,
+		]
+	return "\n".join(lines) + '\n'
diff --git a/restreamer/restreamer/main.py b/restreamer/restreamer/main.py
new file mode 100644
index 0000000..596c846
--- /dev/null
+++ b/restreamer/restreamer/main.py
@@ -0,0 +1,84 @@
+
+import errno
+import json
+import os
+
+from flask import Flask, url_for, request, abort
+from gevent.pywsgi import WSGIServer
+
+import generate_hls
+
+
+app = Flask('restreamer', static_url_path='/segments')
+
+
+"""
+The restreamer is a simple http api for listing available segments and generating
+HLS playlists for them.
+
+The segments themselves are ideally to be served by some external webserver
+under "/segments/<stream>/<variant>/<hour>/<filename>" (ie. with BASE_DIR under "/segments"),
+though this server will also serve them if requested.
+"""
+
+
+def listdir(path, error=True):
+	"""List files in path, excluding hidden files.
+	Behaviour when path doesn't exist depends on error arg.
+	If error is True, raise 404. Otherwise, return [].
+	"""
+	try:
+		return [name for name in os.listdir(path) if not name.startswith('.')]
+	except OSError as e:
+		if e.errno != errno.ENOENT:
+			raise
+		if error:
+			abort(404)
+		return []
+
+
+@app.route('/files/<stream>/<variant>/<hour>')
+def list_segments(stream, variant, hour):
+	"""Returns a JSON list of segment files for a given stream, variant and hour.
+	Returns empty list on non-existant streams, etc.
+	"""
+	# Check no-one's being sneaky with path traversal or hidden folders
+	if any(arg.startswith('.') for arg in (stream, variant, hour)):
+		return "Parts may not start with period", 403
+	path = os.path.join(
+		app.static_folder,
+		stream,
+		variant,
+		hour,
+	)
+	return json.dumps(listdir(path, error=False))
+
+
+@app.route('/playlist/<stream>.m3u8')
+def generate_master_playlist(stream):
+	"""Returns a HLS master playlist for the given stream.
+	Takes optional params:
+		start, end: The time to begin and end the stream at.
+			See generate_media_playlist for details.
+	"""
+	# path traversal / hidden folders
+	if stream.startswith('.'):
+		return "Stream may not start with period", 403
+	variants = listdir(os.path.join(app.static_folder, stream))
+	playlists = {
+		variant: url_for('generate_media_playlist', stream=stream, variant=variant, **request.args)
+		for variant in variants
+	}
+	return generate_hls.generate_master(playlists)
+
+
+@app.route('/playlist/<stream>/<variant>.m3u8')
+def generate_media_playlist(stream, variant):
+	# TODO
+	return "Not Implemented", 501
+
+
+def main(host='0.0.0.0', port=8000, base_dir='.'):
+	app.static_folder = base_dir
+	server = WSGIServer((host, port), app)
+	server.serve_forever()