stream_curl: set stream url to the effective one in case of a redirect

[MoSal]

Without this, there are two issues I've quickly encountered:

1. (major) HLS segment URLs are broken, because segment lines get appended to the original URL. Not only does this break playback, but it could leak query data (like auth tokens) to a third party.
2. (medium) HLS master playlists are opened as actual playlists, with an entry per variant stream.

---

First issue basically broke playback in almost all IPTV use-cases 🫢

To test this. Here is a trivial python script:

Details

from http.server import HTTPServer, BaseHTTPRequestHandler
from urllib.parse import urlparse, parse_qs

class RedirectHandler(BaseHTTPRequestHandler):
    
    def do_GET(self):
        """Handle GET requests."""
        parsed_path = urlparse(self.path)
        path = parsed_path.path
        query_params = parse_qs(parsed_path.query)
        
        # Extract status code from path (e.g., /301, /302)
        if path.startswith('/'):
            status_str = path.lstrip('/').split('/')[0]
            
            try:
                status_code = int(status_str)
            except ValueError:
                self.send_error(400, "Bad Request")
                return
            
            # Validate status code
            if status_code not in [301, 302, 303, 307, 308]:
                self.send_error(400, "Invalid status code")
                return
            
            # Extract target URL from query string
            if 'url' not in query_params:
                self.send_error(400, "Missing 'url' parameter")
                return
            
            target_url = query_params['url'][0]
            
            # Perform redirect
            self.send_response(status_code)
            self.send_header('Location', target_url)
            self.end_headers()
        else:
            self.send_error(404, "Not Found")
    
    def log_message(self, format, *args):
        """Suppress default logging."""
        pass

if __name__ == '__main__':
    server = HTTPServer(('localhost', 8000), RedirectHandler)
    print("Server running on http://localhost:8000")
    print("Usage: http://localhost:8000/301?url=https://example.com")
    print("       http://localhost:8000/302?url=https://example.com")
    print("Press Ctrl+C to stop")
    server.serve_forever()

To trigger the issues:

First Issue

Works

mpv --curl-enabled=no --tls-verify=no 'http://localhost:8000/301?url=https://live-qt-primary.global.ssl.fastly.net/qt/Channel-QT-TX-AWS-virginia-2/Source-QT-10M-2-sn9jy9-BP-07-04-vXxkCqNs5ul_live.m3u8'

Broken

mpv  'http://localhost:8000/301?url=https://live-qt-primary.global.ssl.fastly.net/qt/Channel-QT-TX-AWS-virginia-2/Source-QT-10M-2-sn9jy9-BP-07-04-vXxkCqNs5ul_live.m3u8'

Segment URL's constructed are of the template:

http://localhost:8000/Source-QT-10M-2-sn9jy9-BP-07-04-vXxkCqNs5ul/$<n>.ts

Second issue

Opens as a stream

mpv --curl-enabled=no --tls-verify=no 'http://localhost:8000/301?url=https://bloomberg.com/media-manifest/streams/qt.m3u8'

Opens as a playlist

mpv 'http://localhost:8000/301?url=https://bloomberg.com/media-manifest/streams/qt.m3u8'

[kasper93]

This should be a single log and probably MP_VERBOSE at best.