# Buggy code
def render_GET(self, request):
    """
    .. http:get:: /torrentinfo

    A GET request to this endpoint will return information from a torrent found at a provided URI.
    This URI can either represent a file location, a magnet link or a HTTP(S) url.
    - torrent: the URI of the torrent file that should be downloaded. This parameter is required.

        **Example request**:

            .. sourcecode:: none

                curl -X PUT http://localhost:8085/torrentinfo?torrent=file:/home/me/test.torrent

        **Example response**:

            .. sourcecode:: javascript

                {"metainfo": <torrent metainfo dictionary>}
    """

    def on_got_metainfo(metainfo):
        if not isinstance(metainfo, dict) or "info" not in metainfo:
            self._logger.warning("Received metainfo is not a valid dictionary")
            request.setResponseCode(http.INTERNAL_SERVER_ERROR)
            request.write(json.dumps({"error": "invalid response"}))
            self.finish_request(request)
            return

        infohash = hashlib.sha1(bencode(metainfo["info"])).digest()

        # Check if the torrent is already in the downloads
        metainfo["download_exists"] = infohash in self.session.lm.downloads

        # Update the torrent database with metainfo if it is an unnamed torrent
        if self.session.lm.torrent_db:
            self.session.lm.torrent_db.update_torrent_with_metainfo(infohash, metainfo)
            self.session.lm.torrent_db._db.commit_now()

        # Save the torrent to our store
        try:
            self.session.save_collected_torrent(infohash, bencode(metainfo))
        except TypeError:
            # Note: in libtorrent 1.1.1, bencode throws a TypeError which is a known bug
            pass

        request.write(json.dumps({"metainfo": metainfo}, ensure_ascii=False))
        self.finish_request(request)

    def on_metainfo_timeout(_):
        if not request.finished:
            request.setResponseCode(http.REQUEST_TIMEOUT)
            request.write(json.dumps({"error": "timeout"}))
        # If the above request.write failed, the request will have already been finished
        if not request.finished:
            self.finish_request(request)

    def on_lookup_error(failure):
        failure.trap(ConnectError, DNSLookupError, HttpError, ConnectionLost)
        request.setResponseCode(http.INTERNAL_SERVER_ERROR)
        request.write(json.dumps({"error": failure.getErrorMessage()}))
        self.finish_request(request)

    def _on_loaded(response):
        if response.startswith("magnet"):
            _, infohash, _ = parse_magnetlink(response)
            if infohash:
                self.session.lm.ltmgr.get_metainfo(
                    response,
                    callback=metainfo_deferred.callback,
                    timeout=20,
                    timeout_callback=on_metainfo_timeout,
                    notify=True,
                )
                return
        metainfo_deferred.callback(bdecode(response))

    def on_mdblob(filename):
        try:
            with open(filename, "rb") as f:
                serialized_data = f.read()
            payload = read_payload(serialized_data)
            if payload.metadata_type not in [REGULAR_TORRENT, CHANNEL_TORRENT]:
                request.setResponseCode(http.INTERNAL_SERVER_ERROR)
                return json.dumps({"error": "Non-torrent metadata type"})
            magnet = payload.get_magnet()
        except InvalidSignatureException:
            request.setResponseCode(http.INTERNAL_SERVER_ERROR)
            return json.dumps({"error": "metadata has incorrect signature"})
        else:
            return on_magnet(magnet)

    def on_file():
        try:
            filename = url2pathname(
                uri[5:].encode("utf-8") if isinstance(uri, unicode) else uri[5:]
            )
            if filename.endswith(BLOB_EXTENSION):
                return on_mdblob(filename)
            metainfo_deferred.callback(bdecode(fix_torrent(filename)))
            return NOT_DONE_YET
        except TypeError:
            request.setResponseCode(http.INTERNAL_SERVER_ERROR)
            return json.dumps({"error": "error while decoding torrent file"})

    def on_magnet(mlink=None):
        infohash = parse_magnetlink(mlink or uri)[1]
        if infohash is None:
            request.setResponseCode(http.BAD_REQUEST)
            return json.dumps({"error": "missing infohash"})

        if self.session.has_collected_torrent(infohash):
            try:
                tdef = TorrentDef.load_from_memory(
                    self.session.get_collected_torrent(infohash)
                )
            except ValueError as exc:
                request.setResponseCode(http.INTERNAL_SERVER_ERROR)
                return json.dumps({"error": "invalid torrent file: %s" % str(exc)})
            on_got_metainfo(tdef.get_metainfo())
            return NOT_DONE_YET

        self.session.lm.ltmgr.get_metainfo(
            mlink or uri,
            callback=metainfo_deferred.callback,
            timeout=20,
            timeout_callback=on_metainfo_timeout,
            notify=True,
        )
        return NOT_DONE_YET

    metainfo_deferred = Deferred()
    metainfo_deferred.addCallback(on_got_metainfo)

    if "uri" not in request.args or not request.args["uri"]:
        request.setResponseCode(http.BAD_REQUEST)
        return json.dumps({"error": "uri parameter missing"})

    uri = unicode(request.args["uri"][0], "utf-8")

    if uri.startswith("file:"):
        return on_file()
    elif uri.startswith("http"):
        http_get(uri.encode("utf-8")).addCallback(_on_loaded).addErrback(
            on_lookup_error
        )
    elif uri.startswith("magnet"):
        return on_magnet()
    else:
        request.setResponseCode(http.BAD_REQUEST)
        return json.dumps({"error": "invalid uri"})

    return NOT_DONE_YET


# Traceback (RuntimeError)
Traceback (most recent call last):
File "TriblerGUI\event_request_manager.py", line 130, in on_read_data
RuntimeError: [Failure instance: Traceback: <type 'exceptions.UnicodeDecodeError'>: 'utf8' codec can't decode byte 0x75 in position 33: could not dump:
dict[error]->str::'TCP connection timed out: 10060: \x90...\xc5\
lib\site-packages\twisted\internet\base.py:1080:connectionFailed
lib\site-packages\twisted\internet\endpoints.py:246:clientConnectionFailed
lib\site-packages\twisted\internet\defer.py:496:errback
lib\site-packages\twisted\internet\defer.py:563:_startRunCallbacks
--- <exception caught here> ---
lib\site-packages\twisted\internet\defer.py:649:_runCallbacks
Tribler\Core\Modules\restapi\torrentinfo_endpoint.py:93:on_lookup_error
Tribler\Core\Utilities\json_util.py:100:dumps
]

# Fixed code
def render_GET(self, request):
    """
    .. http:get:: /torrentinfo

    A GET request to this endpoint will return information from a torrent found at a provided URI.
    This URI can either represent a file location, a magnet link or a HTTP(S) url.
    - torrent: the URI of the torrent file that should be downloaded. This parameter is required.

        **Example request**:

            .. sourcecode:: none

                curl -X PUT http://localhost:8085/torrentinfo?torrent=file:/home/me/test.torrent

        **Example response**:

            .. sourcecode:: javascript

                {"metainfo": <torrent metainfo dictionary>}
    """

    def on_got_metainfo(metainfo):
        if not isinstance(metainfo, dict) or "info" not in metainfo:
            self._logger.warning("Received metainfo is not a valid dictionary")
            request.setResponseCode(http.INTERNAL_SERVER_ERROR)
            request.write(json.dumps({"error": "invalid response"}))
            self.finish_request(request)
            return

        infohash = hashlib.sha1(bencode(metainfo["info"])).digest()

        # Check if the torrent is already in the downloads
        metainfo["download_exists"] = infohash in self.session.lm.downloads

        # Update the torrent database with metainfo if it is an unnamed torrent
        if self.session.lm.torrent_db:
            self.session.lm.torrent_db.update_torrent_with_metainfo(infohash, metainfo)
            self.session.lm.torrent_db._db.commit_now()

        # Save the torrent to our store
        try:
            self.session.save_collected_torrent(infohash, bencode(metainfo))
        except TypeError:
            # Note: in libtorrent 1.1.1, bencode throws a TypeError which is a known bug
            pass

        request.write(json.dumps({"metainfo": metainfo}, ensure_ascii=False))
        self.finish_request(request)

    def on_metainfo_timeout(_):
        if not request.finished:
            request.setResponseCode(http.REQUEST_TIMEOUT)
            request.write(json.dumps({"error": "timeout"}))
        # If the above request.write failed, the request will have already been finished
        if not request.finished:
            self.finish_request(request)

    def on_lookup_error(failure):
        failure.trap(ConnectError, DNSLookupError, HttpError, ConnectionLost)
        request.setResponseCode(http.INTERNAL_SERVER_ERROR)
        request.write(json.dumps({"error": unichar_string(failure.getErrorMessage())}))
        self.finish_request(request)

    def _on_loaded(response):
        if response.startswith("magnet"):
            _, infohash, _ = parse_magnetlink(response)
            if infohash:
                self.session.lm.ltmgr.get_metainfo(
                    response,
                    callback=metainfo_deferred.callback,
                    timeout=20,
                    timeout_callback=on_metainfo_timeout,
                    notify=True,
                )
                return
        metainfo_deferred.callback(bdecode(response))

    def on_mdblob(filename):
        try:
            with open(filename, "rb") as f:
                serialized_data = f.read()
            payload = read_payload(serialized_data)
            if payload.metadata_type not in [REGULAR_TORRENT, CHANNEL_TORRENT]:
                request.setResponseCode(http.INTERNAL_SERVER_ERROR)
                return json.dumps({"error": "Non-torrent metadata type"})
            magnet = payload.get_magnet()
        except InvalidSignatureException:
            request.setResponseCode(http.INTERNAL_SERVER_ERROR)
            return json.dumps({"error": "metadata has incorrect signature"})
        else:
            return on_magnet(magnet)

    def on_file():
        try:
            filename = url2pathname(
                uri[5:].encode("utf-8") if isinstance(uri, unicode) else uri[5:]
            )
            if filename.endswith(BLOB_EXTENSION):
                return on_mdblob(filename)
            metainfo_deferred.callback(bdecode(fix_torrent(filename)))
            return NOT_DONE_YET
        except TypeError:
            request.setResponseCode(http.INTERNAL_SERVER_ERROR)
            return json.dumps({"error": "error while decoding torrent file"})

    def on_magnet(mlink=None):
        infohash = parse_magnetlink(mlink or uri)[1]
        if infohash is None:
            request.setResponseCode(http.BAD_REQUEST)
            return json.dumps({"error": "missing infohash"})

        if self.session.has_collected_torrent(infohash):
            try:
                tdef = TorrentDef.load_from_memory(
                    self.session.get_collected_torrent(infohash)
                )
            except ValueError as exc:
                request.setResponseCode(http.INTERNAL_SERVER_ERROR)
                return json.dumps({"error": "invalid torrent file: %s" % str(exc)})
            on_got_metainfo(tdef.get_metainfo())
            return NOT_DONE_YET

        self.session.lm.ltmgr.get_metainfo(
            mlink or uri,
            callback=metainfo_deferred.callback,
            timeout=20,
            timeout_callback=on_metainfo_timeout,
            notify=True,
        )
        return NOT_DONE_YET

    metainfo_deferred = Deferred()
    metainfo_deferred.addCallback(on_got_metainfo)

    if "uri" not in request.args or not request.args["uri"]:
        request.setResponseCode(http.BAD_REQUEST)
        return json.dumps({"error": "uri parameter missing"})

    uri = unicode(request.args["uri"][0], "utf-8")

    if uri.startswith("file:"):
        return on_file()
    elif uri.startswith("http"):
        http_get(uri.encode("utf-8")).addCallback(_on_loaded).addErrback(
            on_lookup_error
        )
    elif uri.startswith("magnet"):
        return on_magnet()
    else:
        request.setResponseCode(http.BAD_REQUEST)
        return json.dumps({"error": "invalid uri"})

    return NOT_DONE_YET