Grafana Live: Unable to push strings with certain valid Unicode characters

[Sh4pe]

What went wrong?

What happened:

I'm pushing metrics to Grafana Live over WebSockets. These metrics contain strings. When the strings contain a form feed (U+000C) or carriage return (U+000D), the metrics are rejected. In the Grafana logs, I even see that the line protocol telegram appears to be truncated after the carriage return - the timestamp is left off, see my examples below.

Error log in case of form feed:

ERROR[05-04|10:05:02] Error converting metrics                 logger=live.push_ws error="error converting metrics: error parsing metrics: metric parse error: expected field at 1:17: \"something test=\\\"\\f\\\" 1681164826166000000\"" frameFormat=labels_column

Error log in case of carriage return:

ERROR[05-04|10:05:08] Error converting metrics                 logger=live.push_ws error="error converting metrics: error parsing metrics: metric parse error: expected field at 1:18: \"something test=\\\"\"" frameFormat=labels_column

I've tested this against both v9.1.5 and v9.5.1 (bc353e4).

What did you expect to happen:

I expect that Grafana Live can consume any metric containing valid UTF-8 strings. In case that is not possible, I expect the strict subset of UTF-8 that is supported by Grafana Live to be documented somewhere.

How do we reproduce it?

Step 1:

Establish WebSocket connection to Grafana Live instance.

Step 2:

Send either of these line protocol messages (generated with Python code):

websocket_messages = [
    f'something_metric some_string="{chr(12)}" 1681164826166000000',
    f'something_metric some_string="{chr(13)}" 1681164826166000000'
]

Step 3:

See the error logs for the rejection message.

What Grafana version are you using?

v9.1.5, v9.5.1 (bc353e4)

Optional Questions:

Is the bug inside a Dashboard Panel?

Copy the panel's "get-help" data here

Grafana Platform?

None

User's OS?

No response

User's Browser?

No response

Is this a Regression?

None

Are Datasources involved?

No response

Anything else to add?

No response

[Sh4pe]

This might be related to #43765.