TCP microservice does NOT have a max message length about nest

[kamilmysliwiec]

IMO even the 512 MB setting is much more than needed. We could keep it this high though just to avoid introducing another configuration option.

[kamilmysliwiec]

TCP microservices should never be exposed as public services so there's no risk of anyone sending malicious data.

Still, we should fix this issue either way. Would you like to create a PR for this?

[raw-phil]

@kamilmysliwiec sure I'd like to create a PR, I just don't know how big the maximum size needs to be set for incoming json message. Maybe to the max string size of V8 engine, that if I remember correctly is 1GB.

[underfisk]

@raw-phil I would say that it could be adjustable, the developer might want to specify whatever value he has in mind as sometimes it's hard to accurately read the value. Applying the default based on the max string for v8 engine could work but allowing the developer to override should be possible 🤔

[raw-phil]

@kamilmysliwiec I agree with you. In the next days I'll work on the PR. Thanks

[raw-phil]

I have noticed that the length used before the delimiter character(#) represents the number of characters sent instead of the bytes of the message.

nest/packages/microservices/helpers/json-socket.ts

Lines 61 to 66 in d6a6f30

	private formatMessageData(message: any) {
	const messageData = JSON.stringify(message);
	const length = messageData.length;
	const data = length + this.delimiter + messageData;
	return data;
	}

I've done a couple of researches, and JS use the UTF-16 encoding which is variable-length, code points are encoded with one or two 16-bit code units.
IMO, if we want to set the maximum string/buffer size to 512MB, we have to consider the worst case where all characters need 32 bits to be encoded, and then I think that the maximum length (in characters) of the message should be set to 512MB / 32 bit = 134217728, or something like that