> DDos is already handled cleanly by something like netcode.io using access tokens.

I can set up a netcode.io server and cause it to list any IP addresses I want as "server addresses", then cause a netcode.io client accept that challenge token and permit traffic to that address. If netcode.io is widespread (i.e. in browsers) I can buy some advertising to knock out any client or server I want.

Unless you are in advertising, you might not be aware I can do that: I can purchase something like a million clients for something like $10. Knowing how certain formats work make it possible to purchase more traffic for even cheaper.

These attacks are well known to Google and the WebRTC designers and as such, is not possible with WebRTC: The browser does not permit traffic at volume until ICE/SDP negotiation is complete which means that signalling must have occurred.

By simply limiting the netcode.io clients size to the games that use it (i.e. games distributed with one of the non-browser implementations of netcode.io), this attack is mitigated substantially, but as soon as we try to use netcode.io as a "simpler webRTC" it falls flat on it's face.

Splat.

Perhaps we are lucky that the window.netcode browser extension isn't more popular, or that all those users have ad blockers.

Anyway. The workaround I suggested would probably be sufficient to stop this attack as stated, but it requires a netcode 1.1 or maybe a 2.0 since all clients and servers need to be upgraded. And there might also be other attacks.

> Anything more than the most trivial NAT traversal isn't needed since any online game worth their salt uses dedicated servers in order to prevent cheating and gamestate manipulation.

What Cisco calls Dynamic NAT doesn't work with this scheme. It is popular. Perhaps these people don't play games because game servers don't support their network configuration, or perhaps these people don't play games for another reason.

Non-game uses of UDP are very interested in talking to these networks however. It will be difficult to get buy-in from other parties interested in UDP unless you solve these problems.

> Most networking stacks keep the packet size well under 200 bytes since they don't want to saturate the connection and dead-reckoning deals with state reconciliation.

IP packets fragment once they go above a certain size. That size can only be discovered by experimentation, but will never be smaller than 576 bytes. Many networks block the standard discovery process (called Path-MTU discovery) for misguided reasons, but protocol developers still have to deal with it.

If your UDP packets are bigger than this size, and everything else is working, then losing either fragment will delay the receipt of the datagram and waste kernel memory. Developers who can do their own fragmentation smarter use setsockopt+IP_DONTFRAG and save everyone a potential denial of service opportunity.

If all you want to do is avoid head-of-line blocking on the player's network connection, then multiplexing several TCP connections (even websockets!) will provide the same latency and throughput guarantees that UDP will, getting correct NAT behaviour and resistance to D/DoS for free. Simply drop and reconnect any link on packet loss (trivial to detect on either side), and you only need enough connections to handle the maximum number of dropped packets you can tolerate within the time it takes to reconnect.

I've seen at least one game on HN use this trick in the last year, so I know it isn't unknown.

> Binary size also matters, so the fact that you want to bring in a whole codec when it may not be wanted isn't a great selling point either.

That statement might have been over your head. Sorry about that.

1kb of code "on the hot path" is a shorthand way of describing the code that is executing in L1 and refers absolutely to binary size. My i7 only has 64kb of L1, and anything larger than that requires memory fetch and waits. Keeping the hot path within L1 is a good way to get 1000x speedups (and is a big part of why my code tends to be so fast).

Ulrich Drepper's "what every programmer should know about memory"[1] might be good introductory material for some of these concepts, and I highly recommend you read it.

[1]: futuretech.blinkenlights.nl/misc/cpumemory.pdf

> However I don't think you know enough about the domain to be able to sell it successfully.

Perhaps, and it is a small domain: The only people who think WebRTC is "too complicated" seem to be game developers.