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RFC: dialMe protocol #64

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RFC: dialMe protocol #64

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7d1c23c
feat: adding dialme protocol
dryajov May 29, 2018
b826284
fix: reword requirements
dryajov May 30, 2018
89075f0
feat: change addrs field to string, to prevent sending multiple multi…
dryajov May 30, 2018
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40 changes: 40 additions & 0 deletions dialme/README.md
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# Simple protocol to request dial backs

> Allow a peer in a network to be dialed back after an initial connection has been negotiated

In certain scenarios, it might be desirable for a peer to ask another peer to dial it back after an initial connection has been established. This might be useful in scenarios where the dialing peer has learned enough about the network topology and it knows of a better route to be reached over (NATed peers vs non NATed peers). This protocol will allow it to ask its counterpart to dial it back on a hopefully better route.

#### Requirements

- Should be transports agnostic
- Should be connection agnostic
- Can work with or without connection upgrades
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couldnt this all be simplified by saying that the dialme protocol is a standard libp2p protocol? all libp2p protocols are transport and connection agnostic and assume nothing about the network stack implementation

- this implies that the `dialme` protocol assumes nothing about the network stack implementation and is only concerned with requesting dial backs.

In order for dial back to happen a prior connection is required. This prior connection could be established over a circuit (the most likely scenario) or any other preexisting connection. The prior connection is only required to request the dial back, and the `dialme` protocol assumes nothing about it at all.

## Typical `dialme` (back) flow

A `dialme` flow might look similar to the one described below:

- Lets assume that `Peer A` wants to dial `Peer B`
- `Peer A` is publicly reachable on the wider internet
- `Peer B` is behind an impenetrable NAT
- `Peer A` dials `Peer B` using some relay(s)
- Once a connection has been established over the relay(s), `Peer A` asks `Peer B` to dial it back over the provided address using the `dialme` protocol
- `Peer B` proceeds to dial `Peer A` over the provided addresses, dropping the circuited connection once the new connection succeeds
- `Peer A` accepts the dial back and proceeds to use the new connection dropping the relayed one

### The protocol

This is a rather simple protocol that communicates a multiaddress to perform the dial back:

```protobuf
message DialMe {
message Peer {
required bytes id = 1; // peer id
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I wouldn't include this, the remote side should already know our peer ID and we definitely don't want to end up dialing a different peer.

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Hmm... I agree with you, I can't think of a use for this honestly. Unless anyone objects I'll remove it.

repeated bytes addrs = 2; // array of multiadrs
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my main concern with this protocol (and probably the reason it hasnt moved forward until now) is figuring out how to deal with spam and fake dials. If i can tell any peer to try dialing some random set of addresses, i could hypothetically use this to DoS a given ip address. Just connecting to a bunch of libp2p peers and saying "dialme at [all these addresses that are really the sameish]"

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@dryajov dryajov May 30, 2018 •
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Good point. I think in this case, having an array of addresses is a huge attack vector, we can limit that to only one address per request, as well as throttle dial back requests coming from the same peer. I though about nonces and challenge response schemes, but they don't seem to work in this case.

}

optional Peer peer = 1;
```