Bugfix pubkey keepalive overflow and "forever orders"

[Alrighttt]

This PR addresses two issues caused by trusting peers to report a valid timestamp for PubkeyKeepAlive network messages.

First, this can cause an integer overflow during this operation:
https://github.com/KomodoPlatform/atomicDEX-API/blob/4c66f02ea78bd097c5313bcec938229346073099/mm2src/mm2_main/src/lp_ordermatch.rs#L2986

Second, it prevents a malicious node from setting a timestamp very far into the future. A timestamp set very far into the future would result in the orders staying in a node's orderbook even after the peer that broadcasted it has gone offline.

What this does is ignore the timestamp value sent from the peer and instead set it to the current time at which the message was received.

[cipig]

What this does is ignore the timestamp value sent from the peer and instead set it to the current time at which the message was received.

What do we do when nodes have the wrong time set? Can we make sure that seed nodes have the correct time? Can we drop seed nodes with wrong clock from the network? Or better all nodes with wrong clock? There is also this issue related to wrong clock: #1115

[onur-ozkan]

What this does is ignore the timestamp value sent from the peer and instead set it to the current time at which the message was received.

What do we do when nodes have the wrong time set? Can we make sure that seed nodes have the correct time? Can we drop seed nodes with wrong clock from the network? Or better all nodes with wrong clock? There is also this issue related to wrong clock: #1115

We design the solution, but it's not implemented yet.

[Alrighttt]

What this does is ignore the timestamp value sent from the peer and instead set it to the current time at which the message was received.

What do we do when nodes have the wrong time set? Can we make sure that seed nodes have the correct time? Can we drop seed nodes with wrong clock from the network? Or better all nodes with wrong clock? There is also this issue related to wrong clock: #1115

I wouldn't consider misaligned clocks relevant to this issue.

[shamardy]

Thanks a lot for the fix!
I agree with @Alrighttt, misaligned clocks is not relevant to this issue since the order receiving node local time is now used for calculating the received time for the last keep alive msg, it was actually more of an issue before this fix since a node/seednode with a misaligned clock might have deleted non timed out maker orders straight away.

[ca333]

What this does is ignore the timestamp value sent from the peer and instead set it to the current time at which the message was received.

What do we do when nodes have the wrong time set? Can we make sure that seed nodes have the correct time? Can we drop seed nodes with wrong clock from the network? Or better all nodes with wrong clock? There is also this issue related to wrong clock: #1115

we had this topic in the past and DEX/mm2 (or any other blockchain based dapp/SW) shouldn't (purely) orientate towards local/"central" timestamps as they can always be off. Also comparing against some online source isn't reliable neither and won't ensure sync across the network. We did in the past solve similar (time-related) issues by sourcing timestamp from the blockchain stack (ensures sync / eq across network).

Added additional small comment for clarification on issue close: #1115 (comment)