bolt07: enforce htlc_maximum_msat >= htlc_minimum_msat

[carlaKC]

Bolt 7 specifies how to set hltc_minimum_msat and htlc_maximum_msat but does not explicitly enforce hltc_minimum_msat <= htlc_maximum_msat.

Since a channel where the largest HTLC that the advertising node will send through it is smaller than the minimum value the peer will accept is unusable, it seems reasonable to blacklist this type of gossip?

[TheBlueMatt]

I don't see why we should ban an entire node for such a thing, like I could see a bug on this resulting in this happening, but we should just ignore the channel, not ban the node and all their channels, no? Did you come across this somewhere?

[carlaKC]

I don't see why we should ban an entire node for such a thing, like I could see a bug on this resulting in this happening, but we should just ignore the channel, not ban the node and all their channels, no?

I think ignore is also fine. Was following the pattern from "if htlc_maximum_msat is greater than channel capacity" since that's also a reaction to a bug?

Did you come across this somewhere?

No, just noticed it when I was checking up on some route blinding stuff.

[TheBlueMatt]

I think ignore is also fine. Was following the pattern from "if htlc_maximum_msat is greater than channel capacity" since that's also a reaction to a bug?

Yea, and arguably that also shouldn't result in us punishing a node entirely - we reject the gossip anyway, but at least that one is maybe harder to hit?

[carlaKC]

Yea, and arguably that also shouldn't result in us punishing a node entirely

Yeah fair point, bumped this one to should ignore during route construction.

[t-bast]

ACK d6b2177

[ProofOfKeags]

ACK d6b2177