Find shorter route assertion #3519
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Breaks `tools/build-release.sh` Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
We can actually fail to find a shorter route, but it's a fairly obscure case. Fixes: ElementsProject#3517 Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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I think this needs a testcase, but I couldn't trigger it, do you know a setup that lead to this code?
@s-tikhomirov wanted to find a parallel local paths by setting maxhops to 1 and excluding specific channels. As I see its somehow relative to having a higher fee parallel path that may be selected internally by using a lower risk factor, and also a specific amount is required to trigger this.
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ACK 992dce8 |
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It would be tricky, but possible, to have a situation where we find a route with low riskfactor, and fail with high. That's what happens here. Imagine A with channels to B & C, both with channels to D, which goes to E. A-B is low fee, high delay. A-C is higher fee, lower delay. With low riskfactor we choose A-B, with high, A-C. Now, when we get to D we have different amounts, and the higher amount can't do D-E due to the max. |
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Thanks to @s-tikhomirov for the great bug report!
Fixes: #3517
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