Add Particl Support

[dasource]

This implements the partatomicswap command.
Happy to run some tests with you.

Thank for the great work!

[dajohi]

Rebase?

[jrick]

Does particl have a running testnet network? (only asking because some alts seem to not bother running one)

[dasource]

@jrick sure do.
You can also see the testnet explorer here: https://explorer-testnet.particl.io

[jrick]

Seems to work well with the exception of the fee estimation. I noticed that when the estimatefee RPC failed (probably because my node had not been online for 6 blocks) that the contract transaction was created with a low fee. This was accepted on testnet but I imagine it would be rejected on mainnet due to standard checks.

For example:

Contract fee: 0.00000171 PART (0.00000753 PART/kB)

Which is lower than the mempool fee rate policy than I see from getinfo:

  "relayfee": 0.00001000,

The refund and redemption transaction fee estimation appeared to work fine (the fee rate was never lower than 1e3).

[jrick]

Actually on further inspection, I don't seem to be getting any valid results out of the estimatefee RPC using particl-cli. Should this part of the getFeePerKb func be removed?

[dasource]

Thanks @jrick for testing this.

1. estimatefee is deprecated in 0.15.0.x and should be replaced with estimatesmartfee.
2. in either case both where returning -1 during your tests due to lack of TXs across testnet (was fine on mainnet) since your node came online. Once we sent some TXs on testnet this started returning correct data.

Thanks again for the initiative on this and helping to test it.

[jrick]

After discussion with @dasource, the estimatefee RPC does work but was failing to produce any estimates on testnet due to low transaction activity at the time. I have confirmed that estimatefee does produce results after testnet was spammed with transactions.

This should be using estimatesmartfee, not estimatefee. This is being tracked in #32 and I can either update it later or partatomicswap can be the first of the tools to use this RPC.

The issues with the contract transaction having a low fee rate is due to the fee being applied by fundrawtransaction. I will need to do more testing against Bitcoin Core's 0.15 branch to see if this applies to all of the non-DCR tools or is a bug with particld.

[jrick]

I tested against bitcoin core 0.15 and the contract is created with the correct fee, so this does appear to be a bug with particld. I expect contract transactions to be rejected on mainnet due to low fees (but have not tested this, only tested on testnet so far).