getrawmempool JSON-RPC method

[teor2345]

Motivation

lightwalletd uses the getrawmempool JSON-RPC method.

Assumptions

lightwalletd doesn't need witnessed mempool transaction IDs for Orchard (UnminedTxId).
https://discord.com/channels/809218587167293450/809250822579028008/943326658042163270

Required Fields

The method is documented here: https://zcash.github.io/rpc/getrawmempool.html

lightwalletd always uses the no-argument format: https://github.com/zcash/lightwalletd/blob/master/common/mempool.go#L95

And only these fields are used by lightwalletd: https://github.com/zcash/lightwalletd/blob/master/common/mempool.go#L106

Response:

[                     (json array of string)
  "transactionid"     (string) The transaction id - this is a TXID, not a WTXID
  ,...
]

Tasks

• Implement the RPC method
• Add RPC acceptance tests to CI
• Test that the RPC method works with lightwalletd

API Reference

We plan to use jsonrpc_core with:

• jsonrpc_http_server
• jsonrpc-derive

Example Code

Here are examples of:

• declaring RPC methods as Rust functions

[ftm1000]

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