getblock JSON-RPC method

[mpguerra]

Motivation

lightwalletd uses the getblock JSON-RPC method.

lightwalletd caches all the blocks from Sapling activation, asking for them in height order.

So this RPC needs to be fast:

• Use smaller keys for block and transaction database indexes #3152

NU5 & Orchard

lightwalletd implemented NU5 & Orchard changes here:

• parse V5 (nu5) transactions zcash/lightwalletd#367
• add NU5 Orchard transaction data to CompactBlock zcash/lightwalletd#371
• compact blocks should include Orchard transactions zcash/lightwalletd#372

Required Fields

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

lightwalletd only uses height and verbosity = 0 as arguments.

And only the following fields are used by lightwalletd: https://github.com/zcash/lightwalletd/blob/master/common/common.go#L232

Field list:

"data"             (string) A string that is serialized, hex-encoded data for the block.

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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