sendrawtransaction JSON-RPC method

[mpguerra]

Motivation

lightwalletd uses the sendrawtransaction JSON-RPC method.

Design Decisions

zcashd puts the transaction in its mempool, so Zebra should do the same thing.

What should we do if we think the transaction is invalid?

• log it at warning level
• If Zebra rejects a transaction that zcashd accepts, that's a bug in Zebra we need to fix

Zebra doesn't implement pending transactions in the mempool, so the transaction can't depend on another mempool transaction.

Required Fields

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

lightwalletd only uses hexstring (raw transaction data) as an argument: https://github.com/zcash/lightwalletd/blob/master/frontend/service.go#L302

Field list:

"hex"             (string) The transaction hash in hex - ignored by `lightwalletd`?

Tasks

• Implement the RPC method
• Add RPC acceptance tests to CI
• Test that the RPC method works with lightwalletd
• Test with transactions that get split across multiple TCP packets - use a max-sized transaction

We need to test with large transactions because our JSON protocol fixes operate on each packet.

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

Out of Scope

lightwalletd seems to do some weird error handling, but this is out of scope for Zebra: https://github.com/zcash/lightwalletd/blob/master/frontend/service.go#L308

[ftm1000]

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