add Sapling and Orchard tree commitment sizes to GetBlock result

[LarryRuane]

Closes #432.

(These are also added to GetBlockRange.) This requires an updated version of zcashd getblock RPC that returns these values. This is planned to be added in zcash release v5.6.0.

These values are written to the compact block cache (/var/lib/lightwalletd/db/main/blocks), but of course older cached compact blocks won't have these values. To get these values into all cached blocks, shut down lightwalletd, restart it with the --redownload option, and let it sync (which will take 12 hours or more). This needs to be done only once. Or remove that file (which has the same effect as --redownload) and restart.

Here's an example of the new output:

$ grpcurl -plaintext -d '{"height":2091941}' localhost:9067 cash.z.wallet.sdk.rpc.CompactTxStreamer/GetBlock
{
  "height": "2091941",
  "hash": "3YuXLwZEKxefuXhZFrWU8ceujZcT7ldB0SNJAQAAAAA=",
  "prevHash": "qUUafE5QSka8lBVSPDRGHf88ilQvg0v2miEeAQAAAAA=",
  "time": 1684534214,
  "vtx": [
    {
      "index": "1",
      "hash": "AQ9hMLIbQFewkoBu3tvWThGbBjkPOikgYsUL7Etj++g=",
      "actions": [
        {
          "nullifier": "CWyqMBMUtyMxx2tu6jxTGoEqnae1OrYj2Zbu73bqMA8=",
          "cmx": "p0jePfxZ8/U/t8HbVRabKOTRkCvyzLJ7ixUMqllttiM=",
          "ephemeralKey": "tRmdkZ4OmKu4UoHf2wVSrqrvoJf1sK2ia0EpdzUEbrI=",
          "ciphertext": "bK3YNV9UHYdkF0kffKkhepGwPdAgibYO/RhZ4lwFzOn2/bpqQozCE3d0rXiGeX3V6f5mww=="
        },
        {
          "nullifier": "NUeun9DQdYyN5pyk6mBUBVRwCBKcF0GCfHTOckWRzzk=",
          "cmx": "aOSig8t9Y7ImjIC7yAu4y227OEMdbfiqH+46I0pY5zk=",
          "ephemeralKey": "e8Lbd2qB1SUVMP/x60B+6wfXopH/5ZqDP+nWfkGAzCc=",
          "ciphertext": "avS/hvokWzkL71jP3SnhNF0A7X6AG2AGJ2+e1Gv80D2MQoEdR0s5fZwRYYCt7UMOnp4/7g=="
        }
      ]
    }
  ],
  "saplingCommitmentTreeSize": 71859610,
  "orchardCommitmentTreeSize": 46561151
}

Note that if the version of the running zcashd's getblock RPC doesn't include these new fields, then they will be set to zero in the compact block (it's not considered an error).

[nuttycom]

I didn't realize there were multiple versions of this .proto file around; there's also one in librustzcash. We should perhaps figure out a way to have a single source of truth.

[LarryRuane]

Yes, I noticed this some time ago, but didn't know how to have multiple repositories share a single copy. Maybe a submodule? It looks like currently this file is replicated in 23 repositories:

https://github.com/search?q=path%3Acompact_formats.proto&type=code

But that list is incomplete since for some reason it doesn't include zcash/librustzcash.

The good news is that this file doesn't change often, so maybe it's okay. But I can investigate setting up a submodule (or something similar) if you think it's worth it.