zcash_client_backend: Switch from protobuf 2 to prost 0.11

.gitattributes

@@ -0,0 +1 @@
+zcash_client_backend/src/proto/compact_formats.rs linguist-generated=true

.github/workflows/ci.yml

@@ -43,6 +43,9 @@ jobs:
           command: test
           args: --all-features --verbose --release --all -- --ignored
 
+      - name: Verify working directory is clean
+        run: git diff --exit-code
+
   build:
     name: Build target ${{ matrix.target }}
     runs-on: ubuntu-latest
@@ -200,14 +203,6 @@ jobs:
           toolchain: 1.56.1
           override: true
 
-      # cargo fmt does not build the code, and running it in a fresh clone of
-      # the codebase will fail because the protobuf code has not been generated.
-      - name: cargo build
-        uses: actions-rs/cargo@v1
-        with:
-          command: build
-          args: --all
-
       # Ensure all code has been formatted with rustfmt
       - run: rustup component add rustfmt
       - name: Check formatting

zcash_client_backend/CHANGELOG.md

@@ -41,6 +41,7 @@ and this library adheres to Rust's notion of
   - `WalletWrite::remove_unmined_tx` (behind the `unstable` feature flag).
   - `WalletWrite::get_next_available_address`
   - `WalletWrite::put_received_transparent_utxo`
+  - `impl From<prost::DecodeError> for error::Error`
 - `zcash_client_backend::decrypt`:
   - `TransferType`
 - `zcash_client_backend::proto`:
@@ -68,6 +69,8 @@ and this library adheres to Rust's notion of
 - Bumped dependencies to `ff 0.12`, `group 0.12`, `bls12_381 0.7`, `jubjub 0.9`,
   `zcash_primitives 0.8`, `orchard 0.3`.
 - `zcash_client_backend::proto`:
+  - The Protocol Buffers bindings are now generated for `prost 0.11` instead of
+    `protobuf 2`.
   - `compact_formats::CompactSpend` has been renamed to `CompactSaplingSpend`,
     and its `epk` field (and associated `set_epk` method) has been renamed to
     `ephemeralKey` (and `set_ephemeralKey`).
@@ -104,6 +107,8 @@ and this library adheres to Rust's notion of
   `store_decrypted_tx`.
 - `data_api::ReceivedTransaction` has been renamed to `DecryptedTransaction`,
   and its `outputs` field has been renamed to `sapling_outputs`.
+- `data_api::error::Error::Protobuf` now wraps `prost::DecodeError` instead of
+  `protobuf::ProtobufError`.
 - `data_api::error::Error` has the following additional cases:
   - `Error::MemoForbidden` to report the condition where a memo was
     specified to be sent to a transparent recipient.
@@ -150,6 +155,12 @@ and this library adheres to Rust's notion of
     `WalletRead::get_unified_full_viewing_keys` instead).
   - `WalletRead::get_address` (use `WalletRead::get_current_address` or
     `WalletWrite::get_next_available_address` instead.)
+  - `impl From<protobuf::ProtobufError> for error::Error`
+- `zcash_client_backend::proto::compact_formats`:
+  - `Compact*::new` methods (use `Default::default` or struct instantiation
+    instead).
+  - Getters (use dedicated typed methods or direct field access instead).
+  - Setters (use direct field access instead).
 - The hardcoded `data_api::wallet::ANCHOR_OFFSET` constant.
 - `zcash_client_backend::wallet::AccountId` (moved to `zcash_primitives::zip32::AccountId`).
 

zcash_client_backend/Cargo.toml

@@ -13,6 +13,9 @@ license = "MIT OR Apache-2.0"
 edition = "2021"
 rust-version = "1.56.1"
 
+# Exclude proto files so crates.io consumers don't need protoc.
+exclude = ["*.proto"]
+
 [package.metadata.cargo-udeps.ignore]
 development = ["zcash_proofs"]
 
@@ -40,7 +43,7 @@ memuse = "0.2"
 tracing = "0.1"
 
 # - Protobuf interfaces
-protobuf = "~2.27.1" # MSRV 1.52.1
+prost = "0.11"
 
 # - Secret management
 secrecy = "0.8"
@@ -68,7 +71,8 @@ crossbeam-channel = "0.5"
 rayon = "1.5"
 
 [build-dependencies]
-protobuf-codegen-pure = "~2.27.1" # MSRV 1.52.1
+prost-build = "0.11"
+which = "4"
 
 [dev-dependencies]
 gumdrop = "0.8"

zcash_client_backend/build.rs

@@ -1,8 +1,43 @@
-fn main() {
-    protobuf_codegen_pure::Codegen::new()
-        .out_dir("src/proto")
-        .inputs(["proto/compact_formats.proto"])
-        .includes(["proto"])
-        .run()
-        .expect("Protobuf codegen failed");
+use std::env;
+use std::fs;
+use std::io;
+use std::path::{Path, PathBuf};
+
+const COMPACT_FORMATS_PROTO: &str = "proto/compact_formats.proto";
+
+fn main() -> io::Result<()> {
+    // We don't include the proto files in releases so that downstreams do not need to
+    // regenerate the bindings even if protoc is present.
+    if Path::new(COMPACT_FORMATS_PROTO).exists() {
+        println!("cargo:rerun-if-changed={}", COMPACT_FORMATS_PROTO);
+
+        // We check for the existence of protoc in the same way as prost_build, so that people
+        // building from source do not need to have protoc installed. If they make changes to
+        // the proto files, the discrepancy will be caught by CI.
+        if env::var_os("PROTOC")
+            .map(PathBuf::from)
+            .or_else(|| which::which("protoc").ok())
+            .is_some()
+        {
+            build()?;
+        }
+    }
+
+    Ok(())
+}
+
+fn build() -> io::Result<()> {
+    let out: PathBuf = env::var_os("OUT_DIR")
+        .expect("Cannot find OUT_DIR environment variable")
+        .into();
+
+    prost_build::compile_protos(&[COMPACT_FORMATS_PROTO], &["proto/"])?;
+
+    // Copy the generated files into the source tree so changes can be committed.
+    fs::copy(
+        out.join("cash.z.wallet.sdk.rpc.rs"),
+        "src/proto/compact_formats.rs",
+    )?;
+
+    Ok(())
 }

zcash_client_backend/src/data_api/error.rs

@@ -69,7 +69,7 @@ pub enum Error<NoteId> {
     Builder(builder::Error),
 
     /// An error occurred decoding a protobuf message.
-    Protobuf(protobuf::ProtobufError),
+    Protobuf(prost::DecodeError),
 
     /// The wallet attempted a sapling-only operation at a block
     /// height when Sapling was not yet active.
@@ -180,8 +180,8 @@ impl<N> From<builder::Error> for Error<N> {
     }
 }
 
-impl<N> From<protobuf::ProtobufError> for Error<N> {
-    fn from(e: protobuf::ProtobufError) -> Self {
+impl<N> From<prost::DecodeError> for Error<N> {
+    fn from(e: prost::DecodeError) -> Self {
         Error::Protobuf(e)
     }
 }

zcash_client_backend/src/proto.rs

@@ -11,6 +11,7 @@ use zcash_primitives::{
 
 use zcash_note_encryption::{EphemeralKeyBytes, COMPACT_NOTE_SIZE};
 
+#[rustfmt::skip]
 pub mod compact_formats;
 
 impl compact_formats::CompactBlock {
@@ -44,7 +45,7 @@ impl compact_formats::CompactBlock {
         if let Some(header) = self.header() {
             header.prev_block
         } else {
-            BlockHash::from_slice(&self.prevHash)
+            BlockHash::from_slice(&self.prev_hash)
         }
     }
 
@@ -99,7 +100,7 @@ impl compact_formats::CompactSaplingOutput {
     ///
     /// [`CompactOutput.epk`]: #structfield.epk
     pub fn ephemeral_key(&self) -> Result<EphemeralKeyBytes, ()> {
-        self.ephemeralKey[..]
+        self.ephemeral_key[..]
             .try_into()
             .map(EphemeralKeyBytes)
             .map_err(|_| ())
@@ -110,11 +111,11 @@ impl<A: sapling::Authorization> From<sapling::OutputDescription<A>>
     for compact_formats::CompactSaplingOutput
 {
     fn from(out: sapling::OutputDescription<A>) -> compact_formats::CompactSaplingOutput {
-        let mut result = compact_formats::CompactSaplingOutput::new();
-        result.set_cmu(out.cmu.to_repr().to_vec());
-        result.set_ephemeralKey(out.ephemeral_key.as_ref().to_vec());
-        result.set_ciphertext(out.enc_ciphertext[..COMPACT_NOTE_SIZE].to_vec());
-        result
+        compact_formats::CompactSaplingOutput {
+            cmu: out.cmu.to_repr().to_vec(),
+            ephemeral_key: out.ephemeral_key.as_ref().to_vec(),
+            ciphertext: out.enc_ciphertext[..COMPACT_NOTE_SIZE].to_vec(),
+        }
     }
 }
 

zcash_client_backend/src/welding_rig.rs

@@ -459,16 +459,16 @@ mod tests {
             let fake_epk = SPENDING_KEY_GENERATOR * fake_esk;
             fake_epk.to_bytes().to_vec()
         };
-        let mut cspend = CompactSaplingSpend::new();
-        cspend.set_nf(fake_nf);
-        let mut cout = CompactSaplingOutput::new();
-        cout.set_cmu(fake_cmu);
-        cout.set_ephemeralKey(fake_epk);
-        cout.set_ciphertext(vec![0; 52]);
-        let mut ctx = CompactTx::new();
+        let cspend = CompactSaplingSpend { nf: fake_nf };
+        let cout = CompactSaplingOutput {
+            cmu: fake_cmu,
+            ephemeral_key: fake_epk,
+            ciphertext: vec![0; 52],
+        };
+        let mut ctx = CompactTx::default();
         let mut txid = vec![0; 32];
         rng.fill_bytes(&mut txid);
-        ctx.set_hash(txid);
+        ctx.hash = txid;
         ctx.spends.push(cspend);
         ctx.outputs.push(cout);
         ctx
@@ -503,17 +503,19 @@ mod tests {
             &mut rng,
         );
         let cmu = note.cmu().to_repr().as_ref().to_owned();
-        let epk = encryptor.epk().to_bytes().to_vec();
+        let ephemeral_key = encryptor.epk().to_bytes().to_vec();
         let enc_ciphertext = encryptor.encrypt_note_plaintext();
 
         // Create a fake CompactBlock containing the note
-        let mut cb = CompactBlock::new();
-        cb.set_hash({
-            let mut hash = vec![0; 32];
-            rng.fill_bytes(&mut hash);
-            hash
-        });
-        cb.set_height(height.into());
+        let mut cb = CompactBlock {
+            hash: {
+                let mut hash = vec![0; 32];
+                rng.fill_bytes(&mut hash);
+                hash
+            },
+            height: height.into(),
+            ..Default::default()
+        };
 
         // Add a random Sapling tx before ours
         {
@@ -522,16 +524,16 @@ mod tests {
             cb.vtx.push(tx);
         }
 
-        let mut cspend = CompactSaplingSpend::new();
-        cspend.set_nf(nf.0.to_vec());
-        let mut cout = CompactSaplingOutput::new();
-        cout.set_cmu(cmu);
-        cout.set_ephemeralKey(epk);
-        cout.set_ciphertext(enc_ciphertext.as_ref()[..52].to_vec());
-        let mut ctx = CompactTx::new();
+        let cspend = CompactSaplingSpend { nf: nf.0.to_vec() };
+        let cout = CompactSaplingOutput {
+            cmu,
+            ephemeral_key,
+            ciphertext: enc_ciphertext.as_ref()[..52].to_vec(),
+        };
+        let mut ctx = CompactTx::default();
         let mut txid = vec![0; 32];
         rng.fill_bytes(&mut txid);
-        ctx.set_hash(txid);
+        ctx.hash = txid;
         ctx.spends.push(cspend);
         ctx.outputs.push(cout);
         ctx.index = cb.vtx.len() as u64;