miden-validator 0.16.0-rc.2

use std::sync::atomic::Ordering;

use miden_node_proto::domain::encryption::transaction_inputs_associated_data;
use miden_node_proto::generated as grpc;
use miden_node_utils::ErrorReport;
use miden_node_utils::spawn::spawn_blocking_in_current_span;
use miden_node_utils::tracing::{miden_instrument, miden_span_record};
use miden_protocol::transaction::{ProvenTransaction, TransactionId, TransactionInputs};
use miden_tx::utils::serde::{Deserializable, Serializable};
use rand_core_06::OsRng;
use tonic::Status;
use tracing::{Instrument, info_span};

use super::ValidatorService;
use crate::tx_validation::validate_transaction;
use crate::{COMPONENT, PrivateRecordContext, PrivateRecordId};

#[tonic::async_trait]
impl grpc::server::validator_api::SubmitProvenTransaction for ValidatorService {
    type Input = Input;
    type Output = ();

    #[miden_instrument(
        target = COMPONENT,
        name = "submit_proven_transaction",
        err,
    )]
    async fn handle(
        &self,
        input: Self::Input,
        _metadata: &tonic::metadata::MetadataMap,
        _extensions: &tonic::codegen::http::Extensions,
    ) -> tonic::Result<Self::Output> {
        let Input { tx, sealed } = input;
        let tx_id = tx.id();
        miden_span_record!(
            transaction.id = %tx_id,
        );

        let inputs = self.unseal_transaction_inputs(&sealed, tx_id).await?;

        // Reject requests while a backup subscription is streaming.
        let _guard = self
            .serve_lock
            .try_read()
            .map_err(|_| Status::resource_exhausted("validator is busy streaming a backup"))?;

        // Short-circuit transactions that have already been validated.
        let already_validated = self.db.transaction_exists(tx_id).await.map_err(|err| {
            Status::internal(err.as_report_context("Failed to query transaction"))
        })?;
        if already_validated {
            return Ok(());
        }

        let private_inputs = inputs.to_bytes();

        // Bound concurrent validations; see `tx_validation_semaphore`. Acquired after the
        // already-validated short-circuit so duplicate submissions never wait.
        let _permit = self
            .tx_validation_semaphore
            .acquire()
            .instrument(info_span!("acquire_validation_permit"))
            .await
            .map_err(|err| Status::internal(format!("validation semaphore closed: {err}")))?;

        // Validate the transaction.
        validate_transaction(tx, inputs).await.map_err(|err| {
            Status::invalid_argument(err.as_report_context("Invalid transaction"))
        })?;

        // Re-encrypt the private inputs under a fresh content key. Sealing runs secp256k1 group
        // operations, so it goes to a blocking thread rather than stalling an async worker.
        let record_id = PrivateRecordId::new(tx_id, &self.signer.public_key());
        let context = PrivateRecordContext::new(
            self.private_record_chain_id,
            self.private_record_sealer.key_epoch(),
            tx_id,
        );
        let sealer = self.private_record_sealer.clone();
        let private_record = spawn_blocking_in_current_span(move || {
            sealer.seal(&mut OsRng, record_id, context, &private_inputs)
        })
        .await
        .unwrap_or_else(|e| std::panic::resume_unwind(e.into_panic()))
        .map_err(|err| {
            Status::internal(err.as_report_context("Failed to protect transaction inputs"))
        })?;

        // Store the validated transaction and private record atomically.
        let count =
            self.db
                .insert_validated_private_transaction(private_record)
                .await
                .map_err(|err| {
                    Status::internal(err.as_report_context("Failed to insert transaction"))
                })?;

        self.validated_transactions_count.fetch_add(count as u64, Ordering::Relaxed);
        Ok(())
    }

    fn decode(request: grpc::transaction::ProvenTransaction) -> tonic::Result<Self::Input> {
        let tx = ProvenTransaction::read_from_bytes(&request.transaction).map_err(|err| {
            Status::invalid_argument(err.as_report_context("Invalid proven transaction"))
        })?;
        let sealed = request.sealed_transaction_inputs.ok_or_else(|| {
            Status::invalid_argument(
                "Missing sealed transaction inputs: fetch the encryption key with \
                 GetTransactionEncryptionKey and seal the transaction inputs against it",
            )
        })?;
        if sealed.ciphertext.is_empty() {
            return Err(Status::invalid_argument("Empty sealed transaction inputs ciphertext"));
        }

        Ok(Self::Input { tx, sealed })
    }

    fn encode(output: Self::Output) -> tonic::Result<()> {
        Ok(output)
    }
}

pub struct Input {
    tx: ProvenTransaction,
    sealed: grpc::transaction::SealedTransactionInputs,
}

impl ValidatorService {
    /// Unseals transaction inputs submitted for `tx_id`.
    async fn unseal_transaction_inputs(
        &self,
        sealed: &grpc::transaction::SealedTransactionInputs,
        tx_id: TransactionId,
    ) -> tonic::Result<TransactionInputs> {
        // Checked ahead of the unseal purely to turn what would otherwise be an indistinguishable
        // authentication failure into an actionable one. The key identifier is public metadata, so
        // there is nothing to leak by comparing it. Deliberately does not echo this validator's own
        // key id: the RPC relays this status verbatim to the submitting client.
        if sealed.key_id != self.encryption_key_info.key_id {
            return Err(Status::failed_precondition(
                "Transaction inputs were sealed against an unknown encryption key: re-fetch the \
                 key with GetTransactionEncryptionKey and seal the inputs again",
            ));
        }

        let associated_data = transaction_inputs_associated_data(
            self.encryption_key_info.scheme.as_u32(),
            &self.encryption_key_info.key_id,
            self.genesis_commitment,
            tx_id,
        );
        let plaintext = self
            .decrypter
            .decrypt_transaction_inputs(&sealed.ciphertext, &associated_data)
            .await
            .map_err(|err| {
                // The underlying scheme collapses a wrong key, tampered ciphertext, mismatched
                // associated data and corrupt framing into one error, so this cannot be any more
                // specific than "it did not authenticate". `{:#}` renders the anyhow context chain,
                // which `ErrorReport` cannot because it is not a `std::error::Error`.
                Status::invalid_argument(format!(
                    "Failed to unseal the transaction inputs: {err:#}"
                ))
            })?;

        TransactionInputs::read_from_bytes(&plaintext).map_err(|err| {
            Status::invalid_argument(err.as_report_context("Invalid transaction inputs"))
        })
    }
}