feature(rpc): add fixed values to getblocktemplate response (#5558)

* add fixed values to getblocktemplate rpc call response

* suggestion: Avoid new uses of lazy_static (#5559)

* Avoid using lazy_static

* Add some missing documentation

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

* minor fixes

* move docs to struct

* add fixed values to coinbase tx

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
Co-authored-by: teor <teor@riseup.net>

zebra-chain/src/block.rs

@@ -34,7 +34,7 @@ pub use commitment::{
     ChainHistoryBlockTxAuthCommitmentHash, ChainHistoryMmrRootHash, Commitment, CommitmentError,
 };
 pub use hash::Hash;
-pub use header::{BlockTimeError, CountedHeader, Header};
+pub use header::{BlockTimeError, CountedHeader, Header, ZCASH_BLOCK_VERSION};
 pub use height::Height;
 pub use serialize::{SerializedBlock, MAX_BLOCK_BYTES};
 

zebra-chain/src/block/header.rs

@@ -146,6 +146,12 @@ const BLOCK_HEADER_LENGTH: usize =
 /// A CountedHeader has BLOCK_HEADER_LENGTH bytes + 1 or more bytes for the transaction count
 pub(crate) const MIN_COUNTED_HEADER_LEN: usize = BLOCK_HEADER_LENGTH + 1;
 
+/// The Zcash accepted block version.
+///
+/// The consensus rules do not force the block version to be this value but just equal or greater than it.
+/// However, it is suggested that submitted block versions to be of this exact value.
+pub const ZCASH_BLOCK_VERSION: u32 = 4;
+
 impl TrustedPreallocate for CountedHeader {
     fn max_allocation() -> u64 {
         // Every vector type requires a length field of at least one byte for de/serialization.

zebra-chain/src/block/serialize.rs

@@ -13,7 +13,7 @@ use crate::{
     work::{difficulty::CompactDifficulty, equihash},
 };
 
-use super::{merkle, Block, CountedHeader, Hash, Header};
+use super::{header::ZCASH_BLOCK_VERSION, merkle, Block, CountedHeader, Hash, Header};
 
 /// The maximum size of a Zcash block, in bytes.
 ///
@@ -77,7 +77,7 @@ impl ZcashDeserialize for Header {
         // > The block version number MUST be greater than or equal to 4.
         //
         // https://zips.z.cash/protocol/protocol.pdf#blockheader
-        if version < 4 {
+        if version < ZCASH_BLOCK_VERSION {
             return Err(SerializationError::Parse("version must be at least 4"));
         }
 

zebra-consensus/src/lib.rs

@@ -46,7 +46,7 @@ pub mod chain;
 #[allow(missing_docs)]
 pub mod error;
 
-pub use block::VerifyBlockError;
+pub use block::{VerifyBlockError, MAX_BLOCK_SIGOPS};
 pub use chain::VerifyChainError;
 pub use checkpoint::{
     CheckpointList, VerifyCheckpointError, MAX_CHECKPOINT_BYTE_COUNT, MAX_CHECKPOINT_HEIGHT_GAP,

zebra-rpc/src/methods/get_block_template_rpcs.rs

@@ -13,14 +13,16 @@ use zebra_chain::{
     block::{
         self,
         merkle::{self, AuthDataRoot},
-        Block,
+        Block, MAX_BLOCK_BYTES, ZCASH_BLOCK_VERSION,
     },
     chain_tip::ChainTip,
     parameters::Network,
     serialization::ZcashDeserializeInto,
     transaction::{UnminedTx, VerifiedUnminedTx},
 };
-use zebra_consensus::{BlockError, VerifyBlockError, VerifyChainError, VerifyCheckpointError};
+use zebra_consensus::{
+    BlockError, VerifyBlockError, VerifyChainError, VerifyCheckpointError, MAX_BLOCK_SIGOPS,
+};
 use zebra_node_services::mempool;
 
 use crate::methods::{
@@ -33,6 +35,7 @@ use crate::methods::{
 };
 
 pub mod config;
+pub mod constants;
 pub(crate) mod types;
 
 /// getblocktemplate RPC method signatures.
@@ -278,7 +281,7 @@ where
                 let empty_string = String::from("");
                 return Ok(GetBlockTemplate {
                     capabilities: vec![],
-                    version: 0,
+                    version: ZCASH_BLOCK_VERSION,
                     previous_block_hash: GetBlockHash([0; 32].into()),
                     block_commitments_hash: [0; 32].into(),
                     light_client_root_hash: [0; 32].into(),
@@ -301,10 +304,13 @@ where
                     },
                     target: empty_string.clone(),
                     min_time: 0,
-                    mutable: vec![],
+                    mutable: constants::GET_BLOCK_TEMPLATE_MUTABLE_FIELD
-                    nonce_range: empty_string.clone(),
+                        .iter()
-                    sigop_limit: 0,
+                        .map(ToString::to_string)
-                    size_limit: 0,
+                        .collect(),
+                    nonce_range: constants::GET_BLOCK_TEMPLATE_NONCE_RANGE_FIELD.to_string(),
+                    sigop_limit: MAX_BLOCK_SIGOPS,
+                    size_limit: MAX_BLOCK_BYTES,
                     cur_time: 0,
                     bits: empty_string,
                     height: 0,
@@ -323,7 +329,7 @@ where
             Ok(GetBlockTemplate {
                 capabilities: vec![],
 
-                version: 0,
+                version: ZCASH_BLOCK_VERSION,
 
                 previous_block_hash: GetBlockHash([0; 32].into()),
                 block_commitments_hash: [0; 32].into(),
@@ -344,12 +350,16 @@ where
 
                 min_time: 0,
 
-                mutable: vec![],
+                mutable: constants::GET_BLOCK_TEMPLATE_MUTABLE_FIELD
+                    .iter()
+                    .map(ToString::to_string)
+                    .collect(),
 
-                nonce_range: empty_string.clone(),
+                nonce_range: constants::GET_BLOCK_TEMPLATE_NONCE_RANGE_FIELD.to_string(),
 
-                sigop_limit: 0,
+                sigop_limit: MAX_BLOCK_SIGOPS,
-                size_limit: 0,
+
+                size_limit: MAX_BLOCK_BYTES,
 
                 cur_time: 0,
 

zebra-rpc/src/methods/get_block_template_rpcs/constants.rs

@@ -0,0 +1,7 @@
+//! Constant values used in mining rpcs methods.
+
+/// A range of valid nonces that goes from `u32::MIN` to `u32::MAX` as a string.
+pub const GET_BLOCK_TEMPLATE_NONCE_RANGE_FIELD: &str = "00000000ffffffff";
+
+/// A hardcoded list of fields that the miner can change from the block.
+pub const GET_BLOCK_TEMPLATE_MUTABLE_FIELD: &[&str] = &["time", "transactions", "prevblock"];

zebra-rpc/src/methods/get_block_template_rpcs/types/default_roots.rs

@@ -5,7 +5,10 @@ use zebra_chain::block::{
     ChainHistoryBlockTxAuthCommitmentHash, ChainHistoryMmrRootHash,
 };
 
-/// Documentation to be added in #5452 or #5455.
+/// The block header roots for [`GetBlockTemplate.transactions`].
+///
+/// If the transactions in the block template are modified, these roots must be recalculated
+/// [according to the specification](https://zcash.github.io/rpc/getblocktemplate.html).
 #[derive(Clone, Debug, Eq, PartialEq, serde::Serialize, serde::Deserialize)]
 pub struct DefaultRoots {
     /// The merkle root of the transaction IDs in the block.

zebra-rpc/src/methods/get_block_template_rpcs/types/get_block_template.rs

@@ -12,35 +12,47 @@ use crate::methods::{
 /// Documentation to be added after we document all the individual fields.
 #[derive(Clone, Debug, Eq, PartialEq, serde::Serialize, serde::Deserialize)]
 pub struct GetBlockTemplate {
-    /// Add documentation.
+    /// The getblocktemplate RPC capabilities supported by Zebra.
+    ///
+    /// At the moment, Zebra does not support any of the extra capabilities from the specification:
+    /// - `proposal`: <https://en.bitcoin.it/wiki/BIP_0023#Block_Proposal>
+    /// - `longpoll`: <https://en.bitcoin.it/wiki/BIP_0022#Optional:_Long_Polling>
+    /// - `serverlist`: <https://en.bitcoin.it/wiki/BIP_0023#Logical_Services>
     pub capabilities: Vec<String>,
 
     /// The version of the block format.
     /// Always 4 for new Zcash blocks.
-    //
-    // TODO: add a default block version constant to zebra-chain.
     pub version: u32,
 
-    /// Add documentation.
+    /// The hash of the previous block.
     #[serde(rename = "previousblockhash")]
     pub previous_block_hash: GetBlockHash,
 
-    /// Add documentation.
+    /// The block commitment for the new block's header.
+    ///
+    /// Same as [`DefaultRoots.block_commitments_hash`], see that field for details.
     #[serde(rename = "blockcommitmentshash")]
     #[serde(with = "hex")]
     pub block_commitments_hash: ChainHistoryBlockTxAuthCommitmentHash,
 
-    /// Add documentation.
+    /// Legacy backwards-compatibility header root field.
+    ///
+    /// Same as [`DefaultRoots.block_commitments_hash`], see that field for details.
     #[serde(rename = "lightclientroothash")]
     #[serde(with = "hex")]
     pub light_client_root_hash: ChainHistoryBlockTxAuthCommitmentHash,
 
-    /// Add documentation.
+    /// Legacy backwards-compatibility header root field.
+    ///
+    /// Same as [`DefaultRoots.block_commitments_hash`], see that field for details.
     #[serde(rename = "finalsaplingroothash")]
     #[serde(with = "hex")]
     pub final_sapling_root_hash: ChainHistoryBlockTxAuthCommitmentHash,
 
-    /// Add documentation.
+    /// The block header roots for [`GetBlockTemplate.transactions`].
+    ///
+    /// If the transactions in the block template are modified, these roots must be recalculated
+    /// [according to the specification](https://zcash.github.io/rpc/getblocktemplate.html).
     #[serde(rename = "defaultroots")]
     pub default_roots: DefaultRoots,
 
@@ -62,22 +74,18 @@ pub struct GetBlockTemplate {
     // TODO: use DateTime32 type?
     pub min_time: u32,
 
-    /// Add documentation.
+    /// Hardcoded list of block fields the miner is allowed to change.
     pub mutable: Vec<String>,
 
-    /// Add documentation.
+    /// A range of valid nonces that goes from `u32::MIN` to `u32::MAX`.
     #[serde(rename = "noncerange")]
     pub nonce_range: String,
 
-    /// Add documentation.
+    /// Max legacy signature operations in the block.
-    ///
-    /// The same as `MAX_BLOCK_SIGOPS`.
     #[serde(rename = "sigoplimit")]
     pub sigop_limit: u64,
 
-    /// Add documentation.
+    /// Max block size in bytes
-    ///
-    /// The same as `MAX_BLOCK_BYTES`.
     #[serde(rename = "sizelimit")]
     pub size_limit: u64,
 

zebra-rpc/src/methods/tests/snapshot/get_block_template_rpcs.rs

@@ -15,7 +15,9 @@ use zebra_state::LatestChainTip;
 use zebra_test::mock_service::{MockService, PanicAssertion};
 
 use crate::methods::{
-    get_block_template_rpcs::types::{hex_data::HexData, submit_block},
+    get_block_template_rpcs::types::{
+        get_block_template::GetBlockTemplate, hex_data::HexData, submit_block,
+    },
     GetBlockHash, GetBlockTemplateRpc, GetBlockTemplateRpcImpl,
 };
 
@@ -122,10 +124,7 @@ fn snapshot_rpc_getblockhash(block_hash: GetBlockHash, settings: &insta::Setting
 }
 
 /// Snapshot `getblocktemplate` response, using `cargo insta` and JSON serialization.
-fn snapshot_rpc_getblocktemplate(
+fn snapshot_rpc_getblocktemplate(block_template: GetBlockTemplate, settings: &insta::Settings) {
-    block_template: crate::methods::get_block_template_rpcs::types::get_block_template::GetBlockTemplate,
-    settings: &insta::Settings,
-) {
     settings.bind(|| insta::assert_json_snapshot!("get_block_template", block_template));
 }
 

zebra-rpc/src/methods/tests/snapshot/snapshots/get_block_template@mainnet_10.snap

@@ -1,10 +1,11 @@
 ---
 source: zebra-rpc/src/methods/tests/snapshot/get_block_template_rpcs.rs
+assertion_line: 128
 expression: block_template
 ---
 {
   "capabilities": [],
-  "version": 0,
+  "version": 4,
   "previousblockhash": "0000000000000000000000000000000000000000000000000000000000000000",
   "blockcommitmentshash": "0000000000000000000000000000000000000000000000000000000000000000",
   "lightclientroothash": "0000000000000000000000000000000000000000000000000000000000000000",
@@ -27,10 +28,14 @@ expression: block_template
   },
   "target": "",
   "mintime": 0,
-  "mutable": [],
+  "mutable": [
-  "noncerange": "",
+    "time",
-  "sigoplimit": 0,
+    "transactions",
-  "sizelimit": 0,
+    "prevblock"
+  ],
+  "noncerange": "00000000ffffffff",
+  "sigoplimit": 20000,
+  "sizelimit": 2000000,
   "curtime": 0,
   "bits": "",
   "height": 0

zebra-rpc/src/methods/tests/snapshot/snapshots/get_block_template@testnet_10.snap

@@ -1,10 +1,11 @@
 ---
 source: zebra-rpc/src/methods/tests/snapshot/get_block_template_rpcs.rs
+assertion_line: 128
 expression: block_template
 ---
 {
   "capabilities": [],
-  "version": 0,
+  "version": 4,
   "previousblockhash": "0000000000000000000000000000000000000000000000000000000000000000",
   "blockcommitmentshash": "0000000000000000000000000000000000000000000000000000000000000000",
   "lightclientroothash": "0000000000000000000000000000000000000000000000000000000000000000",
@@ -27,10 +28,14 @@ expression: block_template
   },
   "target": "",
   "mintime": 0,
-  "mutable": [],
+  "mutable": [
-  "noncerange": "",
+    "time",
-  "sigoplimit": 0,
+    "transactions",
-  "sizelimit": 0,
+    "prevblock"
+  ],
+  "noncerange": "00000000ffffffff",
+  "sigoplimit": 20000,
+  "sizelimit": 2000000,
   "curtime": 0,
   "bits": "",
   "height": 0

zebra-rpc/src/methods/tests/vectors.rs

@@ -782,6 +782,12 @@ async fn rpc_getblockhash() {
 async fn rpc_getblocktemplate() {
     use std::panic;
 
+    use crate::methods::get_block_template_rpcs::constants::{
+        GET_BLOCK_TEMPLATE_MUTABLE_FIELD, GET_BLOCK_TEMPLATE_NONCE_RANGE_FIELD,
+    };
+    use zebra_chain::block::{MAX_BLOCK_BYTES, ZCASH_BLOCK_VERSION};
+    use zebra_consensus::MAX_BLOCK_SIGOPS;
+
     let _init_guard = zebra_test::init();
 
     // Create a continuous chain of mainnet blocks from genesis
@@ -835,14 +841,20 @@ async fn rpc_getblocktemplate() {
         .expect("unexpected error in getblocktemplate RPC call");
 
     assert!(get_block_template.capabilities.is_empty());
-    assert_eq!(get_block_template.version, 0);
+    assert_eq!(get_block_template.version, ZCASH_BLOCK_VERSION);
     assert!(get_block_template.transactions.is_empty());
     assert!(get_block_template.target.is_empty());
     assert_eq!(get_block_template.min_time, 0);
-    assert!(get_block_template.mutable.is_empty());
+    assert_eq!(
-    assert!(get_block_template.nonce_range.is_empty());
+        get_block_template.mutable,
-    assert_eq!(get_block_template.sigop_limit, 0);
+        GET_BLOCK_TEMPLATE_MUTABLE_FIELD.to_vec()
-    assert_eq!(get_block_template.size_limit, 0);
+    );
+    assert_eq!(
+        get_block_template.nonce_range,
+        GET_BLOCK_TEMPLATE_NONCE_RANGE_FIELD
+    );
+    assert_eq!(get_block_template.sigop_limit, MAX_BLOCK_SIGOPS);
+    assert_eq!(get_block_template.size_limit, MAX_BLOCK_BYTES);
     assert_eq!(get_block_template.cur_time, 0);
     assert!(get_block_template.bits.is_empty());
     assert_eq!(get_block_template.height, 0);