Add a json-conversion feature for converting JSON to valid Heights

Cargo.lock

@@ -5755,6 +5755,7 @@ dependencies = [
  "secp256k1",
  "serde",
  "serde-big-array",
+ "serde_json",
  "serde_with 2.3.2",
  "sha2 0.9.9",
  "spandoc",

zebra-chain/Cargo.toml

@@ -12,6 +12,11 @@ default = []
 
 # Production features that activate extra functionality
 
+# Consensus-critical conversion from JSON to Zcash types
+json-conversion = [
+    "serde_json",
+]
+
 # Experimental mining RPC support
 getblocktemplate-rpcs = [
     "zcash_address",
@@ -88,6 +93,9 @@ ed25519-zebra = "3.1.0"
 redjubjub = "0.5.0"
 reddsa = "0.5.0"
 
+# Production feature json-conversion
+serde_json = { version = "1.0.95", optional = true }
+
 # Experimental feature getblocktemplate-rpcs
 zcash_address = { version = "0.2.0", optional = true }
 

zebra-chain/src/block.rs

@@ -35,7 +35,7 @@ pub use commitment::{
 };
 pub use hash::Hash;
 pub use header::{BlockTimeError, CountedHeader, Header, ZCASH_BLOCK_VERSION};
-pub use height::{Height, HeightDiff};
+pub use height::{Height, HeightDiff, TryIntoHeight};
 pub use serialize::{SerializedBlock, MAX_BLOCK_BYTES};
 
 #[cfg(any(test, feature = "proptest-impl"))]

zebra-chain/src/block/height.rs

@@ -2,7 +2,10 @@
 
 use std::ops::{Add, Sub};
 
-use crate::serialization::SerializationError;
+use crate::{serialization::SerializationError, BoxError};
+
+#[cfg(feature = "json-conversion")]
+pub mod json_conversion;
 
 /// The length of the chain back to the genesis block.
 ///
@@ -70,6 +73,9 @@ impl Height {
 /// even if they are outside the valid height range (for example, in buggy RPC code).
 pub type HeightDiff = i64;
 
+// We don't implement TryFrom<u64>, because it causes type inference issues for integer constants.
+// Instead, use 1u64.try_into_height().
+
 impl TryFrom<u32> for Height {
     type Error = &'static str;
 
@@ -84,6 +90,47 @@ impl TryFrom<u32> for Height {
     }
 }
 
+/// Convenience trait for converting a type into a valid Zcash [`Height`].
+pub trait TryIntoHeight {
+    /// The error type returned by [`Height`] conversion failures.
+    type Error;
+
+    /// Convert `self` to a `Height`, if possible.
+    fn try_into_height(&self) -> Result<Height, Self::Error>;
+}
+
+impl TryIntoHeight for u64 {
+    type Error = BoxError;
+
+    fn try_into_height(&self) -> Result<Height, Self::Error> {
+        u32::try_from(*self)?.try_into().map_err(Into::into)
+    }
+}
+
+impl TryIntoHeight for usize {
+    type Error = BoxError;
+
+    fn try_into_height(&self) -> Result<Height, Self::Error> {
+        u32::try_from(*self)?.try_into().map_err(Into::into)
+    }
+}
+
+impl TryIntoHeight for str {
+    type Error = BoxError;
+
+    fn try_into_height(&self) -> Result<Height, Self::Error> {
+        self.parse().map_err(Into::into)
+    }
+}
+
+impl TryIntoHeight for String {
+    type Error = BoxError;
+
+    fn try_into_height(&self) -> Result<Height, Self::Error> {
+        self.as_str().try_into_height()
+    }
+}
+
 // We don't implement Add<u32> or Sub<u32>, because they cause type inference issues for integer constants.
 
 impl Sub<Height> for Height {

zebra-chain/src/block/height/json_conversion.rs

@@ -0,0 +1,24 @@
+//! Consensus-critical conversion from JSON [`Value`] to [`Height`].
+
+use serde_json::Value;
+
+use crate::BoxError;
+
+use super::{Height, TryIntoHeight};
+
+impl TryIntoHeight for Value {
+    type Error = BoxError;
+
+    fn try_into_height(&self) -> Result<Height, Self::Error> {
+        if self.is_number() {
+            let height = self.as_u64().ok_or("JSON value outside u64 range")?;
+            return height.try_into_height();
+        }
+
+        if let Some(height) = self.as_str() {
+            return height.try_into_height();
+        }
+
+        Err("JSON value must be a number or string".into())
+    }
+}

zebra-rpc/Cargo.toml

@@ -63,7 +63,7 @@ zcash_address = { version = "0.2.0", optional = true }
 # Test-only feature proptest-impl
 proptest = { version = "1.1.0", optional = true }
 
-zebra-chain = { path = "../zebra-chain" }
+zebra-chain = { path = "../zebra-chain", features = ["json-conversion"] }
 zebra-consensus = { path = "../zebra-consensus" }
 zebra-network = { path = "../zebra-network" }
 zebra-node-services = { path = "../zebra-node-services" }