zcash_primitives: Extract bundle-specific parts of tx serialization

zcash_primitives/src/transaction/builder.rs

@@ -942,7 +942,7 @@ mod tests {
     #[cfg(feature = "transparent-inputs")]
     use crate::{
         legacy::keys::{AccountPrivKey, IncomingViewingKey},
-        transaction::{builder::DEFAULT_TX_EXPIRY_DELTA, OutPoint, TxOut},
+        transaction::{builder::DEFAULT_TX_EXPIRY_DELTA, transparent::TxOut, OutPoint},
         zip32::AccountId,
     };
 

zcash_primitives/src/transaction/components.rs

@@ -1,5 +1,6 @@
 //! Types representing the components within Zcash transactions.
 
+use std::io;
 use std::marker::PhantomData;
 
 use zcash_protocol::value::BalanceError;
@@ -184,17 +185,74 @@ impl<A: tze::Authorization> TzePart for Tze<A> {
 }
 
 /// The Transparent part of an authorized transaction.
-pub trait AuthorizedTransparentPart: TransparentPart {}
+pub trait AuthorizedTransparentPart: TransparentPart {
+    fn read_bundle<R: io::Read>(reader: R) -> io::Result<Option<Self::Bundle>>;
+
+    fn write_bundle<W: io::Write>(bundle: Option<&Self::Bundle>, writer: W) -> io::Result<()>;
+}
 
 /// The Sprout part of an authorized transaction.
-pub trait AuthorizedSproutPart: SproutPart {}
+pub trait AuthorizedSproutPart: SproutPart {
+    fn read_v4_bundle<R: io::Read>(
+        reader: R,
+        tx_has_sprout: bool,
+        use_groth: bool,
+    ) -> io::Result<Option<Self::Bundle>>;
+
+    fn write_v4_bundle<W: io::Write>(
+        bundle: Option<&Self::Bundle>,
+        writer: W,
+        tx_has_sprout: bool,
+    ) -> io::Result<()>;
+}
 
 /// The Sapling part of an authorized transaction.
-pub trait AuthorizedSaplingPart: SaplingPart {}
+pub trait AuthorizedSaplingPart: SaplingPart {
+    type V4Components;
+
+    fn read_v4_components<R: io::Read>(
+        reader: R,
+        tx_has_sapling: bool,
+    ) -> io::Result<Self::V4Components>;
+
+    fn read_v4_binding_sig<R: io::Read>(
+        reader: R,
+        tx_has_sapling: bool,
+        components: Self::V4Components,
+    ) -> io::Result<Option<Self::Bundle>>;
+
+    fn write_v4_components<W: io::Write>(
+        bundle: Option<&Self::Bundle>,
+        writer: W,
+        tx_has_sapling: bool,
+    ) -> io::Result<()>;
+
+    fn write_v4_binding_sig<W: io::Write>(
+        bundle: Option<&Self::Bundle>,
+        writer: W,
+        tx_has_sapling: bool,
+    ) -> io::Result<()>;
+
+    fn read_v5_bundle<R: io::Read>(reader: R) -> io::Result<Option<Self::Bundle>>;
+
+    fn write_v5_bundle<W: io::Write>(bundle: Option<&Self::Bundle>, writer: W) -> io::Result<()>;
+}
 
 /// The Orchard part of an authorized transaction.
-pub trait AuthorizedOrchardPart: OrchardPart {}
+pub trait AuthorizedOrchardPart: OrchardPart {
+    fn read_v5_bundle<R: io::Read>(reader: R) -> io::Result<Option<Self::Bundle>>;
+
+    fn write_v5_bundle<W: io::Write>(bundle: Option<&Self::Bundle>, writer: W) -> io::Result<()>;
+}
 
 /// The TZE part of an authorized transaction.
 #[cfg(zcash_unstable = "zfuture")]
-pub trait AuthorizedTzePart: TzePart {}
+pub trait AuthorizedTzePart: TzePart {
+    fn read_bundle<R: io::Read>(reader: R, tx_has_tze: bool) -> io::Result<Option<Self::Bundle>>;
+
+    fn write_bundle<W: io::Write>(
+        bundle: Option<&Self::Bundle>,
+        writer: W,
+        tx_has_tze: bool,
+    ) -> io::Result<()>;
+}

zcash_primitives/src/transaction/components/orchard.rs

@@ -44,7 +44,15 @@ impl MapAuth<Authorized, Authorized> for () {
     }
 }
 
-impl AuthorizedOrchardPart for Orchard<orchard::bundle::Authorized> {}
+impl AuthorizedOrchardPart for Orchard<orchard::bundle::Authorized> {
+    fn read_v5_bundle<R: Read>(reader: R) -> io::Result<Option<Self::Bundle>> {
+        read_v5_bundle(reader)
+    }
+
+    fn write_v5_bundle<W: Write>(bundle: Option<&Self::Bundle>, writer: W) -> io::Result<()> {
+        write_v5_bundle(bundle, writer)
+    }
+}
 
 /// Reads an [`orchard::Bundle`] from a v5 transaction format.
 pub fn read_v5_bundle<R: Read>(

zcash_primitives/src/transaction/components/sapling.rs

@@ -84,7 +84,74 @@ impl MapAuth<Authorized, Authorized> for () {
     }
 }
 
-impl AuthorizedSaplingPart for Sapling<sapling::bundle::Authorized> {}
+impl AuthorizedSaplingPart for Sapling<sapling::bundle::Authorized> {
+    type V4Components = (
+        Amount,
+        Vec<sapling::bundle::SpendDescription<sapling::bundle::Authorized>>,
+        Vec<sapling::bundle::OutputDescription<sapling::bundle::GrothProofBytes>>,
+    );
+
+    fn read_v4_components<R: Read>(
+        reader: R,
+        tx_has_sapling: bool,
+    ) -> io::Result<Self::V4Components> {
+        read_v4_components(reader, tx_has_sapling)
+    }
+
+    fn read_v4_binding_sig<R: Read>(
+        mut reader: R,
+        tx_has_sapling: bool,
+        (value_balance, shielded_spends, shielded_outputs): Self::V4Components,
+    ) -> io::Result<Option<Self::Bundle>> {
+        let binding_sig =
+            if tx_has_sapling && !(shielded_spends.is_empty() && shielded_outputs.is_empty()) {
+                let mut sig = [0; 64];
+                reader.read_exact(&mut sig)?;
+                Some(redjubjub::Signature::from(sig))
+            } else {
+                None
+            };
+
+        Ok(binding_sig.and_then(|binding_sig| {
+            sapling::Bundle::from_parts(
+                shielded_spends,
+                shielded_outputs,
+                value_balance,
+                sapling::bundle::Authorized { binding_sig },
+            )
+        }))
+    }
+
+    fn write_v4_components<W: Write>(
+        bundle: Option<&Self::Bundle>,
+        writer: W,
+        tx_has_sapling: bool,
+    ) -> io::Result<()> {
+        write_v4_components(writer, bundle, tx_has_sapling)
+    }
+
+    fn write_v4_binding_sig<W: Write>(
+        bundle: Option<&Self::Bundle>,
+        mut writer: W,
+        tx_has_sapling: bool,
+    ) -> io::Result<()> {
+        if tx_has_sapling {
+            if let Some(bundle) = bundle {
+                writer.write_all(&<[u8; 64]>::from(bundle.authorization().binding_sig))?;
+            }
+        }
+
+        Ok(())
+    }
+
+    fn read_v5_bundle<R: Read>(reader: R) -> io::Result<Option<Self::Bundle>> {
+        read_v5_bundle(reader)
+    }
+
+    fn write_v5_bundle<W: Write>(bundle: Option<&Self::Bundle>, writer: W) -> io::Result<()> {
+        write_v5_bundle(writer, bundle)
+    }
+}
 
 /// Consensus rules (§4.4) & (§4.5):
 /// - Canonical encoding is enforced here.

zcash_primitives/src/transaction/components/sprout.rs

@@ -2,6 +2,8 @@
 
 use std::io::{self, Read, Write};
 
+use zcash_encoding::{CompactSize, Vector};
+
 use super::{amount::Amount, AuthorizedSproutPart, Sprout, GROTH_PROOF_SIZE};
 
 // π_A + π_A' + π_B + π_B' + π_C + π_C' + π_K + π_H
@@ -29,7 +31,50 @@ impl Bundle {
     }
 }
 
-impl AuthorizedSproutPart for Sprout {}
+impl AuthorizedSproutPart for Sprout {
+    fn read_v4_bundle<R: io::Read>(
+        mut reader: R,
+        tx_has_sprout: bool,
+        use_groth: bool,
+    ) -> io::Result<Option<Self::Bundle>> {
+        if tx_has_sprout {
+            let joinsplits = Vector::read(&mut reader, |r| JsDescription::read(r, use_groth))?;
+
+            if !joinsplits.is_empty() {
+                let mut bundle = Bundle {
+                    joinsplits,
+                    joinsplit_pubkey: [0; 32],
+                    joinsplit_sig: [0; 64],
+                };
+                reader.read_exact(&mut bundle.joinsplit_pubkey)?;
+                reader.read_exact(&mut bundle.joinsplit_sig)?;
+                Ok(Some(bundle))
+            } else {
+                Ok(None)
+            }
+        } else {
+            Ok(None)
+        }
+    }
+
+    fn write_v4_bundle<W: io::Write>(
+        bundle: Option<&Self::Bundle>,
+        mut writer: W,
+        tx_has_sprout: bool,
+    ) -> io::Result<()> {
+        if tx_has_sprout {
+            if let Some(bundle) = bundle {
+                Vector::write(&mut writer, &bundle.joinsplits, |w, e| e.write(w))?;
+                writer.write_all(&bundle.joinsplit_pubkey)?;
+                writer.write_all(&bundle.joinsplit_sig)?;
+            } else {
+                CompactSize::write(&mut writer, 0)?;
+            }
+        }
+
+        Ok(())
+    }
+}
 
 #[derive(Clone)]
 #[allow(clippy::upper_case_acronyms)]

zcash_primitives/src/transaction/components/transparent.rs

@@ -1,6 +1,7 @@
 //! Structs representing the components within Zcash transactions.
 
 use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
+use zcash_encoding::{CompactSize, Vector};
 
 use std::fmt::Debug;
 use std::io::{self, Read, Write};
@@ -192,7 +193,33 @@ impl TxOut {
     }
 }
 
-impl AuthorizedTransparentPart for Transparent<Authorized> {}
+impl AuthorizedTransparentPart for Transparent<Authorized> {
+    fn read_bundle<R: Read>(mut reader: R) -> io::Result<Option<Self::Bundle>> {
+        let vin = Vector::read(&mut reader, TxIn::read)?;
+        let vout = Vector::read(&mut reader, TxOut::read)?;
+        Ok(if vin.is_empty() && vout.is_empty() {
+            None
+        } else {
+            Some(Bundle {
+                vin,
+                vout,
+                authorization: Authorized,
+            })
+        })
+    }
+
+    fn write_bundle<W: Write>(bundle: Option<&Self::Bundle>, mut writer: W) -> io::Result<()> {
+        if let Some(bundle) = bundle {
+            Vector::write(&mut writer, &bundle.vin, |w, e| e.write(w))?;
+            Vector::write(&mut writer, &bundle.vout, |w, e| e.write(w))?;
+        } else {
+            CompactSize::write(&mut writer, 0)?;
+            CompactSize::write(&mut writer, 0)?;
+        }
+
+        Ok(())
+    }
+}
 
 #[cfg(any(test, feature = "test-dependencies"))]
 pub mod testing {

zcash_primitives/src/transaction/components/tze.rs

@@ -211,7 +211,43 @@ impl TzeOut {
     }
 }
 
-impl AuthorizedTzePart for Tze<Authorized> {}
+impl AuthorizedTzePart for Tze<Authorized> {
+    fn read_bundle<R: Read>(mut reader: R, tx_has_tze: bool) -> io::Result<Option<Self::Bundle>> {
+        if tx_has_tze {
+            let vin = Vector::read(&mut reader, TzeIn::read)?;
+            let vout = Vector::read(&mut reader, TzeOut::read)?;
+            Ok(if vin.is_empty() && vout.is_empty() {
+                None
+            } else {
+                Some(Bundle {
+                    vin,
+                    vout,
+                    authorization: Authorized,
+                })
+            })
+        } else {
+            Ok(None)
+        }
+    }
+
+    fn write_bundle<W: Write>(
+        bundle: Option<&Self::Bundle>,
+        mut writer: W,
+        tx_has_tze: bool,
+    ) -> io::Result<()> {
+        if tx_has_tze {
+            if let Some(bundle) = bundle {
+                Vector::write(&mut writer, &bundle.vin, |w, e| e.write(w))?;
+                Vector::write(&mut writer, &bundle.vout, |w, e| e.write(w))?;
+            } else {
+                CompactSize::write(&mut writer, 0)?;
+                CompactSize::write(&mut writer, 0)?;
+            }
+        }
+
+        Ok(())
+    }
+}
 
 #[cfg(any(test, feature = "test-dependencies"))]
 pub mod testing {