From 3abdbf5ba0e29b034bf29ad642ce86f69721b682 Mon Sep 17 00:00:00 2001
From: FadedCoder <hello@sohamsen.me>
Date: Sun, 27 Feb 2022 11:19:53 +0530
Subject: [PATCH 1/2] Add support for custom sorting and deprecate BIP69

---
 src/wallet/mod.rs        |  1 +
 src/wallet/tx_builder.rs | 36 ++++++++++++++++++++++++++++++++++--
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/src/wallet/mod.rs b/src/wallet/mod.rs
index a24f922dc..103c69f9c 100644
--- a/src/wallet/mod.rs
+++ b/src/wallet/mod.rs
@@ -2145,6 +2145,7 @@ pub(crate) mod test {
         let (wallet, _, _) = get_funded_wallet(get_test_wpkh());
         let addr = wallet.get_address(New).unwrap();
         let mut builder = wallet.build_tx();
+        #[allow(deprecated)]
         builder
             .add_recipient(addr.script_pubkey(), 30_000)
             .add_recipient(addr.script_pubkey(), 10_000)
diff --git a/src/wallet/tx_builder.rs b/src/wallet/tx_builder.rs
index 66b037854..9fa009350 100644
--- a/src/wallet/tx_builder.rs
+++ b/src/wallet/tx_builder.rs
@@ -36,11 +36,14 @@
 //! # Ok::<(), bdk::Error>(())
 //! ```
 
+use std::cmp::Ordering;
 use std::collections::BTreeMap;
 use std::collections::HashSet;
 use std::default::Default;
 use std::marker::PhantomData;
+use std::sync::Arc;
 
+use bitcoin::blockdata::transaction::{TxIn, TxOut};
 use bitcoin::util::psbt::{self, PartiallySignedTransaction as Psbt};
 use bitcoin::{OutPoint, Script, SigHashType, Transaction};
 
@@ -646,14 +649,22 @@ impl<'a, B, D: BatchDatabase> TxBuilder<'a, B, D, DefaultCoinSelectionAlgorithm,
 }
 
 /// Ordering of the transaction's inputs and outputs
-#[derive(Debug, Ord, PartialOrd, Eq, PartialEq, Hash, Clone, Copy)]
+#[derive(Clone)]
 pub enum TxOrdering {
     /// Randomized (default)
     Shuffle,
     /// Unchanged
     Untouched,
     /// BIP69 / Lexicographic
+    #[deprecated = "BIP69 does not improve privacy as was the intention of the BIP"]
     Bip69Lexicographic,
+    /// Provide custom comparison functions for sorting
+    Custom {
+        /// Transaction inputs sort function
+        input_sort: Arc<dyn Fn(&TxIn, &TxIn) -> Ordering>,
+        /// Transaction outputs sort function
+        output_sort: Arc<dyn Fn(&TxOut, &TxOut) -> Ordering>,
+    },
 }
 
 impl Default for TxOrdering {
@@ -662,6 +673,18 @@ impl Default for TxOrdering {
     }
 }
 
+impl std::fmt::Debug for TxOrdering {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        match self {
+            TxOrdering::Shuffle => write!(f, "Randomized"),
+            TxOrdering::Untouched => write!(f, "Unchanged"),
+            #[allow(deprecated)]
+            TxOrdering::Bip69Lexicographic => write!(f, "BIP69 / Lexicographic"),
+            TxOrdering::Custom { .. } => write!(f, "Custom"),
+        }
+    }
+}
+
 impl TxOrdering {
     /// Sort transaction inputs and outputs by [`TxOrdering`] variant
     pub fn sort_tx(&self, tx: &mut Transaction) {
@@ -679,6 +702,7 @@ impl TxOrdering {
 
                 tx.output.shuffle(&mut rng);
             }
+            #[allow(deprecated)]
             TxOrdering::Bip69Lexicographic => {
                 tx.input.sort_unstable_by_key(|txin| {
                     (txin.previous_output.txid, txin.previous_output.vout)
@@ -686,6 +710,13 @@ impl TxOrdering {
                 tx.output
                     .sort_unstable_by_key(|txout| (txout.value, txout.script_pubkey.clone()));
             }
+            TxOrdering::Custom {
+                input_sort,
+                output_sort,
+            } => {
+                tx.input.sort_unstable_by(|a, b| input_sort(a, b));
+                tx.output.sort_unstable_by(|a, b| output_sort(a, b));
+            }
         }
     }
 }
@@ -769,7 +800,7 @@ mod test {
 
     #[test]
     fn test_output_ordering_default_shuffle() {
-        assert_eq!(TxOrdering::default(), TxOrdering::Shuffle);
+        assert!(std::matches!(TxOrdering::default(), TxOrdering::Shuffle));
     }
 
     #[test]
@@ -800,6 +831,7 @@ mod test {
         let original_tx = ordering_test_tx!();
         let mut tx = original_tx;
 
+        #[allow(deprecated)]
         TxOrdering::Bip69Lexicographic.sort_tx(&mut tx);
 
         assert_eq!(

From 946819f8e7a7059fb1b812f3422ce6187718949e Mon Sep 17 00:00:00 2001
From: Soham Sen <hello@sohamsen.me>
Date: Sun, 27 Feb 2022 11:46:10 +0530
Subject: [PATCH 2/2] Updated CHANGELOG

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 17bf16242..4550eb1c2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Removed default verification from `wallet::sync`. sync-time verification is added in `script_sync` and is activated by `verify` feature flag.
 - `verify` flag removed from `TransactionDetails`.
+- Deprecated `TxOrdering::Bip69Lexicographic` and added `TxOrdering::Custom`.
 
 ## [v0.16.1] - [v0.16.0]