From d0e93e260e080d1961560131992369a9e16716d9 Mon Sep 17 00:00:00 2001
From: spacebear <144076611+grizznaut@users.noreply.github.com>
Date: Tue, 30 Apr 2024 21:27:07 -0400
Subject: [PATCH] respect disableoutputsubstitution

payjoin-cli receiver should not substitute its output address if
explicitly disallowed by the sender.
---
 payjoin-cli/src/app/v1.rs  | 13 ++++++++-----
 payjoin-cli/src/app/v2.rs  | 13 ++++++++-----
 payjoin/src/receive/mod.rs |  4 ++++
 payjoin/src/receive/v2.rs  |  4 ++++
 4 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/payjoin-cli/src/app/v1.rs b/payjoin-cli/src/app/v1.rs
index e991b07c5..946a9758c 100644
--- a/payjoin-cli/src/app/v1.rs
+++ b/payjoin-cli/src/app/v1.rs
@@ -298,11 +298,14 @@ impl App {
                 .map_err(|e| log::warn!("Failed to contribute inputs: {}", e));
         }
 
-        let receiver_substitute_address = bitcoind
-            .get_new_address(None, None)
-            .map_err(|e| Error::Server(e.into()))?
-            .assume_checked();
-        provisional_payjoin.substitute_output_address(receiver_substitute_address);
+        if !provisional_payjoin.is_output_substitution_disabled() {
+            // Substitute the receiver output address.
+            let receiver_substitute_address = bitcoind
+                .get_new_address(None, None)
+                .map_err(|e| Error::Server(e.into()))?
+                .assume_checked();
+            provisional_payjoin.substitute_output_address(receiver_substitute_address);
+        }
 
         let payjoin_proposal = provisional_payjoin.finalize_proposal(
             |psbt: &Psbt| {
diff --git a/payjoin-cli/src/app/v2.rs b/payjoin-cli/src/app/v2.rs
index 63175f98a..e84090b86 100644
--- a/payjoin-cli/src/app/v2.rs
+++ b/payjoin-cli/src/app/v2.rs
@@ -280,11 +280,14 @@ impl App {
                 .map_err(|e| log::warn!("Failed to contribute inputs: {}", e));
         }
 
-        let receiver_substitute_address = bitcoind
-            .get_new_address(None, None)
-            .map_err(|e| Error::Server(e.into()))?
-            .assume_checked();
-        provisional_payjoin.substitute_output_address(receiver_substitute_address);
+        if !provisional_payjoin.is_output_substitution_disabled() {
+            // Substitute the receiver output address.
+            let receiver_substitute_address = bitcoind
+                .get_new_address(None, None)
+                .map_err(|e| Error::Server(e.into()))?
+                .assume_checked();
+            provisional_payjoin.substitute_output_address(receiver_substitute_address);
+        }
 
         let payjoin_proposal = provisional_payjoin.finalize_proposal(
             |psbt: &Psbt| {
diff --git a/payjoin/src/receive/mod.rs b/payjoin/src/receive/mod.rs
index 3701a90cb..7aab95371 100644
--- a/payjoin/src/receive/mod.rs
+++ b/payjoin/src/receive/mod.rs
@@ -473,6 +473,10 @@ impl ProvisionalProposal {
         );
     }
 
+    pub fn is_output_substitution_disabled(&self) -> bool {
+        self.params.disable_output_substitution
+    }
+
     /// Just replace an output address with
     pub fn substitute_output_address(&mut self, substitute_address: bitcoin::Address) {
         self.payjoin_psbt.unsigned_tx.output[self.owned_vouts[0]].script_pubkey =
diff --git a/payjoin/src/receive/v2.rs b/payjoin/src/receive/v2.rs
index 5e6e10d83..223c3c367 100644
--- a/payjoin/src/receive/v2.rs
+++ b/payjoin/src/receive/v2.rs
@@ -443,6 +443,10 @@ impl ProvisionalProposal {
         self.inner.contribute_non_witness_input(tx, outpoint)
     }
 
+    pub fn is_output_substitution_disabled(&self) -> bool {
+        self.inner.is_output_substitution_disabled()
+    }
+
     /// Just replace an output address with
     pub fn substitute_output_address(&mut self, substitute_address: bitcoin::Address) {
         self.inner.substitute_output_address(substitute_address)