From 8d495579e1f0b2bd329d3d299e707491c02a31bd Mon Sep 17 00:00:00 2001
From: pythcoiner <pythcoiner@proton.me>
Date: Fri, 19 Jul 2024 13:00:21 +0200
Subject: [PATCH] lianad: DesKeyChecker.check() => check the change multipath
 is not hardened

---
 src/descriptors/analysis.rs | 70 +++++++++++++++++++++++++++++++++++--
 1 file changed, 68 insertions(+), 2 deletions(-)

diff --git a/src/descriptors/analysis.rs b/src/descriptors/analysis.rs
index 2420672f..8ea2a358 100644
--- a/src/descriptors/analysis.rs
+++ b/src/descriptors/analysis.rs
@@ -116,11 +116,10 @@ impl DescKeyChecker {
             // without origin entirely.
             if let Some(ref origin) = xpub.origin {
                 let der_paths = xpub.derivation_paths.paths();
-                let first_der_path = der_paths.first().expect("Cannot be empty");
                 // We also rule out xpubs with hardened derivation steps (non-normalized xpubs).
                 let valid = xpub.wildcard == descriptor::Wildcard::Unhardened
                     && der_paths.len() == 2
-                    && first_der_path.into_iter().all(|step| step.is_normal());
+                    && der_paths.iter().flatten().all(|step| step.is_normal());
                 if valid {
                     return Ok(origin.0);
                 }
@@ -776,3 +775,70 @@ impl PartialSpendInfo {
         &self.recovery_paths
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::str::FromStr;
+
+    #[test]
+    fn valid_key() {
+        let xpub_str =
+            "[8c3ffb6e/48'/1'/0'/2']tpubDEMt3bpQMa99W81K9h8f2FJH1C81eSd6bbSkBP8tcqQHAfSKvuGp2fz6xiVpfShzT9sKPx7DVBphChjxvNd15WcbsCca5oVz1AcUTWHxkdS/<0;1>/*";
+        let key = descriptor::DescriptorPublicKey::from_str(xpub_str).unwrap();
+        let mut checker = DescKeyChecker::new();
+        assert!(checker.check(&key).is_ok());
+    }
+    #[test]
+    fn invalid_key() {
+        // Multipath of size 3
+        let xpub_str =
+            "[8c3ffb6e/48'/1'/0'/2']tpubDEMt3bpQMa99W81K9h8f2FJH1C81eSd6bbSkBP8tcqQHAfSKvuGp2fz6xiVpfShzT9sKPx7DVBphChjxvNd15WcbsCca5oVz1AcUTWHxkdS/<0;1;2>/*";
+        let key = descriptor::DescriptorPublicKey::from_str(xpub_str).unwrap();
+        let mut checker = DescKeyChecker::new();
+        assert!(matches!(
+            checker.check(&key),
+            Err(LianaPolicyError::InvalidKey(k)) if k == key.into()
+        ));
+
+        // No multipath
+        let xpub_str =
+            "[8c3ffb6e/48'/1'/0'/2']tpubDEMt3bpQMa99W81K9h8f2FJH1C81eSd6bbSkBP8tcqQHAfSKvuGp2fz6xiVpfShzT9sKPx7DVBphChjxvNd15WcbsCca5oVz1AcUTWHxkdS/0/*";
+        let key = descriptor::DescriptorPublicKey::from_str(xpub_str).unwrap();
+        let mut checker = DescKeyChecker::new();
+        assert!(matches!(
+            checker.check(&key),
+            Err(LianaPolicyError::InvalidKey(k)) if k == key.into()
+        ));
+
+        // Hardened receive path
+        let xpub_str =
+            "[8c3ffb6e/48'/1'/0'/2']tpubDEMt3bpQMa99W81K9h8f2FJH1C81eSd6bbSkBP8tcqQHAfSKvuGp2fz6xiVpfShzT9sKPx7DVBphChjxvNd15WcbsCca5oVz1AcUTWHxkdS/<0';1>/*";
+        let key = descriptor::DescriptorPublicKey::from_str(xpub_str).unwrap();
+        let mut checker = DescKeyChecker::new();
+        assert!(matches!(
+            checker.check(&key),
+            Err(LianaPolicyError::InvalidKey(k)) if k == key.into()
+        ));
+
+        // Hardened change path
+        let xpub_str =
+            "[8c3ffb6e/48'/1'/0'/2']tpubDEMt3bpQMa99W81K9h8f2FJH1C81eSd6bbSkBP8tcqQHAfSKvuGp2fz6xiVpfShzT9sKPx7DVBphChjxvNd15WcbsCca5oVz1AcUTWHxkdS/<0;1'>/*";
+        let key = descriptor::DescriptorPublicKey::from_str(xpub_str).unwrap();
+        let mut checker = DescKeyChecker::new();
+        assert!(matches!(
+            checker.check(&key),
+            Err(LianaPolicyError::InvalidKey(k)) if k == key.into()
+        ));
+
+        // Hardened wildcard
+        let xpub_str =
+            "[8c3ffb6e/48'/1'/0'/2']tpubDEMt3bpQMa99W81K9h8f2FJH1C81eSd6bbSkBP8tcqQHAfSKvuGp2fz6xiVpfShzT9sKPx7DVBphChjxvNd15WcbsCca5oVz1AcUTWHxkdS/<0;1>/*'";
+        let key = descriptor::DescriptorPublicKey::from_str(xpub_str).unwrap();
+        let mut checker = DescKeyChecker::new();
+        assert!(matches!(
+            checker.check(&key),
+            Err(LianaPolicyError::InvalidKey(k)) if k == key.into()
+        ));
+    }
+}