common: improve WalletConnect

* add gas limit
* remove nonce (could cause issue)
* don't transform `v` as it's legacy
* improve signature extraction
* add error for when WalletConnect API failed to sign

Signed-off-by: xphoniex <dj.2dixx@gmail.com>

Author: xphoniex

common/src/ethereum.rs

@@ -143,7 +143,7 @@ pub enum WalletError {
     #[error(transparent)]
     Local(#[from] ethers::signers::WalletError),
     #[error(transparent)]
-    WalletConnect(#[from] ::walletconnect::client::CallError),
+    WalletConnect(#[from] walletconnect::WalletError),
     #[error("no wallet specified")]
     NoWallet,
 }

common/src/ethereum/walletconnect.rs

@@ -12,6 +12,14 @@ pub struct WalletConnect {
     address: Address,
 }
 
+#[derive(Debug, thiserror::Error)]
+pub enum WalletError {
+    #[error(transparent)]
+    CallError(#[from] CallError),
+    #[error("failed to sign the tx")]
+    FailedToSignTx,
+}
+
 impl WalletConnect {
     pub fn new() -> Result<Self, Box<dyn Error>> {
         let client = Client::new(
@@ -61,14 +69,15 @@ impl WalletConnect {
     pub async fn sign_message<S: Send + Sync + AsRef<[u8]>>(
         &self,
         msg: S,
-    ) -> Result<Signature, CallError> {
+    ) -> Result<Signature, WalletError> {
         let msg = unsafe { std::str::from_utf8_unchecked(msg.as_ref()) };
         self.client
             .personal_sign(&[msg, &self.address_string()])
             .await
+            .map_err(WalletError::from)
     }
 
-    pub async fn sign_transaction(&self, msg: &TypedTransaction) -> Result<Signature, CallError> {
+    pub async fn sign_transaction(&self, msg: &TypedTransaction) -> Result<Signature, WalletError> {
         let to = if let Some(NameOrAddress::Address(address)) = msg.to() {
             Some(*address)
         } else {
@@ -77,28 +86,125 @@ impl WalletConnect {
         let tx = Transaction {
             from: *msg.from().unwrap(),
             to,
-            gas_limit: None,
+            gas_limit: msg.gas().cloned(),
             gas_price: msg.gas_price(),
             value: *msg.value().unwrap_or(&U256::from(0)),
             data: msg.data().unwrap().to_vec(),
-            nonce: msg.nonce().copied(),
+            nonce: None,
         };
 
         let raw = self.client.sign_transaction(tx).await?.to_vec();
-        assert_eq!(raw[raw.len() - 66], 160);
-        assert_eq!(raw[raw.len() - 33], 160);
-
-        // Transform `v` according to:
-        // https://github.com/ethereum/EIPs/blob/master/EIPS/eip-155.md#specification
-        let mut v = raw[raw.len() - 67] as u64;
-        if v == 27 || v == 28 {
-            v += 2 * self.chain_id() + 8;
+        let mut v_r_s = None;
+        for offset in 0..7 {
+            let mut head = raw.len() - 67 + offset;
+            v_r_s = extract_v_r_s(&raw[head..]);
+            if v_r_s.is_some() {
+                break;
+            }
+
+            if offset == 0 {
+                continue;
+            }
+            head = raw.len() - 67 - offset;
+            v_r_s = extract_v_r_s(&raw[head..]);
+            if v_r_s.is_some() {
+                break;
+            }
         }
 
+        let (v, r, s) = v_r_s.ok_or(WalletError::FailedToSignTx)?;
         Ok(Signature {
             v,
-            r: U256::from(&raw[raw.len() - 65..raw.len() - 33]),
-            s: U256::from(&raw[raw.len() - 32..]),
+            r: U256::from(r),
+            s: U256::from(s),
         })
     }
 }
+
+fn extract_v_r_s(tx: &[u8]) -> Option<(u64, &[u8], &[u8])> {
+    let mut head = 0_usize;
+    let v: u64 = tx[head].into();
+
+    head += 1;
+    if tx[head] <= 0x80 {
+        return None;
+    }
+    let len_r = (tx[head] - 0x80) as usize;
+    if head + len_r >= tx.len() {
+        return None;
+    }
+    let r = &tx[head + 1..head + 1 + len_r];
+
+    head += 1 + len_r;
+    if tx[head] <= 0x80 {
+        return None;
+    }
+    let len_s = (tx[head] - 0x80) as usize;
+    if head + len_s >= tx.len() {
+        return None;
+    }
+    let s = &tx[head + 1..head + 1 + len_s];
+
+    if 1 + r.len() + s.len() + 2 != tx.len() {
+        return None;
+    }
+
+    Some((v, r, s))
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_regular_sig() {
+        let tx = [
+            0x1c, 0xa0, 0x88, 0xff, 0x6c, 0xf0, 0xfe, 0xfd, 0x94, 0xdb, 0x46, 0x11, 0x11, 0x49,
+            0xae, 0x4b, 0xfc, 0x17, 0x9e, 0x9b, 0x94, 0x72, 0x1f, 0xff, 0xd8, 0x21, 0xd3, 0x8d,
+            0x16, 0x46, 0x4b, 0x3f, 0x71, 0xd0, 0xa0, 0x45, 0xe0, 0xaf, 0xf8, 0x00, 0x96, 0x1c,
+            0xfc, 0xe8, 0x05, 0xda, 0xef, 0x70, 0x16, 0xb9, 0xb6, 0x75, 0xc1, 0x37, 0xa6, 0xa4,
+            0x1a, 0x54, 0x8f, 0x7b, 0x60, 0xa3, 0x48, 0x4c, 0x06, 0xa3, 0x3a,
+        ];
+
+        let v_r_s = extract_v_r_s(&tx);
+        assert!(v_r_s.is_some());
+        let (v, r, s) = v_r_s.unwrap();
+
+        assert_eq!(v, 0x1c);
+        assert_eq!(r, &tx[tx.len() - 65..tx.len() - 33]);
+        assert_eq!(s, &tx[tx.len() - 32..]);
+    }
+
+    #[test]
+    fn test_variable_sig() {
+        let tx = [
+            0x2c, 0xa0, 0x09, 0x0c, 0x0a, 0x25, 0xaf, 0x16, 0x3b, 0x51, 0x86, 0xd5, 0x6f, 0x61,
+            0xd2, 0xd1, 0xe7, 0xcf, 0xf1, 0x05, 0xb8, 0x9e, 0x24, 0xed, 0x48, 0x26, 0x7c, 0x43,
+            0xa0, 0x22, 0x27, 0xd9, 0xf7, 0x14, 0x9f, 0x9b, 0xcc, 0xf7, 0x3a, 0xef, 0xa7, 0x7d,
+            0x2c, 0xcb, 0x0b, 0x81, 0x59, 0x15, 0x04, 0xde, 0xcc, 0x07, 0xc1, 0x26, 0x92, 0xf9,
+            0x0f, 0xfe, 0x47, 0xd0, 0xf0, 0xbd, 0xea, 0x99, 0xa6, 0x8d,
+        ];
+
+        let v_r_s = extract_v_r_s(&tx);
+        assert!(v_r_s.is_some());
+        let (v, r, s) = v_r_s.unwrap();
+
+        assert_eq!(v, 0x2c);
+        assert_eq!(r, &tx[tx.len() - 64..tx.len() - 32]);
+        assert_eq!(s, &tx[tx.len() - 31..]);
+    }
+
+    #[test]
+    fn test_malformed_sig() {
+        let tx = [
+            0x2c, 0xa0, 0x09, 0x0c, 0x0a, 0x25, 0xaf, 0x16, 0x3b, 0x51, 0x86, 0xd5, 0x6f, 0x61,
+            0xd2, 0xd1, 0xe7, 0xcf, 0xf1, 0x05, 0xb8, 0x9e, 0x24, 0xed, 0x48, 0x26, 0x7c, 0x43,
+            0xa0, 0x22, 0x27, 0xd9, 0xf7, 0x14, 0x81, 0x9b, 0xcc, 0xf7, 0x3a, 0xef, 0xa7, 0x7d,
+            0x2c, 0xcb, 0x0b, 0x81, 0x59, 0x15, 0x04, 0xde, 0xcc, 0x07, 0xc1, 0x26, 0x92, 0xf9,
+            0x0f, 0xfe, 0x47, 0xd0, 0xf0, 0xbd, 0xea, 0x99, 0xa6, 0x8d,
+        ];
+
+        let v_r_s = extract_v_r_s(&tx);
+        assert!(v_r_s.is_none());
+    }
+}