feat: add sign_txn_env to Signer trait

`tx sign` should append a signature to the provided transaction envelope and not throw away the original ones.

FULL_HELP_DOCS.md

@@ -1041,7 +1041,7 @@ Sign, Simulate, and Send transactions
 
 * `simulate` — Simulate a transaction envelope from stdin
 * `hash` — Calculate the hash of a transaction envelope from stdin
-* `sign` — Sign a transaction
+* `sign` — Sign a transaction envolope appending the signature to the envelope
 * `send` — Send a transaction envelope to the network
 
 
@@ -1083,7 +1083,7 @@ Calculate the hash of a transaction envelope from stdin
 
 ## `stellar tx sign`
 
-Sign a transaction
+Sign a transaction envolope appending the signature to the envelope
 
 **Usage:** `stellar tx sign [OPTIONS]`
 

cmd/soroban-cli/src/commands/tx/mod.rs

@@ -15,7 +15,7 @@ pub enum Cmd {
     Simulate(simulate::Cmd),
     /// Calculate the hash of a transaction envelope from stdin
     Hash(hash::Cmd),
-    /// Sign a transaction
+    /// Sign a transaction envolope appending the signature to the envelope
     Sign(sign::Cmd),
     /// Send a transaction envelope to the network
     Send(send::Cmd),
@@ -25,7 +25,6 @@ pub enum Cmd {
 pub enum Error {
     #[error(transparent)]
     Simulate(#[from] simulate::Error),
-    /// An error during hash calculation
     #[error(transparent)]
     Hash(#[from] hash::Error),
     #[error(transparent)]

cmd/soroban-cli/src/commands/tx/sign.rs

@@ -1,6 +1,6 @@
 use crate::{
     config::sign_with,
-    xdr::{self, Limits, Transaction, TransactionEnvelope, WriteXdr},
+    xdr::{self, Limits, TransactionEnvelope, WriteXdr},
 };
 
 #[derive(thiserror::Error, Debug)]
@@ -24,14 +24,12 @@ impl Cmd {
     #[allow(clippy::unused_async)]
     pub async fn run(&self) -> Result<(), Error> {
         let txn_env = super::xdr::tx_envelope_from_stdin()?;
-        let envelope = self
-            .sign_tx(super::xdr::unwrap_envelope_v1(txn_env)?)
-            .await?;
+        let envelope = self.sign_tx_env(txn_env).await?;
         println!("{}", envelope.to_xdr_base64(Limits::none())?.trim());
         Ok(())
     }
 
-    pub async fn sign_tx(&self, tx: Transaction) -> Result<TransactionEnvelope, Error> {
-        Ok(self.sign_with.sign(tx).await?)
+    pub async fn sign_tx_env(&self, tx: TransactionEnvelope) -> Result<TransactionEnvelope, Error> {
+        Ok(self.sign_with.sign_txn_env(tx).await?)
     }
 }

cmd/soroban-cli/src/config/mod.rs

@@ -63,7 +63,7 @@ impl Args {
     }
 
     pub async fn sign(&self, tx: Transaction) -> Result<TransactionEnvelope, Error> {
-        Ok(self.sign_with.sign(tx).await?)
+        Ok(self.sign_with.sign_txn(tx).await?)
     }
 
     pub async fn sign_soroban_authorizations(

cmd/soroban-cli/src/config/sign_with.rs

@@ -78,18 +78,26 @@ impl Args {
         Ok(self.signer()?.get_public_key().await?)
     }
 
-    pub async fn sign(&self, tx: Transaction) -> Result<TransactionEnvelope, Error> {
+    pub async fn sign_txn(&self, tx: Transaction) -> Result<TransactionEnvelope, Error> {
         let signer = self.signer()?;
-        self.sign_with_signer(&signer, tx).await
+        self.sign_tx_env_with_signer(&signer, tx.into()).await
     }
 
-    pub async fn sign_with_signer(
+    pub async fn sign_txn_env(
+        &self,
+        tx: TransactionEnvelope,
+    ) -> Result<TransactionEnvelope, Error> {
+        let signer = self.signer()?;
+        self.sign_tx_env_with_signer(&signer, tx).await
+    }
+
+    pub async fn sign_tx_env_with_signer(
         &self,
         signer: &(impl Stellar + std::marker::Sync),
-        tx: Transaction,
+        tx_env: TransactionEnvelope,
     ) -> Result<TransactionEnvelope, Error> {
         let network = self.get_network()?;
-        Ok(signer.sign_txn(tx, &network).await?)
+        Ok(signer.sign_txn_env(tx_env, &network).await?)
     }
 
     pub async fn sign_soroban_authorizations(

cmd/soroban-cli/src/signer.rs

@@ -28,6 +28,8 @@ pub enum Error {
     Rpc(#[from] crate::rpc::Error),
     #[error("User cancelled signing, perhaps need to remove --check")]
     UserCancelledSigning,
+    #[error("Only Transaction envelope V1 type is supported")]
+    UnsupportedTransactionEnvelopeType,
 }
 
 fn requires_auth(txn: &Transaction) -> Option<xdr::Operation> {
@@ -81,6 +83,26 @@ pub trait Stellar {
             signature: Signature(tx_signature.try_into()?),
         })
     }
+
+    async fn sign_txn_env(
+        &self,
+        txn_env: TransactionEnvelope,
+        network: &Network,
+    ) -> Result<TransactionEnvelope, Error> {
+        match txn_env {
+            TransactionEnvelope::Tx(TransactionV1Envelope { tx, signatures }) => {
+                let decorated_signature = self.sign_txn(&tx, network).await?;
+                let mut sigs = signatures.to_vec();
+                sigs.push(decorated_signature);
+                Ok(TransactionEnvelope::Tx(TransactionV1Envelope {
+                    tx,
+                    signatures: sigs.try_into()?,
+                }))
+            }
+            _ => Err(Error::UnsupportedTransactionEnvelopeType),
+        }
+    }
+
     /// Sign a Stellar transaction with the given source account
     /// This is a default implementation that signs the transaction hash and returns a decorated signature
     ///
@@ -89,17 +111,13 @@ pub trait Stellar {
     /// Returns an error if the source account is not found
     async fn sign_txn(
         &self,
-        txn: Transaction,
+        txn: &Transaction,
         Network {
             network_passphrase, ..
         }: &Network,
-    ) -> Result<TransactionEnvelope, Error> {
-        let hash = transaction_hash(&txn, network_passphrase)?;
-        let decorated_signature = self.sign_txn_hash(hash).await?;
-        Ok(TransactionEnvelope::Tx(TransactionV1Envelope {
-            tx: txn,
-            signatures: vec![decorated_signature].try_into()?,
-        }))
+    ) -> Result<DecoratedSignature, Error> {
+        let hash = transaction_hash(txn, network_passphrase)?;
+        self.sign_txn_hash(hash).await
     }
 
     /// Sign a Soroban authorization entries for a given transaction and set the expiration ledger