fix(asb): send zero quote on failure (#379)

* fix(asb): send zero quote on failure

* static function for BidQuote::ZERO

CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 
 - ASB: The maker will take Monero funds needed for ongoing swaps into consideration when making a quote. A warning will be displayed if the Monero funds do not cover all ongoing swaps.
+- ASB: Return a zero quote when quoting fails instead of letting the request time out
 
 ## [1.1.7] - 2025-06-04
 

swap/src/asb/event_loop.rs

@@ -259,8 +259,17 @@ where
                                 // The error is already logged in the make_quote_or_use_cached function
                                 // We don't log it here to avoid spamming on each request
                                 Err(_) => {
-                                    // TODO: Respond with the error to Bob. Currently this will timeout on Bob's side.
-                                    continue;
+                                    // We respond with a zero quote. This will stop Bob from trying to start a swap but doesn't require
+                                    // a breaking network change by changing the definition of the quote protocol
+                                    if self
+                                        .swarm
+                                        .behaviour_mut()
+                                        .quote
+                                        .send_response(channel, BidQuote::ZERO)
+                                        .is_err()
+                                    {
+                                        tracing::debug!(%peer, "Failed to respond with zero quote");
+                                    }
                                 }
                             }
                         }

swap/src/network/quote.rs

@@ -40,6 +40,15 @@ pub struct BidQuote {
     pub max_quantity: bitcoin::Amount,
 }
 
+impl BidQuote {
+    /// A zero quote with all amounts set to zero
+    pub const ZERO: Self = Self {
+        price: bitcoin::Amount::ZERO,
+        min_quantity: bitcoin::Amount::ZERO,
+        max_quantity: bitcoin::Amount::ZERO,
+    };
+}
+
 #[derive(Clone, Copy, Debug, thiserror::Error)]
 #[error("Received quote of 0")]
 pub struct ZeroQuoteReceived;