feat(router): send connector timeouts and connection closures as 2xx response instead of giving 5xx response (#2047)

Cargo.lock

@@ -2362,9 +2362,9 @@ dependencies = [
 
 [[package]]
 name = "hyper"
-version = "0.14.26"
+version = "0.14.27"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ab302d72a6f11a3b910431ff93aae7e773078c769f0a3ef15fb9ec692ed147d4"
+checksum = "ffb1cfd654a8219eaef89881fdb3bb3b1cdc5fa75ded05d6933b2b382e395468"
 dependencies = [
  "bytes",
  "futures-channel",
@@ -3789,6 +3789,8 @@ dependencies = [
  "futures",
  "hex",
  "http",
+ "hyper",
+ "image",
  "infer 0.13.0",
  "josekit",
  "jsonwebtoken",

crates/router/Cargo.toml

@@ -51,6 +51,7 @@ error-stack = "0.3.1"
 futures = "0.3.28"
 hex = "0.4.3"
 http = "0.2.9"
+hyper = "0.14.27"
 image = "0.23.14"
 infer = "0.13.0"
 josekit = "0.8.3"

crates/router/src/consts.rs

@@ -13,6 +13,9 @@ pub(crate) const ALPHABETS: [char; 62] = [
 pub const REQUEST_TIME_OUT: u64 = 30;
 pub const REQUEST_TIMEOUT_ERROR_CODE: &str = "TIMEOUT";
 pub const REQUEST_TIMEOUT_ERROR_MESSAGE: &str = "Connector did not respond in specified time";
+pub const CONNECTION_CLOSED_ERROR_CODE: &str = "CONNECTION_CLOSED";
+pub const CONNECTION_CLOSED_ERROR_MESSAGE: &str =
+    "Connection closed before a message could complete";
 
 ///Payment intent fulfillment default timeout (in seconds)
 pub const DEFAULT_FULFILLMENT_TIME: i64 = 15 * 60;

crates/router/src/core/errors.rs

@@ -273,6 +273,9 @@ pub enum ApiClientError {
     #[error("Server responded with Request Timeout")]
     RequestTimeoutReceived,
 
+    #[error("connection closed before a message could complete")]
+    ConnectionClosed,
+
     #[error("Server responded with Internal Server Error")]
     InternalServerErrorReceived,
     #[error("Server responded with Bad Gateway")]
@@ -566,6 +569,9 @@ impl ApiClientError {
     pub fn is_upstream_timeout(&self) -> bool {
         self == &Self::RequestTimeoutReceived
     }
+    pub fn is_connection_closed(&self) -> bool {
+        self == &Self::ConnectionClosed
+    }
 }
 
 impl ConnectorError {

crates/router/src/core/payments/access_token.rs

@@ -172,7 +172,7 @@ pub async fn refresh_connector_auth(
                     code: consts::REQUEST_TIMEOUT_ERROR_CODE.to_string(),
                     message: consts::REQUEST_TIMEOUT_ERROR_MESSAGE.to_string(),
                     reason: Some(consts::REQUEST_TIMEOUT_ERROR_MESSAGE.to_string()),
-                    status_code: 200,
+                    status_code: 504,
                 };
 
                 Ok(Err(error_response))

crates/router/src/services/api.rs

@@ -3,6 +3,7 @@ pub mod request;
 
 use std::{
     collections::HashMap,
+    error::Error,
     fmt::Debug,
     future::Future,
     str,
@@ -384,8 +385,27 @@ where
                         }
                         Err(error) => {
                             if error.current_context().is_upstream_timeout() {
-                                Err(error
+                                let error_response = ErrorResponse {
-                                    .change_context(errors::ConnectorError::RequestTimeoutReceived))
+                                    code: consts::REQUEST_TIMEOUT_ERROR_CODE.to_string(),
+                                    message: consts::REQUEST_TIMEOUT_ERROR_MESSAGE.to_string(),
+                                    reason: Some(consts::REQUEST_TIMEOUT_ERROR_MESSAGE.to_string()),
+                                    status_code: 504,
+                                };
+                                router_data.response = Err(error_response);
+                                router_data.connector_http_status_code = Some(504);
+                                Ok(router_data)
+                            } else if error.current_context().is_connection_closed() {
+                                let error_response = ErrorResponse {
+                                    code: consts::CONNECTION_CLOSED_ERROR_CODE.to_string(),
+                                    message: consts::CONNECTION_CLOSED_ERROR_MESSAGE.to_string(),
+                                    reason: Some(
+                                        consts::CONNECTION_CLOSED_ERROR_MESSAGE.to_string(),
+                                    ),
+                                    status_code: 504,
+                                };
+                                router_data.response = Err(error_response);
+                                router_data.connector_http_status_code = Some(504);
+                                Ok(router_data)
                             } else {
                                 Err(error.change_context(
                                     errors::ConnectorError::ProcessingStepFailed(None),
@@ -505,6 +525,10 @@ pub async fn send_request(
                 metrics::REQUEST_BUILD_FAILURE.add(&metrics::CONTEXT, 1, &[]);
                 errors::ApiClientError::RequestTimeoutReceived
             }
+            error if is_connection_closed(&error) => {
+                metrics::REQUEST_BUILD_FAILURE.add(&metrics::CONTEXT, 1, &[]);
+                errors::ApiClientError::ConnectionClosed
+            }
             _ => errors::ApiClientError::RequestNotSent(error.to_string()),
         })
         .into_report()
@@ -519,6 +543,19 @@ pub async fn send_request(
     .await
 }
 
+fn is_connection_closed(error: &reqwest::Error) -> bool {
+    let mut source = error.source();
+    while let Some(err) = source {
+        if let Some(hyper_err) = err.downcast_ref::<hyper::Error>() {
+            if hyper_err.is_incomplete_message() {
+                return true;
+            }
+        }
+        source = err.source();
+    }
+    false
+}
+
 #[instrument(skip_all)]
 async fn handle_response(
     response: CustomResult<reqwest::Response, errors::ApiClientError>,