fix(labrinth): let through emails when neverbounce hangs or fails (#6898)

* fix(labrinth): let through emails when neverbounce hangs or fails

* chore(ci): stack size

.github/workflows/turbo-ci.yml

@@ -81,7 +81,7 @@ jobs:
       REDIS_CONNECTION_TYPE: multiplexed
       REDIS_URL: redis://127.0.0.1:7000,redis://127.0.0.1:7001,redis://127.0.0.1:7002,redis://127.0.0.1:7003,redis://127.0.0.1:7004,redis://127.0.0.1:7005
       # Avoid stack overflows in tests
-      RUST_MIN_STACK: 67108864
+      RUST_MIN_STACK: 134217728
 
     steps:
       - name: Check out code

apps/labrinth/src/util/neverbounce.rs

@@ -2,7 +2,8 @@ use std::time::Instant;
 
 use eyre::{WrapErr, eyre};
 use neverbounce::{
-    ResponseStatus, SingleCheckParams, SingleCheckResponse, VerificationResult,
+    ReqwestErrorReason, ResponseStatus, SingleCheckParams, SingleCheckResponse,
+    VerificationResult,
 };
 use tracing::{debug, error};
 
@@ -27,11 +28,21 @@ pub async fn check_email(email: &str) -> eyre::Result<VerificationResult> {
     {
         Ok(response) => response,
         Err(source) => {
+            let reason = ReqwestErrorReason::from(&source);
+            let is_transient = reason.is_transient();
+
             error!(
                 result = "unknown",
+                request.error_reason = ?reason,
+                request.time_ms = check_time_start.elapsed().as_millis(),
                 error = ?source,
                 "NeverBounce email check failed",
             );
+
+            if is_transient {
+                return Ok(VerificationResult::Unknown);
+            }
+
             return Err(eyre!(source)).wrap_err("failed to check email");
         }
     };
@@ -65,16 +76,22 @@ pub async fn check_email(email: &str) -> eyre::Result<VerificationResult> {
         }
         failure_type => {
             let result = result.unwrap_or(VerificationResult::Unknown);
+            let is_transient = failure_type.is_transient();
             error!(
                 failure_type = response_failure_type(&failure_type),
                 result = result.as_str(),
                 request.time_ms = check_time.as_millis(),
                 "NeverBounce email check failed",
             );
+
+            if is_transient {
+                Ok(VerificationResult::Unknown)
+            } else {
                 Err(email_check_error_generic())
             }
         }
     }
+}
 
 pub fn email_check_error_generic() -> eyre::Error {
     eyre!("Please try a different email address!")

packages/neverbounce/src/lib.rs

@@ -4,7 +4,65 @@ use std::time::Duration;
 
 pub const DEFAULT_API_URL: &str = "https://api.neverbounce.com";
 pub const SINGLE_CHECK_PATH: &str = "/v4/single/check";
-pub const TIMEOUT: Duration = Duration::from_secs(10);
+pub const TIMEOUT: Duration = Duration::from_secs(5);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[non_exhaustive]
+pub enum ReqwestErrorReason {
+    Builder,
+    Redirect,
+    Status(reqwest::StatusCode),
+    Timeout,
+    Request,
+    Connect,
+    Body,
+    Decode,
+    Unknown,
+}
+
+impl ReqwestErrorReason {
+    #[must_use]
+    pub fn is_transient(&self) -> bool {
+        match self {
+            Self::Status(status) => {
+                status.is_server_error()
+                    || matches!(
+                        *status,
+                        reqwest::StatusCode::REQUEST_TIMEOUT
+                            | reqwest::StatusCode::TOO_MANY_REQUESTS
+                    )
+            }
+            Self::Timeout | Self::Request | Self::Connect | Self::Body => true,
+            Self::Builder | Self::Redirect | Self::Decode | Self::Unknown => {
+                false
+            }
+        }
+    }
+}
+
+impl From<&reqwest::Error> for ReqwestErrorReason {
+    fn from(error: &reqwest::Error) -> Self {
+        if error.is_timeout() {
+            Self::Timeout
+        } else if error.is_connect() {
+            Self::Connect
+        } else if error.is_builder() {
+            Self::Builder
+        } else if error.is_redirect() {
+            Self::Redirect
+        } else if error.is_status() {
+            error.status().map_or(Self::Unknown, Self::Status)
+        } else if error.is_request() {
+            Self::Request
+        } else if error.is_body() {
+            Self::Body
+        } else if error.is_decode() {
+            Self::Decode
+        } else {
+            Self::Unknown
+        }
+    }
+}
 
 /// Authentication and email parameters for a single verification.
 ///
@@ -71,6 +129,13 @@ pub enum ResponseStatus {
     Unrecognized(String),
 }
 
+impl ResponseStatus {
+    #[must_use]
+    pub fn is_transient(&self) -> bool {
+        matches!(self, Self::TemporarilyUnavailable | Self::ThrottleTriggered)
+    }
+}
+
 impl<'de> Deserialize<'de> for ResponseStatus {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -201,7 +266,7 @@ struct SingleCheckRequest<'a> {
 /// This endpoint should only be called in response to an action such as a form
 /// submission. Existing lists and databases must use NeverBounce's bulk API.
 /// Both the server verification timeout and the complete HTTP request timeout
-/// are ten seconds.
+/// are five seconds.
 pub async fn single_check(
     client: &Client,
     params: &SingleCheckParams<'_>,