feat(backend): Support RCH_SMTP_TIMEOUT (#1407)

* feat(backend): Support RCH_SMTP_TIMEOUT

* fix clippy

backend/README.md

@@ -61,6 +61,7 @@ These are the environment variables used to configure the HTTP server. To pass t
 | `RCH_HEADER_SECRET`                 | No                          | If set, then all HTTP requests must have the `x-reacher-secret` header set to this value. This is used to protect the backend against public unwanted HTTP requests.                                                                        | undefined               |
 | `RCH_FROM_EMAIL`                    | No                          | Email to use in the `<MAIL FROM:>` SMTP step. Can be overwritten by each API request's `from_email` field.                                                                                                                                  | reacher.email@gmail.com |
 | `RCH_HELLO_NAME`                    | No                          | Name to use in the `<EHLO>` SMTP step. Can be overwritten by each API request's `hello_name` field.                                                                                                                                         | gmail.com               |
+| `RCH_SMTP_TIMEOUT`                  | No                          | Timeout for each SMTP connection.                                                                                                                                                                                                           | 45s                     |
 | `RCH_WEBDRIVER_ADDR`                | No                          | Set to a running WebDriver process endpoint (e.g. `http://localhost:9515`) to use a headless navigator to password recovery pages to check Yahoo and Hotmail/Outlook addresses. We recommend `chromedriver` as it allows parallel requests. | not defined             |
 
 ## REST API Documentation

backend/src/check.rs

@@ -16,7 +16,7 @@
 
 //! This file contains shared logic for checking one email.
 
-use std::env;
+use std::{env, time::Duration};
 
 use check_if_email_exists::{check_email as ciee_check_email, CheckEmailInput, CheckEmailOutput};
 use warp::Filter;
@@ -30,12 +30,18 @@ pub async fn check_email(input: CheckEmailInput) -> CheckEmailOutput {
 		env::var("RCH_FROM_EMAIL").unwrap_or_else(|_| CheckEmailInput::default().from_email);
 	let hello_name =
 		env::var("RCH_HELLO_NAME").unwrap_or_else(|_| CheckEmailInput::default().hello_name);
+	let smtp_timeout = env::var("RCH_SMTP_TIMEOUT")
+		.ok()
+		.and_then(|s| s.parse::<u64>().ok())
+		.map(Duration::from_secs)
+		.or_else(|| CheckEmailInput::default().smtp_timeout);
 
 	let input = CheckEmailInput {
 		// If we want to override core check-if-email-exists's default values
 		// for CheckEmailInput for the backend, we do it here.
 		from_email,
 		hello_name,
+		smtp_timeout,
 		..input
 	};