feat(core): Add domain-specific rules as JSON file

core/Cargo.toml

@@ -21,17 +21,18 @@ async-std-resolver = "0.21.2"
 fantoccini = { version = "0.19.3", optional = true }
 futures = { version = "0.3.27", optional = true }
 fast-socks5 = "0.9.1"
+levenshtein = "1.0.5"
 log = "0.4.20"
 mailchecker = "5.0.7"
+md5 = "0.7.0"
+once_cell = "1.17.1"
+pwned = "0.5.0"
 rand = { version = "0.8.5", features = ["small_rng"] }
 regex = "1.9.4"
 reqwest = { version = "0.11.16", features = ["json", "socks"] }
 serde = { version = "1.0.157", features = ["derive"] }
 serde_json = "1.0.95"
 trust-dns-proto = "0.21.2"
-md5 = "0.7.0"
-levenshtein = "1.0.5"
-pwned = "0.5.0"
 
 [dev-dependencies]
 tokio = { version = "1.28.2" }

core/src/lib.rs

@@ -65,6 +65,7 @@
 mod haveibeenpwned;
 pub mod misc;
 pub mod mx;
+mod rules;
 pub mod smtp;
 pub mod syntax;
 mod util;

core/src/rules.json

@@ -0,0 +1,19 @@
+{
+	"by_domain": {
+		"gmail.com": { "rules": ["SkipCatchAll"] },
+		"hotmail.com": { "rules": ["SkipCatchAll"] },
+		"hotmail.fr": { "rules": ["SkipCatchAll"] },
+		"hotmail.nl": { "rules": ["SkipCatchAll"] },
+		"yahoo.com": { "rules": ["SkipCatchAll"] },
+		"yahoo.fr": { "rules": ["SkipCatchAll"] }
+	},
+	"by_mx_suffix": {
+		".antispamcloud.com.": {
+			"rules": ["SkipCatchAll"],
+			"_comment": "Some <RCPT TO> take exactly 30s to respond, so we skip the catch-all one, and bump the timeout."
+		}
+	},
+	"rules": {
+		"SkipCatchAll": { "_comment": "Don't perform catch-all check." }
+	}
+}

core/src/rules.rs

@@ -0,0 +1,71 @@
+// check-if-email-exists
+// Copyright (C) 2018-2022 Reacher
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published
+// by the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+//! Read provider- and domain-specific rules from a JSON, then match each
+//! email verification to the domain/provider, and translate those rules into
+//! code.
+//!
+//! IMPORTANT: This is still a beta feature, and probably needs refining.
+
+use once_cell::sync::Lazy;
+use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
+
+#[derive(Debug, Deserialize, Eq, Hash, PartialEq, Serialize)]
+pub enum Rule {
+	/// Don't perform catch-all check.
+	SkipCatchAll,
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+struct RulesByDomain {
+	rules: Vec<Rule>,
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+struct AllRules {
+	/// Apply rules by domain name, i.e. after the @ symbol.
+	by_domain: HashMap<String, RulesByDomain>,
+	/// Apply rules by the MX host. Since each domain potentially has multiple
+	/// MX records, we match by their suffix.
+	by_mx_suffix: HashMap<String, RulesByDomain>,
+}
+
+static ALL_RULES: Lazy<AllRules> =
+	Lazy::new(|| serde_json::from_str::<AllRules>(include_str!("rules.json")).unwrap());
+
+fn does_domain_have_rule(domain: &str, rule: &Rule) -> bool {
+	if let Some(v) = ALL_RULES.by_domain.get(domain) {
+		return v.rules.contains(rule);
+	}
+
+	false
+}
+
+fn does_mx_have_rule(host: &str, rule: &Rule) -> bool {
+	for (k, v) in ALL_RULES.by_mx_suffix.iter() {
+		if host.ends_with(k) {
+			return v.rules.contains(rule);
+		}
+	}
+
+	false
+}
+
+/// Check if either the domain or the MX host has any given rule.
+pub fn has_rule(domain: &str, host: &str, rule: &Rule) -> bool {
+	does_domain_have_rule(domain, rule) || does_mx_have_rule(host, rule)
+}

core/src/smtp/connect.rs

@@ -27,11 +27,12 @@ use std::iter;
 use std::str::FromStr;
 use std::time::Duration;
 
-use trust_dns_proto::rr::Name;
-
-use super::{gmail::is_gmail, outlook::is_hotmail, parser, yahoo::is_yahoo};
+use super::parser;
 use super::{SmtpDetails, SmtpError};
-use crate::util::{constants::LOG_TARGET, input_output::CheckEmailInput};
+use crate::{
+	rules::{has_rule, Rule},
+	util::{constants::LOG_TARGET, input_output::CheckEmailInput},
+};
 
 /// Try to send an smtp command, close and return Err if fails.
 macro_rules! try_smtp (
@@ -48,13 +49,12 @@ macro_rules! try_smtp (
 
 /// Attempt to connect to host via SMTP, and return SMTP client on success.
 async fn connect_to_host(
-	host: &Name,
+	host: &str,
 	port: u16,
 	input: &CheckEmailInput,
 ) -> Result<SmtpTransport, SmtpError> {
 	// hostname verification fails if it ends with '.', for example, using
 	// SOCKS5 proxies we can `io: incomplete` error.
-	let host = host.to_string();
 	let host = host.trim_end_matches('.').to_string();
 
 	let security = {
@@ -220,11 +220,16 @@ async fn email_deliverable(
 async fn smtp_is_catch_all(
 	smtp_transport: &mut SmtpTransport,
 	domain: &str,
-	host: &Name,
+	host: &str,
+	input: &CheckEmailInput,
 ) -> Result<bool, SmtpError> {
 	// Skip catch-all check for known providers.
-	let host = host.to_string();
-	if is_gmail(&host) || is_hotmail(&host) || is_yahoo(&host) {
+	if has_rule(domain, host, &Rule::SkipCatchAll) {
+		log::debug!(
+			target: LOG_TARGET,
+			"[email={}] Skipping catch-all check for [domain={domain}]",
+			input.to_email
+		);
 		return Ok(false);
 	}
 
@@ -247,7 +252,7 @@ async fn smtp_is_catch_all(
 
 async fn create_smtp_future(
 	to_email: &EmailAddress,
-	host: &Name,
+	host: &str,
 	port: u16,
 	domain: &str,
 	input: &CheckEmailInput,
@@ -256,7 +261,7 @@ async fn create_smtp_future(
 	// Ok(SmtpDetails { can_connect_smtp: false, ... }).
 	let mut smtp_transport = connect_to_host(host, port, input).await?;
 
-	let is_catch_all = smtp_is_catch_all(&mut smtp_transport, domain, host)
+	let is_catch_all = smtp_is_catch_all(&mut smtp_transport, domain, host, input)
 		.await
 		.unwrap_or(false);
 	let deliverability = if is_catch_all {
@@ -278,7 +283,8 @@ async fn create_smtp_future(
 			if parser::is_err_io_errors(e) {
 				log::debug!(
 					target: LOG_TARGET,
-					"Got `io: incomplete` error, reconnecting."
+					"[email={}] Got `io: incomplete` error, reconnecting.",
+					input.to_email
 				);
 
 				let _ = smtp_transport.close().await;
@@ -299,7 +305,7 @@ async fn create_smtp_future(
 /// retries.
 async fn check_smtp_without_retry(
 	to_email: &EmailAddress,
-	host: &Name,
+	host: &str,
 	port: u16,
 	domain: &str,
 	input: &CheckEmailInput,
@@ -325,7 +331,7 @@ async fn check_smtp_without_retry(
 #[async_recursion]
 pub async fn check_smtp_with_retry(
 	to_email: &EmailAddress,
-	host: &Name,
+	host: &str,
 	port: u16,
 	domain: &str,
 	input: &CheckEmailInput,
@@ -376,3 +382,26 @@ pub async fn check_smtp_with_retry(
 		_ => result,
 	}
 }
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	#[tokio::test]
+	async fn should_skip_catch_all() {
+		let smtp_client = SmtpClient::new("gmail.com".into());
+		let mut smtp_transport = smtp_client.into_transport();
+
+		let r = smtp_is_catch_all(
+			&mut smtp_transport,
+			"gmail.com",
+			"alt4.aspmx.l.google.com.",
+			&CheckEmailInput::default(),
+		)
+		.await;
+
+		assert!(!smtp_transport.is_connected()); // We shouldn't connect to google servers.
+		assert!(r.is_ok());
+		assert_eq!(false, r.unwrap())
+	}
+}

core/src/smtp/gmail.rs

@@ -76,7 +76,8 @@ pub async fn check_gmail(
 	})
 }
 
-/// Check if the MX host is from Gmail.
+/// Check if the MX host is from Google, i.e. either a @gmail.com address, or
+/// a Google Suite email.
 pub fn is_gmail(host: &str) -> bool {
 	host.to_lowercase().ends_with(".google.com.")
 }

core/src/smtp/mod.rs

@@ -62,29 +62,25 @@ pub async fn check_smtp(
 	domain: &str,
 	input: &CheckEmailInput,
 ) -> Result<SmtpDetails, SmtpError> {
-	let host_lowercase = host.to_lowercase().to_string();
+	let host = host.to_string();
 
-	if input
-		.skipped_domains
-		.iter()
-		.any(|d| host_lowercase.contains(d))
-	{
+	if input.skipped_domains.iter().any(|d| host.contains(d)) {
 		return Err(SmtpError::SkippedDomain(format!(
 			"Reacher currently cannot verify emails from @{domain}"
 		)));
 	}
 
-	if input.yahoo_use_api && is_yahoo(&host_lowercase) {
+	if input.yahoo_use_api && is_yahoo(&host) {
 		return yahoo::check_yahoo(to_email, input)
 			.await
 			.map_err(|err| err.into());
 	}
-	if input.gmail_use_api && is_gmail(&host_lowercase) {
+	if input.gmail_use_api && is_gmail(&host) {
 		return gmail::check_gmail(to_email, input)
 			.await
 			.map_err(|err| err.into());
 	}
-	if input.microsoft365_use_api && is_microsoft365(&host_lowercase) {
+	if input.microsoft365_use_api && is_microsoft365(&host) {
 		match outlook::microsoft365::check_microsoft365_api(to_email, input).await {
 			Ok(Some(smtp_details)) => return Ok(smtp_details),
 			// Continue in the event of an error/ambiguous result.
@@ -101,14 +97,14 @@ pub async fn check_smtp(
 	}
 	#[cfg(feature = "headless")]
 	if let Some(webdriver) = &input.hotmail_use_headless {
-		if is_outlook(&host_lowercase) {
+		if is_outlook(&host) {
 			return outlook::hotmail::check_password_recovery(to_email, webdriver)
 				.await
 				.map_err(|err| err.into());
 		}
 	}
 
-	check_smtp_with_retry(to_email, host, port, domain, input, input.retries).await
+	check_smtp_with_retry(to_email, &host, port, domain, input, input.retries).await
 }
 
 #[cfg(test)]