feat: Add suggestions for syntax errors (#1192)

* Add suggestions for syntax errors * Fix lint * Add suggested PR feedback * Apply pr request feedback
reacherhq · Oct 6, 2022 · 2d385f3 · 2d385f3
1 parent 49c8f5c
commit 2d385f3
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Showing 7 changed files with 73 additions and 8 deletions.
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/README.md b/README.md
@@ -127,7 +127,8 @@ The output will be a JSON with the below format, the fields should be self-expla
 	"syntax": {
 		"domain": "gmail.com",
 		"is_valid_syntax": true,
-		"username": "someone"
+		"username": "someone",
+		"suggestion": null
 	}
 }
 ```

diff --git a/backend/tests/check_email.rs b/backend/tests/check_email.rs
@@ -22,8 +22,8 @@ use serde_json;
 use warp::http::StatusCode;
 use warp::test::request;
 
-const FOO_BAR_RESPONSE: &str = r#"{"input":"foo@bar","is_reachable":"invalid","misc":{"is_disposable":false,"is_role_account":false,"gravatar_url":null},"mx":{"accepts_mail":false,"records":[]},"smtp":{"can_connect_smtp":false,"has_full_inbox":false,"is_catch_all":false,"is_deliverable":false,"is_disabled":false},"syntax":{"address":null,"domain":"","is_valid_syntax":false,"username":""}}"#;
-const FOO_BAR_BAZ_RESPONSE: &str = r#"{"input":"foo@bar.baz","is_reachable":"invalid","misc":{"is_disposable":false,"is_role_account":false,"gravatar_url":null},"mx":{"accepts_mail":false,"records":[]},"smtp":{"can_connect_smtp":false,"has_full_inbox":false,"is_catch_all":false,"is_deliverable":false,"is_disabled":false},"syntax":{"address":"foo@bar.baz","domain":"bar.baz","is_valid_syntax":true,"username":"foo"}}"#;
+const FOO_BAR_RESPONSE: &str = r#"{"input":"foo@bar","is_reachable":"invalid","misc":{"is_disposable":false,"is_role_account":false,"gravatar_url":null},"mx":{"accepts_mail":false,"records":[]},"smtp":{"can_connect_smtp":false,"has_full_inbox":false,"is_catch_all":false,"is_deliverable":false,"is_disabled":false},"syntax":{"address":null,"domain":"","is_valid_syntax":false,"username":"","suggestion":null}}"#;
+const FOO_BAR_BAZ_RESPONSE: &str = r#"{"input":"foo@bar.baz","is_reachable":"invalid","misc":{"is_disposable":false,"is_role_account":false,"gravatar_url":null},"mx":{"accepts_mail":false,"records":[]},"smtp":{"can_connect_smtp":false,"has_full_inbox":false,"is_catch_all":false,"is_deliverable":false,"is_disabled":false},"syntax":{"address":"foo@bar.baz","domain":"bar.baz","is_valid_syntax":true,"username":"foo","suggestion":null}}"#;
 
 #[tokio::test]
 async fn test_input_foo_bar() {

diff --git a/core/Cargo.toml b/core/Cargo.toml
@@ -30,6 +30,7 @@ serde = { version = "1.0.145", features = ["derive"] }
 serde_json = "1.0.85"
 trust-dns-proto = "0.21.2"
 md5 = "0.7.0"
+levenshtein = "1.0.5"
 
 [dev-dependencies]
 tokio = { version = "1.21.2" }

diff --git a/core/src/lib.rs b/core/src/lib.rs
@@ -72,7 +72,7 @@ mod util;
 use misc::{check_misc, MiscDetails};
 use mx::check_mx;
 use smtp::{check_smtp, SmtpDetails, SmtpError};
-use syntax::check_syntax;
+use syntax::{check_syntax, get_similar_mail_provider};
 pub use util::constants::LOG_TARGET;
 pub use util::input_output::*;
 
@@ -116,7 +116,7 @@ pub async fn check_email(input: &CheckEmailInput) -> CheckEmailOutput {
 		to_email,
 		to_email
 	);
-	let my_syntax = check_syntax(to_email.as_ref());
+	let mut my_syntax = check_syntax(to_email.as_ref());
 	if !my_syntax.is_valid_syntax {
 		return CheckEmailOutput {
 			input: to_email.to_string(),
@@ -136,6 +136,8 @@ pub async fn check_email(input: &CheckEmailInput) -> CheckEmailOutput {
 	let my_mx = match check_mx(&my_syntax).await {
 		Ok(m) => m,
 		e => {
+			get_similar_mail_provider(&mut my_syntax);
+
 			// This happens when there's an internal error while checking MX
 			// records. Should happen fairly rarely.
 			return CheckEmailOutput {
@@ -150,6 +152,8 @@ pub async fn check_email(input: &CheckEmailInput) -> CheckEmailOutput {
 
 	// Return if we didn't find any MX records.
 	if my_mx.lookup.is_err() {
+		get_similar_mail_provider(&mut my_syntax);
+
 		return CheckEmailOutput {
 			input: to_email.to_string(),
 			is_reachable: Reachable::Invalid,
@@ -213,6 +217,9 @@ pub async fn check_email(input: &CheckEmailInput) -> CheckEmailOutput {
 	let my_smtp = my_smtp.expect(
 		"As long as lookup has at least 1 element (which we checked), my_smtp will be a Some. qed.",
 	);
+	if my_smtp.is_err() {
+		get_similar_mail_provider(&mut my_syntax);
+	}
 
 	CheckEmailOutput {
 		input: to_email.to_string(),

diff --git a/core/src/syntax.rs b/core/src/syntax.rs
@@ -15,6 +15,7 @@
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 use async_smtp::EmailAddress;
+use levenshtein::levenshtein;
 use serde::{Deserialize, Serialize};
 use std::str::FromStr;
 
@@ -32,6 +33,7 @@ pub struct SyntaxDetails {
 	/// The username, before "@". It will be the empty string if the email
 	/// address if ill-formed.
 	pub username: String,
+	pub suggestion: Option<String>,
 }
 
 impl Default for SyntaxDetails {
@@ -41,6 +43,7 @@ impl Default for SyntaxDetails {
 			domain: "".into(),
 			is_valid_syntax: false,
 			username: "".into(),
+			suggestion: None,
 		}
 	}
 }
@@ -58,6 +61,7 @@ pub fn check_syntax(email_address: &str) -> SyntaxDetails {
 					domain: "".into(),
 					is_valid_syntax: false,
 					username: "".into(),
+					suggestion: None,
 				};
 			}
 		}
@@ -67,6 +71,7 @@ pub fn check_syntax(email_address: &str) -> SyntaxDetails {
 				domain: "".into(),
 				is_valid_syntax: false,
 				username: "".into(),
+				suggestion: None,
 			}
 		}
 	};
@@ -87,6 +92,34 @@ pub fn check_syntax(email_address: &str) -> SyntaxDetails {
 		domain,
 		is_valid_syntax: true,
 		username,
+		suggestion: None,
+	}
+}
+
+const MAIL_PROVIDERS: &[&str] = &[
+	"gmail.com",
+	"yahoo.com",
+	"outlook.com",
+	"hotmail.com",
+	"protonmail.com",
+	"icloud.com",
+	"yandex.com",
+];
+// Supplies the syntax parameter with a suggestion that matches the mail domain best by levenshtein
+// distance.
+pub fn get_similar_mail_provider(syntax: &mut SyntaxDetails) {
+	for possible_provider in MAIL_PROVIDERS {
+		let distance = levenshtein(&syntax.domain, possible_provider);
+
+		if distance < 3 {
+			// Return full address
+			syntax.suggestion = Some(format!(
+				"{}@{}",
+				syntax.username,
+				String::from(*possible_provider),
+			));
+			break;
+		}
 	}
 }
 
@@ -103,6 +136,7 @@ mod tests {
 				domain: "".into(),
 				is_valid_syntax: false,
 				username: "".into(),
+				suggestion: None,
 			}
 		);
 	}
@@ -116,6 +150,7 @@ mod tests {
 				domain: "".into(),
 				is_valid_syntax: false,
 				username: "".into(),
+				suggestion: None,
 			}
 		);
 	}
@@ -129,7 +164,21 @@ mod tests {
 				domain: "bar.com".into(),
 				is_valid_syntax: true,
 				username: "foo".into(),
+				suggestion: None,
 			}
 		);
 	}
+
+	#[test]
+	fn should_suggest_a_correct_mail_if_similar() {
+		let mut syntax = SyntaxDetails {
+			address: Some(EmailAddress::new("test@gmali.com".into()).unwrap()),
+			domain: "gmali.com".into(),
+			is_valid_syntax: true,
+			username: "test".into(),
+			suggestion: None,
+		};
+		get_similar_mail_provider(&mut syntax);
+		assert_eq!(syntax.suggestion, Some("test@gmail.com".to_string()))
+	}
 }
diff --git a/core/src/util/input_output.rs b/core/src/util/input_output.rs
@@ -405,20 +405,20 @@ mod tests {
 		let res = dummy_response_with_message("blacklist");
 		let actual = serde_json::to_string(&res).unwrap();
 		// Make sure the `description` is present with IpBlacklisted.
-		let expected = r#"{"input":"foo","is_reachable":"unknown","misc":{"is_disposable":false,"is_role_account":false,"gravatar_url":null},"mx":{"accepts_mail":false,"records":[]},"smtp":{"error":{"type":"SmtpError","message":"transient: blacklist"},"description":"IpBlacklisted"},"syntax":{"address":null,"domain":"","is_valid_syntax":false,"username":""}}"#;
+		let expected = r#"{"input":"foo","is_reachable":"unknown","misc":{"is_disposable":false,"is_role_account":false,"gravatar_url":null},"mx":{"accepts_mail":false,"records":[]},"smtp":{"error":{"type":"SmtpError","message":"transient: blacklist"},"description":"IpBlacklisted"},"syntax":{"address":null,"domain":"","is_valid_syntax":false,"username":"","suggestion":null}}"#;
 		assert_eq!(expected, actual);
 
 		let res =
 			dummy_response_with_message("Client host rejected: cannot find your reverse hostname");
 		let actual = serde_json::to_string(&res).unwrap();
 		// Make sure the `description` is present with NeedsRDNs.
-		let expected = r#"{"input":"foo","is_reachable":"unknown","misc":{"is_disposable":false,"is_role_account":false,"gravatar_url":null},"mx":{"accepts_mail":false,"records":[]},"smtp":{"error":{"type":"SmtpError","message":"transient: Client host rejected: cannot find your reverse hostname"},"description":"NeedsRDNS"},"syntax":{"address":null,"domain":"","is_valid_syntax":false,"username":""}}"#;
+		let expected = r#"{"input":"foo","is_reachable":"unknown","misc":{"is_disposable":false,"is_role_account":false,"gravatar_url":null},"mx":{"accepts_mail":false,"records":[]},"smtp":{"error":{"type":"SmtpError","message":"transient: Client host rejected: cannot find your reverse hostname"},"description":"NeedsRDNS"},"syntax":{"address":null,"domain":"","is_valid_syntax":false,"username":"","suggestion":null}}"#;
 		assert_eq!(expected, actual);
 
 		let res = dummy_response_with_message("foobar");
 		let actual = serde_json::to_string(&res).unwrap();
 		// Make sure the `description` is NOT present.
-		let expected = r#"{"input":"foo","is_reachable":"unknown","misc":{"is_disposable":false,"is_role_account":false,"gravatar_url":null},"mx":{"accepts_mail":false,"records":[]},"smtp":{"error":{"type":"SmtpError","message":"transient: foobar"}},"syntax":{"address":null,"domain":"","is_valid_syntax":false,"username":""}}"#;
+		let expected = r#"{"input":"foo","is_reachable":"unknown","misc":{"is_disposable":false,"is_role_account":false,"gravatar_url":null},"mx":{"accepts_mail":false,"records":[]},"smtp":{"error":{"type":"SmtpError","message":"transient: foobar"}},"syntax":{"address":null,"domain":"","is_valid_syntax":false,"username":"","suggestion":null}}"#;
 		assert_eq!(expected, actual);
 	}
 }