comply with rfc1034, section 3.6.2. Aliases and canonical names

zns-daemon/src/handlers/query.rs

@@ -42,6 +42,8 @@ impl ResponseHandler for QueryHandler {
                             connection,
                         )?;
 
+                        rrs.extend(try_cname(&domain_records));
+
                         if domain_records.is_empty() && !question.qname.is_empty() {
                             rrs.extend(try_wildcard(question, connection)?);
                         }
@@ -75,6 +77,14 @@ impl ResponseHandler for QueryHandler {
     }
 }
 
+fn try_cname(records: &[RR]) -> Vec<RR> {
+    records
+        .iter()
+        .filter(|rr| rr._type == Type::Type(RRType::CNAME))
+        .cloned()
+        .collect()
+}
+
 fn try_wildcard(question: &Question, connection: &mut PgConnection) -> Result<Vec<RR>, ZNSError> {
     let mut qname = question.qname.clone().to_vec();
     qname[0] = String::from("*");
@@ -87,7 +97,6 @@ fn try_wildcard(question: &Question, connection: &mut PgConnection) -> Result<Ve
     .into_iter()
     .map(|mut rr| {
         rr.name.clone_from(&question.qname);
-        println!("{:#?}", rr);
         rr
     })
     .collect())
@@ -141,7 +150,7 @@ mod tests {
     use crate::db::{lib::tests::get_test_connection, models::insert_into_database};
     use zns::{
         parser::ToBytes,
-        test_utils::{get_message, get_rr},
+        test_utils::{get_cname_rr, get_message, get_rr},
     };
 
     #[tokio::test]
@@ -197,4 +206,28 @@ mod tests {
         assert_eq!(result.answer.len(), 2);
         assert_eq!(result.answer[0], rr);
     }
+
+    #[tokio::test]
+    async fn test_cname() {
+        let mut connection = get_test_connection();
+        let rr = get_cname_rr(Some(Config::get().authoritative_zone.clone()));
+
+        assert!(insert_into_database(&rr, &mut connection).is_ok());
+
+        let mut message = get_message(Some(Config::get().authoritative_zone.clone()));
+        message.header.ancount = 0;
+        message.answer = vec![];
+
+        let result = QueryHandler::handle(
+            &message,
+            &Message::to_bytes(message.clone()),
+            &mut connection,
+        )
+        .await
+        .unwrap();
+        assert_eq!(result.header.ancount, 2);
+        assert_eq!(result.answer.len(), 2);
+        assert_eq!(result.answer[0], rr);
+        assert_eq!(result.answer[1], rr);
+    }
 }

zns-daemon/src/handlers/update/mod.rs

@@ -2,11 +2,11 @@ use diesel::PgConnection;
 
 use crate::{
     config::Config,
-    db::models::{delete_from_database, insert_into_database},
+    db::models::{delete_from_database, get_from_database, insert_into_database},
 };
 
-use zns::errors::ZNSError;
 use zns::structs::{Class, Message, RRClass, RRType, Type};
+use zns::{errors::ZNSError, structs::RR};
 
 use self::sig::Sig;
 
@@ -90,6 +90,9 @@ impl ResponseHandler for UpdateHandler {
 
         for rr in &message.authority {
             if rr.class == zone.qclass {
+                if let Some(message) = validate_record(rr, connection)? {
+                    return Err(ZNSError::Refused { message });
+                }
                 insert_into_database(rr, connection)?;
             } else if rr.class == Class::Class(RRClass::ANY) {
                 if rr._type == Type::Type(RRType::ANY) {
@@ -133,3 +136,19 @@ impl ResponseHandler for UpdateHandler {
         Ok(response)
     }
 }
+
+fn validate_record(record: &RR, connection: &mut PgConnection) -> Result<Option<String>, ZNSError> {
+    let rr_type = match record._type {
+        Type::Type(RRType::CNAME) => None,
+        _ => Some(Type::Type(RRType::CNAME)),
+    };
+
+    let records = get_from_database(&record.name, rr_type, record.class.clone(), connection)?;
+    if !records.is_empty() {
+        Ok(Some(
+            "Another record with the same name already exists".to_string(),
+        ))
+    } else {
+        Ok(None)
+    }
+}

zns/src/errors.rs

@@ -22,6 +22,8 @@ pub enum ZNSError {
     NotAuth { message: String },
     #[error("I refuse to answer the query: {message:?}")]
     Refused { message: String },
+    #[error("Update RR is outside zone: {message:?}")]
+    UpdateZone { message: String },
 }
 
 impl ZNSError {
@@ -35,6 +37,7 @@ impl ZNSError {
             ZNSError::NXDomain { .. } => RCODE::NXDOMAIN,
             ZNSError::NotImp { .. } => RCODE::NOTIMP,
             ZNSError::Refused { .. } | ZNSError::Key { .. } => RCODE::REFUSED,
+            ZNSError::UpdateZone { .. } => RCODE::NOTZONE,
         }
     }
 }

zns/src/test_utils.rs

@@ -1,7 +1,9 @@
 #![cfg(feature = "test-utils")]
+use rand::distributions::Alphanumeric;
+use rand::Rng;
+
 use crate::structs::*;
 
-#[cfg(feature = "test-utils")]
 use crate::labelstring::LabelString;
 pub fn get_rr(name: Option<LabelString>) -> RR {
     RR {
@@ -19,6 +21,17 @@ pub fn get_rr(name: Option<LabelString>) -> RR {
     }
 }
 
+pub fn get_cname_rr(name: Option<LabelString>) -> RR {
+    RR {
+        name: name.unwrap_or(LabelString::from("example.org")),
+        _type: Type::Type(RRType::CNAME),
+        class: Class::Class(RRClass::IN),
+        ttl: 10,
+        rdlength: 4,
+        rdata: RData::LabelString(random_domain()),
+    }
+}
+
 pub fn get_message(name: Option<LabelString>) -> Message {
     Message {
         header: Header {
@@ -46,3 +59,17 @@ pub fn get_message(name: Option<LabelString>) -> Message {
         additional: vec![get_rr(name)],
     }
 }
+
+fn random_domain() -> LabelString {
+    let part1 = random_string();
+    let part2 = random_string();
+    LabelString::from(&format!("{part1}.{part2}"))
+}
+
+fn random_string() -> String {
+    rand::thread_rng()
+        .sample_iter(&Alphanumeric)
+        .take(7)
+        .map(char::from)
+        .collect()
+}