Add support for CNAME resource records

diff --git a/src/lib.rs b/src/lib.rs
index af11329e15000cb1a6146fedb6d6bd53960ead65..c0a024c62a270eae8489de361bc3e33400e0c047 100644 (file)
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -89,6 +89,8 @@ pub enum RR {
        Txt(Txt),
        /// A TLS Certificate Association resource record
        TLSA(TLSA),
+       /// A Canonical Name record
+       CName(CName),
        /// A DNS (Public) Key resource record
        DnsKey(DnsKey),
        /// A Delegated Signer resource record
@@ -101,6 +103,7 @@ impl RR {
        pub fn name(&self) -> &Name {
                match self {
                        RR::Txt(rr) => &rr.name,
+                       RR::CName(rr) => &rr.name,
                        RR::TLSA(rr) => &rr.name,
                        RR::DnsKey(rr) => &rr.name,
                        RR::DS(rr) => &rr.name,
@@ -110,6 +113,7 @@ impl RR {
        fn ty(&self) -> u16 {
                match self {
                        RR::Txt(_) => Txt::TYPE,
+                       RR::CName(_) => CName::TYPE,
                        RR::TLSA(_) => TLSA::TYPE,
                        RR::DnsKey(_) => DnsKey::TYPE,
                        RR::DS(_) => DS::TYPE,
@@ -119,6 +123,7 @@ impl RR {
        fn write_u16_len_prefixed_data(&self, out: &mut Vec<u8>) {
                match self {
                        RR::Txt(rr) => StaticRecord::write_u16_len_prefixed_data(rr, out),
+                       RR::CName(rr) => StaticRecord::write_u16_len_prefixed_data(rr, out),
                        RR::TLSA(rr) => StaticRecord::write_u16_len_prefixed_data(rr, out),
                        RR::DnsKey(rr) => StaticRecord::write_u16_len_prefixed_data(rr, out),
                        RR::DS(rr) => StaticRecord::write_u16_len_prefixed_data(rr, out),
@@ -127,6 +132,7 @@ impl RR {
        }
 }
 impl From<Txt> for RR { fn from(txt: Txt) -> RR { RR::Txt(txt) } }
+impl From<CName> for RR { fn from(cname: CName) -> RR { RR::CName(cname) } }
 impl From<TLSA> for RR { fn from(tlsa: TLSA) -> RR { RR::TLSA(tlsa) } }
 impl From<DnsKey> for RR { fn from(dnskey: DnsKey) -> RR { RR::DnsKey(dnskey) } }
 impl From<DS> for RR { fn from(ds: DS) -> RR { RR::DS(ds) } }
@@ -250,6 +256,9 @@ fn parse_rr(inp: &mut &[u8]) -> Result<RR, ()> {
                        }
                        Ok(RR::Txt(Txt { name, data: parsed_data }))
                }
+               CName::TYPE => {
+                       Ok(RR::CName(CName { name, canonical_name: read_name(&mut data)? }))
+               }
                TLSA::TYPE => {
                        if data_len <= 3 { return Err(()); }
                        Ok(RR::TLSA(TLSA {
@@ -366,6 +375,26 @@ impl StaticRecord for TLSA {
        }
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
+/// A Canonical Name resource record, referring all queries for this name to another name.
+pub struct CName {
+       /// The name this record is at.
+       pub name: Name,
+       /// The canonical name.
+       ///
+       /// A resolver should use this name when looking up any further records for [`Self::name`].
+       pub canonical_name: Name,
+}
+impl StaticRecord for CName {
+       const TYPE: u16 = 5;
+       fn name(&self) -> &Name { &self.name }
+       fn write_u16_len_prefixed_data(&self, out: &mut Vec<u8>) {
+               let len: u16 = name_len(&self.canonical_name);
+               out.extend_from_slice(&len.to_be_bytes());
+               write_name(out, &self.canonical_name);
+       }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
 /// A public key resource record which can be used to validate [`RRSig`]s.
 pub struct DnsKey {
@@ -890,6 +919,20 @@ mod tests {
                (txt_resp, txt_rrsig)
        }
 
+       fn matcorallo_cname_record() -> (CName, RRSig) {
+               let cname_resp = CName {
+                       name: "cname_test.matcorallo.com.".try_into().unwrap(),
+                       canonical_name: "txt_test.matcorallo.com.".try_into().unwrap(),
+               };
+               let cname_rrsig = RRSig {
+                       name: "cname_test.matcorallo.com.".try_into().unwrap(),
+                       ty: CName::TYPE, alg: 13, labels: 3, orig_ttl: 30, expiration: 1708319203,
+                       inception: 1707104203, key_tag: 34530, key_name: "matcorallo.com.".try_into().unwrap(),
+                       signature: base64::decode("5HIrmEotbVb95umE6SX3NrPboKsthdcY8b7DdaYQZzm0Nj5m2VgcfOmEPJYS8o1xE4GvGGF4sdfSy3Uw7TibBg==").unwrap(),
+               };
+               (cname_resp, cname_rrsig)
+       }
+
        #[test]
        fn check_txt_record_a() {
                let dnskeys = mattcorallo_dnskey().0;
@@ -926,7 +969,15 @@ mod tests {
        }
 
        #[test]
-       fn check_double_txt_proof() {
+       fn check_cname_record() {
+               let dnskeys = matcorallo_dnskey().0;
+               let (cname, cname_rrsig) = matcorallo_cname_record();
+               let cname_resp = [cname];
+               verify_rrsig(&cname_rrsig, &dnskeys, cname_resp.iter().collect()).unwrap();
+       }
+
+       #[test]
+       fn check_multi_zone_proof() {
                let mut rr_stream = Vec::new();
                for rr in root_dnskey().1 { write_rr(&rr, 1, &mut rr_stream); }
                for rr in com_dnskey().1 { write_rr(&rr, 1, &mut rr_stream); }
@@ -936,12 +987,14 @@ mod tests {
                for rr in matcorallo_dnskey().1 { write_rr(&rr, 1, &mut rr_stream); }
                let (txt, txt_rrsig) = matcorallo_txt_record();
                for rr in [RR::Txt(txt), RR::RRSig(txt_rrsig)] { write_rr(&rr, 1, &mut rr_stream); }
+               let (cname, cname_rrsig) = matcorallo_cname_record();
+               for rr in [RR::CName(cname), RR::RRSig(cname_rrsig)] { write_rr(&rr, 1, &mut rr_stream); }
 
                let mut rrs = parse_rr_stream(&rr_stream).unwrap();
                rrs.shuffle(&mut rand::rngs::OsRng);
                let mut verified_rrs = verify_rr_stream(&rrs).unwrap();
                verified_rrs.sort();
-               assert_eq!(verified_rrs.len(), 2);
+               assert_eq!(verified_rrs.len(), 3);
                if let RR::Txt(txt) = &verified_rrs[0] {
                        assert_eq!(txt.name.0, "matt.user._bitcoin-payment.mattcorallo.com.");
                        assert_eq!(txt.data, b"bitcoin:?b12=lno1qsgqmqvgm96frzdg8m0gc6nzeqffvzsqzrxqy32afmr3jn9ggkwg3egfwch2hy0l6jut6vfd8vpsc3h89l6u3dm4q2d6nuamav3w27xvdmv3lpgklhg7l5teypqz9l53hj7zvuaenh34xqsz2sa967yzqkylfu9xtcd5ymcmfp32h083e805y7jfd236w9afhavqqvl8uyma7x77yun4ehe9pnhu2gekjguexmxpqjcr2j822xr7q34p078gzslf9wpwz5y57alxu99s0z2ql0kfqvwhzycqq45ehh58xnfpuek80hw6spvwrvttjrrq9pphh0dpydh06qqspp5uq4gpyt6n9mwexde44qv7lstzzq60nr40ff38u27un6y53aypmx0p4qruk2tf9mjwqlhxak4znvna5y");
@@ -950,6 +1003,11 @@ mod tests {
                        assert_eq!(txt.name.0, "txt_test.matcorallo.com.");
                        assert_eq!(txt.data, b"dnssec_prover_test");
                } else { panic!(); }
+               if let RR::CName(cname) = &verified_rrs[2] {
+                       assert_eq!(cname.name.0, "cname_test.matcorallo.com.");
+                       assert_eq!(cname.canonical_name.0, "txt_test.matcorallo.com.");
+               } else { panic!(); }
+
        }
 
        #[test]