add support for SVCB record

This commit add initial support for SVCB and HTTPS record defined in
[draft-ietf-dnsop-svcb-https][1]. It includes basic interaction with
the rdata, convert from/to the wire format.

[1]: https://datatracker.ietf.org/doc/draft-ietf-dnsop-svcb-https/

src/base/iana/mod.rs

@@ -34,6 +34,7 @@ pub use self::opt::OptionCode;
 pub use self::rcode::{OptRcode, Rcode, TsigRcode};
 pub use self::rtype::Rtype;
 pub use self::secalg::SecAlg;
+pub use self::svcb::SvcbParamKey;
 
 #[macro_use]
 mod macros;
@@ -47,3 +48,4 @@ pub mod opt;
 pub mod rcode;
 pub mod rtype;
 pub mod secalg;
+pub mod svcb;

src/base/iana/rtype.rs

@@ -299,6 +299,16 @@ int_enum! {
     /// See draft-wessels-dns-zone-digest.
     (Zonemd => 63, b"ZONEMD")
 
+    /// General Purpose Service Endpoints.
+    ///
+    /// See draft-ietf-dnsop-svcb-httpssvc
+    (Svcb => 64, b"SVCB")
+
+    /// HTTPS Specific Service Endpoints.
+    ///
+    /// See draft-ietf-dnsop-svcb-httpssvc
+    (Https => 65, b"HTTPS")
+
     /// SPF.
     ///
     /// RFC 7208.

src/base/iana/svcb.rs

@@ -0,0 +1,43 @@
+//! Service Binding (SVCB) Parameter Registry
+
+use core::fmt;
+
+//------------ Service Binding Parameters -----------
+
+int_enum! {
+    =>
+    SvcbParamKey, u16;
+
+    (Mandatory => 0, b"Mandatory keys in this RR")
+    (Alpn => 1, b"Additional supported protocols")
+    (NoDefaultAlpn => 2, b"Additional supported protocols")
+    (Port => 3, b"Port for alternative endpoint")
+    (Ipv4Hint => 4, b"IPv4 address hints")
+    // https://datatracker.ietf.org/doc/draft-ietf-tls-esni/
+    (Ech => 5, b"Encrypted ClientHello info")
+    (Ipv6Hint => 6, b"IPv6 address hints")
+    // https://datatracker.ietf.org/doc/draft-ietf-add-svcb-dns/
+    (DohPath => 7, b"DNS over HTTPS path template")
+}
+
+pub const SVCB_PARAM_KEY_PRIVATE_RANGE_BEGIN: u16 = 65280;
+pub const SVCB_PARAM_KEY_PRIVATE_RANGE_END: u16 = 65534;
+pub const SVCB_PARAM_KEY_INVALID: u16 = 65535;
+
+impl fmt::Display for SvcbParamKey {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let s = match self {
+            Self::Mandatory => "mandatory",
+            Self::Alpn => "alpn",
+            Self::NoDefaultAlpn => "nodefaultalpn",
+            Self::Port => "port",
+            Self::Ipv4Hint => "ipv4hint",
+            Self::Ech => "ech",
+            Self::Ipv6Hint => "ipv6hint",
+            Self::DohPath => "dohpath",
+            Self::Int(n) => return write!(f, "key{}", n),
+        };
+
+        f.write_str(s)
+    }
+}

src/rdata/mod.rs

@@ -35,6 +35,7 @@ pub mod rfc4034;
 pub mod rfc5155;
 pub mod rfc6672;
 pub mod rfc7344;
+pub mod svcb;
 
 // The rdata_types! macro (defined in self::macros) re-exports the record data
 // types here and creates the ZoneRecordData and AllRecordData enums
@@ -113,4 +114,10 @@ rdata_types! {
             Cds<O>,
         }
     }
+    svcb::{
+        pseudo {
+            Svcb<O, N>,
+            Https<O, N>,
+        }
+    }
 }