add Present trait for printing Records as zonefile

src/base/iana/macros.rs

@@ -201,6 +201,24 @@ macro_rules! int_enum_str_decimal {
 
         impl core::fmt::Display for $ianatype {
             fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
+                use std::fmt::Write;
+
+                write!(f, "{}", self.to_int())?;
+
+                if let Some(m) = self.to_mnemonic() {
+                    write!(f, "(")?;
+                    for ch in m {
+                        f.write_char(*ch as char)?;
+                    }
+                    write!(f, ")")?;
+                }
+                Ok(())
+            }
+        }
+        
+        impl $crate::zonefile::present::Present for $ianatype {
+            fn present(&self, f: &mut $crate::zonefile::present::ZoneFileFormatter) -> core::fmt::Result {
+                use std::fmt::Write;
                 write!(f, "{}", self.to_int())
             }
         }
@@ -275,6 +293,26 @@ macro_rules! int_enum_str_with_decimal {
             fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
                 use core::fmt::Write;
 
+                match self.to_mnemonic() {
+                    Some(m) => {
+                        for ch in m {
+                            f.write_char(*ch as char)?
+                        }
+                        write!(f, "({})", self.to_int())
+                    }
+                    None => {
+                        write!(f, "{}", self.to_int())
+                    }
+                }
+            }
+        }
+
+        impl $crate::zonefile::present::Present for $ianatype {
+            fn present(
+                &self,
+                f: &mut $crate::zonefile::present::ZoneFileFormatter<'_>,
+            ) -> core::fmt::Result {
+                use std::fmt::Write;
                 match self.to_mnemonic() {
                     Some(m) => {
                         for ch in m {
@@ -389,7 +427,16 @@ macro_rules! int_enum_str_with_prefix {
 
         impl core::fmt::Display for $ianatype {
             fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
-                use core::fmt::Write;
+                $crate::zonefile::present::Present::write_presentation(self, f)
+            }
+        }
+
+        impl $crate::zonefile::present::Present for $ianatype {
+            fn present(
+                &self,
+                f: &mut $crate::zonefile::present::ZoneFileFormatter<'_>,
+            ) -> core::fmt::Result {
+                use std::fmt::Write;
 
                 match self.to_mnemonic() {
                     Some(m) => {

src/base/iana/secalg.rs

@@ -116,4 +116,4 @@ int_enum! {
     (PRIVATEOID => 254, b"PRIVATEOID")
 }
 
-int_enum_str_with_decimal!(SecAlg, u8, "unknown algorithm");
+int_enum_str_decimal!(SecAlg, u8);

src/base/opt/mod.rs

@@ -47,6 +47,7 @@ use super::rdata::{ComposeRecordData, ParseRecordData, RecordData};
 use super::record::{Record, Ttl};
 use super::wire::{Compose, Composer, FormError, ParseError};
 use crate::utils::base16;
+use crate::zonefile::present::{Present, ZoneFileFormatter};
 use core::cmp::Ordering;
 use core::marker::PhantomData;
 use core::{fmt, hash, mem};
@@ -358,6 +359,16 @@ impl<Octs: AsRef<[u8]> + ?Sized> fmt::Debug for Opt<Octs> {
     }
 }
 
+//--- Present
+
+impl<Octs: AsRef<[u8]> + ?Sized> Present for Opt<Octs> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        // XXX TODO Print this properly.
+        use std::fmt::Write;
+        f.write_str("OPT ...")
+    }
+}
+
 //------------ OptHeader -----------------------------------------------------
 
 /// The header of an OPT record.

src/base/rdata.rs

@@ -20,6 +20,7 @@ use super::iana::Rtype;
 use super::scan::{Scan, Scanner, ScannerError, Symbol};
 use super::wire::{Compose, Composer, ParseError};
 use crate::utils::base16;
+use crate::zonefile::present::{Present, ZoneFileFormatter};
 use core::cmp::Ordering;
 use core::fmt;
 use octseq::octets::{Octets, OctetsFrom};
@@ -477,6 +478,19 @@ impl<Octs: AsRef<[u8]>> fmt::Debug for UnknownRecordData<Octs> {
     }
 }
 
+//--- Present
+
+impl<Octs: AsRef<[u8]>> Present for UnknownRecordData<Octs> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(f, "\\# {}", self.data.as_ref().len())?;
+        for ch in self.data.as_ref() {
+            write!(f, " {:02x}", *ch)?
+        }
+        Ok(())
+    }
+}
+
 //============ Errors ========================================================
 
 //------------ LongRecordData ------------------------------------------------

src/base/record.rs

@@ -15,6 +15,8 @@
 //! [`RecordHeader`]: struct.RecordHeader.html
 //! [`ParsedRecord`]: struct.ParsedRecord.html
 
+use crate::zonefile::present::{Present, ZoneFileFormatter};
+
 use super::cmp::CanonicalOrd;
 use super::iana::{Class, Rtype};
 use super::name::{FlattenInto, ParsedName, ToName};
@@ -431,6 +433,26 @@ where
     }
 }
 
+//--- Present
+impl<Name, Data> Present for Record<Name, Data>
+where
+    Name: fmt::Display,
+    Data: RecordData + Present,
+{
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+
+        write!(f, "{} ", self.owner)?;
+        self.ttl.present(f)?;
+        f.write_char(' ')?;
+        self.class.present(f)?;
+        f.write_char(' ')?;
+        self.data.rtype().present(f)?;
+        f.write_char(' ')?;
+        self.data.present(f)
+    }
+}
+
 //------------ ComposeRecord -------------------------------------------------
 
 /// A helper trait allowing construction of records on the fly.
@@ -1481,6 +1503,13 @@ impl Ttl {
     }
 }
 
+impl Present for Ttl {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(f, "{}", self.as_secs())
+    }
+}
+
 impl core::ops::Add for Ttl {
     type Output = Ttl;
 

src/rdata/aaaa.rs

@@ -10,6 +10,7 @@ use crate::base::net::Ipv6Addr;
 use crate::base::rdata::{ComposeRecordData, ParseRecordData, RecordData};
 use crate::base::scan::{Scanner, ScannerError};
 use crate::base::wire::{Composer, Parse, ParseError};
+use crate::zonefile::present::Present;
 use core::cmp::Ordering;
 use core::convert::Infallible;
 use core::str::FromStr;
@@ -156,6 +157,15 @@ impl fmt::Display for Aaaa {
     }
 }
 
+//--- Present
+
+impl Present for Aaaa {
+    fn present(&self, f: &mut crate::zonefile::present::ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(f, "{}", self.addr)
+    }
+}
+
 //--- AsRef and AsMut
 
 impl AsRef<Ipv6Addr> for Aaaa {

src/rdata/cds.rs

@@ -9,6 +9,7 @@ use crate::base::rdata::{
 use crate::base::scan::{Scan, Scanner, ScannerError};
 use crate::base::wire::{Compose, Composer, Parse, ParseError};
 use crate::utils::{base16, base64};
+use crate::zonefile::present::{Present, ZoneFileFormatter};
 use core::cmp::Ordering;
 use core::{fmt, hash};
 use octseq::octets::{Octets, OctetsFrom, OctetsInto};
@@ -319,6 +320,18 @@ impl<Octs: AsRef<[u8]>> fmt::Debug for Cdnskey<Octs> {
     }
 }
 
+//--- Present
+
+impl<Octs: AsRef<[u8]>> Present for Cdnskey<Octs> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(f, "{} {} ", self.flags, self.protocol)?;
+        self.algorithm.present(f)?;
+        f.write_char(' ')?;
+        base64::display(&self.public_key, f)
+    }
+}
+
 //------------ Cds -----------------------------------------------------------
 
 #[derive(Clone)]
@@ -646,6 +659,23 @@ impl<Octs: AsRef<[u8]>> fmt::Debug for Cds<Octs> {
     }
 }
 
+//--- Present
+
+impl<Octs: AsRef<[u8]>> Present for Cds<Octs> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(
+            f,
+            "{} {} {} ",
+            self.key_tag, self.algorithm, self.digest_type
+        )?;
+        for ch in self.digest.as_ref() {
+            write!(f, "{:02x}", ch)?
+        }
+        Ok(())
+    }
+}
+
 //------------ parsed --------------------------------------------------------
 
 pub mod parsed {

src/rdata/dnssec.rs

@@ -15,6 +15,7 @@ use crate::base::serial::Serial;
 use crate::base::wire::{Compose, Composer, FormError, Parse, ParseError};
 use crate::base::Ttl;
 use crate::utils::{base16, base64};
+use crate::zonefile::present::{Present, ZoneFileFormatter};
 use core::cmp::Ordering;
 use core::convert::TryInto;
 use core::{cmp, fmt, hash, str};
@@ -431,6 +432,18 @@ impl<Octs: AsRef<[u8]>> fmt::Debug for Dnskey<Octs> {
     }
 }
 
+//--- Present
+
+impl<Octs: AsRef<[u8]>> Present for Dnskey<Octs> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(f, "{} {} ", self.flags, self.protocol)?;
+        self.algorithm.present(f)?;
+        f.write_char(' ')?;
+        base64::display(&self.public_key, f)
+    }
+}
+
 //------------ ProtoRrsig ----------------------------------------------------
 
 /// The RRSIG RDATA to be included when creating the signature.
@@ -757,6 +770,15 @@ impl fmt::Display for Timestamp {
     }
 }
 
+//--- Present
+
+impl Present for Timestamp {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(f, "{}", self.0)
+    }
+}
+
 //--- PartialOrd and CanonicalOrd
 
 impl cmp::PartialOrd for Timestamp {
@@ -1354,6 +1376,30 @@ where
     }
 }
 
+//--- Present
+
+impl<Octs, Name> Present for Rrsig<Octs, Name>
+where
+    Octs: AsRef<[u8]>,
+    Name: fmt::Display,
+{
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        self.type_covered.present(f)?;
+        f.write_char(' ')?;
+        self.algorithm.present(f)?;
+        f.write_char(' ')?;
+        self.original_ttl.present(f)?;
+        f.write_char(' ')?;
+        self.expiration.present(f)?;
+        f.write_char(' ')?;
+        self.inception.present(f)?;
+        f.write_char(' ')?;
+        write!(f, " {} {}. ", self.key_tag, self.signer_name)?;
+        base64::display(&self.signature, f)
+    }
+}
+
 //------------ Nsec ----------------------------------------------------------
 
 #[derive(Clone)]
@@ -1634,6 +1680,19 @@ where
     }
 }
 
+//--- Present
+
+impl<Octs, Name> Present for Nsec<Octs, Name>
+where
+    Octs: AsRef<[u8]>,
+    Name: fmt::Display,
+{
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(f, "{}. {}", self.next_name, self.types)
+    }
+}
+
 //------------ Ds -----------------------------------------------------------
 
 #[derive(Clone)]
@@ -1945,7 +2004,7 @@ impl<Octs: AsRef<[u8]>> fmt::Display for Ds<Octs> {
         write!(
             f,
             "{} {} {} ",
-            self.key_tag, self.algorithm.to_int(), self.digest_type
+            self.key_tag, self.algorithm, self.digest_type
         )?;
         for ch in self.digest.as_ref() {
             write!(f, "{:02x}", ch)?
@@ -1967,6 +2026,24 @@ impl<Octs: AsRef<[u8]>> fmt::Debug for Ds<Octs> {
     }
 }
 
+//--- Present
+
+impl<Octs: AsRef<[u8]>> Present for Ds<Octs> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+
+        write!(f, "{} ", self.key_tag)?;
+        self.algorithm.present(f)?;
+        f.write_char(' ')?;
+        self.digest_type.present(f)?;
+        f.write_char(' ')?;
+        for ch in self.digest.as_ref() {
+            write!(f, "{:02x}", ch)?
+        }
+        Ok(())
+    }
+}
+
 //------------ RtypeBitmap ---------------------------------------------------
 
 #[derive(Clone)]
@@ -2432,7 +2509,7 @@ where
         let buf_len = self.buf.as_ref().len();
         for src_pos in (0..buf_len).step_by(34) {
             let chunk_len = (self.buf.as_ref()[src_pos + 1] as usize) + 2;
-                let buf = self.buf.as_mut();
+            let buf = self.buf.as_mut();
             buf.copy_within(src_pos..src_pos+chunk_len, dst_pos);
             dst_pos += chunk_len;
         }

src/rdata/macros.rs

@@ -499,6 +499,25 @@ macro_rules! rdata_types {
             }
         }
 
+        ///--- Present
+
+        impl<O, N> $crate::zonefile::present::Present for ZoneRecordData<O, N>
+        where
+        O: AsRef<[u8]>,
+        N: fmt::Display
+        {
+            fn present(&self, f: &mut $crate::zonefile::present::ZoneFileFormatter) -> fmt::Result {
+                match *self {
+                    $( $( $(
+                        ZoneRecordData::$mtype(ref inner) => {
+                            inner.present(f)
+                        }
+                    )* )* )*
+                    ZoneRecordData::Unknown(ref inner) => inner.present(f),
+                }
+            }
+        }
+
         //------------- AllRecordData ----------------------------------------
 
         /// Record data for all record types.
@@ -1102,6 +1121,28 @@ macro_rules! rdata_types {
             }
         }
 
+        //--- Present
+        impl<O, N> $crate::zonefile::present::Present for AllRecordData<O, N>
+        where O: Octets, N: fmt::Display {
+            fn present(
+                &self, f: &mut $crate::zonefile::present::ZoneFileFormatter
+            ) -> fmt::Result {
+                match *self {
+                    $( $( $(
+                        AllRecordData::$mtype(ref inner) => {
+                            inner.present(f)
+                        }
+                    )* )* )*
+                    $( $( $(
+                        AllRecordData::$ptype(ref inner) => {
+                            inner.present(f)
+                        }
+                    )* )* )*
+                    AllRecordData::Opt(ref inner) => inner.present(f),
+                    AllRecordData::Unknown(ref inner) => inner.present(f),
+                }
+            }
+        }
     }
 }
 
@@ -1288,6 +1329,15 @@ macro_rules! name_type_base {
                 write!(f, "{}.", self.$field)
             }
         }
+
+        //--- Present
+
+        impl<N: fmt::Display> $crate::zonefile::present::Present for $target<N> {
+            fn present(&self, f: &mut $crate::zonefile::present::ZoneFileFormatter) -> fmt::Result {
+                use std::fmt::Write;
+                write!(f, "{}.", self.$field)
+            }
+        }
     }
 }
 

src/rdata/nsec3.rs

@@ -13,6 +13,7 @@ use crate::base::scan::{
 };
 use crate::base::wire::{Compose, Composer, Parse, ParseError};
 use crate::utils::{base16, base32};
+use crate::zonefile::present::{Present, ZoneFileFormatter};
 #[cfg(feature = "bytes")]
 use bytes::Bytes;
 use core::cmp::Ordering;
@@ -369,6 +370,27 @@ impl<Octs: AsRef<[u8]>> fmt::Debug for Nsec3<Octs> {
     }
 }
 
+
+//--- Present
+
+//--- Present
+
+impl<Octs: AsRef<[u8]>> Present for Nsec3<Octs>
+where
+    Octs: AsRef<[u8]>,
+{
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+
+        self.hash_algorithm.present(f)?;
+        write!(f, " {} {} ", self.flags, self.iterations)?;
+        self.salt.present(f)?;
+        f.write_char(' ')?;
+        base32::display_hex(&self.next_owner, f)?;
+        write!(f, " {}", self.types)
+    }
+}
+
 //------------ Nsec3Param ----------------------------------------------------
 
 #[derive(Clone)]
@@ -661,6 +683,17 @@ impl<Octs: AsRef<[u8]>> fmt::Debug for Nsec3param<Octs> {
     }
 }
 
+//--- Present
+
+impl<Octs: AsRef<[u8]>> Present for Nsec3param<Octs> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        self.hash_algorithm.present(f)?;
+        write!(f, " {} {} ", self.flags, self.iterations)?;
+        self.salt.present(f)
+    }
+}
+
 //------------ Nsec3Salt -----------------------------------------------------
 
 /// The salt value of an NSEC3 record.
@@ -970,6 +1003,14 @@ impl<Octs: AsRef<[u8]> + ?Sized> fmt::Debug for Nsec3Salt<Octs> {
     }
 }
 
+//--- Present
+
+impl<Octs: AsRef<[u8]> + ?Sized> Present for Nsec3Salt<Octs> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        base16::display(self.as_slice(), f)
+    }
+}
+
 //--- Serialize and Deserialize
 
 #[cfg(feature = "serde")]

src/rdata/rfc1035/a.rs

@@ -10,6 +10,7 @@ use crate::base::rdata::{
 };
 use crate::base::scan::{Scanner, ScannerError};
 use crate::base::wire::{Composer, Parse, ParseError};
+use crate::zonefile::present::{Present, ZoneFileFormatter};
 use core::{fmt, str};
 use core::cmp::Ordering;
 use core::convert::Infallible;
@@ -172,6 +173,15 @@ impl fmt::Display for A {
     }
 }
 
+//--- Display
+
+impl Present for A {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(f, "{}", self.addr)
+    }
+}
+
 //--- AsRef and AsMut
 
 impl AsRef<Ipv4Addr> for A {

src/rdata/rfc1035/hinfo.rs

@@ -10,6 +10,7 @@ use crate::base::rdata::{
 };
 use crate::base::scan::Scanner;
 use crate::base::wire::{Composer, ParseError};
+use crate::zonefile::present::{Present, ZoneFileFormatter};
 use core::{fmt, hash};
 use core::cmp::Ordering;
 #[cfg(feature = "serde")]
@@ -236,6 +237,15 @@ impl<Octs: AsRef<[u8]>> fmt::Debug for Hinfo<Octs> {
     }
 }
 
+//--- Present
+
+impl<Octs: AsRef<[u8]>> Present for Hinfo<Octs> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(f, "{} {}", self.cpu, self.os)
+    }
+}
+
 //============ Testing =======================================================
 
 #[cfg(test)]

src/rdata/rfc1035/minfo.rs

@@ -10,6 +10,7 @@ use crate::base::rdata::{
 };
 use crate::base::scan::Scanner;
 use crate::base::wire::{Composer, ParseError};
+use crate::zonefile::present::{Present, ZoneFileFormatter};
 use core::fmt;
 use core::cmp::Ordering;
 use octseq::octets::{Octets, OctetsFrom, OctetsInto};
@@ -242,6 +243,15 @@ impl<N: fmt::Display> fmt::Display for Minfo<N> {
     }
 }
 
+//--- Present
+
+impl<N: fmt::Display> Present for Minfo<N> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(f, "{}. {}.", self.rmailbx, self.emailbx)
+    }
+}
+
 //============ Testing =======================================================
 
 #[cfg(test)]

src/rdata/rfc1035/mx.rs

@@ -10,6 +10,7 @@ use crate::base::rdata::{
 };
 use crate::base::scan::{Scan, Scanner};
 use crate::base::wire::{Compose, Composer, Parse, ParseError};
+use crate::zonefile::present::{Present, ZoneFileFormatter};
 use core::fmt;
 use core::cmp::Ordering;
 use octseq::octets::{Octets, OctetsFrom, OctetsInto};
@@ -227,6 +228,15 @@ impl<N: fmt::Display> fmt::Display for Mx<N> {
     }
 }
 
+//--- Present
+
+impl<N: fmt::Display> Present for Mx<N> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(f, "{} {}.", self.preference, self.exchange)
+    }
+}
+
 //============ Testing =======================================================
 
 #[cfg(test)]

src/rdata/rfc1035/null.rs

@@ -8,6 +8,7 @@ use crate::base::rdata::{
     ComposeRecordData, LongRecordData, ParseRecordData, RecordData,
 };
 use crate::base::wire::{Composer, ParseError};
+use crate::zonefile::present::{Present, ZoneFileFormatter};
 use core::{fmt, hash, mem};
 use core::cmp::Ordering;
 use octseq::octets::{Octets, OctetsFrom, OctetsInto};
@@ -277,6 +278,19 @@ impl<Octs: AsRef<[u8]>> fmt::Debug for Null<Octs> {
     }
 }
 
+//--- Present
+
+impl<Octs: AsRef<[u8]>> Present for Null<Octs> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(f, "\\# {}", self.data.as_ref().len())?;
+        for ch in self.data.as_ref().iter() {
+            write!(f, " {:02x}", ch)?;
+        }
+        Ok(())
+    }
+}
+
 //============ Testing =======================================================
 
 #[cfg(test)]

src/rdata/rfc1035/soa.rs

@@ -12,6 +12,7 @@ use crate::base::record::Ttl;
 use crate::base::scan::{Scan, Scanner};
 use crate::base::serial::Serial;
 use crate::base::wire::{Compose, Composer, ParseError};
+use crate::zonefile::present::{Present, ZoneFileFormatter};
 use core::fmt;
 use core::cmp::Ordering;
 use octseq::octets::{Octets, OctetsFrom, OctetsInto};
@@ -401,6 +402,23 @@ impl<N: fmt::Display> fmt::Display for Soa<N> {
     }
 }
 
+impl<N: fmt::Display> Present for Soa<N> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(
+            f,
+            "{}. {}. {} {} {} {} {}",
+            self.mname,
+            self.rname,
+            self.serial,
+            self.refresh.as_secs(),
+            self.retry.as_secs(),
+            self.expire.as_secs(),
+            self.minimum.as_secs()
+        )
+    }
+}
+
 //============ Testing =======================================================
 
 #[cfg(test)]

src/rdata/rfc1035/txt.rs

@@ -14,6 +14,7 @@ use crate::base::scan::Scanner;
 #[cfg(feature = "serde")]
 use crate::base::scan::Symbol;
 use crate::base::wire::{Composer, FormError, ParseError};
+use crate::zonefile::present::{Present, ZoneFileFormatter};
 #[cfg(feature = "bytes")]
 use bytes::BytesMut;
 use core::cmp::Ordering;
@@ -464,6 +465,24 @@ impl<Octs: AsRef<[u8]>> fmt::Debug for Txt<Octs> {
     }
 }
 
+//--- Present
+
+impl<Octs: AsRef<[u8]>> Present for Txt<Octs> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        let mut first = true;
+        for slice in self.iter_charstrs() {
+            if !first {
+                f.write_str(" ")?;
+            } else {
+                first = false;
+            }
+            write!(f, "{}", slice.display_quoted())?;
+        }
+        Ok(())
+    }
+}
+
 //--- Serialize and Deserialize
 
 #[cfg(feature = "serde")]

src/rdata/srv.rs

@@ -10,6 +10,7 @@ use crate::base::name::{FlattenInto, ParsedName, ToName};
 use crate::base::rdata::{ComposeRecordData, ParseRecordData, RecordData};
 use crate::base::scan::{Scan, Scanner};
 use crate::base::wire::{Compose, Composer, Parse, ParseError};
+use crate::zonefile::present::{Present, ZoneFileFormatter};
 use core::cmp::Ordering;
 use core::fmt;
 use octseq::octets::{Octets, OctetsFrom, OctetsInto};
@@ -282,6 +283,19 @@ impl<N: fmt::Display> fmt::Display for Srv<N> {
     }
 }
 
+//--- Present
+
+impl<N: fmt::Display> Present for Srv<N> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(
+            f,
+            "{} {} {} {}",
+            self.priority, self.weight, self.port, self.target
+        )
+    }
+}
+
 //============ Testing ======================================================
 
 #[cfg(test)]

src/rdata/svcb/params.rs

@@ -7,6 +7,7 @@ use crate::base::cmp::CanonicalOrd;
 use crate::base::iana::SvcParamKey;
 use crate::base::scan::Symbol;
 use crate::base::wire::{Compose, Parse, ParseError};
+use crate::zonefile::present::{Present, ZoneFileFormatter};
 use octseq::builder::{EmptyBuilder, FromBuilder, OctetsBuilder, ShortBuf};
 use octseq::octets::{Octets, OctetsFrom, OctetsInto};
 use octseq::parse::{Parser, ShortInput};
@@ -361,6 +362,36 @@ impl<Octs: Octets + ?Sized> fmt::Debug for SvcParams<Octs> {
     }
 }
 
+//-- Present
+
+impl<Octs: Octets + ?Sized> Present for SvcParams<Octs> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        let mut parser = Parser::from_ref(self.as_slice());
+        let mut first = true;
+        while parser.remaining() > 0 {
+            let key = SvcParamKey::parse(
+                &mut parser
+            ).expect("invalid SvcbParam");
+            let len = usize::from(
+                u16::parse(&mut parser).expect("invalid SvcParam")
+            );
+            let mut parser = parser.parse_parser(
+                len
+            ).expect("invalid SvcParam");
+            if first {
+                first = false;
+            }
+            else {
+                f.write_str(" ")?;
+            }
+            write!(
+                f, "{}", super::value::AllValues::parse_any(key, &mut parser)
+            )?;
+        };
+        Ok(())
+    }
+}
 
 //------------ ValueIter -----------------------------------------------------
 

src/rdata/svcb/rdata.rs

@@ -10,6 +10,7 @@ use crate::base::rdata::{
     ComposeRecordData, LongRecordData, ParseRecordData, RecordData,
 };
 use crate::base::wire::{Compose, Composer, Parse, ParseError};
+use crate::zonefile::present::{Present, ZoneFileFormatter};
 use octseq::octets::{Octets, OctetsFrom, OctetsInto};
 use octseq::parse::Parser;
 use core::{cmp, fmt, hash};
@@ -464,6 +465,20 @@ where
     }
 }
 
+//--- Present
+
+impl<Variant, Octs, Name> Present for SvcbRdata<Variant, Octs, Name>
+where
+    Octs: Octets,
+    Name: fmt::Display,
+{
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(f, "{} {} ", self.priority, self.target)?;
+        self.params.present(f)
+    }
+}
+
 //============ Tests =========================================================
 
 #[cfg(test)]

src/rdata/tsig.rs

@@ -12,6 +12,7 @@ use crate::base::rdata::{
 };
 use crate::base::wire::{Compose, Composer, Parse, ParseError};
 use crate::utils::base64;
+use crate::zonefile::present::{Present, ZoneFileFormatter};
 use core::cmp::Ordering;
 use core::{fmt, hash};
 use octseq::builder::OctetsBuilder;
@@ -600,6 +601,23 @@ impl<O: AsRef<[u8]>, N: fmt::Debug> fmt::Debug for Tsig<O, N> {
     }
 }
 
+//--- Present
+
+impl<O: AsRef<[u8]>, N: fmt::Display> Present for Tsig<O, N> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(
+            f,
+            "{}. {} {} ",
+            self.algorithm, self.time_signed, self.fudge
+        )?;
+        base64::display(&self.mac, f)?;
+        write!(f, " {} {} \"", self.original_id, self.error)?;
+        base64::display(&self.other, f)?;
+        write!(f, "\"")
+    }
+}
+
 //------------ Time48 --------------------------------------------------------
 
 /// A 48-bit Unix timestamp.

src/rdata/zonemd.rs

@@ -11,6 +11,7 @@ use crate::base::scan::{Scan, Scanner};
 use crate::base::serial::Serial;
 use crate::base::wire::{Composer, ParseError};
 use crate::utils::base16;
+use crate::zonefile::present::{Present, ZoneFileFormatter};
 use core::cmp::Ordering;
 use core::{fmt, hash};
 use octseq::octets::{Octets, OctetsFrom, OctetsInto};
@@ -223,6 +224,21 @@ impl<Octs: AsRef<[u8]>> fmt::Debug for Zonemd<Octs> {
     }
 }
 
+impl<Octs: AsRef<[u8]>> Present for Zonemd<Octs> {
+    fn present(&self, f: &mut ZoneFileFormatter) -> fmt::Result {
+        use std::fmt::Write;
+        write!(
+            f,
+            "{} {} {} ( ",
+            self.serial,
+            u8::from(self.scheme),
+            u8::from(self.algo)
+        )?;
+        base16::display(&self.digest, f)?;
+        write!(f, " )")
+    }
+}
+
 impl<Octs, Other> PartialOrd<Zonemd<Other>> for Zonemd<Octs>
 where
     Octs: AsRef<[u8]>,

src/zonefile/mod.rs

@@ -3,3 +3,4 @@
 #![cfg_attr(docsrs, doc(cfg(feature = "zonefile")))]
 
 pub mod inplace;
+pub mod present;

src/zonefile/present.rs

@@ -0,0 +1,55 @@
+//! Modelled roughly after `std::fmt::Display`
+
+use core::fmt::{self, Write};
+use std::string::String;
+
+pub struct ZoneFileFormatter<'a> {
+    buf: &'a mut (dyn Write + 'a),
+}
+
+pub struct Error;
+
+/// Print as presentation format
+pub trait Present {
+    fn present(&self, w: &mut ZoneFileFormatter) -> fmt::Result;
+
+    fn write_presentation<W: Write>(&self, mut w: W) -> fmt::Result {
+        let mut formatter = ZoneFileFormatter {
+            buf: &mut w,
+        };
+        self.present(&mut formatter)
+    }
+
+    fn to_presentation_string(&self) -> String {
+        let mut s = String::new();
+        self.write_presentation(&mut s).unwrap();
+        s
+    }
+}
+
+impl ZoneFileFormatter<'_> {
+    pub fn format<P: Present>(&mut self, item: &P) -> fmt::Result {
+        item.present(self)
+    }
+
+    pub fn write_bytes(&mut self, b: &[u8]) -> fmt::Result {
+        for byte in b {
+            self.write_char(*byte as char)?;
+        }
+        Ok(())
+    }
+}
+
+impl Write for ZoneFileFormatter<'_> {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        self.buf.write_str(s)
+    }
+
+    fn write_char(&mut self, c: char) -> fmt::Result {
+        self.buf.write_char(c)
+    }
+
+    fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> fmt::Result {
+        self.buf.write_fmt(args)
+    }
+}