Add support for parsing compressed names out of wire packets

[dnssec-prover] / src / ser.rs

diff --git a/src/ser.rs b/src/ser.rs
index c0566c3e2c4835585322a2f3ea9fbaa887709a98..e88c9ba63a5b5700ed06ae6c2a0cac1bcb341c23 100644 (file)
--- a/src/ser.rs
+++ b/src/ser.rs
@@ -27,20 +27,30 @@ pub(crate) fn read_u32(inp: &mut &[u8]) -> Result<u32, ()> {
        Ok(u32::from_be_bytes(bytes))
 }
 
-pub(crate) fn read_name(inp: &mut &[u8]) -> Result<Name, ()> {
-       let mut name = String::with_capacity(1024);
+fn read_wire_packet_labels(inp: &mut &[u8], wire_packet: &[u8], name: &mut String) -> Result<(), ()> {
        loop {
                let len = read_u8(inp)? as usize;
                if len == 0 {
-                       if name.is_empty() { name += "."; }
+                       if name.is_empty() { *name += "."; }
+                       break;
+               } else if len >= 0xc0 {
+                       let offs = ((len & !0xc0) << 8) | read_u8(inp)? as usize;
+                       if offs >= wire_packet.len() { return Err(()); }
+                       read_wire_packet_labels(&mut &wire_packet[offs..], wire_packet, name)?;
                        break;
                }
                if inp.len() <= len { return Err(()); }
-               name += core::str::from_utf8(&inp[..len]).map_err(|_| ())?;
-               name += ".";
+               *name += core::str::from_utf8(&inp[..len]).map_err(|_| ())?;
+               *name += ".";
                *inp = &inp[len..];
-               if name.len() > 1024 { return Err(()); }
+               if name.len() > 255 { return Err(()); }
        }
+       Ok(())
+}
+
+pub(crate) fn read_wire_packet_name(inp: &mut &[u8], wire_packet: &[u8]) -> Result<Name, ()> {
+       let mut name = String::with_capacity(1024);
+       read_wire_packet_labels(inp, wire_packet, &mut name)?;
        Ok(name.try_into()?)
 }
 
@@ -70,8 +80,8 @@ pub(crate) fn name_len(name: &Name) -> u16 {
        }
 }
 
-pub(crate) fn parse_rr(inp: &mut &[u8]) -> Result<RR, ()> {
-       let name = read_name(inp)?;
+pub(crate) fn parse_wire_packet_rr(inp: &mut &[u8], wire_packet: &[u8]) -> Result<RR, ()> {
+       let name = read_wire_packet_name(inp, wire_packet)?;
        let ty = read_u16(inp)?;
        let class = read_u16(inp)?;
        if class != 1 { return Err(()); } // We only support the INternet
@@ -82,31 +92,23 @@ pub(crate) fn parse_rr(inp: &mut &[u8]) -> Result<RR, ()> {
        *inp = &inp[data_len..];
 
        match ty {
-               A::TYPE => Ok(RR::A(A::read_from_data(name, data)?)),
-               AAAA::TYPE => Ok(RR::AAAA(AAAA::read_from_data(name, data)?)),
-               NS::TYPE => Ok(RR::NS(NS::read_from_data(name, data)?)),
-               Txt::TYPE => {
-                       Ok(RR::Txt(Txt::read_from_data(name, data)?))
-               }
-               CName::TYPE => {
-                       Ok(RR::CName(CName::read_from_data(name, data)?))
-               }
-               TLSA::TYPE => {
-                       Ok(RR::TLSA(TLSA::read_from_data(name, data)?))
-               },
-               DnsKey::TYPE => {
-                       Ok(RR::DnsKey(DnsKey::read_from_data(name, data)?))
-               },
-               DS::TYPE => {
-                       Ok(RR::DS(DS::read_from_data(name, data)?))
-               },
-               RRSig::TYPE => {
-                       Ok(RR::RRSig(RRSig::read_from_data(name, data)?))
-               },
+               A::TYPE => Ok(RR::A(A::read_from_data(name, data, wire_packet)?)),
+               AAAA::TYPE => Ok(RR::AAAA(AAAA::read_from_data(name, data, wire_packet)?)),
+               NS::TYPE => Ok(RR::NS(NS::read_from_data(name, data, wire_packet)?)),
+               Txt::TYPE => Ok(RR::Txt(Txt::read_from_data(name, data, wire_packet)?)),
+               CName::TYPE => Ok(RR::CName(CName::read_from_data(name, data, wire_packet)?)),
+               TLSA::TYPE => Ok(RR::TLSA(TLSA::read_from_data(name, data, wire_packet)?)),
+               DnsKey::TYPE => Ok(RR::DnsKey(DnsKey::read_from_data(name, data, wire_packet)?)),
+               DS::TYPE => Ok(RR::DS(DS::read_from_data(name, data, wire_packet)?)),
+               RRSig::TYPE => Ok(RR::RRSig(RRSig::read_from_data(name, data, wire_packet)?)),
                _ => Err(()),
        }
 }
 
+pub(crate) fn parse_rr(inp: &mut &[u8]) -> Result<RR, ()> {
+       parse_wire_packet_rr(inp, &[])
+}
+
 pub(crate) fn bytes_to_rsa_pk<'a>(pubkey: &'a [u8])
 -> Result<signature::RsaPublicKeyComponents<&'a [u8]>, ()> {
        if pubkey.len() <= 3 { return Err(()); }