Check remaining length when parsing open-ended RDATA. (#664)

This PR adds checks to the parse functions of open-ended RDATA types to
make sure they will not exceed the maximum RDATA length of 65,535 bytes.

Specifically, these checks are added to all types that return an
error-result of LongRecordData in their new function. I hope that covers
all such types.

Changelog.md

@@ -13,10 +13,13 @@ Improvements
 
 Bug fixes
 
-* Detect when an attempt is made to create an dnssec::sign::records::Rrset
-  with records that have different TTLs. Unfortuantely error handling is
-  poor so the code currently panics. At least this prevents bad signatures
-  but the error handling needs to be fixed later. ([#660])
+* Added a length check when parsing open-ended record types like
+  `Dnskey<_>` which are supposed to never be too large. ([#664])
+* Detect when an attempt is made to create a
+  `dnssec::sign::records::Rrset` with records that have different TTLs.
+  Unfortuantely error handling is poor so the code currently panics. At
+  least this prevents bad signatures but the error handling needs to be
+  fixed later. ([#660])
 
 Unstable features
 
@@ -28,6 +31,7 @@ Other changes
 [#641]: https://github.com/NLnetLabs/domain/pull/641
 [#659]: https://github.com/NLnetLabs/domain/pull/659
 [#660]: https://github.com/NLnetLabs/domain/pull/660
+[#664]: https://github.com/NLnetLabs/domain/pull/664
 [@soywod]: https://github.com/soywod
 
 

src/base/rdata.rs

@@ -529,6 +529,12 @@ impl LongRecordData {
     }
 }
 
+impl From<LongRecordData> for ParseError {
+    fn from(src: LongRecordData) -> ParseError {
+        ParseError::form_error(src.as_str())
+    }
+}
+
 impl fmt::Display for LongRecordData {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.write_str(self.as_str())

src/rdata/cds.rs

@@ -137,6 +137,7 @@ impl<Octs> Cdnskey<Octs> {
             Some(len) => len,
             None => return Err(ParseError::ShortInput),
         };
+        LongRecordData::check_len(len)?;
         Ok(unsafe {
             Self::new_unchecked(
                 u16::parse(parser)?,
@@ -470,6 +471,7 @@ impl<Octs> Cds<Octs> {
             Some(len) => len,
             None => return Err(ParseError::ShortInput),
         };
+        LongRecordData::check_len(len)?;
         Ok(unsafe {
             Self::new_unchecked(
                 u16::parse(parser)?,

src/rdata/dnssec.rs

@@ -245,6 +245,7 @@ impl<Octs> Dnskey<Octs> {
             Some(len) => len,
             None => return Err(ParseError::ShortInput),
         };
+        LongRecordData::check_len(len)?;
         Ok(unsafe {
             Self::new_unchecked(
                 u16::parse(parser)?,
@@ -1042,6 +1043,7 @@ impl<Octs> Rrsig<Octs, ParsedName<Octs>> {
     pub fn parse<'a, Src: Octets<Range<'a> = Octs> + ?Sized + 'a>(
         parser: &mut Parser<'a, Src>,
     ) -> Result<Self, ParseError> {
+        LongRecordData::check_len(parser.remaining())?;
         let type_covered = Rtype::parse(parser)?;
         let algorithm = SecurityAlgorithm::parse(parser)?;
         let labels = u8::parse(parser)?;
@@ -1826,6 +1828,7 @@ impl<Octs> Ds<Octs> {
             Some(len) => len,
             None => return Err(ParseError::ShortInput),
         };
+        LongRecordData::check_len(parser.remaining())?;
         Ok(unsafe {
             Self::new_unchecked(
                 u16::parse(parser)?,

src/rdata/rfc1035/null.rs

@@ -137,6 +137,7 @@ impl<Octs> Null<Octs> {
         parser: &mut Parser<'a, Src>,
     ) -> Result<Self, ParseError> {
         let len = parser.remaining();
+        LongRecordData::check_len(len)?;
         parser
             .parse_octets(len)
             .map(|res| unsafe { Self::from_octets_unchecked(res) })

src/rdata/rfc1035/txt.rs

@@ -185,6 +185,7 @@ impl<Octs> Txt<Octs> {
         Octs: AsRef<[u8]>,
     {
         let len = parser.remaining();
+        LongRecordData::check_len(len)?;
         let text = parser.parse_octets(len)?;
         let mut tmp = Parser::from_ref(text.as_ref());
         while tmp.remaining() != 0 {

src/rdata/svcb/rdata.rs

@@ -175,6 +175,7 @@ impl<Variant, Octs: AsRef<[u8]>> SvcbRdata<Variant, Octs, ParsedName<Octs>> {
     pub fn parse<'a, Src: Octets<Range<'a> = Octs> + ?Sized + 'a>(
         parser: &mut Parser<'a, Src>,
     ) -> Result<Self, ParseError> {
+        LongRecordData::check_len(parser.remaining())?;
         let priority = u16::parse(parser)?;
         let target = ParsedName::parse(parser)?;
         let params = SvcParams::parse(parser)?;

src/rdata/tsig.rs

@@ -307,6 +307,7 @@ impl<Octs> Tsig<Octs, ParsedName<Octs>> {
     pub fn parse<'a, Src: Octets<Range<'a> = Octs> + ?Sized + 'a>(
         parser: &mut Parser<'a, Src>,
     ) -> Result<Self, ParseError> {
+        LongRecordData::check_len(parser.remaining())?;
         let algorithm = ParsedName::parse(parser)?;
         let time_signed = Time48::parse(parser)?;
         let fudge = u16::parse(parser)?;