RFC 6891 extended RCODE conversion function fixes. #258
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- to_int(): Like from_int(), work with the lowest 12-bits when converting to u16, not the lowest 4-bits. - to_parts(): Like from_parts(), shift by 4-bits, not by 8-bits. - New test optrcode_parts().
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…on-code and to better describe the intended purpose of the block.
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Breaking changes * All types and functions referring to domain names have been changed from using the term “dname” to just “name.” For instance, `Dname` has become `Name`, `ToDname` has become `ToName`, and `ToDname::to_dname` has become `ToName::to_name`. ([#290]) * The `ToName` and `ToRelativeName` traits have been changed to have a pair of methods a la `try_to_name` and `to_name` for octets builders with limited and unlimited buffers, reflecting the pattern used elsewhere. ([#285]) * The types for IANA-registered parameters in `base::iana` have been changed from enums to a newtypes around their underlying integer type and associated constants for the registered values. (This was really always the better way to structure this.) ([#276], [#298]) * The `Txt` record data type now rejects empty record data as invalid. As a consequence `TxtBuilder` converts an empty builder into TXT record data consisting of one empty character string which requires `TxtBuilder::finish` to be able to return an error. ([#267]) * `Txt` record data serialization has been redesigned. It now serialized as a sequence of character strings. It also deserializes from such a sequence. If supported by the format, it alternatively deserializes from a string that is broken up into 255 octet chunks if necessary. ([#268]) * The text formatting for `CharStr` has been redesigned. The `Display` impl now uses a modified version of the representation format that doesn’t escape white space but also doesn’t enclose the string in quotes. Methods for explicitly formatting in quoted and unquoted presentation format are provided. ([#270]) * The `validate::RrsigExt` trait now accepts anything that impls `AsRef<Record<..>>` to allow the use of smart pointers. ([#288] by [@hunts]) * The stub resolver now uses the new client transports. This doesn’t change how it is used but does change how it queries the configured servers. ([#215]) * The sub resolver’s server configuration `Transport` type has been changed to be either `Transport::UdpTcp` for trying UDP and if that leads to a truncated answer try TCP and `Transport::Tcp` for only trying TCP. The stub resolver uses these accordingly now ([#296]) * Many error types have been changed from enums to structs that hide internal error details. Enums have been kept for errors where distinguishing variants might be meaningful for dealing with the error. ([#277]) * Renamed `Dnskey::is_zsk` to `is_zone_key`. ([#292]) * Split RRSIG timestamp handling from `Serial` into a new type `rdata::dnssec::Timestamp`. ([#294]) * Upgraded `octseq` to 0.5. ([#257]) * The minimum Rust version is now 1.70. ([#304]) New * Add impls for `AsRef<RelativeDname<[u8]>>` and `Borrow<RelativeDname<[u8]>>` to `RelativeDname<_>`. ([#251] by [@torin-carey]) * Added `name::Chain::fmt_with_dots` to format an absolute chained name with a final dot. ([#253]) * Added a new `ParseAnyRecordData` trait for record data types that can parse any type of record data. ([#256]) * Added implementations of `OctetsFrom` and `Debug` to `AllOptData` and the specific options types that didn’t have them yet. ([#257]) * Added missing ordering impls to `ZoneRecordData`, `AllRecordData`, `Opt`, and `SvcbRdata`. ([#293]) * Added `Name::reverse_from_addr` that creates a domain name for the reverse lookup of an IP address. ([#289]) * Added `OptBuilder::clone_from` to replace the OPT record with the content of another OPT record. ([#299]) * Added `Message::for_slice_ref` that returns a `Message<&[u8]>`. ([#300]) Bug fixes * Fixed the display implementation of `name::Chain<_, _>`. ([#253]) * Fixed the display implementation of `rdata::Txt<..>`. It now displays each embedded character string separately in quoted form. ([#259]) * Fixed the extended part returned by `OptRcode::to_parts` (it was shifted by 4 bits too many) and return all 12 bits for the `Int` variant in `OptRcode::to_int`. ([#258]) * Fixed a bug in the `inplace` zonefile parser that made it reject character string of length 255. ([#284]) Unstable features * Added the module `net::client` with experimental support for client message transport, i.e., sending of requests and receiving responses as well as caching of responses. This is gated by the `unstable-client-transport` feature. ([#215],[#275]) * Added the module `net::server` with experimental support for server transports, processing requests through a middleware chain and a service trait. This is gated by the `unstable-server-transport` feature. ([#274]) * Added the module `zonetree` providing basic traits representing a collection of zones and their data. The `zonetree::in_memory` module provides an in-memory implementation. The `zonetree::parsed` module provides a way to classify RRsets before inserting them into a tree. This is gated by the `unstable-zonetree` feature. ([#286])
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This PR fixes a couple of bugs in RFC 6891 extended RCODE conversion functions that prevent extended RCODE (values > 15) being handled correctly.
This problem was observed while testing an implementation of RFC 7873 Domain Name System (DNS) Cookies, when responding with extended RCODE
BADCOOKIE(integer value 23).23 is binary 0000_0001_0111 in 12-bit extended RCODE form, with 0000_0001 (1) being the extended part and 0111 (7) being the RFC 1035 DNS header RCODE part.
The wire format should have had the lowest bit of the OPT header extended RCODE field set but it was unset. This can be seen in the following Wireshark screenshot:
This PR fixes the problem by making the following two changes:
to_int(): Likefrom_int(), work with the lowest 12-bits when converting to u16, not the lowest 4-bits.to_parts(): Likefrom_parts(), shift by 4-bits, not by 8-bits.It also adds a new test called
optrcode_parts()that fails without these changes and passes with them.With the fix applied Wireshark shows the OPT header RCODE value being set correctly:
And
digwas then able to correctly detect the BADCOOKIE RCODE and use the accompanying server cookie in subsequent requests, while without the fix the received server cookie was ignored.