pub trait CanonicalOrd<Rhs: ?Sized = Self> {
fn canonical_cmp(&self, other: &Rhs) -> Ordering;
fn canonical_lt(&self, other: &Rhs) -> bool { ... }
fn canonical_le(&self, other: &Rhs) -> bool { ... }
fn canonical_gt(&self, other: &Rhs) -> bool { ... }
fn canonical_ge(&self, other: &Rhs) -> bool { ... }
}Expand description
A trait for the canonical sort order of values.
The canonical sort order is used in DNS security when multiple values are part of constructing or validating a signature. This sort order differs in some cases from the normal sort order. To avoid confusion, only this trait should be used when DNSSEC signatures are involved.
Canonical order is defined in RFC 4034 and clarified in RFC 6840. It is defined for domain names and resource records within an RR set (i.e., a set of records with the same owner name, class, and type).
For domain names, canonical order is the same as the ‘normal’ order as
implemented through the PartialOrd and Ord traits: Labels are compared
from right to left (i.e, starting from the root label) with each pair of
labels compared as octet sequences with ASCII letters lowercased
before comparison. The name_cmp methods of the ToDname and
ToRelativeDname traits can be used to implement this canonical order
for name types.
Resource records within an RR set are ordered by comparing the canonical
wire-format representation of their record data as octet sequences. The
canonical form differs from the regular form by lower-casing domain names
included in the record data for the record types NS, MD, MF, CNAME, SOA,
MB, MG, MR, PTR, MINFO, MX, RP, AFSDB, RT, SIG, PX, NXT, NAPTR, KX, SRV,
DNAME, A6, and RRSIG. (NSEC is listed in RFC 4034 but has been withdrawn
by RFC 6840). This canonical representation is provided via the
Compose::compose_canonical method.
In order to help implementing this trait for record data types, there are implementations of it for some types that can appear in record data that sort differently in their composed representation than normally.
Apart from these explicit use cases, the CanonicalOrd trait is also
implemented for the Record type to allow ordering records of a zone into
RRsets. It does so by ordering by class first, then canonical owner,
record type, and finally canonical record data. The reason for this
somewhat odd ordering is that in this way not only are all records
for the same owner name and class kept together, but also all the records
subordinate to a owner name and class pair (i.e., the records for a zone)
will sort together.
Required Methods
sourcefn canonical_cmp(&self, other: &Rhs) -> Ordering
fn canonical_cmp(&self, other: &Rhs) -> Ordering
Returns the canonical ordering between self and other.
Provided Methods
sourcefn canonical_lt(&self, other: &Rhs) -> bool
fn canonical_lt(&self, other: &Rhs) -> bool
Returns whether self is canonically less than other.
sourcefn canonical_le(&self, other: &Rhs) -> bool
fn canonical_le(&self, other: &Rhs) -> bool
Returns whether self is canonically less than or equal to other.
sourcefn canonical_gt(&self, other: &Rhs) -> bool
fn canonical_gt(&self, other: &Rhs) -> bool
Returns whether self is canonically greater than other.
sourcefn canonical_ge(&self, other: &Rhs) -> bool
fn canonical_ge(&self, other: &Rhs) -> bool
Returns whether self is canonically greater than or equal to other.