replace reference/docker for github.com/distribution/reference v0.5.0

The reference/docker package was a fork of github.com/distribution/distribution,
which could not easily be used as a direct dependency, as it brought many other
dependencies with it.

The "reference' package has now moved to a separate repository, which means
we can replace the local fork, and use the upstream implementation again.

The new module was extracted from the distribution repository at commit:
b9b19409cf

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

vendor/github.com/distribution/reference/regexp.go

@@ -0,0 +1,163 @@
+package reference
+
+import (
+	"regexp"
+	"strings"
+)
+
+// DigestRegexp matches well-formed digests, including algorithm (e.g. "sha256:<encoded>").
+var DigestRegexp = regexp.MustCompile(digestPat)
+
+// DomainRegexp matches hostname or IP-addresses, optionally including a port
+// number. It defines the structure of potential domain components that may be
+// part of image names. This is purposely a subset of what is allowed by DNS to
+// ensure backwards compatibility with Docker image names. It may be a subset of
+// DNS domain name, an IPv4 address in decimal format, or an IPv6 address between
+// square brackets (excluding zone identifiers as defined by [RFC 6874] or special
+// addresses such as IPv4-Mapped).
+//
+// [RFC 6874]: https://www.rfc-editor.org/rfc/rfc6874.
+var DomainRegexp = regexp.MustCompile(domainAndPort)
+
+// IdentifierRegexp is the format for string identifier used as a
+// content addressable identifier using sha256. These identifiers
+// are like digests without the algorithm, since sha256 is used.
+var IdentifierRegexp = regexp.MustCompile(identifier)
+
+// NameRegexp is the format for the name component of references, including
+// an optional domain and port, but without tag or digest suffix.
+var NameRegexp = regexp.MustCompile(namePat)
+
+// ReferenceRegexp is the full supported format of a reference. The regexp
+// is anchored and has capturing groups for name, tag, and digest
+// components.
+var ReferenceRegexp = regexp.MustCompile(referencePat)
+
+// TagRegexp matches valid tag names. From [docker/docker:graph/tags.go].
+//
+// [docker/docker:graph/tags.go]: https://github.com/moby/moby/blob/v1.6.0/graph/tags.go#L26-L28
+var TagRegexp = regexp.MustCompile(tag)
+
+const (
+	// alphanumeric defines the alphanumeric atom, typically a
+	// component of names. This only allows lower case characters and digits.
+	alphanumeric = `[a-z0-9]+`
+
+	// separator defines the separators allowed to be embedded in name
+	// components. This allows one period, one or two underscore and multiple
+	// dashes. Repeated dashes and underscores are intentionally treated
+	// differently. In order to support valid hostnames as name components,
+	// supporting repeated dash was added. Additionally double underscore is
+	// now allowed as a separator to loosen the restriction for previously
+	// supported names.
+	separator = `(?:[._]|__|[-]+)`
+
+	// localhost is treated as a special value for domain-name. Any other
+	// domain-name without a "." or a ":port" are considered a path component.
+	localhost = `localhost`
+
+	// domainNameComponent restricts the registry domain component of a
+	// repository name to start with a component as defined by DomainRegexp.
+	domainNameComponent = `(?:[a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9-]*[a-zA-Z0-9])`
+
+	// optionalPort matches an optional port-number including the port separator
+	// (e.g. ":80").
+	optionalPort = `(?::[0-9]+)?`
+
+	// tag matches valid tag names. From docker/docker:graph/tags.go.
+	tag = `[\w][\w.-]{0,127}`
+
+	// digestPat matches well-formed digests, including algorithm (e.g. "sha256:<encoded>").
+	//
+	// TODO(thaJeztah): this should follow the same rules as https://pkg.go.dev/github.com/opencontainers/go-digest@v1.0.0#DigestRegexp
+	// so that go-digest defines the canonical format. Note that the go-digest is
+	// more relaxed:
+	//   - it allows multiple algorithms (e.g. "sha256+b64:<encoded>") to allow
+	//     future expansion of supported algorithms.
+	//   - it allows the "<encoded>" value to use urlsafe base64 encoding as defined
+	//     in [rfc4648, section 5].
+	//
+	// [rfc4648, section 5]: https://www.rfc-editor.org/rfc/rfc4648#section-5.
+	digestPat = `[A-Za-z][A-Za-z0-9]*(?:[-_+.][A-Za-z][A-Za-z0-9]*)*[:][[:xdigit:]]{32,}`
+
+	// identifier is the format for a content addressable identifier using sha256.
+	// These identifiers are like digests without the algorithm, since sha256 is used.
+	identifier = `([a-f0-9]{64})`
+
+	// ipv6address are enclosed between square brackets and may be represented
+	// in many ways, see rfc5952. Only IPv6 in compressed or uncompressed format
+	// are allowed, IPv6 zone identifiers (rfc6874) or Special addresses such as
+	// IPv4-Mapped are deliberately excluded.
+	ipv6address = `\[(?:[a-fA-F0-9:]+)\]`
+)
+
+var (
+	// domainName defines the structure of potential domain components
+	// that may be part of image names. This is purposely a subset of what is
+	// allowed by DNS to ensure backwards compatibility with Docker image
+	// names. This includes IPv4 addresses on decimal format.
+	domainName = domainNameComponent + anyTimes(`\.`+domainNameComponent)
+
+	// host defines the structure of potential domains based on the URI
+	// Host subcomponent on rfc3986. It may be a subset of DNS domain name,
+	// or an IPv4 address in decimal format, or an IPv6 address between square
+	// brackets (excluding zone identifiers as defined by rfc6874 or special
+	// addresses such as IPv4-Mapped).
+	host = `(?:` + domainName + `|` + ipv6address + `)`
+
+	// allowed by the URI Host subcomponent on rfc3986 to ensure backwards
+	// compatibility with Docker image names.
+	domainAndPort = host + optionalPort
+
+	// anchoredTagRegexp matches valid tag names, anchored at the start and
+	// end of the matched string.
+	anchoredTagRegexp = regexp.MustCompile(anchored(tag))
+
+	// anchoredDigestRegexp matches valid digests, anchored at the start and
+	// end of the matched string.
+	anchoredDigestRegexp = regexp.MustCompile(anchored(digestPat))
+
+	// pathComponent restricts path-components to start with an alphanumeric
+	// character, with following parts able to be separated by a separator
+	// (one period, one or two underscore and multiple dashes).
+	pathComponent = alphanumeric + anyTimes(separator+alphanumeric)
+
+	// remoteName matches the remote-name of a repository. It consists of one
+	// or more forward slash (/) delimited path-components:
+	//
+	//	pathComponent[[/pathComponent] ...] // e.g., "library/ubuntu"
+	remoteName = pathComponent + anyTimes(`/`+pathComponent)
+	namePat    = optional(domainAndPort+`/`) + remoteName
+
+	// anchoredNameRegexp is used to parse a name value, capturing the
+	// domain and trailing components.
+	anchoredNameRegexp = regexp.MustCompile(anchored(optional(capture(domainAndPort), `/`), capture(remoteName)))
+
+	referencePat = anchored(capture(namePat), optional(`:`, capture(tag)), optional(`@`, capture(digestPat)))
+
+	// anchoredIdentifierRegexp is used to check or match an
+	// identifier value, anchored at start and end of string.
+	anchoredIdentifierRegexp = regexp.MustCompile(anchored(identifier))
+)
+
+// optional wraps the expression in a non-capturing group and makes the
+// production optional.
+func optional(res ...string) string {
+	return `(?:` + strings.Join(res, "") + `)?`
+}
+
+// anyTimes wraps the expression in a non-capturing group that can occur
+// any number of times.
+func anyTimes(res ...string) string {
+	return `(?:` + strings.Join(res, "") + `)*`
+}
+
+// capture wraps the expression in a capturing group.
+func capture(res ...string) string {
+	return `(` + strings.Join(res, "") + `)`
+}
+
+// anchored anchors the regular expression by adding start and end delimiters.
+func anchored(res ...string) string {
+	return `^` + strings.Join(res, "") + `$`
+}