9e5bd5a2dc
After review, there are cases where having common requirements for namespaces and identifiers creates contention between applications. One example is that it is nice to have namespaces comply with domain name requirement, but that does not allow underscores, which are required for certain identifiers. The namespaces validation has been reverted to be in line with RFC 1035. Existing identifiers has been modified to allow simply alpha-numeric identifiers, while limiting adjacent separators. We may follow up tweaks for the identifier charset but this split should remove the hard decisions. Signed-off-by: Stephen J Day <stephen.day@docker.com>
68 lines
2.1 KiB
Go
68 lines
2.1 KiB
Go
// Package namespaces provides tools for working with namespaces across
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// containerd.
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//
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// Namespaces collect resources such as containers and images, into a unique
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// identifier space. This means that two applications can use the same
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// identifiers and not conflict while using containerd.
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//
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// This package can be used to ensure that client and server functions
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// correctly store the namespace on the context.
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package namespaces
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import (
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"regexp"
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"github.com/containerd/containerd/errdefs"
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"github.com/pkg/errors"
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)
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const (
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maxLength = 76
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alpha = `[A-Za-z]`
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alphanum = `[A-Za-z0-9]+`
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label = alpha + alphanum + `(:?[-]+` + alpha + alphanum + `)*`
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)
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var (
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// namespaceRe validates that a namespace matches valid identifiers.
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//
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// Rules for domains, defined in RFC 1035, section 2.3.1, are used for
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// namespaces.
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namespaceRe = regexp.MustCompile(reAnchor(label + reGroup("[.]"+reGroup(label)) + "*"))
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)
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// Validate returns nil if the string s is a valid namespace.
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//
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// To allow such namespace identifiers to be used across various contexts
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// safely, the character set has been restricted to that defined for domains in
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// RFC 1035, section 2.3.1. This will make namespace identifiers safe for use
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// across networks, filesystems and other media.
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//
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// The identifier specification departs from RFC 1035 in that it allows
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// "labels" to start with number and only enforces a total length restriction
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// of 76 characters.
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//
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// While the character set may be expanded in the future, namespace identifiers
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// are guaranteed to be safely used as filesystem path components.
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//
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// For the most part, this doesn't need to be called directly when using the
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// context-oriented functions.
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func Validate(s string) error {
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if len(s) > maxLength {
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return errors.Wrapf(errdefs.ErrInvalidArgument, "namespace %q greater than maximum length (%d characters)", s, maxLength)
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}
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if !namespaceRe.MatchString(s) {
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return errors.Wrapf(errdefs.ErrInvalidArgument, "namespace %q must match %v", s, namespaceRe)
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}
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return nil
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}
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func reGroup(s string) string {
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return `(?:` + s + `)`
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}
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func reAnchor(s string) string {
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return `^` + s + `$`
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}
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