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namespaces, identifiers: split validation

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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>
This commit is contained in:
Stephen J Day
2017-07-12 14:46:47 -07:00
parent c63b84dcbc
commit 9e5bd5a2dc
10 changed files with 162 additions and 32 deletions
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37
identifiers/validate.go
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@@ -1,17 +1,11 @@
// Package identifiers provides common validation for identifiers, keys and ids
// Package identifiers provides common validation for identifiers and keys
// across containerd.
//
// To allow such identifiers to be used across various contexts safely, the character
// set has been restricted to that defined for domains in RFC 1035, section
// 2.3.1. This will make identifiers safe for use across networks, filesystems
// and other media.
// Identifiers in containerd must be a alphanumeric, allowing limited
// underscores, dashes and dots.
//
// The identifier specification departs from RFC 1035 in that it allows
// "labels" to start with number and only enforces a total length restriction
// of 76 characters.
//
// While the character set may be expanded in the future, identifiers are
// guaranteed to be safely used as filesystem path components.
// While the character set may be expanded in the future, identifiers
// are guaranteed to be safely used as filesystem path components.
package identifiers
import (
@@ -22,27 +16,28 @@ import (
)
const (
maxLength = 76
charclass = `[A-Za-z0-9]+`
label = charclass + `(:?[-]+` + charclass + `)*`
maxLength = 76
alphanum = `[A-Za-z0-9]+`
separators = `[._-]`
)
var (
// identifierRe validates that a identifier matches valid identifiers.
//
// Rules for domains, defined in RFC 1035, section 2.3.1, are used for
// identifiers.
identifierRe = regexp.MustCompile(reAnchor(label + reGroup("[.]"+reGroup(label)) + "*"))
// identifierRe defines the pattern for valid identifiers.
identifierRe = regexp.MustCompile(reAnchor(alphanum + reGroup(separators+reGroup(alphanum)) + "*"))
)
// Validate return nil if the string s is a valid identifier.
//
// identifiers must be valid domain identifiers according to RFC 1035, section 2.3.1. To
// identifiers must be valid domain names according to RFC 1035, section 2.3.1. To
// enforce case insensitvity, all characters must be lower case.
//
// In general, identifiers that pass this validation, should be safe for use as
// a domain identifier or filesystem path component.
// a domain names or filesystem path component.
func Validate(s string) error {
if len(s) == 0 {
return errors.Wrapf(errdefs.ErrInvalidArgument, "identifier must not be empty")
}
if len(s) > maxLength {
return errors.Wrapf(errdefs.ErrInvalidArgument, "identifier %q greater than maximum length (%d characters)", s, maxLength)
}