identifiers: use common package for identifier validation

A few days ago, we added validation for namespaces. We've decided to
expand these naming rules to include containers. To facilitate this, a
common package `identifiers` now provides a common validation area.
These rules will be extended to apply to task identifiers, snapshot keys
and other areas where user-provided identifiers may be used.

Signed-off-by: Stephen J Day <stephen.day@docker.com>

identifiers/validate.go

@@ -0,0 +1,58 @@
+// Package identifiers provides common validation for identifiers, keys and ids
+// 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.
+//
+// While the character set may expand in the future, we guarantee that the
+// identifiers will be safe for use as filesystem path components.
+package identifiers
+
+import (
+	"regexp"
+
+	"github.com/pkg/errors"
+)
+
+const (
+	label = `[A-Za-z][A-Za-z0-9]+(?:[-]+[A-Za-z0-9]+)*`
+)
+
+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)) + "*"))
+
+	errIdentifierInvalid = errors.Errorf("invalid, must match %v", identifierRe)
+)
+
+// IsInvalid return true if the error was due to an invalid identifer.
+func IsInvalid(err error) bool {
+	return errors.Cause(err) == errIdentifierInvalid
+}
+
+// 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
+// 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.
+func Validate(s string) error {
+	if !identifierRe.MatchString(s) {
+		return errors.Wrapf(errIdentifierInvalid, "identifier %q", s)
+	}
+	return nil
+}
+
+func reGroup(s string) string {
+	return `(?:` + s + `)`
+}
+
+func reAnchor(s string) string {
+	return `^` + s + `$`
+}

identifiers/validate_test.go

@@ -0,0 +1,47 @@
+package identifiers
+
+import (
+	"testing"
+)
+
+func TestValidIdentifiers(t *testing.T) {
+	for _, input := range []string{
+		"default",
+		"Default",
+		t.Name(),
+		"default-default",
+		"default--default",
+		"containerd.io",
+		"foo.boo",
+		"swarmkit.docker.io",
+		"zn--e9.org", // or something like it!
+	} {
+		t.Run(input, func(t *testing.T) {
+			if err := Validate(input); err != nil {
+				t.Fatalf("unexpected error: %v != nil", err)
+			}
+		})
+	}
+}
+
+func TestInvalidIdentifiers(t *testing.T) {
+	for _, input := range []string{
+		".foo..foo",
+		"foo/foo",
+		"foo/..",
+		"foo..foo",
+		"foo.-boo",
+		"-foo.boo",
+		"foo.boo-",
+		"foo_foo.boo_underscores", // boo-urns?
+	} {
+
+		t.Run(input, func(t *testing.T) {
+			if err := Validate(input); err == nil {
+				t.Fatal("expected invalid error")
+			} else if !IsInvalid(err) {
+				t.Fatal("error should be an invalid identifier error")
+			}
+		})
+	}
+}

metadata/containers.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/boltdb/bolt"
 	"github.com/containerd/containerd/containers"
+	"github.com/containerd/containerd/identifiers"
 	"github.com/containerd/containerd/namespaces"
 	"github.com/pkg/errors"
 )
@@ -77,6 +78,10 @@ func (s *containerStore) Create(ctx context.Context, container containers.Contai
 		return containers.Container{}, err
 	}
 
+	if err := identifiers.Validate(container.ID); err != nil {
+		return containers.Container{}, err
+	}
+
 	bkt, err := createContainersBucket(s.tx, namespace)
 	if err != nil {
 		return containers.Container{}, err

metadata/namespaces.go

@@ -4,6 +4,7 @@ import (
 	"context"
 
 	"github.com/boltdb/bolt"
+	"github.com/containerd/containerd/identifiers"
 	"github.com/containerd/containerd/namespaces"
 )
 
@@ -21,7 +22,7 @@ func (s *namespaceStore) Create(ctx context.Context, namespace string, labels ma
 		return err
 	}
 
-	if err := namespaces.Validate(namespace); err != nil {
+	if err := identifiers.Validate(namespace); err != nil {
 		return err
 	}
 

namespaces/context.go

@@ -3,6 +3,7 @@ package namespaces
 import (
 	"os"
 
+	"github.com/containerd/containerd/identifiers"
 	"github.com/pkg/errors"
 	"golang.org/x/net/context"
 )
@@ -61,8 +62,8 @@ func NamespaceRequired(ctx context.Context) (string, error) {
 		return "", errNamespaceRequired
 	}
 
-	if err := Validate(namespace); err != nil {
-		return "", err
+	if err := identifiers.Validate(namespace); err != nil {
+		return "", errors.Wrap(err, "namespace validation")
 	}
 
 	return namespace, nil

services/containers/helpers.go

@@ -3,6 +3,7 @@ package containers
 import (
 	api "github.com/containerd/containerd/api/services/containers/v1"
 	"github.com/containerd/containerd/containers"
+	"github.com/containerd/containerd/identifiers"
 	"github.com/containerd/containerd/metadata"
 	"github.com/containerd/containerd/namespaces"
 	"github.com/gogo/protobuf/types"
@@ -60,7 +61,7 @@ func mapGRPCError(err error, id string) error {
 		return grpc.Errorf(codes.AlreadyExists, "container %v already exists", id)
 	case namespaces.IsNamespaceRequired(err):
 		return grpc.Errorf(codes.InvalidArgument, "namespace required, please set %q header", namespaces.GRPCHeader)
-	case namespaces.IsNamespaceInvalid(err):
+	case identifiers.IsInvalid(err):
 		return grpc.Errorf(codes.InvalidArgument, err.Error())
 	}
 

services/images/helpers.go

@@ -3,6 +3,7 @@ package images
 import (
 	imagesapi "github.com/containerd/containerd/api/services/images/v1"
 	"github.com/containerd/containerd/api/types"
+	"github.com/containerd/containerd/identifiers"
 	"github.com/containerd/containerd/images"
 	"github.com/containerd/containerd/metadata"
 	"github.com/containerd/containerd/namespaces"
@@ -85,7 +86,7 @@ func mapGRPCError(err error, id string) error {
 		return grpc.Errorf(codes.AlreadyExists, "image %v already exists", id)
 	case namespaces.IsNamespaceRequired(err):
 		return grpc.Errorf(codes.InvalidArgument, "namespace required, please set %q header", namespaces.GRPCHeader)
-	case namespaces.IsNamespaceInvalid(err):
+	case identifiers.IsInvalid(err):
 		return grpc.Errorf(codes.InvalidArgument, err.Error())
 	}