Comply to Kubernetes specifications for annotation size.

An annotation is a pair of key-value. The key has two parts, viz. a name and an optional prefix in DNS format.

The limitations on name is 63, prefix 253 chars. The limitation on total size of all key+value pairs combined is 256KB.

https://kubernetes.io/docs/concepts/overview/working-with-objects/annotations/#syntax-and-character-set

Fixes: https://github.com/containers/podman/issues/21663

Signed-off-by: Vikas Goel <vikas.goel@gmail.com>

pkg/annotations/validate.go

@@ -0,0 +1,124 @@
+package annotations
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+
+	"github.com/containers/podman/v5/libpod/define"
+)
+
+// regexErrorMsg returns a string explanation of a regex validation failure.
+func regexErrorMsg(msg string, fmt string, examples ...string) string {
+	if len(examples) == 0 {
+		return msg + " (regex used for validation is '" + fmt + "')"
+	}
+	msg += " (e.g. "
+	for i := range examples {
+		if i > 0 {
+			msg += " or "
+		}
+		msg += "'" + examples[i] + "', "
+	}
+	msg += "regex used for validation is '" + fmt + "')"
+	return msg
+}
+
+const dns1123LabelFmt string = "[a-z0-9]([-a-z0-9]*[a-z0-9])?"
+const dns1123SubdomainFmt string = dns1123LabelFmt + "(\\." + dns1123LabelFmt + ")*"
+const dns1123SubdomainErrorMsg string = "annotations must be formatted as a valid lowercase RFC1123 subdomain of lower case alphanumeric characters, '-' or '.', and must start and end with an alphanumeric character"
+
+// DNS1123SubdomainMaxLength is a subdomain's max length in DNS (RFC 1123)
+const DNS1123SubdomainMaxLength int = 253
+
+var dns1123SubdomainRegexp = regexp.MustCompile("^" + dns1123SubdomainFmt + "$")
+
+// isDNS1123Subdomain tests for a string that conforms to the definition of a
+// subdomain in DNS (RFC 1123).
+func isDNS1123Subdomain(value string) error {
+	if len(value) > DNS1123SubdomainMaxLength {
+		return fmt.Errorf("prefix part must be no more than %d characters", DNS1123SubdomainMaxLength)
+	}
+
+	if !dns1123SubdomainRegexp.MatchString(value) {
+		return fmt.Errorf(regexErrorMsg(dns1123SubdomainErrorMsg, dns1123SubdomainFmt, "example.com"))
+	}
+
+	return nil
+}
+
+const qnameCharFmt string = "[A-Za-z0-9]"
+const qnameExtCharFmt string = "[-A-Za-z0-9_.]"
+const qualifiedNameFmt string = "(" + qnameCharFmt + qnameExtCharFmt + "*)?" + qnameCharFmt
+const qualifiedNameErrMsg string = "must consist of alphanumeric characters, '-', '_' or '.', and must start and end with an alphanumeric character"
+const qualifiedNameMaxLength int = 63
+
+var qualifiedNameRegexp = regexp.MustCompile("^" + qualifiedNameFmt + "$")
+
+// isQualifiedName tests whether the value passed is what Kubernetes calls a
+// "qualified name".  This is a format used in various places throughout the
+// system.  If the value is not valid, a list of error strings is returned.
+// Otherwise an empty list (or nil) is returned.
+func isQualifiedName(value string) error {
+	parts := strings.Split(value, "/")
+	var name string
+
+	switch len(parts) {
+	case 1:
+		name = parts[0]
+	case 2:
+		var prefix string
+		prefix, name = parts[0], parts[1]
+		if len(prefix) == 0 {
+			return fmt.Errorf("prefix part of %s must be non-empty", value)
+		} else if err := isDNS1123Subdomain(prefix); err != nil {
+			return err
+		}
+	default:
+		return fmt.Errorf("a qualified name of %s "+
+			regexErrorMsg(qualifiedNameErrMsg, qualifiedNameFmt, "MyName", "my.name", "123-abc")+
+			" with an optional DNS subdomain prefix and '/' (e.g. 'example.com/MyName')", value)
+	}
+
+	if len(name) == 0 {
+		return fmt.Errorf("name part of %s must be non-empty", value)
+	} else if len(name) > qualifiedNameMaxLength {
+		return fmt.Errorf("name part of %s must be no more than %d characters", value, qualifiedNameMaxLength)
+	}
+
+	if !qualifiedNameRegexp.MatchString(name) {
+		return fmt.Errorf("name part of %s "+
+			regexErrorMsg(qualifiedNameErrMsg, qualifiedNameFmt, "MyName", "my.name", "123-abc"), value)
+	}
+
+	return nil
+}
+
+func validateAnnotationsSize(annotations map[string]string) error {
+	var totalSize int64
+	for k, v := range annotations {
+		totalSize += (int64)(len(k)) + (int64)(len(v))
+	}
+	if totalSize > (int64)(define.TotalAnnotationSizeLimitB) {
+		return fmt.Errorf("annotations size %d is larger than limit %d", totalSize, define.TotalAnnotationSizeLimitB)
+	}
+	return nil
+}
+
+// ValidateAnnotations validates that a set of annotations are correctly
+// defined.
+func ValidateAnnotations(annotations map[string]string) error {
+	for k := range annotations {
+		// The rule is QualifiedName except that case doesn't matter,
+		// so convert to lowercase before checking.
+		if err := isQualifiedName(strings.ToLower(k)); err != nil {
+			return err
+		}
+	}
+
+	if err := validateAnnotationsSize(annotations); err != nil {
+		return err
+	}
+
+	return nil
+}