Initial QSfera import

Server/vendor/github.com/russellhaering/goxmldsig/etreeutils/namespace.go

@@ -0,0 +1,425 @@
+package etreeutils
+
+import (
+	"errors"
+	"fmt"
+	"maps"
+	"sort"
+
+	"github.com/beevik/etree"
+)
+
+const (
+	defaultPrefix = ""
+	xmlnsPrefix   = "xmlns"
+	xmlPrefix     = "xml"
+
+	XMLNamespace   = "http://www.w3.org/XML/1998/namespace"
+	XMLNSNamespace = "http://www.w3.org/2000/xmlns/"
+)
+
+func NewDefaultNSContext() NSContext {
+	defaultLimit := 1000
+	return NSContext{
+		prefixes: map[string]string{
+			defaultPrefix: XMLNamespace,
+			xmlPrefix:     XMLNamespace,
+			xmlnsPrefix:   XMLNSNamespace,
+		},
+		limit: &defaultLimit,
+	}
+}
+
+var (
+	EmptyNSContext = NSContext{}
+
+	ErrReservedNamespace       = errors.New("disallowed declaration of reserved namespace")
+	ErrInvalidDefaultNamespace = errors.New("invalid default namespace declaration")
+	ErrTraversalHalted         = errors.New("traversal halted")
+	ErrTraversalLimit          = errors.New("traversal limit reached")
+)
+
+type ErrUndeclaredNSPrefix struct {
+	Prefix string
+}
+
+func (e ErrUndeclaredNSPrefix) Error() string {
+	return fmt.Sprintf("undeclared namespace prefix: '%s'", e.Prefix)
+}
+
+type NSContext struct {
+	prefixes map[string]string
+	limit    *int
+}
+
+// CheckLimit checks the traversal limit before calling the handler function
+func (ctx NSContext) CheckLimit() error {
+	if *ctx.limit <= 0 {
+		return ErrTraversalLimit
+	}
+	*ctx.limit--
+
+	return nil
+}
+
+func (ctx NSContext) Copy() NSContext {
+	prefixes := make(map[string]string, len(ctx.prefixes)+4)
+	maps.Copy(prefixes, ctx.prefixes)
+
+	return NSContext{prefixes: prefixes, limit: ctx.limit}
+}
+
+func (ctx NSContext) declare(prefix, namespace string) etree.Attr {
+	ctx.prefixes[prefix] = namespace
+
+	switch prefix {
+	case defaultPrefix:
+		return etree.Attr{
+			Key:   xmlnsPrefix,
+			Value: namespace,
+		}
+
+	default:
+		return etree.Attr{
+			Space: xmlnsPrefix,
+			Key:   prefix,
+			Value: namespace,
+		}
+	}
+}
+
+func (ctx NSContext) SubContext(el *etree.Element) (NSContext, error) {
+	// The subcontext should inherit existing declared prefixes
+	newCtx := ctx.Copy()
+
+	// Merge new namespace declarations on top of existing ones.
+	for _, attr := range el.Attr {
+		if attr.Space == xmlnsPrefix {
+			// This attribute is a namespace declaration of the form "xmlns:<prefix>"
+
+			// The 'xml' namespace may only be re-declared with the name 'http://www.w3.org/XML/1998/namespace'
+			if attr.Key == xmlPrefix && attr.Value != XMLNamespace {
+				return ctx, ErrReservedNamespace
+			}
+
+			// The 'xmlns' namespace may not be re-declared
+			if attr.Key == xmlnsPrefix {
+				return ctx, ErrReservedNamespace
+			}
+
+			newCtx.declare(attr.Key, attr.Value)
+		} else if attr.Space == defaultPrefix && attr.Key == xmlnsPrefix {
+			// This attribute is a default namespace declaration
+
+			// The xmlns namespace value may not be declared as the default namespace
+			if attr.Value == XMLNSNamespace {
+				return ctx, ErrInvalidDefaultNamespace
+			}
+
+			newCtx.declare(defaultPrefix, attr.Value)
+		}
+	}
+
+	return newCtx, nil
+}
+
+// Prefixes returns a copy of this context's prefix map.
+func (ctx NSContext) Prefixes() map[string]string {
+	prefixes := make(map[string]string, len(ctx.prefixes))
+	maps.Copy(prefixes, ctx.prefixes)
+
+	return prefixes
+}
+
+// LookupPrefix attempts to find a declared namespace for the specified prefix. If the prefix
+// is an empty string this will be the default namespace for this context. If the prefix is
+// undeclared in this context an ErrUndeclaredNSPrefix will be returned.
+func (ctx NSContext) LookupPrefix(prefix string) (string, error) {
+	if namespace, ok := ctx.prefixes[prefix]; ok {
+		return namespace, nil
+	}
+
+	return "", ErrUndeclaredNSPrefix{
+		Prefix: prefix,
+	}
+}
+
+// NSIterHandler is a function which is invoked with a element and its surrounding
+// NSContext during traversals.
+type NSIterHandler func(NSContext, *etree.Element) error
+
+// NSTraverse traverses an element tree, invoking the passed handler for each element
+// in the tree.
+func NSTraverse(ctx NSContext, el *etree.Element, handle NSIterHandler) error {
+	err := ctx.CheckLimit()
+	if err != nil {
+		return err
+	}
+
+	ctx, err = ctx.SubContext(el)
+	if err != nil {
+		return err
+	}
+
+	err = handle(ctx, el)
+	if err != nil {
+		return err
+	}
+
+	// Recursively traverse child elements.
+	for _, child := range el.ChildElements() {
+		err := NSTraverse(ctx, child, handle)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// NSDetatch makes a copy of the passed element, and declares any namespaces in
+// the passed context onto the new element before returning it.
+func NSDetatch(ctx NSContext, el *etree.Element) (*etree.Element, error) {
+	ctx, err := ctx.SubContext(el)
+	if err != nil {
+		return nil, err
+	}
+
+	el = el.Copy()
+
+	// Build a new attribute list
+	attrs := make([]etree.Attr, 0, len(el.Attr))
+
+	// First copy over anything that isn't a namespace declaration
+	for _, attr := range el.Attr {
+		if attr.Space == xmlnsPrefix {
+			continue
+		}
+
+		if attr.Space == defaultPrefix && attr.Key == xmlnsPrefix {
+			continue
+		}
+
+		attrs = append(attrs, attr)
+	}
+
+	// Append all in-context namespace declarations
+	for prefix, namespace := range ctx.prefixes {
+		// Skip the implicit "xml" and "xmlns" prefix declarations
+		if prefix == xmlnsPrefix || prefix == xmlPrefix {
+			continue
+		}
+
+		// Also skip declararing the default namespace as XMLNamespace
+		if prefix == defaultPrefix && namespace == XMLNamespace {
+			continue
+		}
+
+		if prefix != defaultPrefix {
+			attrs = append(attrs, etree.Attr{
+				Space: xmlnsPrefix,
+				Key:   prefix,
+				Value: namespace,
+			})
+		} else {
+			attrs = append(attrs, etree.Attr{
+				Key:   xmlnsPrefix,
+				Value: namespace,
+			})
+		}
+	}
+
+	sort.Sort(SortedAttrs(attrs))
+
+	el.Attr = attrs
+
+	return el, nil
+}
+
+// NSSelectOne behaves identically to NSSelectOneCtx, but uses DefaultNSContext as the
+// surrounding context.
+func NSSelectOne(el *etree.Element, namespace, tag string) (*etree.Element, error) {
+	return NSSelectOneCtx(NewDefaultNSContext(), el, namespace, tag)
+}
+
+// NSSelectOneCtx conducts a depth-first search for an element with the specified namespace
+// and tag. If such an element is found, a new *etree.Element is returned which is a
+// copy of the found element, but with all in-context namespace declarations attached
+// to the element as attributes.
+func NSSelectOneCtx(ctx NSContext, el *etree.Element, namespace, tag string) (*etree.Element, error) {
+	var found *etree.Element
+
+	err := NSFindIterateCtx(ctx, el, namespace, tag, func(ctx NSContext, el *etree.Element) error {
+		var err error
+
+		found, err = NSDetatch(ctx, el)
+		if err != nil {
+			return err
+		}
+
+		return ErrTraversalHalted
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return found, nil
+}
+
+// NSFindIterate behaves identically to NSFindIterateCtx, but uses DefaultNSContext
+// as the surrounding context.
+func NSFindIterate(el *etree.Element, namespace, tag string, handle NSIterHandler) error {
+	return NSFindIterateCtx(NewDefaultNSContext(), el, namespace, tag, handle)
+}
+
+// NSFindIterateCtx conducts a depth-first traversal searching for elements with the
+// specified tag in the specified namespace. It uses the passed NSContext for prefix
+// lookups. For each such element, the passed handler function is invoked. If the
+// handler function returns an error traversal is immediately halted. If the error
+// returned by the handler is  ErrTraversalHalted then nil will be returned by
+// NSFindIterate. If any other error is returned by the handler, that error will be
+// returned by NSFindIterate.
+func NSFindIterateCtx(ctx NSContext, el *etree.Element, namespace, tag string, handle NSIterHandler) error {
+	err := NSTraverse(ctx, el, func(ctx NSContext, el *etree.Element) error {
+		_ctx, err := ctx.SubContext(el)
+		if err != nil {
+			return err
+		}
+
+		currentNS, err := _ctx.LookupPrefix(el.Space)
+		if err != nil {
+			return err
+		}
+
+		// Base case, el is the sought after element.
+		if currentNS == namespace && el.Tag == tag {
+			return handle(ctx, el)
+		}
+
+		return nil
+	})
+
+	if err != nil && err != ErrTraversalHalted {
+		return err
+	}
+
+	return nil
+}
+
+// NSFindOne behaves identically to NSFindOneCtx, but uses DefaultNSContext for
+// context.
+func NSFindOne(el *etree.Element, namespace, tag string) (*etree.Element, error) {
+	return NSFindOneCtx(NewDefaultNSContext(), el, namespace, tag)
+}
+
+// NSFindOneCtx conducts a depth-first search for the specified element. If such an element
+// is found a reference to it is returned.
+func NSFindOneCtx(ctx NSContext, el *etree.Element, namespace, tag string) (*etree.Element, error) {
+	var found *etree.Element
+
+	err := NSFindIterateCtx(ctx, el, namespace, tag, func(ctx NSContext, el *etree.Element) error {
+		found = el
+		return ErrTraversalHalted
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return found, nil
+}
+
+// NSIterateChildren iterates the children of an element, invoking the passed
+// handler with each direct child of the element, and the context surrounding
+// that child.
+func NSIterateChildren(ctx NSContext, el *etree.Element, handle NSIterHandler) error {
+	ctx, err := ctx.SubContext(el)
+	if err != nil {
+		return err
+	}
+
+	// Iterate the child elements.
+	for _, child := range el.ChildElements() {
+		err := ctx.CheckLimit()
+		if err != nil {
+			return err
+		}
+
+		err = handle(ctx, child)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// NSFindIterateChildrenCtx takes an element and its surrounding context, and iterates
+// the children of that element searching for an element matching the passed namespace
+// and tag. For each such element that is found, handle is invoked with the matched
+// element and its own surrounding context.
+func NSFindChildrenIterateCtx(ctx NSContext, el *etree.Element, namespace, tag string, handle NSIterHandler) error {
+	err := NSIterateChildren(ctx, el, func(ctx NSContext, el *etree.Element) error {
+		_ctx, err := ctx.SubContext(el)
+		if err != nil {
+			return err
+		}
+
+		currentNS, err := _ctx.LookupPrefix(el.Space)
+		if err != nil {
+			return err
+		}
+
+		// Base case, el is the sought after element.
+		if currentNS == namespace && el.Tag == tag {
+			return handle(ctx, el)
+		}
+
+		return nil
+	})
+
+	if err != nil && err != ErrTraversalHalted {
+		return err
+	}
+
+	return nil
+}
+
+// NSFindOneChild behaves identically to NSFindOneChildCtx, but uses
+// DefaultNSContext for context.
+func NSFindOneChild(el *etree.Element, namespace, tag string) (*etree.Element, error) {
+	return NSFindOneChildCtx(NewDefaultNSContext(), el, namespace, tag)
+}
+
+// NSFindOneCtx conducts a depth-first search for the specified element. If such an
+// element is found a reference to it is returned.
+func NSFindOneChildCtx(ctx NSContext, el *etree.Element, namespace, tag string) (*etree.Element, error) {
+	var found *etree.Element
+
+	err := NSFindChildrenIterateCtx(ctx, el, namespace, tag, func(ctx NSContext, el *etree.Element) error {
+		found = el
+		return ErrTraversalHalted
+	})
+
+	if err != nil && err != ErrTraversalHalted {
+		return nil, err
+	}
+
+	return found, nil
+}
+
+// NSBuildParentContext recurses upward from an element in order to build an NSContext
+// for its immediate parent. If the element has no parent DefaultNSContext
+// is returned.
+func NSBuildParentContext(el *etree.Element) (NSContext, error) {
+	parent := el.Parent()
+	if parent == nil {
+		return NewDefaultNSContext(), nil
+	}
+
+	ctx, err := NSBuildParentContext(parent)
+	if err != nil {
+		return ctx, err
+	}
+
+	return ctx.SubContext(parent)
+}