Add comparison methods for DN/RDN/AttributeTypeAndValue

dn.go

@@ -175,3 +175,70 @@ func ParseDN(str string) (*DN, error) {
 	}
 	return dn, nil
 }
+
+// Equal returns true if the DNs are equal as defined by rfc4517 4.2.15 (distinguishedNameMatch).
+// Returns true if they have the same number of relative distinguished names
+// and corresponding relative distinguished names (by position) are the same.
+func (d *DN) Equal(other *DN) bool {
+	if len(d.RDNs) != len(other.RDNs) {
+		return false
+	}
+	for i := range d.RDNs {
+		if !d.RDNs[i].Equal(other.RDNs[i]) {
+			return false
+		}
+	}
+	return true
+}
+
+// AncestorOf returns true if the other DN consists of at least one RDN followed by all the RDNs of the current DN.
+// "ou=widgets,o=acme.com" is an ancestor of "ou=sprockets,ou=widgets,o=acme.com"
+// "ou=widgets,o=acme.com" is not an ancestor of "ou=sprockets,ou=widgets,o=foo.com"
+// "ou=widgets,o=acme.com" is not an ancestor of "ou=widgets,o=acme.com"
+func (d *DN) AncestorOf(other *DN) bool {
+	if len(d.RDNs) >= len(other.RDNs) {
+		return false
+	}
+	// Take the last `len(d.RDNs)` RDNs from the other DN to compare against
+	otherRDNs := other.RDNs[len(other.RDNs)-len(d.RDNs):]
+	for i := range d.RDNs {
+		if !d.RDNs[i].Equal(otherRDNs[i]) {
+			return false
+		}
+	}
+	return true
+}
+
+// Equal returns true if the RelativeDNs are equal as defined by rfc4517 4.2.15 (distinguishedNameMatch).
+// Relative distinguished names are the same if and only if they have the same number of AttributeTypeAndValues
+// and each attribute of the first RDN is the same as the attribute of the second RDN with the same attribute type.
+// The order of attributes is not significant.
+// Case of attribute types is not significant.
+func (r *RelativeDN) Equal(other *RelativeDN) bool {
+	if len(r.Attributes) != len(other.Attributes) {
+		return false
+	}
+	return r.hasAllAttributes(other.Attributes) && other.hasAllAttributes(r.Attributes)
+}
+
+func (r *RelativeDN) hasAllAttributes(attrs []*AttributeTypeAndValue) bool {
+	for _, attr := range attrs {
+		found := false
+		for _, myattr := range r.Attributes {
+			if myattr.Equal(attr) {
+				found = true
+				break
+			}
+		}
+		if !found {
+			return false
+		}
+	}
+	return true
+}
+
+// Equal returns true if the AttributeTypeAndValue is equivalent to the specified AttributeTypeAndValue
+// Case of the attribute type is not significant
+func (a *AttributeTypeAndValue) Equal(other *AttributeTypeAndValue) bool {
+	return strings.EqualFold(a.Type, other.Type) && a.Value == other.Value
+}

dn_test.go

@@ -91,3 +91,119 @@ func TestErrorDNParsing(t *testing.T) {
 		}
 	}
 }
+
+func TestDNEqual(t *testing.T) {
+	testcases := []struct {
+		A     string
+		B     string
+		Equal bool
+	}{
+		// Exact match
+		{"", "", true},
+		{"o=A", "o=A", true},
+		{"o=A", "o=B", false},
+
+		{"o=A,o=B", "o=A,o=B", true},
+		{"o=A,o=B", "o=A,o=C", false},
+
+		{"o=A+o=B", "o=A+o=B", true},
+		{"o=A+o=B", "o=A+o=C", false},
+
+		// Case mismatch in type is ignored
+		{"o=A", "O=A", true},
+		{"o=A,o=B", "o=A,O=B", true},
+		{"o=A+o=B", "o=A+O=B", true},
+
+		// Case mismatch in value is significant
+		{"o=a", "O=A", false},
+		{"o=a,o=B", "o=A,O=B", false},
+		{"o=a+o=B", "o=A+O=B", false},
+
+		// Multi-valued RDN order mismatch is ignored
+		{"o=A+o=B", "O=B+o=A", true},
+		// Number of RDN attributes is significant
+		{"o=A+o=B", "O=B+o=A+O=B", false},
+
+		// Missing values are significant
+		{"o=A+o=B", "O=B+o=A+O=C", false}, // missing values matter
+		{"o=A+o=B+o=C", "O=B+o=A", false}, // missing values matter
+
+		// Whitespace tests
+		// Matching
+		{
+			"cn=John Doe, ou=People, dc=sun.com",
+			"cn=John Doe, ou=People, dc=sun.com",
+			true,
+		},
+		// Difference in leading/trailing chars is ignored
+		{
+			"cn=John Doe, ou=People, dc=sun.com",
+			"cn=John Doe,ou=People,dc=sun.com",
+			true,
+		},
+		// Difference in values is significant
+		{
+			"cn=John Doe, ou=People, dc=sun.com",
+			"cn=John  Doe, ou=People, dc=sun.com",
+			false,
+		},
+	}
+
+	for i, tc := range testcases {
+		a, err := ldap.ParseDN(tc.A)
+		if err != nil {
+			t.Errorf("%d: %v", i, err)
+			continue
+		}
+		b, err := ldap.ParseDN(tc.B)
+		if err != nil {
+			t.Errorf("%d: %v", i, err)
+			continue
+		}
+		if expected, actual := tc.Equal, a.Equal(b); expected != actual {
+			t.Errorf("%d: when comparing '%s' and '%s' expected %v, got %v", i, tc.A, tc.B, expected, actual)
+			continue
+		}
+		if expected, actual := tc.Equal, b.Equal(a); expected != actual {
+			t.Errorf("%d: when comparing '%s' and '%s' expected %v, got %v", i, tc.A, tc.B, expected, actual)
+			continue
+		}
+	}
+}
+
+func TestDNAncestor(t *testing.T) {
+	testcases := []struct {
+		A        string
+		B        string
+		Ancestor bool
+	}{
+		// Exact match returns false
+		{"", "", false},
+		{"o=A", "o=A", false},
+		{"o=A,o=B", "o=A,o=B", false},
+		{"o=A+o=B", "o=A+o=B", false},
+
+		// Mismatch
+		{"ou=C,ou=B,o=A", "ou=E,ou=D,ou=B,o=A", false},
+
+		// Descendant
+		{"ou=C,ou=B,o=A", "ou=E,ou=C,ou=B,o=A", true},
+	}
+
+	for i, tc := range testcases {
+		a, err := ldap.ParseDN(tc.A)
+		if err != nil {
+			t.Errorf("%d: %v", i, err)
+			continue
+		}
+		b, err := ldap.ParseDN(tc.B)
+		if err != nil {
+			t.Errorf("%d: %v", i, err)
+			continue
+		}
+		if expected, actual := tc.Ancestor, a.AncestorOf(b); expected != actual {
+			t.Errorf("%d: when comparing '%s' and '%s' expected %v, got %v", i, tc.A, tc.B, expected, actual)
+			continue
+		}
+	}
+}