lib/protocol: Handle slashified paths in IsEncryptedParent (fixes #7184) (#7187)

lib/protocol/encryption.go

@@ -538,9 +538,8 @@ func IsEncryptedParent(path string) bool {
 }
 
 func isEncryptedParentFromComponents(pathComponents []string) bool {
-	if l := len(pathComponents); l > 2 {
-		return false
-	} else if l == 2 && len(pathComponents[1]) != 2 {
+	l := len(pathComponents)
+	if l == 2 && len(pathComponents[1]) != 2 {
 		return false
 	} else if l == 0 {
 		return false
@@ -548,5 +547,16 @@ func isEncryptedParentFromComponents(pathComponents []string) bool {
 	if len(pathComponents[0]) == 0 {
 		return false
 	}
-	return pathComponents[0][1:] == encryptedDirExtension
+	if pathComponents[0][1:] != encryptedDirExtension {
+		return false
+	}
+	if l < 2 {
+		return true
+	}
+	for _, comp := range pathComponents[2:] {
+		if len(comp) != maxPathComponent {
+			return false
+		}
+	}
+	return true
 }

lib/protocol/encryption_test.go

@@ -11,6 +11,8 @@ import (
 	"reflect"
 	"strings"
 	"testing"
+
+	"github.com/syncthing/syncthing/lib/rand"
 )
 
 func TestEnDecryptName(t *testing.T) {
@@ -97,6 +99,7 @@ func TestEnDecryptFileInfo(t *testing.T) {
 }
 
 func TestIsEncryptedParent(t *testing.T) {
+	comp := rand.String(maxPathComponent)
 	cases := []struct {
 		path string
 		is   bool
@@ -111,6 +114,10 @@ func TestIsEncryptedParent(t *testing.T) {
 		{"1" + encryptedDirExtension + "/bcd", false},
 		{"1" + encryptedDirExtension + "/bc/foo", false},
 		{"1.12/22", false},
+		{"1" + encryptedDirExtension + "/bc/" + comp, true},
+		{"1" + encryptedDirExtension + "/bc/" + comp + "/" + comp, true},
+		{"1" + encryptedDirExtension + "/bc/" + comp + "a", false},
+		{"1" + encryptedDirExtension + "/bc/" + comp + "/a/" + comp, false},
 	}
 	for _, tc := range cases {
 		if res := IsEncryptedParent(tc.path); res != tc.is {