Allow putting signatures into existing field deep in the hierarchy

DEVSIX-3717

Author: Vitali Prudnikovich

sign/src/main/java/com/itextpdf/signatures/PdfSigner.java

@@ -381,15 +381,10 @@ public String getNewSigFieldName() {
      */
     public void setFieldName(String fieldName) {
         if (fieldName != null) {
-            if (fieldName.indexOf('.') >= 0) {
-                throw new IllegalArgumentException(SignExceptionMessageConstant.FIELD_NAMES_CANNOT_CONTAIN_A_DOT);
-            }
-
             PdfAcroForm acroForm = PdfAcroForm.getAcroForm(document, true);
 
-            if (acroForm.getField(fieldName) != null) {
-                PdfFormField field = acroForm.getField(fieldName);
-
+            PdfFormField field = acroForm.getField(fieldName);
+            if (field != null) {
                 if (!PdfName.Sig.equals(field.getFormType())) {
                     throw new IllegalArgumentException(
                             SignExceptionMessageConstant.FIELD_TYPE_IS_NOT_A_SIGNATURE_FIELD_TYPE);
@@ -407,6 +402,12 @@ public void setFieldName(String fieldName) {
                     appearance.setPageRect(getWidgetRectangle(widget));
                     appearance.setPageNumber(getWidgetPageNumber(widget));
                 }
+            } else {
+                // Do not allow dots for new fields
+                // For existing fields dots are allowed because there it might be fully qualified name
+                if (fieldName.indexOf('.') >= 0) {
+                    throw new IllegalArgumentException(SignExceptionMessageConstant.FIELD_NAMES_CANNOT_CONTAIN_A_DOT);
+                }
             }
 
             this.fieldName = fieldName;

sign/src/test/java/com/itextpdf/signatures/sign/SimpleSigningTest.java

@@ -122,6 +122,23 @@ public void signWithoutPKeyTest() throws GeneralSecurityException, IOException,
         Assert.assertNull(SignaturesCompareTool.compareSignatures(outPdf, cmpPdf));
     }
 
+    @Test
+    public void signIntoExistingFieldWithDotsTest() throws GeneralSecurityException, IOException, InterruptedException {
+        String srcFile = SOURCE_FOLDER + "signIntoExistingFieldWithDots.pdf";
+        String cmpPdf = SOURCE_FOLDER + "cmp_signIntoExistingFieldWithDots.pdf";
+        String outPdf = DESTINATION_FOLDER + "signIntoExistingFieldWithDots.pdf";
+
+        Rectangle randomRect = new Rectangle(1, 1, 100, 100);
+        String fieldName = "Signature1.1";
+        sign(srcFile, fieldName, outPdf, chain, pk, DigestAlgorithms.SHA256, PdfSigner.CryptoStandard.CADES, "Test 1",
+                "TestCity", randomRect, false, false, PdfSigner.NOT_CERTIFIED, 12f);
+
+        Assert.assertNull(new CompareTool().compareVisually(outPdf, cmpPdf, DESTINATION_FOLDER, "diff_",
+                getTestMap(new Rectangle(163, 128, 430, 202))));
+
+        Assert.assertNull(SignaturesCompareTool.compareSignatures(outPdf, cmpPdf));
+    }
+
     @Test
     public void signWithTempFileTest() throws GeneralSecurityException, IOException, InterruptedException {
         String srcFile = SOURCE_FOLDER + "simpleDocument.pdf";