Escape JSONP breaking characters

src/main/java/com/fasterxml/jackson/databind/util/JSONPObject.java

@@ -4,6 +4,7 @@
 
 import com.fasterxml.jackson.core.*;
 
+import com.fasterxml.jackson.core.io.CharacterEscapes;
 import com.fasterxml.jackson.databind.*;
 import com.fasterxml.jackson.databind.jsontype.TypeSerializer;
 
@@ -66,18 +67,31 @@ public void serializeWithType(JsonGenerator jgen, SerializerProvider provider, T
     public void serialize(JsonGenerator jgen, SerializerProvider provider)
             throws IOException, JsonProcessingException
     {
-        // First, wrapping:
-        jgen.writeRaw(_function);
-        jgen.writeRaw('(');
-        if (_value == null) {
-            provider.defaultSerializeNull(jgen);
-        } else if (_serializationType != null) {
-            provider.findTypedValueSerializer(_serializationType, true, null).serialize(_value, jgen, provider);
-        } else {
-            Class<?> cls = _value.getClass();
-            provider.findTypedValueSerializer(cls, true, null).serialize(_value, jgen, provider);
+        CharacterEscapes currentCharacterEscapes = jgen.getCharacterEscapes();
+
+        // NOTE: Escape line-separator characters that break JSONP only if no custom character escapes are set.
+        // If custom escapes are in place JSONP-breaking characters will not be escaped and it is recommended to
+        // add escaping for those (see JsonpCharacterEscapes class).
+        if (currentCharacterEscapes == null) {
+            jgen.setCharacterEscapes(JsonpCharacterEscapes.instance());
+        }
+
+        try {
+            // First, wrapping:
+            jgen.writeRaw(_function);
+            jgen.writeRaw('(');
+            if (_value == null) {
+                provider.defaultSerializeNull(jgen);
+            } else if (_serializationType != null) {
+                provider.findTypedValueSerializer(_serializationType, true, null).serialize(_value, jgen, provider);
+            } else {
+                Class<?> cls = _value.getClass();
+                provider.findTypedValueSerializer(cls, true, null).serialize(_value, jgen, provider);
+            }
+            jgen.writeRaw(')');
+        } finally {
+            jgen.setCharacterEscapes(currentCharacterEscapes);
         }
-        jgen.writeRaw(')');
     }
 
     /*

src/test/java/com/fasterxml/jackson/databind/util/JSONPObjectTest.java

@@ -0,0 +1,37 @@
+package com.fasterxml.jackson.databind.util;
+
+import java.io.IOException;
+
+import com.fasterxml.jackson.databind.BaseMapTest;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+public class JSONPObjectTest extends BaseMapTest {
+
+  private final String CALLBACK = "callback";
+  private final ObjectMapper MAPPER = new ObjectMapper();
+
+  /**
+   * Unit tests for checking that JSONP breaking characters U+2028 and U+2029 are escaped when creating a {@link JSONPObject}.
+   */
+
+  public void testU2028Escaped() throws IOException {
+    String containsU2028 = String.format("This string contains %c char", '\u2028');
+    JSONPObject jsonpObject = new JSONPObject(CALLBACK, containsU2028);
+    String valueAsString = MAPPER.writeValueAsString(jsonpObject);
+    assertFalse(valueAsString.contains("\u2028"));
+  }
+
+  public void testU2029Escaped() throws IOException {
+    String containsU2029 = String.format("This string contains %c char", '\u2029');
+    JSONPObject jsonpObject = new JSONPObject(CALLBACK, containsU2029);
+    String valueAsString = MAPPER.writeValueAsString(jsonpObject);
+    assertFalse(valueAsString.contains("\u2029"));
+  }
+
+  public void testU2030NotEscaped() throws IOException {
+    String containsU2030 = String.format("This string contains %c char", '\u2030');
+    JSONPObject jsonpObject = new JSONPObject(CALLBACK, containsU2030);
+    String valueAsString = MAPPER.writeValueAsString(jsonpObject);
+    assertTrue(valueAsString.contains("\u2030"));
+  }
+}