Auto-quote bare string params in content filter expressions

rmw_fastrtps_shared_cpp/include/rmw_fastrtps_shared_cpp/utils.hpp

@@ -15,8 +15,10 @@
 #ifndef RMW_FASTRTPS_SHARED_CPP__UTILS_HPP_
 #define RMW_FASTRTPS_SHARED_CPP__UTILS_HPP_
 
+#include <cctype>
 #include <mutex>
 #include <string>
+#include <vector>
 
 #include "fastdds/dds/topic/TopicDescription.hpp"
 #include "fastdds/dds/topic/TypeSupport.hpp"
@@ -33,6 +35,59 @@
 namespace rmw_fastrtps_shared_cpp
 {
 
+/// Ensure a content filter parameter is a valid DDS SQL literal.
+///
+/// Fast DDS requires content filter parameters to be parseable as DDS SQL
+/// literals.  Bare strings like "hello" must be wrapped in single quotes to
+/// become valid string literals ('hello'), otherwise
+/// DDSFilterParameter::set_value() fails with a parse error.
+/// See https://github.com/eProsima/Fast-DDS/issues/4199
+inline std::string
+ensure_dds_literal(const std::string & value)
+{
+  if (value.empty()) {
+    return "'" + value + "'";
+  }
+
+  // Already a quoted string
+  if ((value.front() == '\'' || value.front() == '`') && value.size() >= 2 &&
+    value.back() == value.front())
+  {
+    return value;
+  }
+
+  // Boolean literals
+  if (value == "TRUE" || value == "FALSE") {
+    return value;
+  }
+
+  // Numeric: optional leading sign, then digit or dot (covers int, float, hex)
+  const char * p = value.c_str();
+  if (*p == '+' || *p == '-') {
+    ++p;
+  }
+  if (*p == '0' && (*(p + 1) == 'x' || *(p + 1) == 'X')) {
+    return value;  // hex
+  }
+  if (std::isdigit(static_cast<unsigned char>(*p)) || *p == '.') {
+    return value;  // numeric
+  }
+
+  // Not a recognized literal — wrap in single quotes
+  return "'" + value + "'";
+}
+
+/// Convert rmw content filter parameters, auto-quoting bare strings for Fast DDS.
+inline std::vector<std::string>
+prepare_content_filter_parameters(const rmw_subscription_content_filter_options_t * options)
+{
+  std::vector<std::string> expression_parameters;
+  for (size_t i = 0; i < options->expression_parameters.size; ++i) {
+    expression_parameters.push_back(ensure_dds_literal(options->expression_parameters.data[i]));
+  }
+  return expression_parameters;
+}
+
 /**
 * Convert a Fast DDS return code into the corresponding rmw_ret_t
 * \param[in] code The Fast DDS return code to be translated

rmw_fastrtps_shared_cpp/src/rmw_subscription.cpp

@@ -120,10 +120,8 @@ __rmw_subscription_set_content_filter(
       "current subscriber has no content filter topic");
     return RMW_RET_ERROR;
   } else if (filtered_topic && !filter_expression_empty) {
-    std::vector<std::string> expression_parameters;
-    for (size_t i = 0; i < options->expression_parameters.size; ++i) {
-      expression_parameters.push_back(options->expression_parameters.data[i]);
-    }
+    std::vector<std::string> expression_parameters =
+      rmw_fastrtps_shared_cpp::prepare_content_filter_parameters(options);
 
     eprosima::fastdds::dds::ReturnCode_t ret =
       filtered_topic->set_filter_expression(options->filter_expression, expression_parameters);

rmw_fastrtps_shared_cpp/src/utils.cpp

@@ -102,10 +102,7 @@ create_content_filtered_topic(
   const rmw_subscription_content_filter_options_t * options,
   eprosima::fastdds::dds::ContentFilteredTopic ** content_filtered_topic)
 {
-  std::vector<std::string> expression_parameters;
-  for (size_t i = 0; i < options->expression_parameters.size; ++i) {
-    expression_parameters.push_back(options->expression_parameters.data[i]);
-  }
+  std::vector<std::string> expression_parameters = prepare_content_filter_parameters(options);
 
   auto topic = dynamic_cast<eprosima::fastdds::dds::Topic *>(topic_desc);
   static std::atomic<uint32_t> cft_counter{0};

rmw_fastrtps_shared_cpp/test/CMakeLists.txt

@@ -54,3 +54,8 @@ ament_add_gtest(test_logging test_logging.cpp)
 if(TARGET test_logging)
   target_link_libraries(test_logging ${PROJECT_NAME} rmw::rmw)
 endif()
+
+ament_add_gtest(test_ensure_dds_literal test_ensure_dds_literal.cpp)
+if(TARGET test_ensure_dds_literal)
+  target_link_libraries(test_ensure_dds_literal ${PROJECT_NAME} rmw::rmw)
+endif()

rmw_fastrtps_shared_cpp/test/test_ensure_dds_literal.cpp

@@ -0,0 +1,79 @@
+// Copyright 2026 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <gtest/gtest.h>
+
+#include <string>
+
+#include "rmw_fastrtps_shared_cpp/utils.hpp"
+
+using rmw_fastrtps_shared_cpp::ensure_dds_literal;
+
+// Bare strings should be wrapped in single quotes
+TEST(EnsureDdsLiteral, bare_string_gets_quoted)
+{
+  EXPECT_EQ("'hello'", ensure_dds_literal("hello"));
+  EXPECT_EQ("'RED'", ensure_dds_literal("RED"));
+  EXPECT_EQ("'some value'", ensure_dds_literal("some value"));
+}
+
+// Already single-quoted strings should pass through unchanged
+TEST(EnsureDdsLiteral, already_single_quoted)
+{
+  EXPECT_EQ("'hello'", ensure_dds_literal("'hello'"));
+  EXPECT_EQ("'with spaces'", ensure_dds_literal("'with spaces'"));
+}
+
+// Backtick-quoted strings should pass through unchanged
+TEST(EnsureDdsLiteral, already_backtick_quoted)
+{
+  EXPECT_EQ("`hello`", ensure_dds_literal("`hello`"));
+}
+
+// Boolean literals should pass through unchanged
+TEST(EnsureDdsLiteral, boolean_literals)
+{
+  EXPECT_EQ("TRUE", ensure_dds_literal("TRUE"));
+  EXPECT_EQ("FALSE", ensure_dds_literal("FALSE"));
+}
+
+// Integer literals should pass through unchanged
+TEST(EnsureDdsLiteral, integer_literals)
+{
+  EXPECT_EQ("42", ensure_dds_literal("42"));
+  EXPECT_EQ("0", ensure_dds_literal("0"));
+  EXPECT_EQ("-1", ensure_dds_literal("-1"));
+  EXPECT_EQ("+5", ensure_dds_literal("+5"));
+}
+
+// Float literals should pass through unchanged
+TEST(EnsureDdsLiteral, float_literals)
+{
+  EXPECT_EQ("3.14", ensure_dds_literal("3.14"));
+  EXPECT_EQ(".5", ensure_dds_literal(".5"));
+  EXPECT_EQ("-0.1", ensure_dds_literal("-0.1"));
+}
+
+// Hex literals should pass through unchanged
+TEST(EnsureDdsLiteral, hex_literals)
+{
+  EXPECT_EQ("0xFF", ensure_dds_literal("0xFF"));
+  EXPECT_EQ("0X1A", ensure_dds_literal("0X1A"));
+}
+
+// Empty string should be quoted
+TEST(EnsureDdsLiteral, empty_string)
+{
+  EXPECT_EQ("''", ensure_dds_literal(""));
+}