[22438] Arithmetic overflow in fragment size calculations

src/cpp/rtps/history/WriterHistory.cpp

@@ -484,9 +484,16 @@ void WriterHistory::set_fragments(
     // If inlineqos for related_sample_identity is required, then remove its size from the final fragment size.
     if (0 < inline_qos_size)
     {
-        final_high_mark_for_frag -= (
-            fastdds::dds::ParameterSerializer<Parameter_t>::PARAMETER_SENTINEL_SIZE +
-            inline_qos_size);
+        uint32_t overhead = fastdds::dds::ParameterSerializer<Parameter_t>::PARAMETER_SENTINEL_SIZE + inline_qos_size;
+        constexpr uint32_t min_fragment_size = 4;
+        if (final_high_mark_for_frag < (overhead + min_fragment_size))
+        {
+            final_high_mark_for_frag = min_fragment_size;
+        }
+        else
+        {
+            final_high_mark_for_frag -= overhead;
+        }
     }
 
     // If it is big data, fragment it.

src/cpp/rtps/participant/RTPSParticipantImpl.cpp

@@ -2320,20 +2320,22 @@ uint32_t RTPSParticipantImpl::getMaxDataSize()
 uint32_t RTPSParticipantImpl::calculateMaxDataSize(
         uint32_t length)
 {
-    uint32_t maxDataSize = length;
-
+    // RTPS header
+    uint32_t overhead = RTPSMESSAGE_HEADER_SIZE;
 #if HAVE_SECURITY
     // If there is rtps messsage protection, reduce max size for messages,
     // because extra data is added on encryption.
     if (security_attributes_.is_rtps_protected)
     {
-        maxDataSize -= m_security_manager.calculate_extra_size_for_rtps_message();
+        overhead += m_security_manager.calculate_extra_size_for_rtps_message();
     }
 #endif // if HAVE_SECURITY
 
-    // RTPS header
-    maxDataSize -= RTPSMESSAGE_HEADER_SIZE;
-    return maxDataSize;
+    if (length <= overhead)
+    {
+        return 0;
+    }
+    return length - overhead;
 }
 
 bool RTPSParticipantImpl::networkFactoryHasRegisteredTransports() const

src/cpp/rtps/writer/BaseWriter.cpp

@@ -189,30 +189,38 @@ uint32_t BaseWriter::calculate_max_payload_size(
     constexpr uint32_t heartbeat_message_length = 32;
 
     uint32_t max_data_size = mp_RTPSParticipant->calculateMaxDataSize(datagram_length);
-
-    max_data_size -= info_dst_message_length +
+    uint32_t overhead = info_dst_message_length +
             info_ts_message_length +
             data_frag_submessage_header_length +
             heartbeat_message_length;
 
-    //TODO(Ricardo) inlineqos in future.
-
 #if HAVE_SECURITY
     if (getAttributes().security_attributes().is_submessage_protected)
     {
-        max_data_size -= mp_RTPSParticipant->security_manager().calculate_extra_size_for_rtps_submessage(m_guid);
+        overhead += mp_RTPSParticipant->security_manager().calculate_extra_size_for_rtps_submessage(m_guid);
     }
 
     if (getAttributes().security_attributes().is_payload_protected)
     {
-        max_data_size -= mp_RTPSParticipant->security_manager().calculate_extra_size_for_encoded_payload(m_guid);
+        overhead += mp_RTPSParticipant->security_manager().calculate_extra_size_for_encoded_payload(m_guid);
     }
 #endif // if HAVE_SECURITY
 
 #ifdef FASTDDS_STATISTICS
-    max_data_size -= eprosima::fastdds::statistics::rtps::statistics_submessage_length;
+    overhead += eprosima::fastdds::statistics::rtps::statistics_submessage_length;
 #endif // FASTDDS_STATISTICS
 
+    constexpr uint32_t min_fragment_size = 4;
+    if ((overhead + min_fragment_size) > max_data_size)
+    {
+        auto min_datagram_length = overhead + min_fragment_size + 1 + (datagram_length - max_data_size);
+        EPROSIMA_LOG_ERROR(RTPS_WRITER, "Datagram length '" << datagram_length << "' is too small." <<
+                "At least " << min_datagram_length << " bytes are needed to send a message. Fixing fragments to " <<
+                min_fragment_size << " bytes.");
+        return min_fragment_size;
+    }
+
+    max_data_size -= overhead;
     return max_data_size;
 }
 

test/blackbox/common/DDSBlackboxTestsListeners.cpp

@@ -2984,7 +2984,7 @@ TEST(DDSStatus, sample_rejected_waitset)
             .disable_heartbeat_piggyback(true)
             .asynchronously(eprosima::fastdds::dds::PublishModeQosPolicyKind::ASYNCHRONOUS_PUBLISH_MODE)
             .add_flow_controller_descriptor_to_pparams( // Be sure are sent in separate submessage each DATA.
-        eprosima::fastdds::rtps::FlowControllerSchedulerPolicy::FIFO, 100, 50)
+        eprosima::fastdds::rtps::FlowControllerSchedulerPolicy::FIFO, 300, 300) // Be sure the first message is processed before sending the second.
             .init();
 
     reader.history_kind(eprosima::fastdds::dds::KEEP_ALL_HISTORY_QOS)

test/unittest/rtps/history/CMakeLists.txt

@@ -76,6 +76,8 @@ set(TOPICPAYLOADPOOLTESTS_SOURCE
     ${PROJECT_SOURCE_DIR}/src/cpp/utils/IPLocator.cpp
     ${PROJECT_SOURCE_DIR}/src/cpp/utils/SystemInfo.cpp)
 
+set(WRITERHISTORYTESTS_SOURCE WriterHistoryTests.cpp)
+
 if(WIN32)
     add_definitions(-D_WIN32_WINNT=0x0601)
 endif()
@@ -164,3 +166,20 @@ target_link_libraries(TopicPayloadPoolTests
     GTest::gtest
     ${CMAKE_DL_LIBS})
 gtest_discover_tests(TopicPayloadPoolTests)
+
+
+
+add_executable(WriterHistoryTests ${WRITERHISTORYTESTS_SOURCE})
+target_compile_definitions(WriterHistoryTests PRIVATE
+    BOOST_ASIO_STANDALONE
+    ASIO_STANDALONE
+    $<$<AND:$<NOT:$<BOOL:${WIN32}>>,$<STREQUAL:"${CMAKE_BUILD_TYPE}","Debug">>:__DEBUG>
+    $<$<BOOL:${INTERNAL_DEBUG}>:__INTERNALDEBUG> # Internal debug activated.
+    )
+target_link_libraries(WriterHistoryTests 
+    fastcdr 
+    fastdds
+    foonathan_memory
+    GTest::gtest
+    ${CMAKE_DL_LIBS})
+gtest_discover_tests(WriterHistoryTests)

test/unittest/rtps/history/WriterHistoryTests.cpp

@@ -0,0 +1,119 @@
+// Copyright 2020 Proyectos y Sistemas de Mantenimiento SL (eProsima).
+//
+// 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 <fastdds/rtps/RTPSDomain.hpp>
+#include <fastdds/rtps/participant/RTPSParticipant.hpp>
+#include <fastdds/rtps/writer/RTPSWriter.hpp>
+#include <fastdds/rtps/history/IPayloadPool.hpp>
+#include <fastdds/rtps/history/WriterHistory.hpp>
+
+
+namespace eprosima {
+namespace fastdds {
+namespace rtps {
+
+using namespace testing;
+
+#define MAX_MESSAGE_SIZE 300
+
+void cache_change_fragment(
+        uint32_t max_message_size,
+        uint32_t inline_qos_length,
+        bool expected_fragmentation)
+{
+    uint32_t domain_id = 0;
+    uint32_t initial_reserved_caches = 10;
+    std::string max_message_size_str = std::to_string(max_message_size);
+
+    RTPSParticipantAttributes p_attr;
+    p_attr.properties.properties().emplace_back("fastdds.max_message_size", max_message_size_str);
+    RTPSParticipant* participant = RTPSDomain::createParticipant(
+        domain_id, true, p_attr);
+
+    ASSERT_NE(participant, nullptr);
+
+    HistoryAttributes h_attr;
+    h_attr.memoryPolicy = DYNAMIC_RESERVE_MEMORY_MODE;
+    h_attr.initialReservedCaches = initial_reserved_caches;
+    h_attr.payloadMaxSize = 250;
+    WriterHistory* history = new WriterHistory(h_attr);
+
+    WriterAttributes w_attr;
+    RTPSWriter* writer = RTPSDomain::createRTPSWriter(participant, w_attr, history);
+
+    ASSERT_NE(writer, nullptr);
+
+    CacheChange_t* change = history->create_change(ALIVE);
+    if (expected_fragmentation)
+    {
+        change->serializedPayload.length = 3 * max_message_size;
+    }
+    else
+    {
+        change->serializedPayload.length = max_message_size / 3;
+    }
+    change->inline_qos.length = inline_qos_length;
+    history->add_change(change);
+
+    auto result = change->getFragmentSize();
+    std::cout << "Fragment size: " << result << std::endl;
+    if (expected_fragmentation)
+    {
+        ASSERT_NE(result, 0);
+    }
+    else
+    {
+        ASSERT_EQ(result, 0);
+    }
+}
+
+/**
+ * This test checks the get_max_allowed_payload_size() method of the BaseWriter class.
+ * When setting the RTPS Participant Attribute property fastdds.max_message_size to a value lower than the
+ * message overhead, if the method does not overflow the fragment size will be set.
+ * If the max_message_size is big enough for the overhead, inline_qos and serializedPayload,
+ * then no fragmentation will occur.
+ */
+TEST(WriterHistoryTests, get_max_allowed_payload_size_overflow)
+{
+    cache_change_fragment(100, 0, true);
+    cache_change_fragment(MAX_MESSAGE_SIZE, 0, false);
+}
+
+/**
+ * This test checks the fragment size calculation for a cache change depending on the inline qos length.
+ * The change.serializedPayload.length is set to 3 times the max_allowed_payload_size, so the fragment size should always be set.
+ * In case of an overflow in the attribute high_mark_for_frag_ the fragment size will not be set, which is an error.
+ */
+TEST(WriterHistoryTests, final_high_mark_for_frag_overflow)
+{
+    for (uint32_t inline_qos_length = 0; inline_qos_length < MAX_MESSAGE_SIZE; inline_qos_length += 40)
+    {
+        cache_change_fragment(MAX_MESSAGE_SIZE, inline_qos_length, true);
+    }
+}
+
+} // namespace rtps
+} // namespace fastdds
+} // namespace eprosima
+
+int main(
+        int argc,
+        char** argv)
+{
+    testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}