Minor fixes to SNIP client and SNIP handler: (#600)

- Adds proper shutdown to SNIP client. This is needed for unittesting purposes.
- Fixes crashing bug in SNIP client when returned payload is empty.
- Moves SNIP handler's static descriptor to a separate compilation unit to avoid
  it being unexpectedly linked into binaries. This is not only flash space wasted,
  but also presents an unexpected dependency on SNIP_DYNAMIC_FILENAME being available.

src/openlcb/SNIPClient.hxx

@@ -39,6 +39,7 @@
 #include "executor/CallableFlow.hxx"
 #include "openlcb/Defs.hxx"
 #include "openlcb/If.hxx"
+#include "os/sleep.h"
 
 namespace openlcb
 {
@@ -88,6 +89,17 @@ public:
     {
     }
 
+    /// Flushes the pending timed operations.
+    void shutdown()
+    {
+        while (!is_waiting())
+        {
+            service()->executor()->sync_run(
+                [this]() { timer_.ensure_triggered(); });
+            microsleep(500);
+        }
+    }
+
     Action entry() override
     {
         request()->resultCode = SNIPClientRequest::OPERATION_PENDING;

src/openlcb/SimpleNodeInfo.cxx

@@ -43,24 +43,6 @@ namespace openlcb
 extern const SimpleNodeStaticValues __attribute__((weak)) SNIP_STATIC_DATA = {
     4, "OpenMRN", "Undefined model", "Undefined HW version", "0.9"};
 
-const SimpleInfoDescriptor SNIPHandler::SNIP_RESPONSE[] = {
-    {SimpleInfoDescriptor::LITERAL_BYTE, 4, 0, nullptr},
-    {SimpleInfoDescriptor::C_STRING, 0, 0, SNIP_STATIC_DATA.manufacturer_name},
-    {SimpleInfoDescriptor::C_STRING, 0, 0, SNIP_STATIC_DATA.model_name},
-    {SimpleInfoDescriptor::C_STRING, 0, 0, SNIP_STATIC_DATA.hardware_version},
-    {SimpleInfoDescriptor::C_STRING, 0, 0, SNIP_STATIC_DATA.software_version},
-#if OPENMRN_HAVE_POSIX_FD
-    {SimpleInfoDescriptor::FILE_LITERAL_BYTE, 2, 0, SNIP_DYNAMIC_FILENAME},
-    {SimpleInfoDescriptor::FILE_C_STRING, 63, 1, SNIP_DYNAMIC_FILENAME},
-    {SimpleInfoDescriptor::FILE_C_STRING, 64, 64, SNIP_DYNAMIC_FILENAME},
-#else
-    /// @todo(balazs.racz) Add eeprom support to arduino.
-    {SimpleInfoDescriptor::LITERAL_BYTE, 2, 0, nullptr},
-    {SimpleInfoDescriptor::LITERAL_BYTE, 0, 0, nullptr},
-    {SimpleInfoDescriptor::LITERAL_BYTE, 0, 0, nullptr},
-#endif
-    {SimpleInfoDescriptor::END_OF_DATA, 0, 0, 0}};
-
 void init_snip_user_file(int fd, const char *user_name,
                          const char *user_description)
 {
@@ -86,7 +68,7 @@ void init_snip_user_file(int fd, const char *user_name,
 }
 
 static size_t find_string_at(const openlcb::Payload& payload, size_t start_pos, string* output) {
-    if (start_pos == string::npos) {
+    if (start_pos >= payload.size()) {
         output->clear();
         return start_pos;
     }
@@ -103,6 +85,10 @@ void decode_snip_response(
     const openlcb::Payload &payload, SnipDecodedData *output)
 {
     output->clear();
+    if (payload.empty())
+    {
+        return;
+    }
     char sys_ver = payload[0];
     size_t pos = 1;
     pos = find_string_at(payload, pos, &output->manufacturer_name);

src/openlcb/SimpleNodeInfoResponse.cxx

@@ -0,0 +1,58 @@
+/** \copyright
+ * Copyright (c) 2022, Balazs Racz
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are  permitted provided that the following conditions are met:
+ *
+ *  - Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  - Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * \file SimpleNodeInfoResponse.cxx
+ *
+ * Response descriptor for the Simple Node Ident Info protocol handler.
+ *
+ * @author Balazs Racz
+ * @date 3 Jan 2022
+ */
+
+#include "openlcb/SimpleNodeInfo.hxx"
+
+namespace openlcb
+{
+
+const SimpleInfoDescriptor SNIPHandler::SNIP_RESPONSE[] = {
+    {SimpleInfoDescriptor::LITERAL_BYTE, 4, 0, nullptr},
+    {SimpleInfoDescriptor::C_STRING, 0, 0, SNIP_STATIC_DATA.manufacturer_name},
+    {SimpleInfoDescriptor::C_STRING, 0, 0, SNIP_STATIC_DATA.model_name},
+    {SimpleInfoDescriptor::C_STRING, 0, 0, SNIP_STATIC_DATA.hardware_version},
+    {SimpleInfoDescriptor::C_STRING, 0, 0, SNIP_STATIC_DATA.software_version},
+#if OPENMRN_HAVE_POSIX_FD
+    {SimpleInfoDescriptor::FILE_LITERAL_BYTE, 2, 0, SNIP_DYNAMIC_FILENAME},
+    {SimpleInfoDescriptor::FILE_C_STRING, 63, 1, SNIP_DYNAMIC_FILENAME},
+    {SimpleInfoDescriptor::FILE_C_STRING, 64, 64, SNIP_DYNAMIC_FILENAME},
+#else
+    /// @todo(balazs.racz) Add eeprom support to arduino.
+    {SimpleInfoDescriptor::LITERAL_BYTE, 2, 0, nullptr},
+    {SimpleInfoDescriptor::LITERAL_BYTE, 0, 0, nullptr},
+    {SimpleInfoDescriptor::LITERAL_BYTE, 0, 0, nullptr},
+#endif
+    {SimpleInfoDescriptor::END_OF_DATA, 0, 0, 0}};
+
+}

src/openlcb/sources

@@ -39,6 +39,7 @@ CXXSRCS += \
            DatagramTcp.cxx \
            MemoryConfig.cxx \
            SimpleNodeInfo.cxx \
+           SimpleNodeInfoResponse.cxx \
            SimpleNodeInfoMockUserFile.cxx \
            SimpleStack.cxx \
            TractionTestTrain.cxx \