Supporting pseudo forwarding encapsulated session in client apps.

client/app/common/AppClient.cpp

@@ -22,6 +22,16 @@ namespace cc_mqttsn_client_app
 namespace 
 {
 
+const std::uint8_t FwdEncMsgType = 0xfe;
+
+enum FwdEncOffset : unsigned
+{
+    FwdEncOffset_Length = 0,
+    FwdEncOffset_MsgType = 1U,
+    FwdEncOffset_Ctrl = 2U,
+    FwdEncOffset_NodeId = 3U,
+};    
+
 AppClient* asThis(void* data)
 {
     return reinterpret_cast<AppClient*>(data);
@@ -92,6 +102,16 @@ bool AppClient::start(int argc, const char* argv[])
         return true;
     }
 
+    auto fwdEncNodeId = parseBinaryData(m_opts.fwdEncNodeId());
+    if (!fwdEncNodeId.empty()) {
+        auto prefixLen = FwdEncOffset_NodeId + fwdEncNodeId.size();
+        m_fwdEncPrefix.resize(prefixLen);
+        m_fwdEncPrefix[FwdEncOffset_Length] = static_cast<std::uint8_t>(prefixLen);
+        m_fwdEncPrefix[FwdEncOffset_MsgType] = FwdEncMsgType;
+        m_fwdEncPrefix[FwdEncOffset_Ctrl] = 0U;
+        std::copy(fwdEncNodeId.begin(), fwdEncNodeId.end(), &m_fwdEncPrefix[FwdEncOffset_NodeId]);
+    }    
+
     if (!createSession()) {
         return false;
     }
@@ -445,7 +465,16 @@ unsigned AppClient::cancelNextTickWaitInternal()
 void AppClient::sendDataInternal(const unsigned char* buf, unsigned bufLen, unsigned broadcastRadius)
 {
     assert(m_session);
-    m_session->sendData(buf, bufLen, broadcastRadius);
+    if (m_fwdEncPrefix.empty()) {
+        m_session->sendData(buf, bufLen, broadcastRadius);
+        return;
+    }
+
+    std::vector<std::uint8_t> encData;
+    encData.reserve(m_fwdEncPrefix.size() + bufLen);
+    encData.insert(encData.end(), m_fwdEncPrefix.begin(), m_fwdEncPrefix.end());
+    encData.insert(encData.end(), buf, buf + bufLen);
+    m_session->sendData(encData.data(), encData.size(), broadcastRadius);    
 }
 
 bool AppClient::createSession()
@@ -461,7 +490,30 @@ bool AppClient::createSession()
         {
             assert(m_client);
             m_lastAddr = addr;
-            ::cc_mqttsn_client_process_data(m_client.get(), buf, static_cast<unsigned>(bufLen), origin);
+
+            if (m_fwdEncPrefix.empty()) {            
+                ::cc_mqttsn_client_process_data(m_client.get(), buf, static_cast<unsigned>(bufLen), origin);
+                return;
+            }
+
+            do {
+                if (bufLen <= m_fwdEncPrefix.size()) {
+                    break;
+                }
+
+                if (!std::equal(m_fwdEncPrefix.begin(), m_fwdEncPrefix.begin() + FwdEncOffset_Ctrl, buf)) {
+                    break;
+                }
+
+                if (!std::equal(m_fwdEncPrefix.begin() + FwdEncOffset_NodeId, m_fwdEncPrefix.end(), &buf[FwdEncOffset_NodeId])) {
+                    break;
+                }                
+
+                ::cc_mqttsn_client_process_data(m_client.get(), buf + m_fwdEncPrefix.size(), static_cast<unsigned>(bufLen - m_fwdEncPrefix.size()), origin);
+                return;
+            } while (false);
+
+            logError() << "Recieved data doesn't have appropriate forwarding encapsulation prefix, ignoring..." << std::endl;            
         });
 
     m_session->setNetworkErrorReportCb(

client/app/common/AppClient.h

@@ -113,6 +113,7 @@ class AppClient
     ProgramOptions m_opts;
     ClientPtr m_client;
     SessionPtr m_session;
+    std::vector<std::uint8_t> m_fwdEncPrefix;
     Addr m_lastAddr;
 };
 

client/app/common/ProgramOptions.cpp

@@ -82,6 +82,16 @@ void ProgramOptions::addWill()
     m_desc.add(opts);
 }
 
+void ProgramOptions::addEncapsulate()
+{
+    po::options_description opts("Forwarder Encapsulation");
+    opts.add_options()
+        ("fwd-enc-node-id", po::value<std::string>()->default_value(std::string()), "Emulate forwarder encapsulation with specified node ID (passed as binary data). Use \"\\x\" prefix before hex value of each byte")
+    ;    
+
+    m_desc.add(opts);
+}
+
 void ProgramOptions::addPublish()
 {
     po::options_description opts("Publish Options");
@@ -202,6 +212,11 @@ unsigned ProgramOptions::willQos() const
     return m_vm["will-qos"].as<unsigned>();
 }
 
+std::string ProgramOptions::fwdEncNodeId() const
+{
+    return m_vm["fwd-enc-node-id"].as<std::string>();
+}
+
 std::string ProgramOptions::pubTopic() const
 {
     return m_vm["pub-topic"].as<std::string>();

client/app/common/ProgramOptions.h

@@ -32,6 +32,7 @@ class ProgramOptions
     void addDiscover();
     void addConnect();
     void addWill();
+    void addEncapsulate();
     void addPublish();
     void addSubscribe();
 
@@ -62,7 +63,10 @@ class ProgramOptions
     // Will Options
     std::string willTopic() const;
     std::string willMessage() const;
-    unsigned willQos() const;       
+    unsigned willQos() const;  
+
+    // Forwarder Encapsulation options
+    std::string fwdEncNodeId() const;     
 
     // Publish Options
     std::string pubTopic() const;

client/app/pub/Pub.cpp

@@ -35,6 +35,7 @@ Pub::Pub(boost::asio::io_context& io, int& result) :
     opts().addNetwork();
     opts().addConnect();
     opts().addWill();
+    opts().addEncapsulate();
     opts().addPublish();
 }    
 

client/app/sub/Sub.cpp

@@ -33,6 +33,7 @@ Sub::Sub(boost::asio::io_context& io, int& result) :
     opts().addNetwork();
     opts().addConnect();
     opts().addWill();
+    opts().addEncapsulate();
     opts().addSubscribe();
 }    
 

gateway/lib/src/session_op/Encapsulate.cpp

@@ -125,7 +125,7 @@ void Encapsulate::sendDataClientReqFromSession(
     unsigned broadcastRadius)
 {
     FwdMsg_SN fwdMsg;
-    fwdMsg.field_ctrl().field_radius().setValue(3); // TODO: make it configurable
+    //fwdMsg.field_ctrl().field_radius().setValue(3); // TODO: make it configurable
     comms::util::assign(fwdMsg.field_nodeId().value(), nodeId.begin(), nodeId.end());
 
     MqttsnFrame frame;