TransferSender is now capable of broadcasting in passive mode; Frame::isValid() was modified to accept SFT broadcasts with zero SNID

libuavcan/include/uavcan/transport/dispatcher.hpp

@@ -115,6 +115,7 @@ public:
         : canio_(driver, allocator, sysclock)
         , sysclock_(sysclock)
         , outgoing_transfer_reg_(otr)
+        , self_node_id_(NodeID::Broadcast)  // Default
         , self_node_id_is_set_(false)
     { }
 

libuavcan/include/uavcan/transport/frame.hpp

@@ -50,7 +50,7 @@ public:
     {
         UAVCAN_ASSERT((transfer_type == TransferTypeMessageBroadcast) == dst_node_id.isBroadcast());
         UAVCAN_ASSERT(data_type_id.isValid());
-        UAVCAN_ASSERT(src_node_id != dst_node_id);
+        UAVCAN_ASSERT(src_node_id.isUnicast() ? (src_node_id != dst_node_id) : true);
         UAVCAN_ASSERT(frame_index <= MaxIndex);
     }
 

libuavcan/include/uavcan/transport/transfer_sender.hpp

@@ -25,6 +25,7 @@ class UAVCAN_EXPORT TransferSender
     const TransferCRC crc_base_;
     CanIOFlags flags_;
     uint8_t iface_mask_;
+    bool allow_broadcasting_in_passive_mode_;
 
     Dispatcher& dispatcher_;
 
@@ -46,6 +47,7 @@ public:
         , crc_base_(data_type.getSignature().toTransferCRC())
         , flags_(CanIOFlags(0))
         , iface_mask_(AllIfacesMask)
+        , allow_broadcasting_in_passive_mode_(false)
         , dispatcher_(dispatcher)
     { }
 
@@ -59,6 +61,13 @@ public:
         iface_mask_ = iface_mask;
     }
 
+    /**
+     * By default, this class will return an error on any attempt to publish a message while the
+     * dispatcher is configured in passive mode. This method allows to permanently enable sending
+     * broadcast transfers in passive mode for this class instance.
+     */
+    void allowBroadcastingInPassiveMode() { allow_broadcasting_in_passive_mode_ = true; }
+
     /**
      * Send with explicit Transfer ID.
      * Should be used only for service responses, where response TID should match request TID.

libuavcan/src/transport/uc_frame.cpp

@@ -170,9 +170,12 @@ bool Frame::isValid() const
     const bool invalid =
         (frame_index_ > MaxIndex) ||
         ((frame_index_ == MaxIndex) && !last_frame_) ||
-        (!src_node_id_.isUnicast()) ||
+        (!src_node_id_.isValid()) ||
         (!dst_node_id_.isValid()) ||
-        (src_node_id_ == dst_node_id_) ||
+        (src_node_id_.isUnicast() ? (src_node_id_ == dst_node_id_) : false) ||
+        (src_node_id_.isBroadcast()
+            ? (!last_frame_ || (frame_index_ > 0) || (transfer_type_ != TransferTypeMessageBroadcast))
+            : false) ||
         ((transfer_type_ == TransferTypeMessageBroadcast) != dst_node_id_.isBroadcast()) ||
         (transfer_type_ >= NumTransferTypes) ||
         (static_cast<int>(payload_len_) > getMaxPayloadLen()) ||

libuavcan/src/transport/uc_transfer_sender.cpp

@@ -19,15 +19,37 @@ int TransferSender::send(const uint8_t* payload, unsigned payload_len, Monotonic
                          MonotonicTime blocking_deadline, TransferType transfer_type, NodeID dst_node_id,
                          TransferID tid)
 {
+    if (payload_len > MaxTransferPayloadLen)
+    {
+        UAVCAN_ASSERT(0);
+        return -ErrInvalidParam;
+    }
+
+    Frame frame(data_type_.getID(), transfer_type, dispatcher_.getNodeID(), dst_node_id, 0, tid);
+    UAVCAN_TRACE("TransferSender", "%s", frame.toString().c_str());
+
+    /*
+     * Checking if we're allowed to send. In passive mode we can send only if:
+     *  - Passive broadcasting is enabled
+     *  - Transfer type is broadcast
+     *  - Transfer payload fits one CAN frame
+     */
     if (dispatcher_.isPassiveMode())
     {
-        return -ErrPassiveMode;
+        const bool allow = allow_broadcasting_in_passive_mode_ &&
+                           (transfer_type == TransferTypeMessageBroadcast) &&
+                           (int(payload_len) <= frame.getMaxPayloadLen());
+        if (!allow)
+        {
+            return -ErrPassiveMode;
+        }
     }
 
     dispatcher_.getTransferPerfCounter().addTxTransfer();
 
-    Frame frame(data_type_.getID(), transfer_type, dispatcher_.getNodeID(), dst_node_id, 0, tid);
-
+    /*
+     * Sending frames
+     */
     if (frame.getMaxPayloadLen() >= int(payload_len))           // Single Frame Transfer
     {
         const int res = frame.setPayload(payload, payload_len);

libuavcan/test/transport/frame.cpp

@@ -162,7 +162,18 @@ TEST(Frame, FrameParsing)
 
     can.id = CanFrame::FlagEFF | // cppcheck-suppress duplicateExpression
              (2 << 0) | (1 << 3) | (0 << 4) | (0 << 10) | (uavcan::TransferTypeMessageUnicast << 17) | (456 << 19);
-    ASSERT_FALSE(frame.parse(can)); // Broadcast Src Node ID
+    ASSERT_FALSE(frame.parse(can)); // Broadcast Src Node ID with unicast transfer
+
+    can.id = CanFrame::FlagEFF | // cppcheck-suppress duplicateExpression
+             (2 << 0) | (0 << 3) | (0 << 4) | (0 << 10) | (uavcan::TransferTypeMessageBroadcast << 17) | (456 << 19);
+    ASSERT_FALSE(frame.parse(can)); // Broadcast Src Node ID with multiframe broadcast transfer
+
+    /*
+     * Broadcast SNID exceptions
+     */
+    can.id = CanFrame::FlagEFF | // cppcheck-suppress duplicateExpression
+             (2 << 0) | (1 << 3) | (0 << 4) | (0 << 10) | (uavcan::TransferTypeMessageBroadcast << 17) | (456 << 19);
+    ASSERT_TRUE(frame.parse(can)); // Broadcast Src Node ID with single frame broadcast transfer
 }
 
 

libuavcan/test/transport/transfer_sender.cpp

@@ -235,11 +235,24 @@ TEST(TransferSender, PassiveMode)
 
     static const uint8_t Payload[] = {1, 2, 3, 4, 5};
 
+    // By default, sending in passive mode is not enabled
     ASSERT_EQ(-uavcan::ErrPassiveMode,
               sender.send(Payload, sizeof(Payload), tsMono(1000), uavcan::MonotonicTime(),
                           uavcan::TransferTypeMessageBroadcast, uavcan::NodeID::Broadcast));
 
+    // Overriding the default
+    sender.allowBroadcastingInPassiveMode();
+
+    // OK, now we can broadcast in any mode
+    ASSERT_LE(0, sender.send(Payload, sizeof(Payload), tsMono(1000), uavcan::MonotonicTime(),
+                             uavcan::TransferTypeMessageBroadcast, uavcan::NodeID::Broadcast));
+
+    // ...but not unicast or anything else
+    ASSERT_EQ(-uavcan::ErrPassiveMode,
+              sender.send(Payload, sizeof(Payload), tsMono(1000), uavcan::MonotonicTime(),
+                          uavcan::TransferTypeMessageUnicast, uavcan::NodeID(42)));
+
     EXPECT_EQ(0, dispatcher.getTransferPerfCounter().getErrorCount());
-    EXPECT_EQ(0, dispatcher.getTransferPerfCounter().getTxTransferCount());
+    EXPECT_EQ(1, dispatcher.getTransferPerfCounter().getTxTransferCount());
     EXPECT_EQ(0, dispatcher.getTransferPerfCounter().getRxTransferCount());
 }