Merge pull request #15 from OpenCyphal-Garage/cleanup

Clean up the libudpard source and test files. With this change we are establishing a baseline with workflows that pass with `-werror` on in the CMake List file.

Author: SchoberMJ

.github/workflows/main.yml

@@ -5,6 +5,7 @@ env:
 jobs:
   debug:
     runs-on: ubuntu-latest
+    container: ghcr.io/opencyphal/toolshed:ts20.4.1
     strategy:
       matrix:
         toolchain: ['clang', 'gcc']
@@ -16,24 +17,17 @@ jobs:
             c-compiler: clang
             cxx-compiler: clang++
     steps:
-      - uses: actions/checkout@v2
-      - run: |
-          wget https://apt.llvm.org/llvm.sh
-          chmod +x llvm.sh
-          sudo ./llvm.sh $LLVM_VERSION
-          sudo apt update -y && sudo apt upgrade -y
-          sudo apt-get -y install gcc-multilib g++-multilib clang-tidy-$LLVM_VERSION
-          sudo update-alternatives --install /usr/bin/clang-tidy clang-tidy /usr/bin/clang-tidy-$LLVM_VERSION 50
-          clang-tidy --version
+      - uses: actions/checkout@v3
       - run: >
           cmake
           -B ${{ github.workspace }}/build
           -DCMAKE_BUILD_TYPE=Debug
           -DCMAKE_C_COMPILER=${{ matrix.c-compiler }}
           -DCMAKE_CXX_COMPILER=${{ matrix.cxx-compiler }}
           tests
-      - working-directory: ${{github.workspace}}/build
+      - name: make
         run: |
+          cd ${{ github.workspace }}/build
           make VERBOSE=1
           make test
       - uses: actions/upload-artifact@v2
@@ -45,6 +39,7 @@ jobs:
 
   optimizations:
     runs-on: ubuntu-latest
+    container: ghcr.io/opencyphal/toolshed:ts20.4.1
     strategy:
       matrix:
         toolchain: ['clang', 'gcc']
@@ -57,10 +52,7 @@ jobs:
             c-compiler: clang
             cxx-compiler: clang++
     steps:
-      - uses: actions/checkout@v2
-      - run: |
-          sudo apt update -y && sudo apt upgrade -y
-          sudo apt install gcc-multilib g++-multilib
+      - uses: actions/checkout@v3
       - run: >
           cmake
           -B ${{ github.workspace }}/build
@@ -69,8 +61,9 @@ jobs:
           -DCMAKE_CXX_COMPILER=${{ matrix.cxx-compiler }}
           -DNO_STATIC_ANALYSIS=1
           tests
-      - working-directory: ${{github.workspace}}/build
+      - name: make
         run: |
+          cd ${{ github.workspace }}/build
           make VERBOSE=1
           make test
       - uses: actions/upload-artifact@v2

libudpard/udpard.c

@@ -51,16 +51,20 @@ extern "C" {
 #define UDPARD_SUCCESS 0
 
 /// MTU values for the supported protocols.
-#define UDPARD_MTU_UDP_IPV4 576U
-#define UDPARD_MTU_UDP_IPV6 1280U
-#define UDPARD_MTU_UDP_IPV4_TEMP 64U
-#define UDPARD_MTU_MAX UDPARD_MTU_UDP_IPV6  /// We may want to set this to 1400/1500 for Ethernet MTU
+/// RFC 791 states that hosts must be prepared to accept datagrams of up to 576 octets and it is expected that this
+/// library will receive non ip-fragmented datagrams thus the minimum MTU should be larger than 576.
+/// That being said, the MTU here is set to 1408 which is derived from 
+/// A 1500B Ethernet MTU RFC 894  - 60B IPv4 max header - 8B UDP Header - 24B Cyphal header which is equal to 1408B
+#define UDPARD_MTU_MAX 1408U // Note that to guarantee a single frame transfer your max payload size shall be 1404
+                             // This value is to accomodate for a 4B CRC which is appended to the transfer.
+#define UDPARD_MTU_UDP_IPV4 UDPARD_MTU_MAX
+#define UDPARD_MTU_UDP_IPV6 UDPARD_MTU_MAX
 
 /// Parameter ranges are inclusive; the lower bound is zero for all. See Cyphal/UDP Specification for background.
 #define UDPARD_SUBJECT_ID_MAX 32767U   /// 15 bits subject ID
 #define UDPARD_SERVICE_ID_MAX 65535U   /// The hard limit for ports
 #define UDPARD_NODE_SUBNET_MAX 31U     /// 5 bits for subnet
-#define UDPARD_NODE_ID_MAX 65535U      /// 16 bits is the hard limit. But this may change pending implementations
+#define UDPARD_NODE_ID_MAX 65534U      /// 16 bits - 1 is the hard limit. But this may change pending implementations
 #define UDPARD_PRIORITY_MAX 7U
 #define UDPARD_TRANSFER_ID_BIT_LENGTH 63ULL
 #define UDPARD_TRANSFER_ID_MAX ((1ULL << UDPARD_TRANSFER_ID_BIT_LENGTH) - 1ULL)
@@ -541,7 +545,6 @@ int8_t udpardRxAccept(UdpardInstance* const         ins,
                       const UdpardMicrosecond       timestamp_usec,
                       UdpardFrame* const            frame,
                       const uint8_t                 redundant_transport_index,
-                      UdpardSessionSpecifier* const specifier,
                       UdpardRxTransfer* const       out_transfer,
                       UdpardRxSubscription** const  out_subscription);
 

libudpard/udpard.h

@@ -37,7 +37,7 @@ set(CMAKE_CXX_STANDARD 17)
 set(CXX_EXTENSIONS OFF)
 add_compile_options(
         -Wall -Wextra -pedantic -fstrict-aliasing -Wdouble-promotion -Wswitch-enum -Wfloat-equal -Wundef
-        # -Werror 
+        -Werror 
         -Wconversion -Wtype-limits -Wsign-conversion -Wcast-align
 )
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Woverloaded-virtual -Wnon-virtual-dtor -Wsign-promo")