Added support for marshalling sockaddr_can on pre-5.4 kernels - Closes …

…#40

src/SocketCANSharp/AbstractSockAddrCan.cs

@@ -0,0 +1,73 @@
+#region License
+/* 
+BSD 3-Clause License
+
+Copyright (c) 2022, Derek Will
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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.
+
+3. Neither the name of the copyright holder nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+
+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. 
+*/
+#endregion
+
+using System.Runtime.InteropServices;
+
+namespace SocketCANSharp
+{
+    /// <summary>
+    /// Represents the base class for all SocketCAN address structures.
+    /// </summary>
+    [StructLayout(LayoutKind.Sequential)]
+    public abstract class AbstractSockAddrCan
+    {
+        /// <summary>
+        /// Address Family.
+        /// </summary>
+        public ushort CanFamily { get; set; }
+        /// <summary>
+        /// Interface Index.
+        /// </summary>
+        public int CanIfIndex { get; set; }
+
+        /// <summary>
+        /// Initializes a SocketCAN address structure with default values of zeroes.
+        /// </summary>
+        public AbstractSockAddrCan()
+        {
+            CanFamily = 0;
+            CanIfIndex = 0;
+        }
+
+        /// <summary>
+        /// Initializes a SocketCAN address structure to the AF_CAN address family and the provided interface index value.
+        /// </summary>
+        /// <param name="interfaceIndex">Interface index value</param>
+        public AbstractSockAddrCan(int interfaceIndex)
+        {
+            CanFamily = SocketCanConstants.AF_CAN;
+            CanIfIndex = interfaceIndex;
+        }
+    }
+}

src/SocketCANSharp/SockAddrCan.cs

@@ -36,38 +36,32 @@ OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 
 namespace SocketCANSharp
 {
+    /*
+    Prior to Linux Kernel 5.4 and the introduction of CAN_J1939, the call to bind or connect expected 
+    a structure length of at least 16 bytes for CAN_RAW and CAN_BCM sockets. Linux Kernel 5.4 and later 
+    only requires 8 bytes for CAN_RAW and CAN_BCM sockets. In order to be compatible with both implementations, 
+    this managed class pads the base class (which just includes the can_family and can_ifindex) by 8 bytes. 
+    */
+
     /// <summary>
     /// Represents a SocketCAN base address structure.
     /// </summary>
-    [StructLayout(LayoutKind.Sequential)]
-    public class SockAddrCan
+    [StructLayout(LayoutKind.Sequential, Size = 8)]
+    public class SockAddrCan : AbstractSockAddrCan
     {
-        /// <summary>
-        /// Address Family.
-        /// </summary>
-        public ushort CanFamily { get; set; }
-        /// <summary>
-        /// Interface Index.
-        /// </summary>
-        public int CanIfIndex { get; set; }
-
         /// <summary>
         /// Initializes a SocketCAN base address structure with default values of zeroes.
         /// </summary>
-        public SockAddrCan()
+        public SockAddrCan() : base()
         {
-            CanFamily = 0;
-            CanIfIndex = 0;
         }
 
         /// <summary>
         /// Initializes a SocketCAN base address structure to the AF_CAN address family and the provided interface index value.
         /// </summary>
         /// <param name="interfaceIndex">Interface index value</param>
-        public SockAddrCan(int interfaceIndex)
+        public SockAddrCan(int interfaceIndex) : base(interfaceIndex)
         {
-            CanFamily = SocketCanConstants.AF_CAN;
-            CanIfIndex = interfaceIndex;
         }
     }
 }

src/SocketCANSharp/SockAddrCanIsoTp.cs

@@ -40,7 +40,7 @@ namespace SocketCANSharp
     /// Represents a SocketCAN ISO-TP address structure.
     /// </summary>
     [StructLayout(LayoutKind.Sequential)]
-    public class SockAddrCanIsoTp : SockAddrCan
+    public class SockAddrCanIsoTp : AbstractSockAddrCan
     {
         private uint _rxId;
         private uint _txId;

src/SocketCANSharp/SockAddrCanJ1939.cs

@@ -40,7 +40,7 @@ namespace SocketCANSharp
     /// Represents a SocketCAN SAE J1939 address structure.
     /// </summary>
     [StructLayout(LayoutKind.Sequential)]
-    public class SockAddrCanJ1939 : SockAddrCan
+    public class SockAddrCanJ1939 : AbstractSockAddrCan
     {
         /// <summary>
         /// 64-bit NAME belonging to a J1939 Node.

test/SocketCANSharpTest/SocketSetupTests.cs

@@ -137,7 +137,7 @@ public void GetSockName_CAN_RAW_on_vcan0_Interface_Test()
             int getSockNameResult = LibcNativeMethods.GetSockName(socketHandle, addr, ref size);
 
             Assert.AreEqual(0, getSockNameResult);
-            Assert.AreEqual(Marshal.SizeOf(typeof(SockAddrCan)), size);
+            Assert.That(size, Is.EqualTo(8) | Is.EqualTo(16));
             Assert.AreEqual(SocketCanConstants.AF_CAN, addr.CanFamily);
             Assert.AreEqual(ifr.IfIndex, addr.CanIfIndex);
         }
@@ -153,7 +153,7 @@ public void GetSockName_CAN_RAW_Unbound_Test()
             int getSockNameResult = LibcNativeMethods.GetSockName(socketHandle, addr, ref size);
 
             Assert.AreEqual(0, getSockNameResult);
-            Assert.AreEqual(Marshal.SizeOf(typeof(SockAddrCan)), size);
+            Assert.That(size, Is.EqualTo(8) | Is.EqualTo(16));
             Assert.AreEqual(SocketCanConstants.AF_CAN, addr.CanFamily);
             Assert.AreEqual(0, addr.CanIfIndex);
         }