Question

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converting C to C#

i have problem in converting by c code to c#
i hav two structers

  struct sockaddr {
      ushort  sa_family;
      char    sa_data[14];
  };

struct sockaddr_in {
    short   sin_family;
    u_short sin_port;
    struct  in_addr sin_addr;
    char    sin_zero[8];
};

and i use to cast it like this…
to get the ip address. from the sockaddr_in structure

 ip = inet_ntoa((( sockaddr_in*)name)->sin_addr); 

now i converted the structure in c# as

 public struct sockaddr
    {
         public static ushort sa_family;            
         public static char[] sa_data = new char[14];

    };

and..

 [StructLayout(LayoutKind.Sequential, Size = 16)]
     public struct sockaddr_in
     {
         public const int Size = 16;

         public short sin_family;
         public ushort sin_port;
         public struct in_addr
         {
             public uint S_addr;
             public struct _S_un_b
             {
                 public byte s_b1, s_b2, s_b3, s_b4;
             }
             public _S_un_b S_un_b;
             public struct _S_un_w
             {
                 public ushort s_w1, s_w2;
             }
             public _S_un_w S_un_w;
         }
         public in_addr sin_addr;
     }

can any one plz help me to get ip address from casting the sockaddr to sockaddr_in as i tried it in c… its working fine… how do i do the same in C#…

thanks u in Advance..

Answer 1

What you try to achieve is certainly possible in C#. Here is an example:

[StructLayout(LayoutKind.Sequential)]
unsafe struct SockAddr {
    public ushort sa_family;
    public fixed byte sa_data[14]; // Note: sizeof(char) == 2 in C#
}

[StructLayout(LayoutKind.Sequential)]
unsafe struct SockAddr_In {
    public short sin_family;
    public ushort sin_port;
    public In_Addr sin_addr;
    public fixed byte sin_zero[8];
}

[StructLayout(LayoutKind.Sequential)]
struct In_Addr {
    public byte s_b1, s_b2, s_b3, s_b4;
}

public static unsafe void CStyle() {
    SockAddr s;
    SockAddr* ps = &s;

    SockAddr_In* psa = (SockAddr_In*)ps;

    var inAddr = new In_Addr();

    inAddr.s_b1 = 192;
    inAddr.s_b2 = 168;
    inAddr.s_b3 = 168;
    inAddr.s_b4 = 56;
    psa->sin_addr = inAddr;
    Console.WriteLine("{0}.{1}.{2}.{3}", 
                       psa->sin_addr.s_b1, psa->sin_addr.s_b2, 
                       psa->sin_addr.s_b3, psa->sin_addr.s_b4);
}

However as others have pointed out, such approaches lead to non-idiomatic C# code and cannot generally be recommended.