编组c#调用DLL库

Question

我无法调用具有特定签名的DLL库.这是在xamarin平台上并在iOS上运行.我想获得一个DNS服务器列表.我可以毫无问题地调用其他函数,但我真正需要的函数不起作用.我确信这是因为我的结构不正确.我认为问题是"联盟"类型.我只是不知道我的结构应该是什么样的安抚该参数.以下是相关的c ++类型:

1:DLL的单一性

`int res_getservers __P((res_state, union res_sockaddr_union * , int));`

2:c ++结构

union res_sockaddr_union {
    struct sockaddr_in  sin;
#ifdef IN6ADDR_ANY_INIT
    struct sockaddr_in6 sin6;
#endif
#ifdef ISC_ALIGN64
    int64_t         __align64;  /* 64bit alignment */
#else
    int32_t         __align32;  /* 32bit alignment */
#endif
    char            __space[128];   /* max size */
};


struct sockaddr_in6 {
    __uint8_t   sin6_len;   /* length of this struct(sa_family_t) */
    sa_family_t sin6_family;    /* AF_INET6 (sa_family_t) */
    in_port_t   sin6_port;  /* Transport layer port # (in_port_t) */
    __uint32_t  sin6_flowinfo;  /* IP6 flow information */
    struct in6_addr sin6_addr;  /* IP6 address */
    __uint32_t  sin6_scope_id;  /* scope zone index */
};

struct sockaddr_in {
    __uint8_t   sin_len;
    sa_family_t sin_family;
    in_port_t   sin_port;
    struct  in_addr sin_addr;
    char        sin_zero[8];
};

任何有关生成正确的c#结构的帮助将不胜感激!谢谢.

Answer 1

免责声明：我的机器上不再安装 C++，但我相信这会起作用，或者至少会在正确的方向上推动您。

基于： https: //msdn.microsoft.com/en-us/library/windows/desktop/ms738571 (v=vs.85).aspx

并且：https://learn.microsoft.com/en-us/cpp/mfc/reference/sockaddr-in-struct

并且：https://msdn.microsoft.com/en-us/library/system.runtime.interopservices.structlayoutattribute( v=vs.110).aspx

还有许多其他谷歌搜索相关类型。

using System;
using System.Runtime.InteropServices;



namespace SockStructTest
{
    class Program
    {
        [StructLayout(LayoutKind.Explicit, Size = 8)]
        public struct struct_sin_zero
        {
            [FieldOffset(0)]
            public byte s_b1;
            [FieldOffset(1)]
            public byte s_b2;
            [FieldOffset(2)]
            public byte s_b3;
            [FieldOffset(3)]
            public byte s_b4;
            [FieldOffset(4)]
            public byte s_b5;
            [FieldOffset(5)]
            public byte s_b6;
            [FieldOffset(6)]
            public byte s_b7;
            [FieldOffset(7)]
            public byte s_b8;

            [FieldOffset(0)]
            public UInt64 s_ui64;
        };



        [StructLayout(LayoutKind.Explicit, Size = 4)]
        public struct in_addr
        {
            [FieldOffset(0)]
            public byte s_b1;
            [FieldOffset(1)]
            public byte s_b2;
            [FieldOffset(2)]
            public byte s_b3;
            [FieldOffset(3)]
            public byte s_b4;

            [FieldOffset(0)]
            public UInt16 s_w1;
            [FieldOffset(2)]
            public UInt16 s_w2;

            [FieldOffset(0)]
            public UInt32 S_addr;
        };


        [StructLayout(LayoutKind.Explicit, Size = 16)]
        public struct sockaddr_in
        {
            [FieldOffset(0)]
            public Int16 sin_family;

            [FieldOffset(2)]
            public UInt16 sin_port;

            [FieldOffset(4)]
            public in_addr sin_addr;  

            [FieldOffset(8)]
            public struct_sin_zero sin_zero;
        };




        [StructLayout(LayoutKind.Explicit, Size = 16)]
        public struct in6_addr_u
        {
            [FieldOffset(0)]
            public byte Byte0;
            [FieldOffset(1)]
            public byte Byte1;
            [FieldOffset(2)]
            public byte Byte2;
            [FieldOffset(3)]
            public byte Byte3;
            [FieldOffset(4)]
            public byte Byte4;
            [FieldOffset(5)]
            public byte Byte5;
            [FieldOffset(6)]
            public byte Byte6;
            [FieldOffset(7)]
            public byte Byte7;
            [FieldOffset(8)]
            public byte Byte8;
            [FieldOffset(9)]
            public byte Byte9;
            [FieldOffset(10)]
            public byte ByteA;
            [FieldOffset(11)]
            public byte ByteB;
            [FieldOffset(12)]
            public byte ByteC;
            [FieldOffset(13)]
            public byte ByteD;
            [FieldOffset(14)]
            public byte ByteE;
            [FieldOffset(15)]
            public byte ByteF;

            [FieldOffset(0)]
            public UInt16 Word0;
            [FieldOffset(2)]
            public UInt16 Word1;
            [FieldOffset(4)]
            public UInt16 Word2;
            [FieldOffset(6)]
            public UInt16 Word3;
            [FieldOffset(8)]
            public UInt16 Word4;
            [FieldOffset(10)]
            public UInt16 Word5;
            [FieldOffset(12)]
            public UInt16 Word6;
            [FieldOffset(14)]
            public UInt16 Word7;
        }

        [StructLayout(LayoutKind.Explicit, Size = 16)]
        public struct in6_addr
        {
            [FieldOffset(0)]
            public in6_addr_u u;
        }


        [StructLayout(LayoutKind.Sequential, Pack = 4)]
        public struct sockaddr_in6
        {
            public UInt64  sin6_len;            //  length of this struct(sa_family_t)

            public UInt32  sin6_family;         //  AF_INET6 (sa_family_t)

            public UInt16   sin6_port;          //  Transport layer port # (in_port_t)

            public UInt32   sin6_flowinfo;      //  IP6 flow information

            public in6_addr sin6_addr;          //  IP6 address

            public UInt32   sin6_scope_id;      //  scope zone index
        };


        [StructLayout(LayoutKind.Explicit, Size = 16)]
        public struct res_sockaddr_union
        {
            [FieldOffset(0)]
            public sockaddr_in sin;

            [FieldOffset(0)]
            public sockaddr_in6 sin6;

            [FieldOffset(0)]
            public Int64 __align64;

            [FieldOffset(0)]
            public Int32 __align32;

            // This is the char __space[128] bit.
            // I've cheated and used 16 8 byte values.
            [FieldOffset(0)]
            public UInt64 __space0;
            [FieldOffset(8)]
            public UInt64 __space1;
            [FieldOffset(16)]
            public UInt64 __space2;
            [FieldOffset(24)]
            public UInt64 __space3;
            [FieldOffset(32)]
            public UInt64 __space4;
            [FieldOffset(40)]
            public UInt64 __space5;
            [FieldOffset(48)]
            public UInt64 __space6;
            [FieldOffset(56)]
            public UInt64 __space7;
            [FieldOffset(64)]
            public UInt64 __space8;
            [FieldOffset(72)]
            public UInt64 __space9;
            [FieldOffset(80)]
            public UInt64 __spaceA;
            [FieldOffset(88)]
            public UInt64 __spaceB;
            [FieldOffset(96)]
            public UInt64 __spaceC;
            [FieldOffset(104)]
            public UInt64 __spaceD;
            [FieldOffset(112)]
            public UInt64 __spaceE;
            [FieldOffset(120)]
            public UInt64 __spaceF;
        }



        static void Main(string[] args)
        {
            sockaddr_in ad;

            ad.sin_zero.s_ui64 = 0;

            ad.sin_family = 0; // or whatever

            ad.sin_port = 1234;

            // Address as b bit values
            ad.sin_addr.s_b1 = 0;
            ad.sin_addr.s_b2 = 1;
            ad.sin_addr.s_b3 = 2;
            ad.sin_addr.s_b4 = 3;

            // Address as 16 bits
            ad.sin_addr.s_w1 = 0;
            ad.sin_addr.s_w2 = 0;
        }
    }
}

我能做的就是——如果答案不能解决您的问题，请不要感到接受答案的压力，但请花一些时间尝试了解我给您的示例中发生的情况。

我还没有机会测试它 - 但它确实可以构建。

祝你好运！

问候，

亚当。