====== 5.1 P/Invoke - Integracija DLL-ova ======

Ova stranica pokazuje kako koristiti OpenSSL putem P/Invoke u .NET-u.

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===== Što je P/Invoke? =====

**P/Invoke** (Platform Invoke) omogućuje pozivanje nativnih DLL funkcija iz .NET-a:

<code>
.NET Kod  →  P/Invoke  →  libcrypto-3-x64.dll  →  OpenSSL
</code>

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===== Pripremite DLL-ove =====

==== 1. Kopirajte DLL-ove u Projekt ====

<code powershell>
cd MojProjekt
copy "D:\Projects\openssl-3.6.0\bin\bin\libcrypto-3-x64.dll" .\
copy "D:\Projects\openssl-3.6.0\bin\bin\libssl-3-x64.dll" .\
</code>

==== 2. Izmijenite .csproj ====

<code xml>
<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <!-- OpenSSL Native Libraries -->
    <None Update="libcrypto-3-x64.dll">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
    <None Update="libssl-3-x64.dll">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
  </ItemGroup>
</Project>
</code>

----

===== Jednostavan P/Invoke Primjer =====

<code csharp>
using System;
using System.Runtime.InteropServices;

namespace MojProjekt;

public static class OpenSslInterop
{
    private const string LIBCRYPTO = "libcrypto-3-x64.dll";

    // Inicijalizacija
    [DllImport(LIBCRYPTO, CallingConvention = CallingConvention.Cdecl)]
    public static extern int OPENSSL_init_crypto(ulong opts, IntPtr settings);

    // Dohvati verziju
    [DllImport(LIBCRYPTO, CallingConvention = CallingConvention.Cdecl)]
    public static extern IntPtr OpenSSL_version(int type);

    // Konstante
    public const int OPENSSL_VERSION_STRING = 6;
    public const ulong OPENSSL_INIT_LOAD_CRYPTO_STRINGS = 0x00000002;
    public const ulong OPENSSL_INIT_ADD_ALL_CIPHERS = 0x00000004;
    public const ulong OPENSSL_INIT_ADD_ALL_DIGESTS = 0x00000008;

    public static void Initialize()
    {
        OPENSSL_init_crypto(
            OPENSSL_INIT_LOAD_CRYPTO_STRINGS |
            OPENSSL_INIT_ADD_ALL_CIPHERS |
            OPENSSL_INIT_ADD_ALL_DIGESTS,
            IntPtr.Zero);
    }

    public static string GetVersion()
    {
        var ptr = OpenSSL_version(OPENSSL_VERSION_STRING);
        return Marshal.PtrToStringAnsi(ptr) ?? "Unknown";
    }
}

// Uporaba:
class Program
{
    static void Main()
    {
        OpenSslInterop.Initialize();
        Console.WriteLine($"OpenSSL Verzija: {OpenSslInterop.GetVersion()}");
    }
}
</code>

----

===== Česte Greške =====

==== "DLL not found" ====

<code>
System.DllNotFoundException: Unable to load DLL 'libcrypto-3-x64.dll'
</code>

**Rješenje:**
  - DLL-ovi prisutni u izlaznom direktoriju (bin/Debug/)?
  - .csproj ''CopyToOutputDirectory'' ispravan?
  - Platforma ispravna? (x64 vs x86)

==== "Entry point not found" ====

<code>
System.EntryPointNotFoundException: Unable to find entry point 'XYZ'
</code>

**Rješenje:**
  - Ime funkcije ispravno napisano?
  - ''CallingConvention.Cdecl'' postavljen?
  - Verzija OpenSSL-a podržava funkciju?

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===== Nastavite na =====

  * [[.:nuget-grundlagen|Stvaranje NuGet paketa]]
  * [[.:verteilung:start|6. Distribucija]]

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//Wolfgang van der Stille @ EMSR DATA d.o.o. - Post-Quantum Cryptography Professional//