Hello everybody, we are trying to integrate Mini UPnP into our project and have run into some issues.
We made an entry on the answer hub here: LNK 2019 Error when importing third party lib (Mini UPnP) - Programming & Scripting - Epic Developer Community Forums
But haven’t had much luck, so we thought to try seeing if any one on the forums had any experience or help.
I’m trying to allow users to host their own multiplayer games without changing the port forwarding on their router. Thanks to Network - How to connect to a remote listening server - Multiplayer & Networking - Epic Developer Community Forums, I’m trying MiniUPnP. In order to add this to my project, I compiled the MiniUPnP project using this tutorial: A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums. I made sure to set the project to export as a .lib and as a multi-threaded DLL. I created two lib files, miniupnpc.x64.lib and miniupnpc.x86.lib (just in case). They’re different sizes so clearly the project understands the x64 configuration.
Next, I moved to Unreal, creating the ThirdParty folder as described in the tutorial (including Libraries and Includes folders). I’ve added MiniUPnP to PublicDependencyModuleNames and created MiniUPnP.Build.cs. I believe I’ve done all of this correctly because if I remove any of these steps, Unreal gives me a compile-time error on #include “miniupnpc.h”. As it is, it reads the includes perfectly but gives me Error LNK2019: unresolved external symbol on each method I call from the MiniUPnP library. I assume this is because something is wrong with the .lib file so it’s having trouble reading it but I wouldn’t know what. I’ve double checked every step in the tutorial and every AnswerHub question I could find but no dice. Anyone know what I’m missing? Or any other libraries that have a similar function?
Here’s my MiniUPnP.Build.cs file if anyone needs it:
public class MiniUPnP : ModuleRules
{
public MiniUPnP(TargetInfo Target)
{
Type = ModuleType.External;
bool isLibrarySupported = false;
string ThirdPartyPath = Path.GetFullPath(Path.Combine(Path.GetDirectoryName(RulesCompiler.GetModuleFilename(this.GetType().Name)), "../../ThirdParty"));
if ((Target.Platform == UnrealTargetPlatform.Win64) || (Target.Platform == UnrealTargetPlatform.Win32))
{
isLibrarySupported = true;
string PlatformString = (Target.Platform == UnrealTargetPlatform.Win64) ? ".x64" : ".x86";
string LibrariesPath = Path.Combine(ThirdPartyPath, "MiniUPnP", "Libraries");
PublicLibraryPaths.Add(LibrariesPath);
PublicAdditionalLibraries.Add(Path.Combine(LibrariesPath, "miniupnpc" + PlatformString + ".lib"));
}
if (isLibrarySupported)
{
// Include path
PublicIncludePaths.Add(Path.Combine(ThirdPartyPath, "MiniUPnP", "Includes"));
PublicSystemIncludePaths.Add(Path.Combine(ThirdPartyPath, "MiniUPnP", "Includes"));
}
Definitions.Add(string.Format("WITH_MINI_UPNP_BINDING={0}", isLibrarySupported ? 1 : 0));
}
}
