Log a warning if a coremod does not follow best practices (#4146)

src/main/java/net/minecraftforge/fml/common/CertificateHelper.java

@@ -19,6 +19,8 @@
 
 package net.minecraftforge.fml.common;
 
+import com.google.common.collect.ImmutableList;
+
 import java.nio.ByteBuffer;
 import java.security.MessageDigest;
 import java.security.cert.Certificate;
@@ -27,6 +29,21 @@ public class CertificateHelper {
 
     private static final String HEXES = "0123456789abcdef";
 
+    public static ImmutableList<String> getFingerprints(Certificate[] certificates)
+    {
+        int len = 0;
+        if (certificates != null)
+        {
+            len = certificates.length;
+        }
+        ImmutableList.Builder<String> certBuilder = ImmutableList.builder();
+        for (int i = 0; i < len; i++)
+        {
+            certBuilder.add(CertificateHelper.getFingerprint(certificates[i]));
+        }
+        return certBuilder.build();
+    }
+
     public static String getFingerprint(Certificate certificate)
     {
         if (certificate == null)

src/main/java/net/minecraftforge/fml/common/FMLModContainer.java

@@ -530,18 +530,7 @@ public class FMLModContainer implements ModContainer
             Class<?> clazz = Class.forName(className, true, modClassLoader);
 
             Certificate[] certificates = clazz.getProtectionDomain().getCodeSource().getCertificates();
-            int len = 0;
-            if (certificates != null)
-            {
-                len = certificates.length;
-            }
-            Builder<String> certBuilder = ImmutableList.builder();
-            for (int i = 0; i < len; i++)
-            {
-                certBuilder.add(CertificateHelper.getFingerprint(certificates[i]));
-            }
-
-            ImmutableList<String> certList = certBuilder.build();
+            ImmutableList<String> certList = CertificateHelper.getFingerprints(certificates);
             sourceFingerprints = ImmutableSet.copyOf(certList);
 
             String expectedFingerprint = (String)descriptor.get("certificateFingerprint");

src/main/java/net/minecraftforge/fml/relauncher/CoreModManager.java

@@ -29,6 +29,7 @@ import java.lang.reflect.Method;
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.net.URLClassLoader;
+import java.security.cert.Certificate;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Calendar;
@@ -46,6 +47,7 @@ import com.google.common.io.Files;
 import net.minecraft.launchwrapper.ITweaker;
 import net.minecraft.launchwrapper.Launch;
 import net.minecraft.launchwrapper.LaunchClassLoader;
+import net.minecraftforge.fml.common.CertificateHelper;
 import net.minecraftforge.fml.common.FMLLog;
 import net.minecraftforge.fml.common.asm.ASMTransformerWrapper;
 import net.minecraftforge.fml.common.asm.transformers.ModAccessTransformer;
@@ -408,7 +410,7 @@ public class CoreModManager {
                 }
                 else
                 {
-                    FMLLog.log.trace("Found FMLCorePluginContainsFMLMod marker in {}, it will be examined later for regular @Mod instances",
+                    FMLLog.log.warn("Found FMLCorePluginContainsFMLMod marker in {}. This is not recommended, @Mods should be in a separate jar from the coremod.",
                             coreMod.getName());
                     candidateModFiles.add(coreMod.getName());
                 }
@@ -591,6 +593,32 @@ public class CoreModManager {
             SortingIndex index = coreModClazz.getAnnotation(IFMLLoadingPlugin.SortingIndex.class);
             int sortIndex = index != null ? index.value() : 0;
 
+            Certificate[] certificates = coreModClazz.getProtectionDomain().getCodeSource().getCertificates();
+            ImmutableList<String> certList = CertificateHelper.getFingerprints(certificates);
+            if (certList.isEmpty())
+            {
+                if (deobfuscatedEnvironment && Arrays.asList(rootPlugins).contains(coreModClass)) //This is probably a forge/mod dev environment - ignore missing forge certificates
+                {
+                    FMLLog.log.info("Ignoring missing certificate for coremod {} ({}), we are in deobf and it's a forge core plugin", coreModName, coreModClass);
+                }
+                else if (deobfuscatedEnvironment && location == null) // This is probably a mod dev workspace
+                {
+                    FMLLog.log.info("Ignoring missing certificate for coremod {} ({}), as this is a probably dev workspace", coreModName, coreModClass);
+                }
+                else // This is a probably a normal minecraft workspace - log at warn
+                {
+                    FMLLog.log.warn("The coremod {} ({}) is not signed!", coreModName, coreModClass);
+                }
+            }
+            else
+            {
+                FMLLog.log.debug("Found signing certificates for coremod {} ({})", coreModName, coreModClass);
+                for (String cert : certList)
+                {
+                    FMLLog.log.debug("Found certificate {}", cert);
+                }
+            }
+
             IFMLLoadingPlugin plugin = (IFMLLoadingPlugin) coreModClazz.newInstance();
             String accessTransformerClass = plugin.getAccessTransformerClass();
             if (accessTransformerClass != null)