rpc: introduce handy RpcAuthTypeUnix#ofCurrentUnixUser method

Motivation:
In situations, where we need to use currently logged user with AUTH_SYS
a handy shortcut can be used to generate corresponding RpcAuthTypeUnix
object.

Modification:
Introduce RpcAuthTypeUnix#ofCurrentUnixUser  that generated an instance of
RpcAuthTypeUnix object by getting logged users uid, gid and gids from
UnixSystem class. Update animal-sniffer-maven-plugin configuration to
allow usage of classes from com.sun.security.auth package at they are
a part of official JDK.

Result:
An instance of RpcAuthTypeUnix can be generated for currently logged
user.

Acked-by: Paul Millar
Target: master

Author: kofemann

oncrpc4j-core/src/main/java/org/dcache/oncrpc4j/rpc/RpcAuthTypeUnix.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2009 - 2018 Deutsches Elektronen-Synchroton,
+ * Copyright (c) 2009 - 2019 Deutsches Elektronen-Synchroton,
  * Member of the Helmholtz Association, (DESY), HAMBURG, GERMANY
  *
  * This library is free software; you can redistribute it and/or modify
@@ -21,6 +21,7 @@
 
 import com.sun.security.auth.UnixNumericGroupPrincipal;
 import com.sun.security.auth.UnixNumericUserPrincipal;
+import com.sun.security.auth.module.UnixSystem;
 import org.dcache.oncrpc4j.xdr.XdrAble;
 import org.dcache.oncrpc4j.xdr.XdrDecodingStream;
 import org.dcache.oncrpc4j.xdr.XdrEncodingStream;
@@ -29,10 +30,14 @@
 
 import javax.security.auth.Subject;
 import java.io.IOException;
+import java.net.InetAddress;
 import java.security.Principal;
+import java.time.Instant;
 import java.util.Arrays;
 import java.util.Set;
 
+import static com.google.common.base.Preconditions.checkState;
+
 public class RpcAuthTypeUnix implements RpcAuth, XdrAble {
 
     private final int _type =  RpcAuthType.UNIX;
@@ -137,4 +142,32 @@ public int gid() {
     public int[] gids() {
         return _gids;
     }
+
+    /**
+     * Get {@link RpcAuthTypeUnix} corresponding to the UNIX user running
+     * this application.
+     * @return RPC auth corresponding to UNIX credentials.
+     * @throws IllegalStateException
+     * @throws IOException if failed to get information to build  UNIX credentials.
+     */
+    public static RpcAuthTypeUnix ofCurrentUnixUser() throws
+            IllegalStateException, IOException {
+
+        String os = System.getProperty("os.name");
+        checkState(!os.toLowerCase().startsWith("windows"), "%s platform not supported", os);
+
+        UnixSystem user = new UnixSystem();
+
+        long uid = user.getUid();
+        long gid = user.getGid();
+        long[] gids = user.getGroups();
+
+        return new RpcAuthTypeUnix(
+                (int)uid,
+                (int)gid,
+                Arrays.stream(gids).mapToInt(l -> (int)l).toArray(),
+                (int)Instant.now().getEpochSecond(),
+                InetAddress.getLocalHost().getHostName()
+        );
+    }
 }

pom.xml

@@ -56,7 +56,7 @@
     <maven-pmd-plugin.version>3.0.1</maven-pmd-plugin.version>
 
     <!--  version of other plugins-->
-    <animal-sniffer-maven-plugin>1.15</animal-sniffer-maven-plugin>
+    <animal-sniffer-maven-plugin>1.18</animal-sniffer-maven-plugin>
     <maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>
     <maven-jar-plugin.version>2.4</maven-jar-plugin.version>
     <maven-release-plugin>2.4.2</maven-release-plugin>
@@ -132,6 +132,10 @@
             <artifactId>java18</artifactId>
             <version>1.0</version>
           </signature>
+          <ignores>
+              <!-- part of official jdk -->
+              <ignore>com.sun.security.auth.*</ignore>
+          </ignores>
         </configuration>
         <executions>
           <execution>
@@ -143,6 +147,7 @@
           </execution>
         </executions>
       </plugin>
+
       <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-release-plugin</artifactId>