1 files changed, 83 insertions, 0 deletions

diff --git a/dozentenmodul/src/main/java/org/openslx/dozmod/util/ContainerUtils.java b/dozentenmodul/src/main/java/org/openslx/dozmod/util/ContainerUtils.java
index 0e5a1d15..62e5dd0d 100644
--- a/dozentenmodul/src/main/java/org/openslx/dozmod/util/ContainerUtils.java
+++ b/dozentenmodul/src/main/java/org/openslx/dozmod/util/ContainerUtils.java
@@ -1,6 +1,11 @@
 package org.openslx.dozmod.util;
 
+import com.google.gson.JsonArray;
+import com.google.gson.JsonParser;
 import org.apache.log4j.Logger;
+import org.kamranzafar.jtar.TarEntry;
+import org.kamranzafar.jtar.TarHeader;
+import org.kamranzafar.jtar.TarInputStream;
 import org.openslx.bwlp.thrift.iface.ImageSummaryRead;
 import org.openslx.bwlp.thrift.iface.LectureSummary;
 import org.openslx.dozmod.gui.Gui;
@@ -10,6 +15,9 @@ import org.openslx.dozmod.thrift.cache.LectureCache;
 import org.openslx.thrifthelper.TConst;
 
 import java.awt.*;
+import java.io.*;
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
 import java.util.List;
 
 /**
@@ -17,6 +25,7 @@ import java.util.List;
  */
 public class ContainerUtils {
 
+	private static final Logger LOGGER = Logger.getLogger(ContainerUtils.class);
 	/**
 	 * Checks ImageBaseId of image if already linked with existing Lectures in LectureCache.
 	 *
@@ -40,4 +49,78 @@ public class ContainerUtils {
 		Gui.showMessageBox(c, I18n.WINDOW.getString("LectureDetails.Message.error.containerLinkedWithLecture"),
 				MessageType.WARNING, logger, null);
 	}
+
+	/**
+	 * Check if a provided tar file contains information about a single docker image.
+	 * To check the validity of the file, the existence of two JSON files is checked
+	 * and one of the files must only contain information for one image.
+	 *
+	 * The tar file have to be created by the 'docker save ...' command.
+	 *
+	 * @param tarFile the user selected tar file.
+	 * @return true if the images imageBaseId is already linked with a lecture.
+	 */
+	public static boolean isValidTar(File tarFile) {
+
+		boolean isValid = false;
+		boolean containsManifest = false;
+		boolean containsRepositories = false;
+		JsonArray manifestJson = null;
+
+		try {
+			TarInputStream tis = new TarInputStream(new FileInputStream(tarFile));
+			ByteArrayOutputStream output = new ByteArrayOutputStream();
+			byte[] rawData = new byte[1024];
+			TarEntry entry;
+
+			// setDefaultSkip seems to fasten things up while processing the file,
+			// because we want only to check manifest.json and repositories file
+			tis.setDefaultSkip(true);
+			while ((entry = tis.getNextEntry()) != null) {
+				if(!TarHeader.USTAR_MAGIC.equals(entry.getHeader().magic.toString()))
+					break;
+				Arrays.fill(rawData, (byte) 0);
+				output.reset();
+				int count = 0;
+
+				if (entry.getName().equals("manifest.json")) {
+					containsManifest = true;
+					while ((count = tis.read(rawData)) != -1) {
+						output.write(rawData, 0, count);
+					}
+					manifestJson = new JsonParser().parse(
+							new String(output.toByteArray(), StandardCharsets.UTF_8)).getAsJsonArray();
+				}
+
+				if (entry.getName().equals("repositories")) {
+					containsRepositories = true;
+					// dont read the file, no checks for the Content
+				}
+
+				if (containsManifest && containsRepositories)
+					break;
+			}
+			tis.close();
+			// check the json files inside the tar file
+			if (containsManifest && containsRepositories && manifestJson.isJsonArray()
+					&& manifestJson.size() == 1) {
+				isValid = true;
+				String repoTag = manifestJson.get(0).getAsJsonObject().get("RepoTags").getAsString();
+				LOGGER.info(String.format("Tar File contains Docker Image with repoTag=%s", repoTag));
+			} else if (containsManifest && containsRepositories && manifestJson.isJsonArray()
+					&& manifestJson.size() > 1) {
+				Gui.showMessageBox("Tar File container more then one Images!", MessageType.ERROR,
+						LOGGER,
+						null);
+			} else {
+				Gui.showMessageBox("No valid Tar File with Images provided!", MessageType.ERROR,
+						LOGGER,
+						null);
+			}
+
+		} catch (IOException e) {
+			LOGGER.error("IOError while processing tar file", e);
+		}
+		return isValid;
+	}
 }