add X-I2P-TorrentLocation class to Java

apps/i2psnark/java/src/org/klomp/snark/web/XI2PTorrentLocationFilter.java

@@ -0,0 +1,98 @@
+package org.klomp.snark.web;
+
+import java.io.IOException;
+import java.io.File;
+import java.nio.charset.StandardCharsets;
+
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.eclipse.jetty.server.Request;
+import org.eclipse.jetty.server.handler.HandlerWrapper;
+
+import net.i2p.I2PAppContext;
+import net.i2p.util.Log;
+
+import org.klomp.snark.Storage;
+
+/**
+ * Adds a header, X-I2P-TorrentLocation, to requests for files which contains
+ * a magnet link. The magnet link contains:
+ * - The infohash of the file to download
+ * - At least one open tracker
+ * - A web seed corresponding to the URL of the file
+ *
+ * @since 0.9.51
+ */
+public class XI2PTorrentLocationFilter extends HandlerWrapper {
+    private static final String encodeUTF = StandardCharsets.UTF_8.toString();
+    private final Log _log = I2PAppContext.getGlobalContext().logManager().getLog(XI2PTorrentLocationFilter.class);
+
+    private synchronized File shouldRecheck(final HttpServletRequest httpRequest) {
+        File recheck = null;
+        // get the request URI path only
+        String path = httpRequest.getRequestURI();
+        if (path != null && !path.endsWith("/")) {
+            // get the docroot
+            String docroot = httpRequest.getContextPath();
+            // combine the docroot with the path
+            File filepath = new File(docroot, path);
+            // exist?
+            if (filepath.exists()) {
+                // is *not* it a torrent file?
+                if (!filepath.getName().endsWith(".torrent")) {
+                    // is it a directory?
+                    if (!filepath.isDirectory()) {
+                        File precheck = filepath.getAbsoluteFile();
+                        File torrentcheck = new File(precheck.getParentFile(), precheck.getName() + ".torrent");
+                        if (torrentcheck.exists()) {
+                            // get the last modified fime of precheck
+                            long lastModified = precheck.lastModified();
+                            // get the last modified time of torrentcheck
+                            long lastModified2 = torrentcheck.lastModified();
+                            // if the last modified time of torrentcheck is less than the last modified
+                            // time of precheck
+                            if (lastModified2 < lastModified) {
+                                // set the recheck to the precheck
+                                recheck = precheck;
+                            }
+                        } else {
+                            // set the recheck to the precheck
+                            recheck = precheck;
+                        }
+                    }
+                }
+            }
+        }
+        return recheck;
+    }
+
+    private synchronized String headerContents(final HttpServletRequest httpRequest) {
+        File recheck = shouldRecheck(httpRequest);
+        if (recheck != null) {
+            // return null;
+
+            Storage torrentData;/*
+                                 * = new Storage(I2PSnarkUtil util,
+                                 * File baseFile,
+                                 * String announce,
+                                 * List<List<String>> announce_list,
+                                 * String created_by,
+                                 * boolean privateTorrent,
+                                 * List<String> url_list,
+                                 * String comment,
+                                 * StorageListener listener)
+                                 */
+        }
+        return "";
+    }
+
+    @Override
+    public void handle(final String target, final Request request, final HttpServletRequest httpRequest,
+            HttpServletResponse httpResponse)
+            throws IOException, ServletException {
+
+        _handler.handle(target, request, httpRequest, httpResponse);
+    }
+}