// Copyright (C) 2009 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.gerrit.httpd.raw;
import com.google.gerrit.reviewdb.client.Change;
import com.google.gerrit.reviewdb.client.Patch;
import com.google.gerrit.reviewdb.client.PatchSet;
import com.google.gerrit.reviewdb.client.Project;
import com.google.gerrit.reviewdb.server.ReviewDb;
import com.google.gerrit.server.FileTypeRegistry;
import com.google.gerrit.server.git.GitRepositoryManager;
import com.google.gerrit.server.project.ChangeControl;
import com.google.gerrit.server.project.NoSuchChangeException;
import com.google.gwtorm.server.OrmException;
import com.google.inject.Inject;
import com.google.inject.Provider;
import com.google.inject.Singleton;
import eu.medsea.mimeutil.MimeType;
import org.eclipse.jgit.errors.RepositoryNotFoundException;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectLoader;
import org.eclipse.jgit.lib.ObjectReader;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevWalk;
import org.eclipse.jgit.treewalk.TreeWalk;
import org.eclipse.jgit.util.NB;
import java.io.IOException;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.security.MessageDigest;
import java.security.SecureRandom;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Exports a single version of a patch as a normal file download.
* <p>
* This can be relatively unsafe with Microsoft Internet Explorer 6.0 as the
* browser will (rather incorrectly) treat an HTML or JavaScript file its
* supposed to download as though it was served by this site, and will execute
* it with the site's own protection domain. This opens a massive security hole
* so we package the content into a zip file.
*/
@SuppressWarnings("serial")
@Singleton
public class CatServlet extends HttpServlet {
private static final MimeType ZIP = new MimeType("application/zip");
private final Provider<ReviewDb> requestDb;
private final GitRepositoryManager repoManager;
private final SecureRandom rng;
private final FileTypeRegistry registry;
private final ChangeControl.Factory changeControl;
@Inject
CatServlet(final GitRepositoryManager grm, final Provider<ReviewDb> sf,
final FileTypeRegistry ftr, final ChangeControl.Factory ccf) {
requestDb = sf;
repoManager = grm;
rng = new SecureRandom();
registry = ftr;
changeControl = ccf;
}
@Override
protected void doGet(final HttpServletRequest req,
final HttpServletResponse rsp) throws IOException {
String keyStr = req.getPathInfo();
// We shouldn't have to do this extra decode pass, but somehow we
// are now receiving our "^1" suffix as "%5E1", which confuses us
// downstream. Other times we get our embedded "," as "%2C", which
// is equally bad. And yet when these happen a "%2F" is left as-is,
// rather than escaped as "%252F", which makes me feel really really
// uncomfortable with a blind decode right here.
//
keyStr = URLDecoder.decode(keyStr, "UTF-8");
if (!keyStr.startsWith("/")) {
rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
return;
}
keyStr = keyStr.substring(1);
final Patch.Key patchKey;
final int side;
{
final int c = keyStr.lastIndexOf('^');
if (c == 0) {
rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
return;
}
if (c < 0) {
side = 0;
} else {
try {
side = Integer.parseInt(keyStr.substring(c + 1));
keyStr = keyStr.substring(0, c);
} catch (NumberFormatException e) {
rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
return;
}
}
try {
patchKey = Patch.Key.parse(keyStr);
} catch (NumberFormatException e) {
rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
return;
}
}
final Change.Id changeId = patchKey.getParentKey().getParentKey();
final Project project;
final PatchSet patchSet;
try {
final ReviewDb db = requestDb.get();
final ChangeControl control = changeControl.validateFor(changeId);
project = control.getProject();
patchSet = db.patchSets().get(patchKey.getParentKey());
if (patchSet == null) {
rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
return;
}
} catch (NoSuchChangeException e) {
rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
return;
} catch (OrmException e) {
getServletContext().log("Cannot query database", e);
rsp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
return;
}
final Repository repo;
try {
repo = repoManager.openRepository(project.getNameKey());
} catch (RepositoryNotFoundException e) {
getServletContext().log("Cannot open repository", e);
rsp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
return;
}
final ObjectLoader blobLoader;
final RevCommit fromCommit;
final String suffix;
final String path = patchKey.getFileName();
try {
final ObjectReader reader = repo.newObjectReader();
try {
final RevWalk rw = new RevWalk(reader);
final RevCommit c;
final TreeWalk tw;
c = rw.parseCommit(ObjectId.fromString(patchSet.getRevision().get()));
if (side == 0) {
fromCommit = c;
suffix = "new";
} else if (1 <= side && side - 1 < c.getParentCount()) {
fromCommit = rw.parseCommit(c.getParent(side - 1));
if (c.getParentCount() == 1) {
suffix = "old";
} else {
suffix = "old" + side;
}
} else {
rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
return;
}
tw = TreeWalk.forPath(reader, path, fromCommit.getTree());
if (tw == null) {
rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
return;
}
if (tw.getFileMode(0).getObjectType() == Constants.OBJ_BLOB) {
blobLoader = reader.open(tw.getObjectId(0), Constants.OBJ_BLOB);
} else {
rsp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
return;
}
} finally {
reader.release();
}
} catch (IOException e) {
getServletContext().log("Cannot read repository", e);
rsp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
return;
} catch (RuntimeException e) {
getServletContext().log("Cannot read repository", e);
rsp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
return;
} finally {
repo.close();
}
final byte[] raw =
blobLoader.isLarge() ? null : blobLoader.getCachedBytes();
final long when = fromCommit.getCommitTime() * 1000L;
rsp.setDateHeader("Last-Modified", when);
rsp.setDateHeader("Expires", 0L);
rsp.setHeader("Pragma", "no-cache");
rsp.setHeader("Cache-Control", "no-cache, must-revalidate");
OutputStream out;
ZipOutputStream zo;
final MimeType contentType = registry.getMimeType(path, raw);
if (!registry.isSafeInline(contentType)) {
// The content may not be safe to transmit inline, as a browser might
// interpret it as HTML or JavaScript hosted by this site. Such code
// might then run in the site's security domain, and may be able to use
// the user's cookies to perform unauthorized actions.
//
// Usually, wrapping the content into a ZIP file forces the browser to
// save the content to the local system instead.
//
rsp.setContentType(ZIP.toString());
rsp.setHeader("Content-Disposition", "attachment; filename=\""
+ safeFileName(path, suffix) + ".zip" + "\"");
zo = new ZipOutputStream(rsp.getOutputStream());
final ZipEntry e = new ZipEntry(safeFileName(path, rand(req, suffix)));
e.setComment(fromCommit.name() + ":" + path);
e.setSize(blobLoader.getSize());
e.setTime(when);
zo.putNextEntry(e);
out = zo;
} else {
rsp.setContentType(contentType.toString());
rsp.setHeader("Content-Length", "" + blobLoader.getSize());
out = rsp.getOutputStream();
zo = null;
}
if (raw != null) {
out.write(raw);
} else {
blobLoader.copyTo(out);
}
if (zo != null) {
zo.closeEntry();
}
out.close();
}
private static String safeFileName(String fileName, final String suffix) {
// Convert a file path (e.g. "src/Init.c") to a safe file name with
// no meta-characters that might be unsafe on any given platform.
//
final int slash = fileName.lastIndexOf('/');
if (slash >= 0) {
fileName = fileName.substring(slash + 1);
}
final StringBuilder r = new StringBuilder(fileName.length());
for (int i = 0; i < fileName.length(); i++) {
final char c = fileName.charAt(i);
if (c == '_' || c == '-' || c == '.' || c == '@') {
r.append(c);
} else if ('0' <= c && c <= '9') {
r.append(c);
} else if ('A' <= c && c <= 'Z') {
r.append(c);
} else if ('a' <= c && c <= 'z') {
r.append(c);
} else if (c == ' ' || c == '\n' || c == '\r' || c == '\t') {
r.append('-');
} else {
r.append('_');
}
}
fileName = r.toString();
final int ext = fileName.lastIndexOf('.');
if (ext <= 0) {
return fileName + "_" + suffix;
} else {
return fileName.substring(0, ext) + "_" + suffix
+ fileName.substring(ext);
}
}
private String rand(final HttpServletRequest req, final String suffix)
throws UnsupportedEncodingException {
// Produce a random suffix that is difficult (or nearly impossible)
// for an attacker to guess in advance. This reduces the risk that
// an attacker could upload a *.class file and have us send a ZIP
// that can be invoked through an applet tag in the victim's browser.
//
final MessageDigest md = Constants.newMessageDigest();
final byte[] buf = new byte[8];
NB.encodeInt32(buf, 0, req.getRemotePort());
md.update(req.getRemoteAddr().getBytes("UTF-8"));
md.update(buf, 0, 4);
NB.encodeInt64(buf, 0, System.currentTimeMillis());
md.update(buf, 0, 8);
rng.nextBytes(buf);
md.update(buf, 0, 8);
return suffix + "-" + ObjectId.fromRaw(md.digest()).name();
}
}