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Add metadata Servlet

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- add new servlet to get meta data from PlantUML diagram
- meta data get not only be requested as text but also as json if you set the `Accept`-header to json
- add `metadata` servlet tests
- GET: like the Proxy where you can pass a URL which the servlet will use to fetch the diagram image
- POST: file upload
This commit is contained in:
Florian
2023-05-11 20:58:36 +02:00
committed by PlantUML
parent 09517cca92
commit ec7b9f9b1a
13 changed files with 594 additions and 22 deletions
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376
src/main/java/net/sourceforge/plantuml/servlet/MetadataServlet.java Normal file
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@@ -0,0 +1,376 @@
/* ========================================================================
* PlantUML : a free UML diagram generator
* ========================================================================
*
* Project Info: https://plantuml.com
*
* This file is part of PlantUML.
*
* PlantUML is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* PlantUML distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*/
package net.sourceforge.plantuml.servlet;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.file.Paths;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.stream.Collectors;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.MultipartConfig;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.Part;
import net.sourceforge.plantuml.FileFormat;
import net.sourceforge.plantuml.code.NoPlantumlCompressionException;
import net.sourceforge.plantuml.code.TranscoderUtil;
import net.sourceforge.plantuml.json.JsonObject;
import net.sourceforge.plantuml.klimt.drawing.svg.SvgGraphics;
import net.sourceforge.plantuml.png.MetadataTag;
/**
* Meta data servlet for the webapp.
* This servlet responses with the meta data of a specific file as text report or JSON object.
*/
@SuppressWarnings("SERIAL")
@MultipartConfig
public class MetadataServlet extends HttpServlet {
@Override
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
request.setCharacterEncoding("UTF-8");
final String urlString = request.getParameter("src");
// validate URL
final URL url = ProxyServlet.validateURL(urlString, response);
if (url == null) {
return; // error is already set/handled inside `validateURL`
}
// fetch image via URL and extract meta data from it
final HttpURLConnection conn = ProxyServlet.getConnection(url);
try (InputStream is = conn.getInputStream()) {
handleRequest(request, response, is, conn.getContentType(), null);
}
}
@Override
protected void doPost(
HttpServletRequest request,
HttpServletResponse response
) throws IOException, ServletException {
request.setCharacterEncoding("UTF-8");
// get image via file upload
final Part filePart = request.getPart("diagram");
final String filename = Paths.get(filePart.getSubmittedFileName()).getFileName().toString(); // MS IE fix
try (InputStream is = filePart.getInputStream()) {
handleRequest(request, response, is, null, filename);
}
}
/**
* Handle request no matter whether GET or POST and
* response with the PlantUML diagram image in the in the desired format if possible.
*
* @param request an HttpServletRequest object that contains the request the client has made of the servlet
* @param response an HttpServletResponse object that contains the response the servlet sends to the client
* @param is PlantUML diagram image as input stream
* @param contentType the PlantUML diagram image content type [optional]
* @param filename the PlantUML diagram image filename [optional
*
* @throws IOException if an input or output error is detected when the servlet handles the request
*/
private void handleRequest(
HttpServletRequest request,
HttpServletResponse response,
InputStream is,
String contentType,
String filename
) throws IOException {
final String formString = request.getParameter("format");
final String accept = request.getHeader("Accept");
final boolean isJsonResponse = accept != null && accept.toLowerCase().contains("json");
// extract meta data
// @see <a href="https://github.com/plantuml/plantuml/blob/26874fe610617738f958b7e8d012128fe621cff6/src/net/sourceforge/plantuml/Run.java#L570-L592">PlantUML Code</a>
final FileFormat format = getImageFileFormat(formString, contentType, filename, response);
if (format == null) {
return; // error is already set/handled inside `getImageFileFormat`
}
final Metadata metadata = getMetadata(is, format, response);
if (metadata == null) {
return; // error is already set/handled inside `getMetadata`
}
response.addHeader("Access-Control-Allow-Origin", "*");
if (isJsonResponse) {
response.setContentType("application/json;charset=UTF-8");
response.getWriter().write(metadata.toJson().toString());
} else {
response.setContentType(FileFormat.UTXT.getMimeType());
response.getWriter().write(metadata.toString());
}
}
/**
* Get the file format from the PlantUML diagram image.
*
* @param format image format passed by the user via the request param `format`
* @param contentType response content type where the PlantUML diagram image is from
* @param filename diagram image file name
* @param response response object to `sendError` including error message
*
* @return PlantUML diagram image format; if unknown format return `null`
*
* @throws IOException `response.sendError` can result in a `IOException`
*/
private FileFormat getImageFileFormat(
String format, String contentType, String filename, HttpServletResponse response
) throws IOException {
if (format != null && !format.isEmpty()) {
return getImageFileFormatFromFormatString(format, response);
}
if (filename != null && !filename.isEmpty()) {
final FileFormat fileFormat = getImageFileFormatFromFilenameExtension(filename);
if (fileFormat != null) {
return fileFormat;
}
}
if (contentType != null && !contentType.isEmpty()) {
final FileFormat fileFormat = getImageFileFormatFromContentType(contentType);
if (fileFormat != null) {
return fileFormat;
}
}
response.sendError(
HttpServletResponse.SC_BAD_REQUEST,
"PlantUML image format detection failed. Please set \"format\" (format) manually."
);
return null;
}
/**
* Get the file format from the PlantUML diagram image based on a format string.
*
* @param format image format passed by the user via the request param `format`
* @param response response object to `sendError` including error message; if `null` no error will be send
*
* @return PlantUML diagram image format; if unknown format return `null`
*
* @throws IOException `response.sendError` can result in a `IOException`
*/
private FileFormat getImageFileFormatFromFormatString(
String format, HttpServletResponse response
) throws IOException {
switch (format.toLowerCase()) {
case "png": return FileFormat.PNG;
case "svg": return FileFormat.SVG;
default:
if (response != null) {
response.sendError(
HttpServletResponse.SC_BAD_REQUEST,
"The format \"" + format + "\" is not supported for meta data extraction."
);
}
return null;
}
}
/**
* Get the file format from the PlantUML diagram image based on the filenames extension.
*
* @param filename PlantUML image file name
*
* @return PlantUML diagram image format; if unknown format return `null`
*
* @throws IOException Can not happend! Will not occur.
*/
private FileFormat getImageFileFormatFromFilenameExtension(String filename) throws IOException {
int extensionPosition = filename.lastIndexOf(".");
if (extensionPosition != -1) {
String extension = filename.substring(extensionPosition + 1);
return getImageFileFormatFromFormatString(extension, null);
}
Logger logger = Logger.getLogger("com.plantuml");
logger.log(Level.WARNING, "File name \"{0}\" is malformed. Should be: name.extension", filename);
return null;
}
/**
* Get the file format from the PlantUML diagram image based on the response content type.
*
* @param contentType response content type where the PlantUML diagram image is from
*
* @return PlantUML diagram image format; if unknown content type return `null`
*/
private FileFormat getImageFileFormatFromContentType(String contentType) {
final String ct = contentType.toLowerCase();
if (ct.contains("png")) {
return FileFormat.PNG;
}
if (ct.contains("svg") || ct.contains("xml")) {
return FileFormat.SVG;
}
Logger logger = Logger.getLogger("com.plantuml");
logger.log(Level.SEVERE, "Unknown content type \"{0}\" for meta data extraction", contentType);
return null;
}
/**
* Get meta data from PlantUML diagram image.
*
* @param is PlantUML diagram image input stream
* @param format PlantUML diagram image file format
* @param response response object to `sendError` including error message
*
* @return parsed meta data; on error return `null`
*
* @throws IOException `response.sendError` can result in a `IOException`
*/
private Metadata getMetadata(
InputStream is, FileFormat format, HttpServletResponse response
) throws IOException {
switch (format) {
case PNG:
return getMetadataFromPNG(is, response);
case SVG:
final String svg;
try (BufferedReader br = new BufferedReader(new InputStreamReader(is))) {
svg = br.lines().collect(Collectors.joining("\n"));
}
return getMetadataFromSVG(svg, response);
default:
response.sendError(HttpServletResponse.SC_BAD_REQUEST, "Unsupported image format.");
return null;
}
}
/**
* Get meta data from PNG PlantUML diagram image.
*
* Challenge: PNG meta data is only a single String and contains more than the PlantUML diagram.
* PNG meta data contains:
* 1. decoded PlantUML code
* 2. empty line
* 3. version information
* Notes:
* - in theory the meta data could contain the PlantUML `RawString` as well as the `PlainString`
* but since both are ALWAYS identical (methods to get them are identical), one will ALWAYS dropped.
* @see <a href="https://github.com/plantuml/plantuml/blob/26874fe610617738f958b7e8d012128fe621cff6/src/net/sourceforge/plantuml/core/UmlSource.java#L173-L189">PlantUML Code</a>
* - version information do not contain any empty lines
* Solution: split meta data at the last occurring empty line the result in
* a. decoded PlantUML diagram
* b. version information
*
* @param is PNG image input stream
* @param response response object to `sendError` including error message
*
* @return parsed meta data; on error return `null`
*
* @throws IOException `response.sendError` can result in a `IOException`
*/
private Metadata getMetadataFromPNG(InputStream is, HttpServletResponse response) throws IOException {
final String rawMetadata = new MetadataTag(is, "plantuml").getData();
if (rawMetadata == null) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, "No meta data found.");
return null;
}
// parse meta data
final Metadata metadata = new Metadata(rawMetadata.trim());
metadata.decoded = metadata.rawContent.substring(0, metadata.rawContent.lastIndexOf("\n\n"));
metadata.encoded = TranscoderUtil.getDefaultTranscoder().encode(metadata.decoded);
metadata.version = metadata.rawContent.substring(rawMetadata.lastIndexOf("\n\n")).trim();
// add additionally the encoded plantuml string to raw meta data since it's missing by default
metadata.rawContent = metadata.encoded + "\n\n" + metadata.rawContent;
return metadata;
}
/**
* Get meta data from SVG PlantUML diagram image.
* @see <a href="https://github.com/plantuml/plantuml/blob/26874fe610617738f958b7e8d012128fe621cff6/src/net/sourceforge/plantuml/Run.java#L574-L587">PlantUML Code</a>
*
* @param svg PlantUML digram in SVG format
* @param response response object to `sendError` including error message
*
* @return parsed meta data; on error return `null`
*
* @throws IOException `response.sendError` can result in a `IOException`
*/
private Metadata getMetadataFromSVG(String svg, HttpServletResponse response) throws IOException {
final Metadata metadata = new Metadata();
// search for meta data start token
final int idx = svg.lastIndexOf(SvgGraphics.META_HEADER);
if (idx == -1) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, "No meta data found.");
return null;
}
// search for meta data end token
final String part = svg.substring(idx + SvgGraphics.META_HEADER.length());
final int idxEnd = part.indexOf("]");
if (idxEnd == -1) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, "Invalid meta data: No end token found.");
return null;
}
// parse meta data
metadata.encoded = part.substring(0, idxEnd);
try {
metadata.decoded = TranscoderUtil.getDefaultTranscoderProtected().decode(metadata.encoded);
} catch (NoPlantumlCompressionException ex) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, "Invalid meta data: PlantUML diagram is corrupted.");
return null;
}
return metadata;
}
/**
* Helper class to store meta data.
*/
@SuppressWarnings("checkstyle:VisibilityModifier")
private class Metadata {
public String rawContent;
public String decoded;
public String encoded;
public String version;
Metadata() { }
Metadata(String rawMetadataContent) {
rawContent = rawMetadataContent;
}
public JsonObject toJson() {
JsonObject metadata = new JsonObject();
metadata.add("encoded", encoded);
metadata.add("decoded", decoded);
if (version != null && !version.isEmpty()) {
metadata.add("version", version);
}
return metadata;
}
@Override
public String toString() {
if (rawContent != null && !rawContent.isEmpty()) {
return rawContent;
}
if (version == null || version.isEmpty()) {
return encoded + "\n\n" + decoded;
}
return encoded + "\n\n" + decoded + "\n\n" + version;
}
}
}

48
src/main/java/net/sourceforge/plantuml/servlet/ProxyServlet.java
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@@ -80,25 +80,45 @@ public class ProxyServlet extends HttpServlet {
return false;
}
/**
* Validate external URL.
*
* @param url URL to validate
* @param response response object to `sendError` including error message; if `null` no error will be send
*
* @return valid URL; otherwise `null`
*
* @throws IOException `response.sendError` can result in a `IOException`
*/
public static URL validateURL(String url, HttpServletResponse response) throws IOException {
final URL parsedUrl;
try {
parsedUrl = new URL(url);
} catch (MalformedURLException mue) {
if (response != null) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, "URL malformed.");
}
return null;
}
// Check if URL is in a forbidden format (e.g. IP-Address)
if (forbiddenURL(url)) {
if (response != null) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, "Forbidden URL format.");
}
return null;
}
return parsedUrl;
}
@Override
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
final String fmt = request.getParameter("fmt");
final String source = request.getParameter("src");
final String index = request.getParameter("idx");
// Check if the src URL is valid
final URL srcUrl;
try {
srcUrl = new URL(source);
} catch (MalformedURLException mue) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, "URL malformed.");
return;
}
// Check if URL is in a forbidden format (e.g. IP-Address)
if (forbiddenURL(source)) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, "Forbidden URL format.");
return;
final URL srcUrl = validateURL(source, response);
if (srcUrl == null) {
return; // error is already set/handled inside `validateURL`
}
// generate the response
@@ -175,7 +195,7 @@ public class ProxyServlet extends HttpServlet {
*
* @throws IOException if an input or output exception occurred
*/
private HttpURLConnection getConnection(final URL url) throws IOException {
public static HttpURLConnection getConnection(final URL url) throws IOException {
final HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
String token = System.getenv("HTTP_AUTHORIZATION");