com.ithit.webdav.integration.servlet.DavStaticFileServlet Maven / Gradle / Ivy
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/*
* Copyright 2018 OmniFaces
*
* 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.ithit.webdav.integration.servlet;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.nio.ByteBuffer;
import java.nio.channels.Channels;
import java.nio.channels.FileChannel;
import java.nio.channels.ReadableByteChannel;
import java.nio.channels.WritableByteChannel;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.UUID;
import java.util.concurrent.TimeUnit;
import java.util.regex.Pattern;
import java.util.zip.GZIPOutputStream;
import jakarta.servlet.ServletConfig;
import jakarta.servlet.ServletOutputStream;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
/**
* Servlet which processes static resources if root context is mapped to WebDAV servlet
*/
public class DavStaticFileServlet extends HttpServlet {
// Constants ------------------------------------------------------------------------------------------------------
private static final long serialVersionUID = 1L;
private static final int DEFAULT_STREAM_BUFFER_SIZE = 10240;
private static final Long DEFAULT_EXPIRE_TIME_IN_SECONDS = TimeUnit.DAYS.toSeconds(1);
private static final long ONE_SECOND_IN_MILLIS = TimeUnit.SECONDS.toMillis(1);
private static final String ETAG = "W/\"%s-%s\"";
private static final Pattern RANGE_PATTERN = Pattern.compile("^bytes=[0-9]*-[0-9]*(,[0-9]*-[0-9]*)*$");
private static final String MULTIPART_BOUNDARY = UUID.randomUUID().toString();
private static final Set DEFAULT_MIMETYPES = new HashSet<>(Arrays.asList("text/plain", "text/html", "text/xml", "text/css", "text/javascript", "text/csv", "text/rtf",
"application/xml", "application/xhtml+xml", "application/javascript", "application/json",
"image/svg+xml"));
private File folder;
// Actions --------------------------------------------------------------------------------------------------------
public void init(ServletConfig servletConfig) {
folder = new File(servletConfig.getServletContext().getRealPath("/"), "WEB-INF");
}
@Override
protected void doHead(HttpServletRequest request, HttpServletResponse response) throws IOException {
doRequest(request, response, true);
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
doRequest(request, response, false);
}
private void doRequest(HttpServletRequest request, HttpServletResponse response, boolean head) throws IOException {
response.reset();
Resource resource;
try {
resource = new Resource(getFile(request));
} catch (IllegalArgumentException e) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST);
return;
}
if (resource.file == null) {
handleFileNotFound(response);
return;
}
if (preconditionFailed(request, resource)) {
response.sendError(HttpServletResponse.SC_PRECONDITION_FAILED);
return;
}
setCacheHeaders(response, resource, getExpireTime());
if (notModified(request, resource)) {
response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
return;
}
List ranges = getRanges(request, resource);
if (ranges == null) {
response.setHeader("Content-Range", "bytes */" + resource.length);
response.sendError(HttpServletResponse.SC_REQUESTED_RANGE_NOT_SATISFIABLE);
return;
}
if (!ranges.isEmpty()) {
response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);
} else {
ranges.add(new Range(0, resource.length - 1)); // Full content.
}
String contentType = setContentHeaders(request, response, resource, ranges);
if (head) {
return;
}
// Checking if client supports gzip
boolean acceptsGzip = false;
if (DEFAULT_MIMETYPES.contains(contentType.split(";", 2)[0])) {
String acceptEncoding = request.getHeader("Accept-Encoding");
acceptsGzip = acceptEncoding != null && accepts(acceptEncoding, "gzip");
contentType += ";charset=UTF-8";
}
writeContent(response, resource, ranges, contentType, acceptsGzip);
}
/**
* Returns the file associated with the given HTTP servlet request.
* If this method throws {@link IllegalArgumentException}, then the servlet will return a HTTP 400 error.
* If this method returns null, or if {@link File#isFile()} returns false, then the
* servlet will invoke {@link #handleFileNotFound(HttpServletResponse)}.
* @param request The involved HTTP servlet request.
* @return The file associated with the given HTTP servlet request.
* @throws IllegalArgumentException When the request is mangled in such way that it's not recognizable as a valid
* file request. The servlet will then return a HTTP 400 error.
*/
private File getFile(HttpServletRequest request) throws IllegalArgumentException {
String servletPath = request.getServletPath();
String pathInfo = request.getPathInfo();
if (servletPath == null || servletPath.isEmpty() || pathInfo == null || pathInfo.isEmpty() || "/".equals(pathInfo)) {
throw new IllegalArgumentException();
}
return Paths.get(folder.getAbsolutePath(), servletPath, pathInfo).toFile();
}
/**
* Handles the case when the file is not found.
*
* The default implementation sends a HTTP 404 error.
* @param response The involved HTTP servlet response.
* @throws IOException When something fails at I/O level.
*/
private void handleFileNotFound(HttpServletResponse response) throws IOException {
response.sendError(HttpServletResponse.SC_NOT_FOUND);
}
/**
* Returns how long the resource may be cached by the client before it expires, in seconds.
*
* The default implementation returns 30 days in seconds.
* @return The client cache expire time in seconds (not milliseconds!).
*/
private long getExpireTime() {
return DEFAULT_EXPIRE_TIME_IN_SECONDS;
}
/**
* Returns the content type associated with the given HTTP servlet request and file.
*
* The default implementation delegates {@link File#getName()} to {@link javax.servlet.ServletContext#getMimeType(String)} with a
* fallback default value of application/octet-stream.
* @param request The involved HTTP servlet request.
* @param file The involved file.
* @return The content type associated with the given HTTP servlet request and file.
*/
private String getContentType(HttpServletRequest request, File file) {
return coalesce(request.getServletContext().getMimeType(file.getName()), "application/octet-stream");
}
/**
* Returns true if we must force a "Save As" dialog based on the given HTTP servlet request and content
* type as obtained from {@link #getContentType(HttpServletRequest, File)}.
*
* The default implementation will return true if the content type does not start with
* text or image, and the Accept request header is either null
* or does not match the given content type.
* @param request The involved HTTP servlet request.
* @param contentType The content type of the involved file.
* @return true if we must force a "Save As" dialog based on the given HTTP servlet request and content
* type.
*/
private boolean isAttachment(HttpServletRequest request, String contentType) {
String accept = request.getHeader("Accept");
return !startsWithOneOf(contentType, "text", "image") && (accept == null || !accepts(accept, contentType));
}
/**
* Returns the file name to be used in Content-Disposition header.
* This does not need to be URL-encoded as this will be taken care of.
*
* The default implementation returns {@link File#getName()}.
* @param file The involved file.
* @return The file name to be used in Content-Disposition header.
*/
private String getAttachmentName(File file) {
return file.getName();
}
// Sub-actions ----------------------------------------------------------------------------------------------------
/**
* Returns true if it's a conditional request which must return 412.
*/
private boolean preconditionFailed(HttpServletRequest request, Resource resource) {
String match = request.getHeader("If-Match");
long unmodified = request.getDateHeader("If-Unmodified-Since");
return (match != null) ? !matches(match, resource.eTag) : (unmodified != -1 && modified(unmodified, resource.lastModified));
}
/**
* Set cache headers.
*/
private void setCacheHeaders(HttpServletResponse response, Resource resource, long expires) {
setCacheHeaders(response, expires);
response.setHeader("ETag", resource.eTag);
response.setDateHeader("Last-Modified", resource.lastModified);
}
/**
* Returns true if it's a conditional request which must return 304.
*/
private boolean notModified(HttpServletRequest request, Resource resource) {
String noMatch = request.getHeader("If-None-Match");
long modified = request.getDateHeader("If-Modified-Since");
return (noMatch != null) ? matches(noMatch, resource.eTag) : (modified != -1 && !modified(modified, resource.lastModified));
}
/**
* Get requested ranges. If this is null, then we must return 416. If this is empty, then we must return full file.
*/
private List getRanges(HttpServletRequest request, Resource resource) {
List ranges = new ArrayList<>(1);
String rangeHeader = request.getHeader("Range");
if (rangeHeader == null) {
return ranges;
} else if (!RANGE_PATTERN.matcher(rangeHeader).matches()) {
return Collections.emptyList(); // Syntax error.
}
String ifRange = request.getHeader("If-Range");
if (ifRange != null && !ifRange.equals(resource.eTag)) {
try {
long ifRangeTime = request.getDateHeader("If-Range");
if (ifRangeTime != -1 && modified(ifRangeTime, resource.lastModified)) {
return ranges;
}
} catch (IllegalArgumentException ifRangeHeaderIsInvalid) {
return ranges;
}
}
for (String rangeHeaderPart : rangeHeader.split("=")[1].split(",")) {
Range range = parseRange(rangeHeaderPart, resource.length);
if (range == null) {
return Collections.emptyList(); // Logic error.
}
ranges.add(range);
}
return ranges;
}
/**
* Parse range header part. Returns null if there's a logic error (i.e. start after end).
*/
private Range parseRange(String range, long length) {
long start = sublong(range, 0, range.indexOf('-'));
long end = sublong(range, range.indexOf('-') + 1, range.length());
if (start == -1) {
start = length - end;
end = length - 1;
} else if (end == -1 || end > length - 1) {
end = length - 1;
}
if (start > end) {
return null; // Logic error.
}
return new Range(start, end);
}
/**
* Set content headers.
*/
private String setContentHeaders(HttpServletRequest request, HttpServletResponse response, Resource resource, List ranges) {
String contentType = getContentType(request, resource.file);
String filename = getAttachmentName(resource.file);
boolean attachment = isAttachment(request, contentType);
response.setHeader("Content-Disposition", formatContentDispositionHeader(filename, attachment));
response.setHeader("Accept-Ranges", "bytes");
if (ranges.size() == 1) {
Range range = ranges.get(0);
response.setContentType(contentType);
if (response.getStatus() == HttpServletResponse.SC_PARTIAL_CONTENT) {
response.setHeader("Content-Range", "bytes " + range.start + "-" + range.end + "/" + resource.length);
}
} else {
response.setContentType("multipart/byteranges; boundary=" + MULTIPART_BOUNDARY);
}
return contentType;
}
/**
* Write given file to response with given content type and ranges.
*/
private void writeContent(HttpServletResponse response, Resource resource, List ranges, String contentType, boolean acceptsGzip) throws IOException {
ServletOutputStream output = response.getOutputStream();
if (ranges.size() == 1) {
Range range = ranges.get(0);
if (acceptsGzip) {
// The browser accepts GZIP, so GZIP the content.
response.setHeader("Content-Encoding", "gzip");
stream(resource.file, new GZIPOutputStream(output, DEFAULT_STREAM_BUFFER_SIZE), range.start, range.length);
} else {
response.setHeader("Content-Length", String.valueOf(range.length));
stream(resource.file, output, range.start, range.length);
}
} else {
for (Range range : ranges) {
output.println();
output.println("--" + MULTIPART_BOUNDARY);
output.println("Content-Type: " + contentType);
output.println("Content-Range: bytes " + range.start + "-" + range.end + "/" + resource.length);
stream(resource.file, output, range.start, range.length);
}
output.println();
output.println("--" + MULTIPART_BOUNDARY + "--");
}
}
// Helpers --------------------------------------------------------------------------------------------------------
/**
* Returns true if the given match header matches the given ETag value.
*/
private static boolean matches(String matchHeader, String eTag) {
String[] matchValues = matchHeader.split("\\s*,\\s*");
Arrays.sort(matchValues);
return Arrays.binarySearch(matchValues, eTag) > -1
|| Arrays.binarySearch(matchValues, "*") > -1;
}
/**
* Returns true if the given modified header is older than the given last modified value.
*/
private static boolean modified(long modifiedHeader, long lastModified) {
return (modifiedHeader + ONE_SECOND_IN_MILLIS <= lastModified); // That second is because the header is in seconds, not millis.
}
/**
* Returns a substring of the given string value from the given begin index to the given end index as a long.
* If the substring is empty, then -1 will be returned.
*/
private static long sublong(String value, int beginIndex, int endIndex) {
String substring = value.substring(beginIndex, endIndex);
return substring.isEmpty() ? -1 : Long.parseLong(substring);
}
/**
* Returns true if the given accept header accepts the given value.
*/
private static boolean accepts(String acceptHeader, String toAccept) {
String[] acceptValues = acceptHeader.split("\\s*(,|;)\\s*");
Arrays.sort(acceptValues);
return Arrays.binarySearch(acceptValues, toAccept) > -1
|| Arrays.binarySearch(acceptValues, toAccept.replaceAll("/.*$", "/*")) > -1
|| Arrays.binarySearch(acceptValues, "*/*") > -1;
}
/**
* Returns the first non-null object of the argument list, or null if there is no such
* element.
* @param The generic object type.
* @param objects The argument list of objects to be tested for non-null.
* @return The first non-null object of the argument list, or null if there is no such
* element.
*/
@SafeVarargs
private final T coalesce(T... objects) {
for (T object : objects) {
if (object != null) {
return object;
}
}
return null;
}
/**
* URL-encode the given string using UTF-8.
* @param string The string to be URL-encoded using UTF-8.
* @return The given string, URL-encoded using UTF-8, or null if null was given.
* @throws UnsupportedOperationException When this platform does not support UTF-8.
*/
private static String encodeURL(String string) {
if (string == null) {
return null;
}
try {
return URLEncoder.encode(string, StandardCharsets.UTF_8.name());
}
catch (UnsupportedEncodingException e) {
throw new UnsupportedOperationException("UTF-8 is apparently not supported on this platform.", e);
}
}
/**
* Returns true if the given string starts with one of the given prefixes.
* @param string The object to be checked if it starts with one of the given prefixes.
* @param prefixes The argument list of prefixes to be checked
* @return true if the given string starts with one of the given prefixes.
*/
private boolean startsWithOneOf(String string, String... prefixes) {
for (String prefix : prefixes) {
if (string.startsWith(prefix)) {
return true;
}
}
return false;
}
/**
* Set the cache headers. If the expires argument is larger than 0 seconds, then the following headers
* will be set:
*
* Cache-Control: public,max-age=[expiration time in seconds],must-revalidateExpires: [expiration date of now plus expiration time in seconds]
* Else the method will delegate to {@link #setNoCacheHeaders(HttpServletResponse)}.
* @param response The HTTP servlet response to set the headers on.
* @param expires The expire time in seconds (not milliseconds!).
*/
private void setCacheHeaders(HttpServletResponse response, long expires) {
if (expires > 0) {
response.setHeader("Cache-Control", "public,max-age=" + expires + ",must-revalidate");
response.setDateHeader("Expires", System.currentTimeMillis() + TimeUnit.SECONDS.toMillis(expires));
response.setHeader("Pragma", ""); // Explicitly set pragma to prevent container from overriding it.
}
else {
setNoCacheHeaders(response);
}
}
/**
*
Set the no-cache headers. The following headers will be set:
*
* Cache-Control: no-cache,no-store,must-revalidateExpires: [expiration date of 0]Pragma: no-cache
* Set the no-cache headers.
* @param response The HTTP servlet response to set the headers on.
*/
private void setNoCacheHeaders(HttpServletResponse response) {
response.setHeader("Cache-Control", "no-cache,no-store,must-revalidate");
response.setDateHeader("Expires", 0);
response.setHeader("Pragma", "no-cache"); // Backwards compatibility for HTTP 1.0.
}
/**
* Format an UTF-8 compatible content disposition header for the given filename and whether it's an attachment.
* @param filename The filename to appear in "Save As" dialogue.
* @param attachment Whether the content should be provided as an attachment or inline.
* @return An UTF-8 compatible content disposition header.
*/
private String formatContentDispositionHeader(String filename, boolean attachment) {
return String.format("%s;filename=\"%2$s\"; filename*=UTF-8''%2$s", (attachment ? "attachment" : "inline"), encodeURI(filename));
}
/**
* URI-encode the given string using UTF-8. URIs (paths and filenames) have different encoding rules as compared to
* URL query string parameters. {@link URLEncoder} is actually only for www (HTML) form based query string parameter
* values (as used when a webbrowser submits a HTML form). URI encoding has a lot in common with URL encoding, but
* the space has to be %20 and some chars doesn't necessarily need to be encoded.
* @param string The string to be URI-encoded using UTF-8.
* @return The given string, URI-encoded using UTF-8, or null if null was given.
* @throws UnsupportedOperationException When this platform does not support UTF-8.
*/
private String encodeURI(String string) {
if (string == null) {
return null;
}
return encodeURL(string)
.replace("+", "%20")
.replace("%21", "!")
.replace("%27", "'")
.replace("%28", "(")
.replace("%29", ")")
.replace("%7E", "~");
}
/**
* Stream the given input to the given output via NIO {@link Channels} and a directly allocated NIO
* {@link ByteBuffer}. Both the input and output streams will implicitly be closed after streaming,
* regardless of whether an exception is been thrown or not.
* @param input The input stream.
* @param output The output stream.
* @return The length of the written bytes.
* @throws IOException When an I/O error occurs.
*/
private long stream(InputStream input, OutputStream output) throws IOException {
try (ReadableByteChannel inputChannel = Channels.newChannel(input);
WritableByteChannel outputChannel = Channels.newChannel(output))
{
ByteBuffer buffer = ByteBuffer.allocateDirect(DEFAULT_STREAM_BUFFER_SIZE);
long size = 0;
while (inputChannel.read(buffer) != -1) {
buffer.flip();
size += outputChannel.write(buffer);
buffer.clear();
}
return size;
}
}
/**
* Stream a specified range of the given file to the given output via NIO {@link Channels} and a directly allocated
* NIO {@link ByteBuffer}. The output stream will only implicitly be closed after streaming when the specified range
* represents the whole file, regardless of whether an exception is been thrown or not.
* @param file The file.
* @param output The output stream.
* @param start The start position (offset).
* @param length The (intented) length of written bytes.
* @return The (actual) length of the written bytes. This may be smaller when the given length is too large.
* @throws IOException When an I/O error occurs.
*/
private long stream(File file, OutputStream output, long start, long length) throws IOException {
if (start == 0 && length >= file.length()) {
return stream(new FileInputStream(file), output);
}
try (FileChannel fileChannel = (FileChannel) Files.newByteChannel(file.toPath(), StandardOpenOption.READ)) {
WritableByteChannel outputChannel = Channels.newChannel(output);
ByteBuffer buffer = ByteBuffer.allocateDirect(DEFAULT_STREAM_BUFFER_SIZE);
long size = 0;
while (fileChannel.read(buffer, start + size) != -1) {
buffer.flip();
if (size + buffer.limit() > length) {
buffer.limit((int) (length - size));
}
size += outputChannel.write(buffer);
if (size >= length) {
break;
}
buffer.clear();
}
return size;
}
}
// Nested classes -------------------------------------------------------------------------------------------------
/**
* Convenience class for a file resource.
*/
private static class Resource {
private final File file;
private final long length;
private final long lastModified;
private final String eTag;
public Resource(File file) {
if (file != null && file.isFile()) {
this.file = file;
length = file.length();
lastModified = file.lastModified();
eTag = String.format(ETAG, encodeURL(file.getName()), lastModified);
} else {
this.file = null;
length = 0;
lastModified = 0;
eTag = null;
}
}
}
/**
* Convenience class for a byte range.
*/
private static class Range {
private final long start;
private final long end;
private final long length;
public Range(long start, long end) {
this.start = start;
this.end = end;
length = end - start + 1;
}
}
}