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MagicJacob
MagicJacob
January 21, 2019
Solved

Downloading multipart file in AEM Sling filter - how?

  • January 21, 2019
  • 9 replies
  • 6504 views

Hi, I am uploading assets to AEM's servlet, but before the file reaches servlet, I want to intercept it with a filter and scan it.

All details aside, I am unable to extract file from ServletRequest.


Here is my filter:

   @Component
   @SlingServletFilter(scope = {SlingServletFilterScope.REQUEST},
                       pattern = ".*createasset.html",
                       methods = {"POST"})
   public class UploadFileFilter implements Filter {
       @Override
       public void init(FilterConfig filterConfig) throws ServletException {
       }
       @Override
       public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
           SlingHttpServletResponse slingResponse = (SlingHttpServletResponse) response;
          //try to download multipart file...
           chain.doFilter(request, slingResponse);
       }
       @Override
       public void destroy() {
       }
   }

I can't read input stream directly in filter, because it has already been read.

I have tried solution from this post:

Re: AEM File Upload

But request.getRequestParameterMap() always return empty map. Is it because I try to access parameters in a filter, not a servlet?

Do you know any working way to download multipart file in a filter?

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9 replies

smacdonald2008
smacdonald2008
Level 10
January 21, 2019

As I stated in the other thread - Sling Has its own way in a Servlet to read the InputStream. That code works to read a file in a Sling Servlet. I have never tried to capture it within a filter. Lets see if other community members have.

Lokesh_Shivalingaiah
Lokesh_Shivalingaiah
Level 10
January 21, 2019

Since you have the same request object in the filter servlet, you should be able to access the inputstream, download it to a local file and scan it.

Are you not able to find the input stream in your filter ? what is the error thrown ?

MagicJacob
MagicJacobAuthor
January 21, 2019

When I request.getInputStream() I get error saying that input data has already been read, which, as far as I know, is the expected behaviour in AEM servlets and filters.

MagicJacob
MagicJacobAuthor
January 22, 2019

Hi, thank you for answering!

Using the code you posted, I get and error inside CreateAssetServlet.java:

22.01.2019 11:54:39.041 *ERROR* [] [] [85.222.102.38 [1548158078795] POST /content/dam/catalogs/myfolder.createasset.html HTTP/1.1] org.apache.sling.engine.impl.SlingMainServlet service: Uncaught Problem handling the request
org.apache.commons.fileupload.FileItemStream$ItemSkippedException: null
  at org.apache.commons.fileupload.MultipartStream$ItemInputStream.read(MultipartStream.java:896)
  at java.io.InputStream.read(InputStream.java:101)
  at org.apache.commons.io.IOUtils.copyLarge(IOUtils.java:2146)
  at org.apache.commons.io.IOUtils.copy(IOUtils.java:2102)
  at org.apache.commons.io.IOUtils.copyLarge(IOUtils.java:2123)
  at org.apache.commons.io.IOUtils.copy(IOUtils.java:2078)
  at org.apache.commons.io.IOUtils.toByteArray(IOUtils.java:721)
  at com.day.cq.dam.core.impl.StreamedRequestParameter.<init>(StreamedRequestParameter.java:45)
  at com.day.cq.dam.core.impl.servlet.CreateAssetServlet.doPost(CreateAssetServlet.java:247)
  at org.apache.sling.api.servlets.SlingAllMethodsServlet.mayService(SlingAllMethodsServlet.java:146)
  at org.apache.sling.api.servlets.SlingSafeMethodsServlet.service(SlingSafeMethodsServlet.java:342)
  at org.apache.sling.api.servlets.SlingSafeMethodsServlet.service(SlingSafeMethodsServlet.java:374)
  at org.apache.sling.engine.impl.request.RequestData.service(RequestData.java:552)
  at org.apache.sling.engine.impl.filter.SlingComponentFilterChain.render(SlingComponentFilterChain.java:44)

This is my code in my filter:

@Override
  public void doFilter(ServletRequest request, ServletResponse response,
    FilterChain chain)
    throws IOException, ServletException {
    if (!(request instanceof SlingHttpServletRequest)
      || !(response instanceof SlingHttpServletResponse)) {
      chain.doFilter(request, response);
      return;
    }
    final SlingHttpServletRequest slingRequest = (SlingHttpServletRequest) request;
    if (!StringUtils.equals("POST", slingRequest.getMethod())
      || !isCreateAssetRequest(slingRequest)) {
      chain.doFilter(request, response);
      return;
    }
    Iterator<Part> partsIter = (Iterator) request.getAttribute("request-parts-iterator");
    if ((partsIter == null) || !partsIter.hasNext()) {
      chain.doFilter(request, response);
      return;
    }
    List<Part> parts = new ArrayList<>();
    while (partsIter.hasNext()) {
      Part part = partsIter.next();
      String tmpDir = System.getProperty(TEMPORARY_DIRECTORY);
      File tmpFile = new File(tmpDir + "/temp-upload-asset.tmp");
      FileOutputStream fileOutputStream = new FileOutputStream(tmpFile);
      ByteArrayOutputStream baos = new ByteArrayOutputStream();
      IOUtils.copy(part.getInputStream(), baos);
      fileOutputStream.write(baos.toByteArray());
      fileOutputStream.close();
      parts.add(part);
    }
    request.setAttribute("request-parts-iterator", parts.iterator());
    chain.doFilter(request, response);
  }
Gaurav-Behl
Gaurav-Behl
Level 10
January 22, 2019

FileItemStream$ItemSkippedException  would happen if you try to use the stream outside the context/block where it was initially read/opened.

I'll test the code later & revert..

Gaurav-Behl
Gaurav-Behl
Level 10
January 22, 2019

Below is the code that worked for me. I've highlighted couple of changes that I did in DecryptAssetsFilter shared in that link:

  • Used slingRequest.getParts() to iterate rather than the custom request attribute
  • changed the method getSubmittedFileName() to getName()

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)

throws IOException, ServletException {

if (!(request instanceof SlingHttpServletRequest) || !(response instanceof SlingHttpServletResponse)) {

chain.doFilter(request, response);

return;

}

final SlingHttpServletRequest slingRequest = (SlingHttpServletRequest) request;

if (!StringUtils.equals("POST", slingRequest.getMethod()) || !isCreateAssetRequest(slingRequest)) {

chain.doFilter(request, response);

return;

}

log.info("Decoding create asset request - " + slingRequest.getRequestURI());

List parts = (ArrayList) slingRequest.getParts();

if ((parts == null) || parts.size() == 0) {

chain.doFilter(request, response);

return;

}

List<Part> otherParts = new ArrayList<Part>();

Part part = null;

for (int i = 0; i < parts.size() - 1; i++) {

part = (Part) parts.get(i);

otherParts.add(new EAEMDecryptRequestPart(part));

}

chain.doFilter(request, response);

}

private boolean isCreateAssetRequest(SlingHttpServletRequest slingRequest) {

String[] selectors = slingRequest.getRequestPathInfo().getSelectors();

if (ArrayUtils.isEmpty(selectors) || (selectors.length > 1)) {

return false;

}

return selectors[0].equals("createasset");

}

public void destroy() {

}

private static class EAEMDecryptRequestPart implements Part {

private final Part part;

private final InputStream inputStream;

private static final String TEMP_PREFIX = "eaem_decrypt_";

public EAEMDecryptRequestPart(Part part) throws IOException {

this.part = part;

if (!isFilePart(part)) {

this.inputStream = new ByteArrayInputStream(IOUtils.toByteArray(part.getInputStream()));

} else {

this.inputStream = this.getDecodedStream(part);

}

}

private InputStream getDecodedStream(Part part) throws IOException {

File tmpFile = File.createTempFile(TEMP_PREFIX, ".tmp");

// byte[] decoded =

// Base64.getDecoder().decode(IOUtils.toByteArray(part.getInputStream()));  //use decode, if the input file is encoded

byte[] decoded = IOUtils.toByteArray(part.getInputStream());

FileOutputStream decodedStream = new FileOutputStream(tmpFile);

decodedStream.write(decoded);

decodedStream.close();

return new FileInputStream(tmpFile);

}

private boolean isFilePart(Part part) {

return StringUtils.isNotEmpty(part.getName());

}

public InputStream getInputStream() throws IOException {

return inputStream;

}

public String getContentType() {

return part.getContentType();

}

public String getName() {

return part.getName();

}

public long getSize() {

return 0;

}

public void write(String s) throws IOException {

throw new UnsupportedOperationException(

"Writing parts directly to disk is not supported by this implementation, use getInputStream instead");

}

public void delete() throws IOException {

}

public String getHeader(String headerName) {

return part.getHeader(headerName);

}

public Collection<String> getHeaders(String headerName) {

return part.getHeaders(headerName);

}

public Collection<String> getHeaderNames() {

return part.getHeaderNames();

}

public String getSubmittedFileName() {

return part.getName();

}

private <T> Collection<T> toCollection(Iterator<T> i) {

if (i == null) {

return Collections.emptyList();

} else {

List<T> c = new ArrayList<T>();

while (i.hasNext()) {

c.add(i.next());

}

return c;

}

}

}

}

MagicJacob
MagicJacobAuthor
January 23, 2019

Hello, unfortunatelly my SlingHttpServletRequest does not have getParts() method. Mine comes from com.adobe.aem:uber-jar:apis:6.3.3

Anyway, I have tried the code that you previously posted from:

https://experience-aem.blogspot.com/2018/11/aem-6420-file-de…

And it seems to work now, except I cant extract code from getDecodedStream method, or else it will throw, the exception I have described above, inside CreateAsserServlet​.

Gaurav-Behl
Gaurav-Behl
Level 10
January 23, 2019

Are you not able to get the byte array/write stream to a file? Process the stream as byte array or as a file, do the scan and return the results accordingly.

getParts() is available in AEM 6.3. You could still use other ways to get the parts.

SlingHttpServletRequest ("The Adobe AEM Quickstart and Web Application.")

Methods inherited from interface javax.servlet.http.HttpServletRequest

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