Post parameters are becoming null (at random)

[Raghuram Duraisamy]

Hi,

My web application is developed with Struts2 and it was working fine till recently. All of a sudden one of the modules has started malfunctioning.

The malfunctioning module is 'Update Student details' page. This page has a lot of fields like 'schoolName', 'degreeName', etc .

School 1: <input name="schoolName">

School 2: <input name="schoolName">

.....
School n: <input name="schoolName">



As mentioned earlier, the page was working perfectly fine till recently. Now, one/many of the values of 'schoolName', 'degreeName', etc are being received as "" (EMPTY STRING) on the server-side.

For debugging, I used firebug and remote-debugging in eclipse. I find that the post-parameters are correct on the client-side. For instance, during one of the submissions the post-parameters were as below (i noted them from firebug).

Content-Type: multipart/form-data; boundary=---------------------------2921238217421
Content-Length: 48893

<OTHER_PARAMETERS> <!--Truncated for clarity -->

-----------------------------2921238217421
Content-Disposition: form-data; name="schoolName"

ABC Institute
-----------------------------2921238217421
Content-Disposition: form-data; name="schoolName"

Test School
-----------------------------2921238217421
Content-Disposition: form-data; name="schoolName"

XYZ
-----------------------------2921238217421
Content-Disposition: form-data; name="schoolName"

Texas Institute
-----------------------------2921238217421
Content-Disposition: form-data; name="schoolName"

XXXX School

-----------------------------2921238217421--


But on the server-side, the request params were as below:

schoolName=[ABC Institute, Test School, XYZ, , XXXX School],

"Texas Institute" was received as "" (EMPTY STRING) in this particular case. This is not happening consistently. The parameters that become NULL (or EMPTY STRING) seem random to me - during one instance, parameter schoolName[3] became null as illustrated above, parameter schoolName[2] became null during yet another submission, etc. At times, none of the parameters are nullified.

The following is the list of the interceptors in the action definition.

List of interceptors:
----------------------
FileUploadInterceptor org.apache.struts2.interceptor.FileUploadInterceptor
ServletConfigInterceptor org.apache.struts2.interceptor.ServletConfigInterceptor
StaticParametersInterceptor com.opensymphony.xwork2.interceptor.StaticParametersInterceptor
ParametersInterceptor com.opensymphony.xwork2.interceptor.ParametersInterceptor
MyCustomInterceptor com.xxxx.yyyy.interceptors.GetLoggedOnUserInterceptor


This issue appears rather weird to me and I have not been able to zero-in on the exact cause of the issue. Any help in this regard would be highly appreciated. Thanks in advance.


Thanks,
Raghuram

[David Newton]

What changed? Did you upgrade anything? Change code? Configs?

[Raghuram Duraisamy]

Hi David,

Sorry for the late reply - was held up elsewhere.

What changed? Did you upgrade anything? Change code? Configs?

I upgraded commons-beanutils from 1.6 to 1.8. But after the issue turned up, i degraded back to 1.6 to check whether this was the cause. But parameters are getting lost even with beanutils1.6.


My form sends a multipart request (needed since file upload is enabled on the form). I decided to log the post-data that comes to the server. I modified RequestDumperFilter.java to log the multipart post data. After i added this filter, the parameter loss issue seems to have ceased (0 loss out of 150 submissions of form). I removed the filter and was able to reproduce the issue again.


Thanks,
Raghuram

   
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* this work for additional information regarding copyright ownership.
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* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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*/


package filters;


import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.sql.Timestamp;
import java.util.Enumeration;
import java.util.Locale;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.xml.ws.RequestWrapper;

import com.oreilly.servlet.multipart.BufferedServletInputStream;



/**
 * Example filter that dumps interesting state information about a request
 * to the associated servlet context log file, before allowing the servlet
 * to process the request in the usual way.  This can be installed as needed
 * to assist in debugging problems.
 *
 * @author Craig McClanahan
 * @version $Revision: 500674 $ $Date: 2007-01-28 00:15:00 +0100 (dim., 28 janv. 2007) $
 */

public final class RequestDumperFilter implements Filter {


    // ----------------------------------------------------- Instance Variables


    /**
     * The filter configuration object we are associated with.  If this value
     * is null, this filter instance is not currently configured.
     */
    private FilterConfig filterConfig = null;

    // --------------------------------------------------------- Public Methods


    /**
     * Take this filter out of service.
     */
    public void destroy() {

        this.filterConfig = null;

    }


    /**
     * Time the processing that is performed by all subsequent filters in the
     * current filter stack, including the ultimately invoked servlet.
     *
     * @param request The servlet request we are processing
     * @param result The servlet response we are creating
     * @param chain The filter chain we are processing
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet error occurs
     */
    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain)
	throws IOException, ServletException {

        if (filterConfig == null)
	    return;

	// Render the generic servlet request properties
	StringWriter sw = new StringWriter();
	PrintWriter writer = new PrintWriter(sw);
	writer.println("Request Received at " +
		       (new Timestamp(System.currentTimeMillis())));
	writer.println(" characterEncoding=" + request.getCharacterEncoding());
	writer.println("     contentLength=" + request.getContentLength());
	writer.println("       contentType=" + request.getContentType());
	writer.println("            locale=" + request.getLocale());
	writer.print("           locales=");
	Enumeration locales = request.getLocales();
	boolean first = true;
	while (locales.hasMoreElements()) {
	    Locale locale = (Locale) locales.nextElement();
	    if (first)
	        first = false;
	    else
	        writer.print(", ");
	    writer.print(locale.toString());
	}
	writer.println();
	Enumeration names = request.getParameterNames();
	while (names.hasMoreElements()) {
	    String name = (String) names.nextElement();
	    writer.print("         parameter=" + name + "=");
	    String values[] = request.getParameterValues(name);
	    for (int i = 0; i < values.length; i++) {
	        if (i > 0)
		    writer.print(", ");
		writer.print(values[i]);
	    }
	    writer.println();
	}
	writer.println("          protocol=" + request.getProtocol());
	writer.println("        remoteAddr=" + request.getRemoteAddr());
	writer.println("        remoteHost=" + request.getRemoteHost());
	writer.println("            scheme=" + request.getScheme());
	writer.println("        serverName=" + request.getServerName());
	writer.println("        serverPort=" + request.getServerPort());
	writer.println("          isSecure=" + request.isSecure());

	// Render the HTTP servlet request properties
	if (request instanceof HttpServletRequest) {
	    writer.println("---------------------------------------------");
	    HttpServletRequest hrequest = (HttpServletRequest) request;
	    writer.println("       contextPath=" + hrequest.getContextPath());
	    Cookie cookies[] = hrequest.getCookies();
            if (cookies == null)
                cookies = new Cookie[0];
	    for (int i = 0; i < cookies.length; i++) {
	        writer.println("            cookie=" + cookies[i].getName() +
			       "=" + cookies[i].getValue());
	    }
	    names = hrequest.getHeaderNames();
	    while (names.hasMoreElements()) {
	        String name = (String) names.nextElement();
		String value = hrequest.getHeader(name);
	        writer.println("            header=" + name + "=" + value);
	    }
	    writer.println("            method=" + hrequest.getMethod());
	    writer.println("          pathInfo=" + hrequest.getPathInfo());
	    writer.println("       queryString=" + hrequest.getQueryString());
	    writer.println("        remoteUser=" + hrequest.getRemoteUser());
	    writer.println("requestedSessionId=" +
			   hrequest.getRequestedSessionId());
	    writer.println("        requestURI=" + hrequest.getRequestURI());
	    writer.println("       servletPath=" + hrequest.getServletPath());
	    
		
		/*
		The following section is added by me to print the post data of a multipart request.
		*/
		writer.println("=============================================");
	    writer.println("POST-DATA:");
	    writer.println("----------");
	    String line;
	    BufferedRequestWrapper bufferedRequest= new BufferedRequestWrapper(hrequest);
	    //Here obtain InputStream to process POST data!
	    InputStream is = bufferedRequest.getInputStream();
	    BufferedReader br = new BufferedReader(new InputStreamReader(is));
	    while((line = br.readLine()) != null){
	          writer.println(line);
	    }
	    writer.println("=============================================");
		// Log the resulting string
		writer.flush();
		filterConfig.getServletContext().log(sw.getBuffer().toString());
		// Pass control on to the next filter
        chain.doFilter(bufferedRequest, response);

   	}
	else
	{
		writer.println("=============================================");
	
		// Log the resulting string
		writer.flush();
		filterConfig.getServletContext().log(sw.getBuffer().toString());
	
		// Pass control on to the next filter
	        chain.doFilter(request, response);
	}
    }


    /**
     * Place this filter into service.
     *
     * @param filterConfig The filter configuration object
     */
    public void init(FilterConfig filterConfig) throws ServletException {

	this.filterConfig = filterConfig;

    }


    /**
     * Return a String representation of this object.
     */
    public String toString() {

	if (filterConfig == null)
	    return ("RequestDumperFilter()");
	StringBuffer sb = new StringBuffer("RequestDumperFilter(");
	sb.append(filterConfig);
	sb.append(")");
	return (sb.toString());

    }

    public class BufferedRequestWrapper extends HttpServletRequestWrapper {

    	ByteArrayInputStream bais;
    	ByteArrayOutputStream baos;
    	BufferedServletInputStream bsis;
    	byte [] buffer; 

    	public BufferedRequestWrapper(HttpServletRequest req) throws IOException {
    	super(req);
    	// Read InputStream and store its content in a buffer.
    	InputStream is = req.getInputStream();
    	baos = new ByteArrayOutputStream();
    	byte buf[] = new byte[1024];
    	int letti;
    	while ((letti=is.read(buf))>0) baos.write(buf,0,letti);
    	buffer = baos.toByteArray();
    	}

    	public ServletInputStream getInputStream() {
    	try {
    	// Generate a new InputStream by stored buffer
    	bais = new ByteArrayInputStream(buffer);
    	// Istantiate a subclass of ServletInputStream
    	// (Only ServletInputStream or subclasses of it are accepted by the servlet engine!)
    	bsis = new BufferedServletInputStream(bais); 
    	} 
    	catch (Exception ex) {
    	ex.printStackTrace();
    	} 
    	finally {
    	return bsis;
    	}
    	}

    	}
    
    /*
    Subclass of ServletInputStream needed by the servlet engine.
    All inputStream methods are wrapped and are delegated to 
    the ByteArrayInputStream (obtained as constructor parameter)!
    */
    public class BufferedServletInputStream extends ServletInputStream {

    ByteArrayInputStream bais;

    public BufferedServletInputStream(ByteArrayInputStream bais) {
    this.bais = bais;
    }

    public int available() {
    return bais.available();
    }

    public int read() {
    return bais.read();
    }

    public int read(byte[] buf,int off,int len) {
    return bais.read(buf,off,len);
    }

    }

    
}

 

[David Newton]

You'll have to show some configuration or something; I don't have enough information to help.

[Stephen Grepnal]

Hi, have you found a reason of the given behavior? Actually, I have the same bug, and your fix with RequestDumperFilter works for me also, but it is weird.