/* IMS POX XML versions of this service */
 public void doErrorXML(
     HttpServletRequest request,
     HttpServletResponse response,
     IMSPOXRequest pox,
     String s,
     String message,
     Exception e)
     throws java.io.IOException {
   if (e != null) {
     M_log.error(e.getLocalizedMessage(), e);
   }
   String msg = rb.getString(s) + ": " + message;
   M_log.info(msg);
   response.setContentType("application/xml");
   PrintWriter out = response.getWriter();
   String output = null;
   if (pox == null) {
     output = IMSPOXRequest.getFatalResponse(msg);
   } else {
     String body = null;
     String operation = pox.getOperation();
     if (operation != null) {
       body = "<" + operation.replace("Request", "Response") + "/>";
     }
     output = pox.getResponseFailure(msg, null, body);
   }
   out.println(output);
   M_log.debug(output);
 }
  @SuppressWarnings("unchecked")
  protected void doPostXml(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
    String ipAddress = request.getRemoteAddr();

    M_log.debug("LTI POX Service request from IP=" + ipAddress);

    String allowOutcomes =
        ServerConfigurationService.getString(
            SakaiBLTIUtil.BASICLTI_OUTCOMES_ENABLED,
            SakaiBLTIUtil.BASICLTI_OUTCOMES_ENABLED_DEFAULT);
    if (!"true".equals(allowOutcomes)) allowOutcomes = null;

    if (allowOutcomes == null) {
      M_log.warn("LTI Services are disabled IP=" + ipAddress);
      response.setStatus(HttpServletResponse.SC_FORBIDDEN);
      return;
    }

    IMSPOXRequest pox = new IMSPOXRequest(request);
    if (!pox.valid) {
      doErrorXML(request, response, pox, "pox.invalid", pox.errorMessage, null);
      return;
    }

    // check lti_message_type
    String lti_message_type = pox.getOperation();

    String sourcedid = null;
    String message_type = null;
    if (M_log.isDebugEnabled()) M_log.debug("POST\n" + XMLMap.prettyPrint(pox.postBody));
    Map<String, String> bodyMap = pox.getBodyMap();
    if (("replaceResultRequest".equals(lti_message_type)
            || "readResultRequest".equals(lti_message_type)
            || "deleteResultRequest".equals(lti_message_type))
        && allowOutcomes != null) {
      sourcedid = bodyMap.get("/resultRecord/sourcedGUID/sourcedId");
      message_type = "basicoutcome";
    } else {
      String output = pox.getResponseUnsupported("Not supported " + lti_message_type);
      response.setContentType("application/xml");
      PrintWriter out = response.getWriter();
      out.println(output);
      return;
    }

    // No point continuing without a sourcedid
    if (BasicLTIUtil.isBlank(sourcedid)) {
      doErrorXML(request, response, pox, "outcomes.missing", "sourcedid", null);
      return;
    }

    // Handle the outcomes here using the new SakaiBLTIUtil code
    if (allowOutcomes != null && "basicoutcome".equals(message_type)) {
      processOutcomeXml(request, response, lti_message_type, sourcedid, pox);
      return;
    }

    // Truncate this to the maximum length to insure no cruft at the end
    if (sourcedid.length() > 2048) sourcedid = sourcedid.substring(0, 2048);

    // Attempt to parse the sourcedid, any failure is fatal
    String placement_id = null;
    String signature = null;
    String user_id = null;
    try {
      int pos = sourcedid.indexOf(":::");
      if (pos > 0) {
        signature = sourcedid.substring(0, pos);
        String dec2 = sourcedid.substring(pos + 3);
        pos = dec2.indexOf(":::");
        user_id = dec2.substring(0, pos);
        placement_id = dec2.substring(pos + 3);
      }
    } catch (Exception e) {
      // Log some detail for ourselves
      M_log.warn(
          "Unable to decrypt result_sourcedid IP=" + ipAddress + " Error=" + e.getMessage(), e);
      signature = null;
      placement_id = null;
      user_id = null;
    }

    // Send a more generic message back to the caller
    if (placement_id == null || user_id == null) {
      doErrorXML(
          request, response, pox, "outcomes.sourcedid", "missing user_id or placement_id", null);
      return;
    }

    M_log.debug("signature=" + signature);
    M_log.debug("user_id=" + user_id);
    M_log.debug("placement_id=" + placement_id);

    Properties pitch = SakaiBLTIUtil.getPropertiesFromPlacement(placement_id, ltiService);
    if (pitch == null) {
      M_log.debug("Error retrieving result_sourcedid information");
      doErrorXML(request, response, pox, "outcomes.sourcedid", "sourcedid", null);
      return;
    }

    String siteId = pitch.getProperty(LTIService.LTI_SITE_ID);
    Site site = null;
    try {
      site = SiteService.getSite(siteId);
    } catch (Exception e) {
      M_log.debug("Error retrieving result_sourcedid site: " + e.getLocalizedMessage(), e);
    }

    // Send a more generic message back to the caller
    if (site == null) {
      doErrorXML(request, response, pox, "outcomes.sourcedid", "sourcedid", null);
      return;
    }

    // Check the message signature using OAuth
    String oauth_consumer_key = pox.getOAuthConsumerKey();
    String oauth_secret = pitch.getProperty(LTIService.LTI_SECRET);
    M_log.debug("oauth_secret: " + oauth_secret);
    oauth_secret = SakaiBLTIUtil.decryptSecret(oauth_secret);
    M_log.debug("oauth_secret (decrypted): " + oauth_secret);

    String URL = SakaiBLTIUtil.getOurServletPath(request);
    pox.validateRequest(oauth_consumer_key, oauth_secret, request, URL);
    if (!pox.valid) {
      if (pox.base_string != null) {
        M_log.warn(pox.base_string);
      }
      doErrorXML(request, response, pox, "outcome.no.validate", oauth_consumer_key, null);
      return;
    }

    // Check the signature of the sourcedid to make sure it was not altered
    String placement_secret = pitch.getProperty(LTIService.LTI_PLACEMENTSECRET);

    // Send a generic message back to the caller
    if (placement_secret == null) {
      M_log.debug("placement_secret is null");
      doErrorXML(request, response, pox, "outcomes.sourcedid", "sourcedid", null);
      return;
    }

    String pre_hash = placement_secret + ":::" + user_id + ":::" + placement_id;
    String received_signature = LegacyShaUtil.sha256Hash(pre_hash);
    M_log.debug("Received signature=" + signature + " received=" + received_signature);
    boolean matched = signature.equals(received_signature);

    String old_placement_secret = pitch.getProperty(LTIService.LTI_OLDPLACEMENTSECRET);
    if (old_placement_secret != null && !matched) {
      pre_hash = placement_secret + ":::" + user_id + ":::" + placement_id;
      received_signature = LegacyShaUtil.sha256Hash(pre_hash);
      M_log.debug("Received signature II=" + signature + " received=" + received_signature);
      matched = signature.equals(received_signature);
    }

    // Send a message back to the caller
    if (!matched) {
      doErrorXML(request, response, pox, "outcomes.sourcedid", "sourcedid", null);
      return;
    }

    response.setContentType("application/xml");
    PrintWriter writer = response.getWriter();
    String desc = "Message received and validated operation=" + pox.getOperation();
    String output = pox.getResponseUnsupported(desc);
    writer.println(output);
  }