/**
  * Create a new default SIPRequest from the original request. Warning: the newly created
  * SIPRequest, shares the headers of this request but we generate any new headers that we need to
  * modify so the original request is umodified. However, if you modify the shared headers after
  * this request is created, then the newly created request will also be modified. If you want to
  * modify the original request without affecting the returned Request make sure you clone it
  * before calling this method.
  *
  * <p>Only required headers are copied.
  *
  * <ul>
  *   <li>Contact headers are not included in the newly created request. Setting the appropriate
  *       sequence number is the responsibility of the caller.
  *   <li>RouteList is not copied for ACK and CANCEL
  *   <li>Note that we DO NOT copy the body of the argument into the returned header. We do not
  *       copy the content type header from the original request either. These have to be added
  *       seperately and the content length has to be correctly set if necessary the content length
  *       is set to 0 in the returned header.
  *   <li>Contact List is not copied from the original request.
  *   <li>RecordRoute List is not included from original request.
  *   <li>Via header is not included from the original request.
  * </ul>
  *
  * @param requestLine is the new request line.
  * @param switchHeaders is a boolean flag that causes to and from headers to switch (set this to
  *     true if you are the server of the transaction and are generating a BYE request). If the
  *     headers are switched, we generate new From and To headers otherwise we just use the
  *     incoming headers.
  * @return a new Default SIP Request which has the requestLine specified.
  */
 public SIPRequest createSIPRequest(RequestLine requestLine, boolean switchHeaders) {
   SIPRequest newRequest = new SIPRequest();
   newRequest.requestLine = requestLine;
   Iterator headerIterator = this.getHeaders();
   while (headerIterator.hasNext()) {
     SIPHeader nextHeader = (SIPHeader) headerIterator.next();
     // For BYE and cancel set the CSeq header to the
     // appropriate method.
     if (nextHeader instanceof CSeq) {
       CSeq newCseq = (CSeq) nextHeader.clone();
       nextHeader = newCseq;
       try {
         newCseq.setMethod(requestLine.getMethod());
       } catch (ParseException e) {
       }
     } else if (nextHeader instanceof ViaList) {
       Via via = (Via) (((ViaList) nextHeader).getFirst().clone());
       via.removeParameter("branch");
       nextHeader = via;
       // Cancel and ACK preserve the branch ID.
     } else if (nextHeader instanceof To) {
       To to = (To) nextHeader;
       if (switchHeaders) {
         nextHeader = new From(to);
         ((From) nextHeader).removeTag();
       } else {
         nextHeader = (SIPHeader) to.clone();
         ((To) nextHeader).removeTag();
       }
     } else if (nextHeader instanceof From) {
       From from = (From) nextHeader;
       if (switchHeaders) {
         nextHeader = new To(from);
         ((To) nextHeader).removeTag();
       } else {
         nextHeader = (SIPHeader) from.clone();
         ((From) nextHeader).removeTag();
       }
     } else if (nextHeader instanceof ContentLength) {
       ContentLength cl = (ContentLength) nextHeader.clone();
       try {
         cl.setContentLength(0);
       } catch (InvalidArgumentException e) {
       }
       nextHeader = cl;
     } else if (!(nextHeader instanceof CallID) && !(nextHeader instanceof MaxForwards)) {
       // Route is kept by dialog.
       // RR is added by the caller.
       // Contact is added by the Caller
       // Any extension headers must be added
       // by the caller.
       continue;
     }
     try {
       newRequest.attachHeader(nextHeader, false);
     } catch (SIPDuplicateHeaderException e) {
       e.printStackTrace();
     }
   }
   if (MessageFactoryImpl.getDefaultUserAgentHeader() != null) {
     newRequest.setHeader(MessageFactoryImpl.getDefaultUserAgentHeader());
   }
   return newRequest;
 }
  /**
   * Creates a default ACK SIPRequest message for this original request. Note that the defaultACK
   * SIPRequest does not include the content of the original SIPRequest. If responseToHeader is null
   * then the toHeader of this request is used to construct the ACK. Note that tag fields are just
   * copied from the original SIP Request. Added by Jeff Keyser.
   *
   * @param responseToHeader To header to use for this request.
   * @return A SIPRequest with an ACK method.
   */
  public SIPRequest createAckRequest(To responseToHeader) {
    SIPRequest newRequest;
    Iterator headerIterator;
    SIPHeader nextHeader;

    newRequest = new SIPRequest();
    newRequest.setRequestLine((RequestLine) this.requestLine.clone());
    newRequest.setMethod(Request.ACK);
    headerIterator = getHeaders();
    while (headerIterator.hasNext()) {
      nextHeader = (SIPHeader) headerIterator.next();
      if (nextHeader instanceof RouteList) {
        // Ack and cancel do not get ROUTE headers.
        // Route header for ACK is assigned by the
        // Dialog if necessary.
        continue;
      } else if (nextHeader instanceof ProxyAuthorization) {
        // Remove proxy auth header.
        // Assigned by the Dialog if necessary.
        continue;
      } else if (nextHeader instanceof ContentLength) {
        // Adding content is responsibility of user.
        nextHeader = (SIPHeader) nextHeader.clone();
        try {
          ((ContentLength) nextHeader).setContentLength(0);
        } catch (InvalidArgumentException e) {
        }
      } else if (nextHeader instanceof ContentType) {
        // Content type header is removed since
        // content length is 0.
        continue;
      } else if (nextHeader instanceof CSeq) {
        // The CSeq header field in the
        // ACK MUST contain the same value for the
        // sequence number as was present in the
        // original request, but the method parameter
        // MUST be equal to "ACK".
        CSeq cseq = (CSeq) nextHeader.clone();
        try {
          cseq.setMethod(Request.ACK);
        } catch (ParseException e) {
        }
        nextHeader = cseq;
      } else if (nextHeader instanceof To) {
        if (responseToHeader != null) {
          nextHeader = responseToHeader;
        } else {
          nextHeader = (SIPHeader) nextHeader.clone();
        }
      } else if (nextHeader instanceof ContactList || nextHeader instanceof Expires) {
        // CONTACT header does not apply for ACK requests.
        continue;
      } else if (nextHeader instanceof ViaList) {
        // Bug reported by Gianluca Martinello
        // The ACK MUST contain a single Via header field,
        // and this MUST be equal to the top Via header
        // field of the original
        // request.

        nextHeader = (SIPHeader) ((ViaList) nextHeader).getFirst().clone();
      } else {
        nextHeader = (SIPHeader) nextHeader.clone();
      }

      try {
        newRequest.attachHeader(nextHeader, false);
      } catch (SIPDuplicateHeaderException e) {
        e.printStackTrace();
      }
    }
    if (MessageFactoryImpl.getDefaultUserAgentHeader() != null) {
      newRequest.setHeader(MessageFactoryImpl.getDefaultUserAgentHeader());
    }
    return newRequest;
  }