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--></style></head><body lang=EN-US link=blue vlink="#954F72" style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal>Hi Junxiao,</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I hope you have a great start to this brand new day!</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I came up with a better approach to avoid creating Interests and Data from existing ones.</p><p class=MsoNormal>(Thanks to ndnSIM, I can do so many amazing things here.)</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I got a new question regarding using the signature in Data packets.</p><p class=MsoNormal>------------------------------</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;text-indent:9.75pt'> Node1<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;text-indent:9.75pt'> |<o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Node 0---Node2---Node3</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>-------------------------------</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Case: Node 0 receives Data /prefix1 from Node 1 and Data /prefix2 from Node 3.</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Goal: By retrieving the signature in the Data packets, Node 0 knows that Data /prefix1 is signed by Node 1 and Data /prefix2 is signed by Node 3.</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>What I have done: 1. I assigned different values to m_signature. (1 to Node 1; 3 to Node 3)</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>---------------------------------------</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>AddAttribute( "Signature", "Fake signature, 0 valid signature (default), other values application-specific",</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>UintegerValue(3), MakeUintegerAccessor(&Producer::m_signature),</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>--------------------------------------</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>2. When I printed: data->getSignature().getValue(), I got the following results for Data from Node 1 and Data from Node 3.</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>23[1]=01</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>23[1]=03</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>3. I wanted to parse signatureValue to obtain “01” or “03”. (The codes are found in the mailing list.)</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>----------------------------------------------------------------------</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> Block signatureValueBlock = data->getSignature().getValue(); </p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> signatureValueBlock.parse();</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> auto parsedSignatureBlock = signatureValueBlock.elements().begin();</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> uint64_t parsedSignatureValue = readNonNegativeInteger(*parsedSignatureBlock);</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>----------------------------------------------------------------------</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>I got an error message.</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>---------------------------------------------------------------</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<ndn::tlv::Error> >'</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> what(): Empty buffer during TLV parsing message.</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>-----------------------------------------------</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>The I printed the buffer and found the buffer is not empty.</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>std::cout<<"Data Sig = " << data->getSignature().getValue().getBuffer()<<std::endl;</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>--------------------------------------------</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Data Sig = 0x55a55b385f10</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>--------------------------------------------</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><o:p> </o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Here are my questions:</p><ol start=1 type=1><li class=MsoListParagraph style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:0in;mso-list:l1 level1 lfo2'>Is there anything wrong in the approach to parsing SignatureValue?</li><li class=MsoListParagraph style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:0in;mso-list:l1 level1 lfo2'>Is there a better way to figure out who signed the Data for the consumer when Data arrives? </li></ol><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Your help would be greatly appreciated. Thank you.</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><o:p> </o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Best,</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>Puming</p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><o:p> </o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><o:p> </o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><div style='mso-element:para-border-div;border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal style='border:none;padding:0in'><b>From: </b><a href="mailto:pfang@umass.edu">Puming Fang</a><br><b>Sent: </b>Monday, April 26, 2021 7:19 PM<br><b>To: </b><a href="mailto:shijunxiao@email.arizona.edu">Junxiao Shi</a><br><b>Cc: </b><a href="mailto:pfang@umass.edu">Puming Fang</a>; <a href="mailto:ndnsim@lists.cs.ucla.edu">ndnsim@lists.cs.ucla.edu</a><br><b>Subject: </b>Re: [EXT][ndnSIM] Create new Interest and new Data from existing ones</p></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Hi Junxiao,<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>You have done me a huge favor!<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I have been working on coming up with a better idea to avoid the potential problems you have pointed out.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>It helps a lot. Thank you.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Best,<o:p></o:p></p></div><div><p class=MsoNormal>Puming<o:p></o:p></p></div><div><p class=MsoNormal><br><br><o:p></o:p></p><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><p class=MsoNormal>On Apr 25, 2021, at 3:08 PM, Junxiao Shi <<a href="mailto:shijunxiao@email.arizona.edu">shijunxiao@email.arizona.edu</a>> wrote:<o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>Hi Puming<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I see two problems:<o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Segoe UI Emoji",sans-serif'>🔸</span> Who's signing the new Data? Applications would not work correctly if you break the signature.<o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Segoe UI Emoji",sans-serif'>🔸</span> If the original Interest name ends with an implicit digest component, how to create the new Interest? A direct transformation would not match the transformed Data.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>If you are trying to <b>encapsulate</b> the Data, you can set the wire encoding of the original Data as the payload of the original Data.<o:p></o:p></p></div><div><p class=MsoNormal>However, this is incompatible with implicit digest.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>If the purpose is to affect forwarding, have a look into <b>forwarding hint</b>, which is the standard solution to "forward /a/b according to FIB entry /b".<o:p></o:p></p></div><div><p class=MsoNormal>It not only preserves the signature, but also is compatible with implicit digest.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Yours, Junxiao <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>On Sun, Apr 25, 2021 at 11:18 Puming Fang <<a href="mailto:pfang@umass.edu">pfang@umass.edu</a>> wrote:<o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt'><p class=MsoNormal style='margin-left:40.8pt'><br>Dear NDN team,<br><br>I hope you are doing great!<br><br>It’s me again. To move forward with my research work on NDN, I need to create new Interest and new Data from existing ones.<br><br>Currently I am writing two applications for a specific node.<br><br>1. When the node receives Interest "/a/b”, it removes “/a” from “/a/b” and sends out the new Interest “/b” to request Data.<br>2. When the node receives Data “/b”, it adds “/a” to the Data “/b”, therefore, the Data is changed to “/a/b”. Then it sends out the Data “/a/b”.<br><br>I have two questions. Any guidance would be greatly appreciated.<br>1. How to create new Interest and new Data from existing ones?<br>2. Since this node is both consumer and producer, would you recommend me to write one application that include these two functions or two separate applications and install them on one node?<br><br>Thank you.<br>Best,<br>Puming<o:p></o:p></p></blockquote></div></div></div></blockquote></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>