lmb@vicom.com (Larry Blair) (09/25/90)
Bug 1: An admin here reposted everything that he found in `junk' (I stopped creating alt groups long ago) by removing the Message-ID and using `inews -d local'. Unfortunately, our version of C News (PL 18, if you were counting) only inserts `Distribution: local' if there is no Distribution header already present. As a result, any of the repostings that already had a Distribution header got sent out to the world with a new Message-ID. Bug 2: (or maybe not) The path contained in the reposting shows `Path: vsi1!vsi1!...'. I'm pretty sure that 2.11 checked for your site in the path to prevent propagation loops. C News obviously doesn't. Is this a bug (or a feature :-)? The path has to be scanned to determine whether to pass the article or not so why not check to see if your site is already in the list? -- Larry Blair ames!vsi1!lmb lmb@vicom.com
mjr@hussar.dco.dec.com (Marcus J. Ranum) (09/25/90)
In article <1990Sep24.220833.230@vicom.com> lmb@vicom.com (Larry Blair) writes: >Bug 2: (or maybe not) >The path contained in the reposting shows `Path: vsi1!vsi1!...'. I'm pretty >sure that 2.11 checked for your site in the path to prevent propagation loops. I've been seeing exactly the same problem, and was starting to wonder if I was hallucinating. [some of our month old+ news has leaked back out onto the net - thanks to those of you who have pointed this out] I'm running Cnews, patchlevel "most recent that I know of" :) If I post an article with a path like Path: deucac!decuac.dec.com!decuac!decuac.dec.com!mjr it propagagates out just fine. We're also getting (though I hope that's fixed, now) articles making a long, slow loop, and reaching our machine after their history entries have expired here, and going back around. What's the best way to ensure against this kind of problem ? I wonder if various Cnews sites have been lucking out by virtue of Bnews sites "compartmenting" article loops... mjr.
henry@zoo.toronto.edu (Henry Spencer) (09/25/90)
In article <1990Sep24.220833.230@vicom.com> lmb@vicom.com (Larry Blair) writes: >... by removing the Message-ID and using `inews -d local'. >Unfortunately, our version of C News (PL 18, if you were counting) only >inserts `Distribution: local' if there is no Distribution header already >present... I don't think it has ever been clear what the semantics are supposed to be if the same header crops up in both inews options and the article itself. (Actually, we think most of the inews options are silly ideas, since it's no harder to just plug the header into the article.) >The path contained in the reposting shows `Path: vsi1!vsi1!...'. I'm pretty >sure that 2.11 checked for your site in the path to prevent propagation loops. >C News obviously doesn't. Is this a bug (or a feature :-)? The path has to >be scanned to determine whether to pass the article or not so why not check to >see if your site is already in the list? It's one more check to do on a critical path, and one that in normal (and most abnormal) circumstances serves no purpose. Loop breaking is normally done by your neighbors not sending you the article, not by you recognizing that it's yours. -- TCP/IP: handling tomorrow's loads today| Henry Spencer at U of Toronto Zoology OSI: handling yesterday's loads someday| henry@zoo.toronto.edu utzoo!henry
jerry@olivey.olivetti.com (Jerry Aguirre) (09/26/90)
In article <1990Sep24.220833.230@vicom.com> lmb@vicom.com (Larry Blair) writes: >The path contained in the reposting shows `Path: vsi1!vsi1!...'. I'm pretty >sure that 2.11 checked for your site in the path to prevent propagation loops. I don't think that it should. Checking the path to see if a site is already listed is an optimization performed by the SENDER. It is important for UUCP feeds to non-leaf sites. The real protections against duplicates are the message ID and posting date. Articles older than what is retained in the history file should be discarded. I think it is a bad idea to rely to heavily on the path because there is no guarantee against duplicate news names. Before someone mentions the UUCP map project remember that is for UUCP, not news. There are sites that run news without UUCP and sites that just don't register. As a specific example I was sending an aged ihave to sun.com with all the articles from the previous day. I monitored the articles they were requesting (finding a minor bug in my sys line for them) and noticed that they were also requesting articles that they should have received. A little further investigation showed that those articles alread had "sun" in the path so none of sun.com's neighbors were sending them to sun. The problem was that the "sun" in question was "sun.soe.clarkson.edu". So, any articles originating on or passing thru the other "sun" won't get to sun.com. As there is no official control, or even registration, of news sites there is no mechanism to prevent such naming clashes. If sun.com rejected those articles then it was doing the wrong thing as it had never seen them before. I wonder how the small amout of overhead C news saves by not parsing the date compares to the CPU, modem, and PEOPLE overhead spent on processing recirculated expired articles. Jerry Aguirre