Arc Forum | IP Source Domain Bug

Arc Forum

5 points by profquail 5586 days ago | 3 comments

I mentioned in a previous thread here on the Arc forum that there was a bug in the way that news.arc handles printing the source domain for story links: http://www.arclanguage.org/item?id=10486

In that case, only the last 2 octets of the IP are printed, along with the port number (in the correct order though).

I was just reading through HN and found it popping up there as well: http://news.ycombinator.com/item?id=811850

In that case, the IP is printed (all 4 octets) in reverse order compared to the link URL

4 points by fallintothis 5586 days ago | link

In the style of my previous response, the offending code from news.arc:

  (def parse-site (url)
    (rev (tokens (cadr (tokens url [in _ #\/ #\?])) #\.)))

  (defmemo sitename (url)
    (and (valid-url url)
         (let toks (parse-site (rem #\space url))
           (if (isa (saferead (car toks)) 'int)
               (tostring (prall toks "" "."))
               (let (t1 t2 t3 . rest) toks  
                 (if (and (~in t3 nil "www")
                          (or (mem t1 multi-tld-countries*) 
                              (mem t2 long-domains*)))
                     (+ t3 "." t2 "." t1)
                     (and t2 (+ t2 "." t1))))))))

In particular,

  (tostring (prall toks "" "."))

will generate a reversed IP because toks is already reversed:

  arc> (= toks (parse-site "http://74.125.95.132/"))
  ("132" "95" "125" "74")
  arc> (isa (saferead (car toks)) 'int)
  t
  arc> (tostring (prall toks "" "."))
  "132.95.125.74"

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3 points by profquail 5586 days ago | link

Thanks for your detective work fallintothis!

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2 points by pg 5585 days ago | link

oops, fixed

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