[MacPorts] #25128: Avoid checksum errors due to broken DNS servers

[MacPorts]

#25128: Avoid checksum errors due to broken DNS servers
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 Reporter:  ryandesign@…             |       Owner:  macports-tickets@…                   
     Type:  defect                   |      Status:  new                                  
 Priority:  Normal                   |   Milestone:  MacPorts 1.9.1                       
Component:  base                     |     Version:  1.8.2                                
 Keywords:  haspatch                 |        Port:                                       
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Comment(by ryandesign@…):

 Replying to [comment:3 jmr@…]:
 > I really don't like the idea of legitimising the completely broken
 behaviour of these DNS servers (and web servers, since they must not even
 be serving the "helpful" page with a 404 code).

 Well, we could go on a campaign of lobbying the ISPs to fix this. I think
 this would be a lot of work and I don't know that it would be successful.
 Meanwhile the attached patch was a couple lines of code and is completely
 successful as far as I can tell in my testing.

 > The checksum failure reports do indicate a genuine issue with the ports
 (even if it would be an extremely minor one given working DNS). Giving
 additional information about the likely cause of a checksum failure would
 be OK.

 The genuine issue is that the port is referring to a server that doesn't
 exist? True, but in the case of a properly-functioning DNS server, we
 simply skip it and move on; the patch in this ticket simply affords that
 same convenience to users with these increasingly-popular DNS servers. And
 the patch does print a detailed error message explaining that the distfile
 file was unexpectedly an HTML page, so if a port maintainer sees this
 output (either experienced themselves or submitted in a ticket) they can
 investigate then, just like they can if they see a message that a server
 could not be contacted.

 For me, without the patch, I encounter the issue extremely often, because
 I often work at friends' houses and coffee shops, each of which generally
 has such a DNS server now. My mirror_sites.tcl on each of my local
 machines is modified to include each of the other machines (so they can
 fetch distfiles from each other quickly); when using my laptop elsewhere,
 these local machine names don't exist so I run into the issue for pretty
 much every port. So I would like to commit this patch.

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Ticket URL: <http://trac.macports.org/ticket/25128#comment:4>
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