[tor-bugs] #4548 [Tor Bridge]: Implement dynamic (rakshasa) primes (part of proposal 179)

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#4548: Implement dynamic (rakshasa) primes (part of proposal 179)
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 Reporter:  asn         |          Owner:                    
     Type:  defect      |         Status:  needs_review      
 Priority:  normal      |      Milestone:  Tor: 0.2.3.x-final
Component:  Tor Bridge  |        Version:                    
 Keywords:              |         Parent:  #3972             
   Points:              |   Actualpoints:                    
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Comment(by nickm):

 Replying to [comment:10 asn]:
 > Replying to [comment:6 nickm]:
 > > Remaining issues, in addition to those above, after second review:
 > >
 > >  * If this new option is going to be on-by-default, then clients
 really shouldn't pay attention to it, since they shouldn't actually need
 to have a group at all.
 >
 > True. I'm only doing dynamic DH stuff to bridges now.

 Hm. This seems like something all servers should want.  I didn't see the
 part that made this bridges-only; where can I find it?

 > >  * Checking a file status right before opening it is prone to race-
 conditions; it's better just to open the file and see if you get an error.
 There should be functions in util.c to do this. (This one could get
 cleaned up later)
 >
 > I didn't find such functions in util.c. We need a FILE* to pass to
 BN_print_fp().
 > I thought of using open() or fdopen() with O_CREAT and O_EXCL, but
 open() seems to be a POSIX thing.

 open is supported on Windows: http://msdn.microsoft.com/en-
 us/library/z0kc8e3z%28v=vs.71%29.aspx

 The functions I meant in util.c are start_writing_to_stdio_file and
 finish/abort_writing to file; they do the open+fdopen thing you want.

 BTW, you *can* do this with DH parameters: d2i_DHparams and i2d_DHparams
 convert DH params to and from strings, and the {d2i,i2d}_DHparams_fp
 variants read and write DH parameters on a FILE*

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/4548#comment:11>
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