[tor-bugs] #5647 [Tor Hidden Services]: rend_parse_client_keys() prints stack in logs if base64_decode fails

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#5647: rend_parse_client_keys() prints stack in logs if base64_decode fails
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 Reporter:  asn                  |          Owner:                    
     Type:  defect               |         Status:  needs_review      
 Priority:  normal               |      Milestone:  Tor: 0.2.2.x-final
Component:  Tor Hidden Services  |        Version:                    
 Keywords:                       |         Parent:                    
   Points:                       |   Actualpoints:                    
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Comment(by asn):

 Your fix looks good.

 Kinda lame that gcc and coverity didn't detect this one as use of
 uninitialized variable. Maybe we should send them an email?

 Also, should `srclen` in `base64_decode` be
 `REND_DESC_COOKIE_LEN_BASE64+2+1` or `REND_DESC_COOKIE_LEN_BASE64+2` to
 match with:
 {{{
  if (strlen(tok->args[0]) != REND_DESC_COOKIE_LEN_BASE64 + 2) {
 }}}
 ?

 It seems to me that if the base64 blob doesn't contain padding characters,
 `base64_decode` will also read the NUL (because of the `+1`) and fail. In
 other cases of `base64_decode()` we are feeding the output of `strlen()`
 as the `srclen`, which does not consider the NUL.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/5647#comment:4>
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