[tor-bugs] #14905 [Tor]: client descriptor-cookies are wrong for stealth auth

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#14905: client descriptor-cookies are wrong for stealth auth
--------------------+----------------------------------
 Reporter:  meejah  |          Owner:
     Type:  defect  |         Status:  new
 Priority:  normal  |      Milestone:
Component:  Tor     |        Version:  Tor: unspecified
 Keywords:          |  Actual Points:
Parent ID:          |         Points:
--------------------+----------------------------------
 Tor writes the descriptor-cookies for stealth-authentications into two
 spots: "client_keys" and the "hostname" files. In the client_keys file,
 there appears to be an off-by-one in rendservice.c:1026, around this code:

       if (base64_encode(desc_cook_out, 3*REND_DESC_COOKIE_LEN_BASE64+1,
                         extended_desc_cookie,
                         REND_DESC_COOKIE_LEN+1) < 0) {
         log_warn(LD_BUG, "Could not base64-encode descriptor cookie.");
         goto err;
       }

 The REND_DESC_COOKIE_LEN shouldn't have the +1, I don't believe. (Or, the
 base64_encode call higher up *should* have one). In any case, both
 descriptor cookies are the same after that change (and work).

 This is in master, as of commit 3bcdb26267502e0d1de5d01854c8a2cf29a5e5f4

 I put a simple fix in https://github.com/meejah/tor/tree/descriptor-
 cookie-serialization

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/14905>
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