[tor-bugs] #23107 [Core Tor/Tor]: prop224: Optimize hs_circ_service_get_intro_circ() digest calculation

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#23107: prop224: Optimize hs_circ_service_get_intro_circ() digest calculation
-------------------------------------------------+-------------------------
 Reporter:  asn                                  |          Owner:  neel
     Type:  defect                               |         Status:
                                                 |  needs_revision
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  unspecified
Component:  Core Tor/Tor                         |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  prop224, prop224-extra, tor-hs,      |  Actual Points:
  optimization, 032-unreached                    |
Parent ID:                                       |         Points:
 Reviewer:  dgoulet                              |        Sponsor:
-------------------------------------------------+-------------------------
Changes (by dgoulet):

 * status:  needs_review => needs_revision
 * reviewer:   => dgoulet
 * points:  0.2 =>
 * sponsor:  SponsorR-can =>


Comment:

 Thanks neel!

 Couple of things.

 1. We should set the digest right away when creating the legacy key
 instead of this:

  {{{memset(ip->digest, 0, sizeof(ip->digest));}}}

 2. We don't need to check for mem is zero when using the legacy IP because
 if `is_only_legacy` is set, then digest + legacy_key MUST be set.
 Actually, considering that we set the digest when an IP is allocated, we
 don't need this whole if().

 3. I would rename the `digest` to maybe something like `legacy_key_digest`
 because there are so many keys in that object that we should just be
 precise about what digest that is.

 Huge thanks!

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/23107#comment:6>
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