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| author | Nick Mathewson <nickm@torproject.org> | 2021-11-09 13:43:48 -0500 |
|---|---|---|
| committer | Nick Mathewson <nickm@torproject.org> | 2021-11-09 13:43:48 -0500 |
| commit | 96f1e69f24ec5c056964b44cb8538004649c504d (patch) | |
| tree | 6bbf5f621bd666f863c9db6d214aca666bbab2ed /src/feature/dirauth | |
| parent | 1d2c918dfdfc1356890775bc57358b3523830224 (diff) | |
| download | tor-96f1e69f24ec5c056964b44cb8538004649c504d.tar.gz tor-96f1e69f24ec5c056964b44cb8538004649c504d.zip | |
Implement proposal 275: don't put "published" times in md consensus
When a new consensus method is negotiated, these values will all get
replaced with "2038-01-01 00:00:00".
This change should be safe because:
* As of 0.2.9.11 / 0.3.0.7 / 0.3.1.1-alpha, Tor takes no action
about published_on times in the future.
* The only remaining parties relying on published_on values are (we
believe) relays running 0.3.5.x, which rely on the values in a NS
consensus to see whether their descriptors are out of date. But
this patch only changes microdesc consensuses.
* The latest Tor no longer looks at this field in consensuses.
Why make this change? In experiments, replacing these values with a
fixed value made the size of compressed consensus diffs much much
smaller. (Like, by over 50%!)
Implements proposal 275; Implements #40130.
Diffstat (limited to 'src/feature/dirauth')
| -rw-r--r-- | src/feature/dirauth/dirvote.c | 16 | ||||
| -rw-r--r-- | src/feature/dirauth/dirvote.h | 8 |
2 files changed, 22 insertions, 2 deletions
diff --git a/src/feature/dirauth/dirvote.c b/src/feature/dirauth/dirvote.c index 71f059dbc8..b4a9f83f19 100644 --- a/src/feature/dirauth/dirvote.c +++ b/src/feature/dirauth/dirvote.c @@ -2048,7 +2048,6 @@ networkstatus_compute_consensus(smartlist_t *votes, memcpy(rs_out.descriptor_digest, rs->status.descriptor_digest, DIGEST_LEN); tor_addr_copy(&rs_out.ipv4_addr, &rs->status.ipv4_addr); - time_t published_on = rs->published_on; rs_out.ipv4_dirport = rs->status.ipv4_dirport; rs_out.ipv4_orport = rs->status.ipv4_orport; tor_addr_copy(&rs_out.ipv6_addr, &alt_orport.addr); @@ -2056,6 +2055,21 @@ networkstatus_compute_consensus(smartlist_t *votes, rs_out.has_bandwidth = 0; rs_out.has_exitsummary = 0; + time_t published_on = rs->published_on; + + /* Starting with this consensus method, we no longer include a + meaningful published_on time for microdescriptor consensuses. This + makes their diffs smaller and more compressible. + + We need to keep including a meaningful published_on time for NS + consensuses, however, until 035 relays are all obsolete. (They use + it for a purpose similar to the current StaleDesc flag.) + */ + if (consensus_method >= MIN_METHOD_TO_SUPPRESS_MD_PUBLISHED && + flavor == FLAV_MICRODESC) { + published_on = -1; + } + if (chosen_name && !naming_conflict) { strlcpy(rs_out.nickname, chosen_name, sizeof(rs_out.nickname)); } else { diff --git a/src/feature/dirauth/dirvote.h b/src/feature/dirauth/dirvote.h index 64aaec116e..ae8d43a6f0 100644 --- a/src/feature/dirauth/dirvote.h +++ b/src/feature/dirauth/dirvote.h @@ -53,7 +53,7 @@ #define MIN_SUPPORTED_CONSENSUS_METHOD 28 /** The highest consensus method that we currently support. */ -#define MAX_SUPPORTED_CONSENSUS_METHOD 32 +#define MAX_SUPPORTED_CONSENSUS_METHOD 33 /** * Lowest consensus method where microdescriptor lines are put in canonical @@ -74,6 +74,12 @@ */ #define MIN_METHOD_FOR_MIDDLEONLY 32 +/** + * Lowest consensus method for which we suppress the published time in + * microdescriptor consensuses. + */ +#define MIN_METHOD_TO_SUPPRESS_MD_PUBLISHED 33 + /** Default bandwidth to clip unmeasured bandwidths to using method >= * MIN_METHOD_TO_CLIP_UNMEASURED_BW. (This is not a consensus method; do not * get confused with the above macros.) */ |