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Diffstat (limited to 'dir-spec.txt')
| -rw-r--r-- | dir-spec.txt | 63 |
1 files changed, 62 insertions, 1 deletions
diff --git a/dir-spec.txt b/dir-spec.txt index 68a1319..a29d86a 100644 --- a/dir-spec.txt +++ b/dir-spec.txt @@ -855,7 +855,7 @@ sorted by keyword. Values should be numerically ascending within each entry. (This implies that there should be no overlapping ranges.) Ranges should be represented as compactly as possible. Ints must be no - more than 2^32 - 2. (Yes, 2.) + larger than 63. This field was first added in Tor 0.2.9.x. @@ -3466,6 +3466,10 @@ FPRLIST is +-separated list of recognized authority identity fingerprints as in appendix B. +4.6 Retrying failed downloads + + See section 5.5 below; it applies to caches as well as clients. + 5. Client operation Every Tor that is not a directory server (that is, those that do @@ -3676,6 +3680,63 @@ (This section is removed; authorities no longer assign the 'Named' flag.) +5.5. Retrying failed downloads + + This section applies to caches as well as to clients. + + When a client fails to download a resource (a consensus, a router + descriptor, a microdescriptor, etc) it waits for a certain amount of + time before retrying the download. To determine the amount of time + to wait, clients use a randomized exponential backoff algorithm. + (Specifically, they use a variation of the "decorrelated jitter" + algorithm from + https://aws.amazon.com/blogs/architecture/exponential-backoff-and-jitter/ .) + + The specific formula used to compute the 'i+1'th delay is: + + Delay_{i+1} = MIN(cap, random_between(lower_bound, upper_bound))) + where upper_bound = MAX(lower_bound+1, Delay_i * 3) + lower_bound = MAX(1, base_delay). + + The value of 'cap' is set to INT_MAX; the value of 'base_delay' + depends on what is being downloaded, whether the client is fully + bootstrapped, how the client is configured, and where it is + downloading from. Current base_delay values are: + + Consensus objects, as a non-bridge cache: + 0 (TestingServerConsensusDownloadInitialDelay) + + Consensus objects, as a client or bridge that has bootstrapped: + 0 (TestingClientConsensusDownloadInitialDelay) + + Consensus objects, as a client or bridge that is bootstrapping, + when connecting to an authority because no "fallback" caches are + known: + 0 (ClientBootstrapConsensusAuthorityOnlyDownloadInitialDelay) + + Consensus objects, as a client or bridge that is bootstrapping, + when "fallback" caches are known but connecting to an authority + anyway: + 6 (ClientBootstrapConsensusAuthorityDownloadInitialDelay) + + Consensus objects, as a client or bridge that is bootstrapping, + when downloading from a "fallback" cache. + 0 (ClientBootstrapConsensusFallbackDownloadInitialDelay) + + Bridge descriptors, as a bridge-using client when at least one bridge + is usable: + 10800 (TestingBridgeDownloadInitialDelay) + + Bridge descriptors, otherwise: + 0 (TestingBridgeBootstrapDownloadInitialDelay) + + Other objects, as cache or authority: + 0 (TestingServerDownloadInitialDelay) + + Other objects, as client: + 0 (TestingClientDownloadInitialDelay) + + 6. Standards compliance All clients and servers MUST support HTTP 1.0. Clients and servers MAY |