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| author | Nick Mathewson <nickm@torproject.org> | 2012-08-09 12:37:40 -0400 |
|---|---|---|
| committer | Nick Mathewson <nickm@torproject.org> | 2012-08-09 12:40:03 -0400 |
| commit | 640a51684ce5a6cdae5c5f92cd2f932922380c00 (patch) | |
| tree | 0cfaffe7e783cc8fb1b26d8da07a44067d2d04fc /changes | |
| parent | e106812a778f53760c819ab20a214ac3222b3b15 (diff) | |
| download | tor-640a51684ce5a6cdae5c5f92cd2f932922380c00.tar tor-640a51684ce5a6cdae5c5f92cd2f932922380c00.tar.gz | |
Remove remaining timing-dependency in choosing nodes by bandwidth
The old approach, because of its "tmp >= rand_bw &&
!i_has_been_chosen" check, would run through the second part of the
loop slightly slower than the first part. Now, we remove
i_has_been_chosen, and instead set rand_bw = UINT64_MAX, so that
every instance of the loop will do exactly the same amount of work
regardless of the initial value of rand_bw.
Fix for bug 6538.
Diffstat (limited to 'changes')
| -rw-r--r-- | changes/bug6538 | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/changes/bug6538 b/changes/bug6538 index 1e882eb1c..fc9e583d5 100644 --- a/changes/bug6538 +++ b/changes/bug6538 @@ -2,3 +2,11 @@ - Switch weighted node selection rule from using a list of doubles to using a list of int64_t. This should make the process slightly easier to debug and maintain. Needed for fix for bug 6538. + + o Security features: + - Switch to a completely time-invariant approach for picking nodes + weighted by bandwidth. Our old approach would run through the + part of the loop after it had made its choice slightly slower + than it ran through the part of the loop before it had made its + choice. Fix for bug 6538. + |