Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Improve shuffling algorithm of connection list #634

Open
wants to merge 2 commits into
base: master
Choose a base branch
from
+10 −3
Open

Improve shuffling algorithm of connection list #634

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
12df21f
Improve shuffling algorithm of connection list
Oct 26, 2024
2b24aeb
Explain how the new algorithm reduces bias
Hurukawa2121 Nov 16, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
13 changes: 10 additions & 3 deletions src/openvpn/init.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -467,7 +467,14 @@ ce_management_query_remote(struct context *c)
#endif /* ENABLE_MANAGEMENT */

/*
* Initialize and possibly randomize connection list.
* Initialize and randomize the connection list.
*
* Applies the Fisher-Yates shuffle algorithm to ensure all permutations are equally probable,
* thereby eliminating shuffling bias in the previous method.
*
* The algorithm randomly selects an element from the unshuffled portion and places it at position i.
* There's only one way to obtain each permutation through these swaps.
* This guarantees that each permutation occurs with equal probability in theory.
*/
static void
init_connection_list(struct context *c)
Expand All @@ -478,9 +485,9 @@ init_connection_list(struct context *c)
if (c->options.remote_random)
{
int i;
for (i = 0; i < l->len; ++i)
for (i = l->len - 1; i > 0; --i)
{
const int j = get_random() % l->len;
const int j = get_random() % (i + 1);
if (i != j)
{
struct connection_entry *tmp;
Expand Down