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author | David Goulet <dgoulet@torproject.org> | 2019-04-24 10:25:29 -0400 |
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committer | David Goulet <dgoulet@torproject.org> | 2019-04-29 12:17:57 -0400 |
commit | 7c8e519b3452ce3eb3d3c854d80be5b7e49164b4 (patch) | |
tree | 646b171eaebe4e7f29f35515d68df624115ec7bd /src/core/or/sendme.c | |
parent | aef7095c3e52e2f98850e72c68b00f54a39608a6 (diff) | |
download | tor-7c8e519b3452ce3eb3d3c854d80be5b7e49164b4.tar.gz tor-7c8e519b3452ce3eb3d3c854d80be5b7e49164b4.zip |
sendme: Helper to know if next cell is a SENDME
We'll use it this in order to know when to hash the cell for the SENDME
instead of doing it at every cell.
Part of #26288
Signed-off-by: David Goulet <dgoulet@torproject.org>
Diffstat (limited to 'src/core/or/sendme.c')
-rw-r--r-- | src/core/or/sendme.c | 25 |
1 files changed, 24 insertions, 1 deletions
diff --git a/src/core/or/sendme.c b/src/core/or/sendme.c index 3dcd9df08e..c66e947bc4 100644 --- a/src/core/or/sendme.c +++ b/src/core/or/sendme.c @@ -286,6 +286,29 @@ send_circuit_level_sendme(circuit_t *circ, crypt_path_t *layer_hint, return 0; } +/* + * Public API + */ + +/** Return true iff the next cell for the given cell window is expected to be + * a SENDME. + * + * We are able to know that because the package or deliver window value minus + * one cell (the possible SENDME cell) should be a multiple of the increment + * window value. */ +bool +sendme_circuit_is_next_cell(int window) +{ + /* Is this the last cell before a SENDME? The idea is that if the package or + * deliver window reaches a multiple of the increment, after this cell, we + * should expect a SENDME. */ + if (((window - 1) % CIRCWINDOW_INCREMENT) != 0) { + return false; + } + /* Next cell is expected to be a SENDME. */ + return true; +} + /** Called when we've just received a relay data cell, when we've just * finished flushing all bytes to stream <b>conn</b>, or when we've flushed * *some* bytes to the stream <b>conn</b>. @@ -550,7 +573,7 @@ sendme_note_cell_digest(circuit_t *circ) /* Is this the last cell before a SENDME? The idea is that if the * package_window reaches a multiple of the increment, after this cell, we * should expect a SENDME. */ - if (((circ->package_window - 1) % CIRCWINDOW_INCREMENT) != 0) { + if (!sendme_circuit_is_next_cell(circ->package_window)) { return; } |