commit 7c8e519b3452ce3eb3d3c854d80be5b7e49164b4 Author: David Goulet dgoulet@torproject.org Date: Wed Apr 24 10:25:29 2019 -0400
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 --- src/core/or/sendme.c | 25 ++++++++++++++++++++++++- src/core/or/sendme.h | 3 +++ 2 files changed, 27 insertions(+), 1 deletion(-)
diff --git a/src/core/or/sendme.c b/src/core/or/sendme.c index 3dcd9df08..c66e947bc 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; }
diff --git a/src/core/or/sendme.h b/src/core/or/sendme.h index 71df9b6f0..0965b5b22 100644 --- a/src/core/or/sendme.h +++ b/src/core/or/sendme.h @@ -37,6 +37,9 @@ int sendme_note_stream_data_packaged(edge_connection_t *conn); /* Track cell digest. */ void sendme_note_cell_digest(circuit_t *circ);
+/* Circuit level information. */ +bool sendme_circuit_is_next_cell(int window); + /* Private section starts. */ #ifdef SENDME_PRIVATE