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prop289: Move digest matching in its own function
No behavior change but code had to be refactored a bit. Also, the tor_memcmp() was changed to tor_memneq(). Part of #26288 Signed-off-by: David Goulet <dgoulet@torproject.org>
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@ -59,6 +59,49 @@ get_accept_min_version(void)
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SENDME_ACCEPT_MIN_VERSION_MAX);
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}
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/* Return true iff the given cell digest matches the first digest in the
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* circuit sendme list. */
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static bool
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v1_digest_matches(const circuit_t *circ, const uint8_t *cell_digest)
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{
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bool ret = false;
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uint8_t *circ_digest = NULL;
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tor_assert(circ);
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tor_assert(cell_digest);
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/* We shouldn't have received a SENDME if we have no digests. Log at
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* protocol warning because it can be tricked by sending many SENDMEs
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* without prior data cell. */
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if (circ->sendme_last_digests == NULL ||
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smartlist_len(circ->sendme_last_digests) == 0) {
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log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
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"We received a SENDME but we have no cell digests to match. "
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"Closing circuit.");
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goto no_match;
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}
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/* Pop the first element that was added (FIFO) and compare it. */
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circ_digest = smartlist_get(circ->sendme_last_digests, 0);
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smartlist_del_keeporder(circ->sendme_last_digests, 0);
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/* Compare the digest with the one in the SENDME. This cell is invalid
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* without a perfect match. */
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if (tor_memneq(circ_digest, cell_digest, TRUNNEL_SENDME_V1_DIGEST_LEN)) {
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log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
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"SENDME v1 cell digest do not match.");
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goto no_match;
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}
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/* Digests matches! */
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ret = true;
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no_match:
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/* This digest was popped from the circuit list. Regardless of what happens,
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* we have no more use for it. */
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tor_free(circ_digest);
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return ret;
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}
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/* Return true iff the given decoded SENDME version 1 cell is valid and
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* matches the expected digest on the circuit.
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*
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@ -68,44 +111,11 @@ get_accept_min_version(void)
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static bool
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cell_v1_is_valid(const sendme_cell_t *cell, const circuit_t *circ)
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{
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const uint8_t *cell_digest = NULL;
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tor_assert(cell);
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tor_assert(circ);
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cell_digest = sendme_cell_getconstarray_data_v1_digest(cell);
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/* We shouldn't have received this SENDME if we have no digests. Log at
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* protocol warning because it can be tricked by sending many SENDMEs
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* without prior data cell. */
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if (circ->sendme_last_digests == NULL ||
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smartlist_len(circ->sendme_last_digests) == 0) {
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log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
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"We received a SENDME but we have no cell digests to match. "
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"Closing circuit.");
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goto invalid;
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}
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/* Pop the first element that was added (FIFO) and compare it. */
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{
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uint8_t *digest = smartlist_get(circ->sendme_last_digests, 0);
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smartlist_del_keeporder(circ->sendme_last_digests, 0);
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/* Compare the digest with the one in the SENDME. This cell is invalid
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* without a perfect match. */
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if (tor_memcmp(digest, cell_digest, TRUNNEL_SENDME_V1_DIGEST_LEN)) {
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tor_free(digest);
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log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
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"SENDME v1 cell digest do not match.");
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goto invalid;
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}
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tor_free(digest);
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}
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/* Validated SENDME v1 cell. */
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return 1;
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invalid:
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return 0;
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const uint8_t *cell_digest = sendme_cell_getconstarray_data_v1_digest(cell);
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return v1_digest_matches(circ, cell_digest);
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}
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/* Return true iff the given cell version can be handled or if the minimum
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