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nr rlc am: bugfix: discard a control PDU if ack-sn is invalid

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It is possible to receive an ACK that is not expected, in which
case the whole control PDU has to be discarded.
This commit is contained in:
Cedric Roux
2023-09-04 11:00:23 +02:00
parent 67a3184bb3
commit b4fea523b9
1 changed files with 11 additions and 0 deletions
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openair2/LAYER2/nr_rlc/nr_rlc_entity_am.c
+11
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@@ -354,6 +354,17 @@ static void process_control_pdu(nr_rlc_entity_am_t *entity,
nr_rlc_pdu_decoder_get_bits(&decoder, 7); R(decoder); nr_rlc_pdu_decoder_get_bits(&decoder, 7); R(decoder);
} }
/* discard the whole control PDU if ack_sn is invalid, that is
* if it does not satisfy tx_next_ack <= ack_sn <= tx_next
* (no need to test tx_next_ack <= ack_sn, this is always true since
* tx_next_ack is the modulus base)
*/
if (sn_compare_tx(entity, ack_sn, entity->tx_next) > 0) {
LOG_W(RLC, "ack_sn (%d) not valid (tx_next_ack %d tx_next %d), discard control PDU\n",
ack_sn, entity->tx_next_ack, entity->tx_next);
return;
}
/* 38.322 5.3.3.3 says to stop t_poll_retransmit if a ACK or NACK is /* 38.322 5.3.3.3 says to stop t_poll_retransmit if a ACK or NACK is
* received for the SN 'poll_sn' - check ACK case (NACK done below) * received for the SN 'poll_sn' - check ACK case (NACK done below)
*/ */