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nr rlc am: rewrite process_control_pdu()

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A first pass checks that the control PDU is valid.
A second pass processes it for real.
This commit is contained in:
Cedric Roux
2023-09-05 21:52:30 +02:00
parent f7fe3b448f
commit 1272847fea
1 changed files with 78 additions and 27 deletions
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openair2/LAYER2/nr_rlc/nr_rlc_entity_am.c
+78 -27
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@@ -329,21 +329,14 @@ static void process_control_pdu(nr_rlc_entity_am_t *entity,
nr_rlc_sdu_segment_t head_retransmit_list;
int cmp;
head_wait_list.next = entity->wait_list;
cur_wait_list = entity->wait_list;
prev_wait_list = &head_wait_list;
head_retransmit_list.next = NULL;
cur_retransmit_list = entity->retransmit_list;
new_retransmit_list = &head_retransmit_list;
/* validate the control PDU: read it, check the values of ACK and NACKs */
nr_rlc_pdu_decoder_init(&decoder, buffer, size);
nr_rlc_pdu_decoder_get_bits(&decoder, 1); R(decoder); /* dc */
cpt = nr_rlc_pdu_decoder_get_bits(&decoder, 3); R(decoder);
if (cpt != 0) {
LOG_E(RLC, "%s:%d:%s: warning: discard PDU, CPT not 0 (%d)\n",
__FILE__, __LINE__, __FUNCTION__, cpt);
LOG_E(RLC, "discard PDU, CPT not 0 (%d)\n", cpt);
goto err;
}
ack_sn = nr_rlc_pdu_decoder_get_bits(&decoder, entity->sn_field_length); R(decoder);
@@ -366,12 +359,9 @@ static void process_control_pdu(nr_rlc_entity_am_t *entity,
return;
}
/* 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)
/* discard the whole control PDU if NACKs are bad (not <= ack_sn, not in
* increasing order)
*/
if (sn_compare_tx(entity, entity->poll_sn, ack_sn) < 0)
entity->t_poll_retransmit_start = 0;
while (e1) {
nack_sn = nr_rlc_pdu_decoder_get_bits(&decoder, entity->sn_field_length); R(decoder);
e1 = nr_rlc_pdu_decoder_get_bits(&decoder, 1); R(decoder);
@@ -399,15 +389,13 @@ static void process_control_pdu(nr_rlc_entity_am_t *entity,
if (so_end == 0xffff)
so_end = -1;
/* process nacks */
for (i = 0; i < range; i++) {
int cur_nack_sn = (nack_sn + i) % entity->sn_modulus;
int cur_so_start = i == 0 ? so_start : 0;
int cur_so_end = i == range - 1 ? so_end : -1;
/* check that current nack is > previous nack and <= ack
* if not then skip it and all following nacks, and
* do not touch t_poll_retransmit
* if not then reject the control PDU
*/
if (prev_nack_sn != -1) {
cmp = sn_compare_tx(entity, cur_nack_sn, prev_nack_sn);
@@ -415,19 +403,84 @@ static void process_control_pdu(nr_rlc_entity_am_t *entity,
|| (cmp == 0
&& (prev_so_end == -1
|| cur_so_start <= prev_so_end))) {
LOG_E(RLC, "%s:%d:%s: bad NACK (nack sn %d so start/end %d/%d, previous nack sn %d so start/end %d/%d), skip it and all following NACKs\n",
__FILE__, __LINE__, __FUNCTION__,
LOG_E(RLC, "bad NACK, not bigger than previous NACK (nack sn %d so start/end %d/%d, previous nack sn %d so start/end %d/%d)\n",
cur_nack_sn, cur_so_start, cur_so_end,
prev_nack_sn, prev_so_start, prev_so_end);
goto nacks_done;
goto err;
}
}
if (sn_compare_tx(entity, cur_nack_sn, ack_sn) > 0) {
LOG_E(RLC, "%s:%d:%s: bad NACK (nack %d ack %d), skip it and all following NACKs\n",
__FILE__, __LINE__, __FUNCTION__,
cur_nack_sn, ack_sn);
goto nacks_done;
LOG_E(RLC, "bad NACK, bigger than ACK (nack %d ack %d) (tx_next_ack %d tx_next %d)\n",
cur_nack_sn, ack_sn, entity->tx_next_ack, entity->tx_next);
goto err;
}
}
}
/* process the control PDU for real (checks not needed now, previous steps
* validated everything)
*/
head_wait_list.next = entity->wait_list;
cur_wait_list = entity->wait_list;
prev_wait_list = &head_wait_list;
head_retransmit_list.next = NULL;
cur_retransmit_list = entity->retransmit_list;
new_retransmit_list = &head_retransmit_list;
nr_rlc_pdu_decoder_init(&decoder, buffer, size);
nr_rlc_pdu_decoder_get_bits(&decoder, 1); /* dc */
cpt = nr_rlc_pdu_decoder_get_bits(&decoder, 3);
ack_sn = nr_rlc_pdu_decoder_get_bits(&decoder, entity->sn_field_length);
e1 = nr_rlc_pdu_decoder_get_bits(&decoder, 1);
/* r bits */
if (entity->sn_field_length == 18) {
nr_rlc_pdu_decoder_get_bits(&decoder, 1);
} else {
nr_rlc_pdu_decoder_get_bits(&decoder, 7);
}
/* 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)
*/
if (sn_compare_tx(entity, entity->poll_sn, ack_sn) < 0)
entity->t_poll_retransmit_start = 0;
while (e1) {
nack_sn = nr_rlc_pdu_decoder_get_bits(&decoder, entity->sn_field_length);
e1 = nr_rlc_pdu_decoder_get_bits(&decoder, 1);
e2 = nr_rlc_pdu_decoder_get_bits(&decoder, 1);
e3 = nr_rlc_pdu_decoder_get_bits(&decoder, 1);
/* r bits */
if (entity->sn_field_length == 18) {
nr_rlc_pdu_decoder_get_bits(&decoder, 3);
} else {
nr_rlc_pdu_decoder_get_bits(&decoder, 1);
}
if (e2) {
so_start = nr_rlc_pdu_decoder_get_bits(&decoder, 16);
so_end = nr_rlc_pdu_decoder_get_bits(&decoder, 16);
} else {
so_start = 0;
so_end = 0xffff;
}
if (e3) {
range = nr_rlc_pdu_decoder_get_bits(&decoder, 8);
} else {
range = 1;
}
/* special value 0xffff indicates 'all bytes to the end' */
if (so_end == 0xffff)
so_end = -1;
/* process nacks */
for (i = 0; i < range; i++) {
int cur_nack_sn = (nack_sn + i) % entity->sn_modulus;
int cur_so_start = i == 0 ? so_start : 0;
int cur_so_end = i == range - 1 ? so_end : -1;
process_next_pdu:
/* process smallest SN either from wait_list or retransmit list */
@@ -599,7 +652,6 @@ lists_over:
entity->t_poll_retransmit_start = 0;
} /* while (e1) */
nacks_done:
/* nacks done, finish with ack */
/* we may report successful delivery out of order, if it's a problem
* then we can have a single loop and deal with the smallest sn of
@@ -679,8 +731,7 @@ nacks_done:
return;
err:
LOG_E(RLC, "%s:%d:%s: error decoding PDU, NR RLC entity in inconsistent state\n",
__FILE__, __LINE__, __FUNCTION__);
LOG_E(RLC, "error decoding control PDU, discarding\n");
#undef R
}