[mynewt-nimble] 02/02: nimble/ll: Fix encrypted payload length

[an...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

andk pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/mynewt-nimble.git

commit 4a89a4c5cb1a33e8eae3c01a2108fedfb7eb180e
Author: Andrzej Kaczmarek <an...@codecoup.pl>
AuthorDate: Mon Nov 8 11:23:31 2021 +0100

    nimble/ll: Fix encrypted payload length
    
    ble_ll_pdu_max_tx_octets_get() returns number of bytes that can be
    added between LL header and CRC so the complete PDU is no longer than
    maxTxTime allowed. However, if link is encrypted there will be also
    MIC added after the payload so effectively we need to stript that extra
    4 bytes from allowed payload length.
---
 nimble/controller/src/ble_ll_conn.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/nimble/controller/src/ble_ll_conn.c b/nimble/controller/src/ble_ll_conn.c
index 20b578a..30a381e 100644
--- a/nimble/controller/src/ble_ll_conn.c
+++ b/nimble/controller/src/ble_ll_conn.c
@@ -854,7 +854,7 @@ ble_ll_conn_chk_csm_flags(struct ble_ll_conn_sm *connsm)
 static uint16_t
 ble_ll_conn_adjust_pyld_len(struct ble_ll_conn_sm *connsm, uint16_t pyld_len)
 {
-    uint16_t phy_max_tx_octets;
+    uint16_t max_pyld_len;
     uint16_t ret;
 
 #if (BLE_LL_BT5_PHY_SUPPORTED == 1)
@@ -867,22 +867,28 @@ ble_ll_conn_adjust_pyld_len(struct ble_ll_conn_sm *connsm, uint16_t pyld_len)
         phy_mode = connsm->phy_data.tx_phy_mode;
     }
 
-    phy_max_tx_octets = ble_ll_pdu_max_tx_octets_get(connsm->eff_max_tx_time,
-                                                     phy_mode);
+    max_pyld_len = ble_ll_pdu_max_tx_octets_get(connsm->eff_max_tx_time,
+                                                phy_mode);
 
 #else
-    phy_max_tx_octets = ble_ll_pdu_max_tx_octets_get(connsm->eff_max_tx_time,
-                                                     BLE_PHY_MODE_1M);
+    max_pyld_len = ble_ll_pdu_max_tx_octets_get(connsm->eff_max_tx_time,
+                                                BLE_PHY_MODE_1M);
 #endif
 
     ret = pyld_len;
 
+#if MYNEWT_VAL(BLE_LL_CFG_FEAT_LE_ENCRYPTION)
+    if (CONN_F_ENCRYPTED(connsm)) {
+        max_pyld_len -= BLE_LL_DATA_MIC_LEN;
+    }
+#endif
+
     if (ret > connsm->eff_max_tx_octets) {
         ret = connsm->eff_max_tx_octets;
     }
 
-    if (ret > phy_max_tx_octets) {
-        ret = phy_max_tx_octets;
+    if (ret > max_pyld_len) {
+        ret = max_pyld_len;
     }
 
     return ret;