diff options
Diffstat (limited to 'src/osmo-bts-sysmo')
| -rw-r--r-- | src/osmo-bts-sysmo/l1_if.c | 43 |
1 files changed, 31 insertions, 12 deletions
diff --git a/src/osmo-bts-sysmo/l1_if.c b/src/osmo-bts-sysmo/l1_if.c index 5bda73fd..90d3f426 100644 --- a/src/osmo-bts-sysmo/l1_if.c +++ b/src/osmo-bts-sysmo/l1_if.c @@ -339,6 +339,7 @@ get_lapdm_chan_by_hl2(struct gsm_bts_trx *trx, uint32_t hLayer2) static int check_for_ciph_cmd(struct femtol1_hdl *fl1h, struct msgb *msg, struct gsm_lchan *lchan) { + uint8_t n_s; /* only do this if we are in the right state */ switch (lchan->ciph_state) { @@ -359,12 +360,41 @@ static int check_for_ciph_cmd(struct femtol1_hdl *fl1h, if ((msg->data[4] & 0x3F) != GSM48_MT_RR_CIPH_M_CMD) return 0; + /* Remember N(S) + 1 to find the first ciphered frame */ + n_s = (msg->data[1] >> 1) & 0x7; + lchan->ciph_ns = (n_s + 1) % 8; + lchan->ciph_state = LCHAN_CIPH_RX_REQ; l1if_set_ciphering(fl1h, lchan, 0); return 1; } +static inline void check_for_first_ciphrd(struct femtol1_hdl *fl1h, + GsmL1_MsgUnitParam_t *msgUnitParam, + struct gsm_lchan *lchan) +{ + uint8_t n_s; + + /* if this is the first valid message after enabling Rx + * decryption, we have to enable Tx encryption */ + if (lchan->ciph_state != LCHAN_CIPH_RX_CONF) + return; + + /* HACK: check if it's an I frame, in order to + * ignore some still buffered/queued UI frames received + * before decryption was enabled */ + if (msgUnitParam->u8Buffer[0] != 0x01) + return; + if ((msgUnitParam->u8Buffer[1] & 0x01) != 0) + return; + n_s = msgUnitParam->u8Buffer[1] >> 5; + if (lchan->ciph_ns != n_s) + return; + lchan->ciph_state = LCHAN_CIPH_TXRX_REQ; + l1if_set_ciphering(fl1h, lchan, 1); +} + static const uint8_t fill_frame[GSM_MACBLOCK_LEN] = { 0x03, 0x03, 0x01, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, @@ -744,18 +774,7 @@ static int handle_ph_data_ind(struct femtol1_hdl *fl1, GsmL1_PhDataInd_t *data_i break; } - /* if this is the first valid message after enabling Rx - * decryption, we have to enable Tx encryption */ - if (lchan->ciph_state == LCHAN_CIPH_RX_CONF) { - /* HACK: check if it's an I frame, in order to - * ignore some still buffered/queued UI frames received - * before decryption was enabled */ - if (data_ind->msgUnitParam.u8Buffer[0] == 0x01 && - (data_ind->msgUnitParam.u8Buffer[1] & 0x01) == 0) { - lchan->ciph_state = LCHAN_CIPH_TXRX_REQ; - l1if_set_ciphering(fl1, lchan, 1); - } - } + check_for_first_ciphrd(fl1, &data_ind->msgUnitParam, lchan); /* SDCCH, SACCH and FACCH all go to LAPDm */ le = le_by_l1_sapi(&lchan->lapdm_ch, data_ind->sapi); |