laforge has submitted this change. ( https://gerrit.osmocom.org/c/osmo-bts/+/35124?usp=email )
Change subject: Add GSMTAP encapsulation of RLP frames in CSD NT mode ......................................................................
Add GSMTAP encapsulation of RLP frames in CSD NT mode
In CSD (Circuit Switched Data) NT (Non-Transparent) mode, there are RLP (Radio Link Protocol) frames inside the modified V.110.
wireshark alrady has a dissector for this, and we've introduced a GSMTAP type for RLP some time ago. So with this patch, we now generate such GSMTAP RLP frames.
Change-Id: I6a258458822bcb3fe7290a9b9b3d104beecda219 --- M include/osmo-bts/bts.h M include/osmo-bts/lchan.h M src/common/l1sap.c M src/common/vty.c M tests/osmo-bts.vty 5 files changed, 127 insertions(+), 4 deletions(-)
Approvals: laforge: Looks good to me, approved; Verified fixeria: Looks good to me, but someone else must approve osmith: Looks good to me, but someone else must approve
diff --git a/include/osmo-bts/bts.h b/include/osmo-bts/bts.h index 60e308c..b12125c 100644 --- a/include/osmo-bts/bts.h +++ b/include/osmo-bts/bts.h @@ -377,6 +377,7 @@ char *local_host; uint32_t sapi_mask; uint8_t sapi_acch; + bool rlp; } gsmtap;
struct osmux_state osmux; diff --git a/include/osmo-bts/lchan.h b/include/osmo-bts/lchan.h index 92973a7..585483b 100644 --- a/include/osmo-bts/lchan.h +++ b/include/osmo-bts/lchan.h @@ -287,7 +287,11 @@ } dtx_fr_hr_efr; uint8_t last_cmr; uint32_t last_fn; - + struct { + /* buffers to re-combine RLP frame from multiple Um blocks */ + uint8_t rlp_buf_ul[576/8]; /* maximum size of RLP frame */ + uint8_t rlp_buf_dl[576/8]; /* maximum size of RLP frame */ + } csd; } tch;
/* 3GPP TS 48.058 § 9.3.37: [0; 255] ok, -1 means invalid*/ diff --git a/src/common/l1sap.c b/src/common/l1sap.c index 90a61e2..c579af5 100644 --- a/src/common/l1sap.c +++ b/src/common/l1sap.c @@ -1848,19 +1848,88 @@ return 1; }
-static void send_ul_rtp_packet_data(struct gsm_lchan *lchan, uint32_t fn, +/* process one MAC block of unpacked bits of a non-transparent CSD channel */ +static void gsmtap_csd_rlp_process(struct gsm_lchan *lchan, bool is_uplink, + const struct ph_tch_param *tch_ind, + const uint8_t *data, unsigned int data_len) +{ + struct gsm_bts_trx *trx = lchan->ts->trx; + struct gsmtap_inst *inst = trx->bts->gsmtap.inst; + pbit_t *rlp_buf; + int byte_len; + + if (!inst || !trx->bts->gsmtap.rlp) + return; + + if (lchan->csd_mode != LCHAN_CSD_M_NT) + return; + + if (is_uplink) + rlp_buf = lchan->tch.csd.rlp_buf_ul; + else + rlp_buf = lchan->tch.csd.rlp_buf_dl; + + /* TCH/F 9.6: 4x60bit block => 240bit RLP frame + * TCH/F 4.8: 2x 2x60bit blocks starting at B0/B2/B4 => 240bit RLP frame + * TCH/H 4.8: 4x60bit block => 240bit RLP frame + * TCH/F 2.4: 2x36bit blocks => transparent only + * TCH/H 2.4: 4x36bit blocks => transparent only + * TCH/F 14.4: 2x 290 bit block (starting with M1=0) => 576-bit RLP frame + */ + + if (lchan->type == GSM_LCHAN_TCH_F && lchan->tch_mode == GSM48_CMODE_DATA_6k0) { + /* in this mode we have 120bit MAC blocks; two of them need to be concatenated + * to render a 240-bit RLP frame. The fist block is present in B0/B2/B4. + * The E7 bit is used to indicate the Frame MF0a */ + OSMO_ASSERT(data_len == 120); + ubit_t e7 = data[4*7+3]; + if (e7 == 0) { + osmo_ubit2pbit_ext(rlp_buf, 0, data, 0, data_len, 1); + return; + } else { + osmo_ubit2pbit_ext(rlp_buf, 120, data, 0, data_len, 1); + byte_len = 240/8; + } + } else if (lchan->type == GSM_LCHAN_TCH_F && lchan->tch_mode == GSM48_CMODE_DATA_14k5) { + /* in this mode we have 290bit MAC blocks containing M1, M2 and 288 data bits; + * two of them need to be concatenated to render a + * 576-bit RLP frame. The start of a RLP frame is + * denoted by a block with M1-bit set to 0. */ + OSMO_ASSERT(data_len == 290); + ubit_t m1 = data[0]; + if (m1 == 0) { + osmo_ubit2pbit_ext(rlp_buf, 0, data, 2, data_len, 1); + return; + } else { + osmo_ubit2pbit_ext(rlp_buf, 288, data, 2, data_len, 1); + byte_len = 576/8; + } + } else { + byte_len = osmo_ubit2pbit_ext(rlp_buf, 0, data, 0, data_len, 1); + } + + gsmtap_send_ex(inst, GSMTAP_TYPE_GSM_RLP, trx->arfcn | is_uplink ? GSMTAP_ARFCN_F_UPLINK : 0, + lchan->ts->nr, + lchan->type == GSM_LCHAN_TCH_H ? GSMTAP_CHANNEL_VOICE_H : GSMTAP_CHANNEL_VOICE_F, + lchan->nr, tch_ind->fn, tch_ind->rssi, 0, rlp_buf, byte_len); + +} + +static void send_ul_rtp_packet_data(struct gsm_lchan *lchan, const struct ph_tch_param *tch_ind, const uint8_t *data, uint16_t data_len) { uint8_t rtp_pl[RFC4040_RTP_PLEN]; int rc;
+ gsmtap_csd_rlp_process(lchan, true, tch_ind, data, data_len); + rc = csd_v110_rtp_encode(lchan, &rtp_pl[0], data, data_len); if (rc < 0) return;
osmo_rtp_send_frame_ext(lchan->abis_ip.rtp_socket, &rtp_pl[0], sizeof(rtp_pl), - fn_ms_adj(fn, lchan), + fn_ms_adj(tch_ind->fn, lchan), lchan->rtp_tx_marker); /* Only clear the marker bit once we have sent a RTP packet with it */ lchan->rtp_tx_marker = false; @@ -2000,7 +2069,7 @@ send_ul_rtp_packet_speech(lchan, fn, msg->data, msg->len); break; case RSL_CMOD_SPD_DATA: - send_ul_rtp_packet_data(lchan, fn, msg->data, msg->len); + send_ul_rtp_packet_data(lchan, tch_ind, msg->data, msg->len); break; case RSL_CMOD_SPD_SIGN: return 0; /* drop stale TCH.ind */ @@ -2309,6 +2378,10 @@ int rc = csd_v110_rtp_decode(lchan, msg->tail, rtp_pl, rtp_pl_len); if (rc > 0) { + /* 'fake' tch_ind containing all-zero so gsmtap code can be shared + * between UL and DL */ + static const struct ph_tch_param fake_tch_ind = {}; + gsmtap_csd_rlp_process(lchan, false, &fake_tch_ind, msg->tail, rc); msgb_put(msg, rc); } else { msgb_free(msg); @@ -2420,6 +2493,10 @@ lchan->ecu_state = NULL; }
+ /* reset CSD RLP buffers to avoid any user plane data leaking from + * one previous lchan into a later one */ + memset(&lchan->tch.csd, 0, sizeof(lchan->tch.csd)); + return l1sap_chan_act_dact_modify(trx, chan_nr, PRIM_INFO_DEACTIVATE, 0); } diff --git a/src/common/vty.c b/src/common/vty.c index 014042d..b5ab132 100644 --- a/src/common/vty.c +++ b/src/common/vty.c @@ -447,6 +447,8 @@ sapi_buf = osmo_str_tolower(get_value_string(gsmtap_sapi_names, GSMTAP_CHANNEL_ACCH)); vty_out(vty, " gsmtap-sapi %s%s", sapi_buf, VTY_NEWLINE); } + if (bts->gsmtap.rlp) + vty_out(vty, " gsmtap-rlp%s", VTY_NEWLINE); vty_out(vty, " min-qual-rach %d%s", bts->min_qual_rach, VTY_NEWLINE); vty_out(vty, " min-qual-norm %d%s", bts->min_qual_norm, @@ -2386,6 +2388,24 @@ return CMD_SUCCESS; }
+DEFUN(cfg_bts_gsmtap_rlp, cfg_bts_gsmtap_rlp_cmd, + "gsmtap-rlp", + "Enable generation of GSMTAP frames for RLP (non-transparent CSD)\n") +{ + struct gsm_bts *bts = vty->index; + bts->gsmtap.rlp = true; + return CMD_SUCCESS; +} + +DEFUN(cfg_bts_no_gsmtap_rlp, cfg_bts_no_gsmtap_rlp_cmd, + "no gsmtap-rlp", + NO_STR "Disable generation of GSMTAP frames for RLP (non-transparent CSD)\n") +{ + struct gsm_bts *bts = vty->index; + bts->gsmtap.rlp = false; + return CMD_SUCCESS; +} + static struct cmd_node phy_node = { PHY_NODE, "%s(phy)# ", @@ -2757,6 +2777,8 @@ install_element(BTS_NODE, &cfg_bts_gsmtap_sapi_all_cmd); install_element(BTS_NODE, &cfg_bts_gsmtap_sapi_cmd); install_element(BTS_NODE, &cfg_bts_no_gsmtap_sapi_cmd); + install_element(BTS_NODE, &cfg_bts_gsmtap_rlp_cmd); + install_element(BTS_NODE, &cfg_bts_no_gsmtap_rlp_cmd);
/* Osmux Node */ install_element(BTS_NODE, &cfg_bts_osmux_cmd); diff --git a/tests/osmo-bts.vty b/tests/osmo-bts.vty index 8c58aca..a7be40c 100644 --- a/tests/osmo-bts.vty +++ b/tests/osmo-bts.vty @@ -262,6 +262,8 @@ gsmtap-sapi (enable-all|disable-all) gsmtap-sapi (bcch|ccch|rach|agch|pch|sdcch|tch/f|tch/h|pacch|pdtch|ptcch|cbch|sacch) no gsmtap-sapi (bcch|ccch|rach|agch|pch|sdcch|tch/f|tch/h|pacch|pdtch|ptcch|cbch|sacch) + gsmtap-rlp + no gsmtap-rlp osmux trx <0-254> ... @@ -285,6 +287,7 @@ gsmtap-remote-host Enable GSMTAP Um logging (see also 'gsmtap-sapi') gsmtap-local-host Enable local bind for GSMTAP Um logging (see also 'gsmtap-sapi') gsmtap-sapi Enable/disable sending of UL/DL messages over GSMTAP + gsmtap-rlp Enable generation of GSMTAP frames for RLP (non-transparent CSD) osmux Configure Osmux trx Select a TRX to configure ...
-
laforge