diff options
| author | Andreas Eversberg <jolly@eversberg.eu> | 2023-05-10 13:23:55 +0200 |
|---|---|---|
| committer | laforge <laforge@osmocom.org> | 2023-06-09 15:06:34 +0000 |
| commit | 0370018eae5a84ae943a459a7c3ef7ea58f28fe3 (patch) | |
| tree | e8099e1702976e3fa70861ef2eea726ff125f0db /src/gsm | |
| parent | 6799741699946d916f38c4ec46ac7c4223d204cc (diff) | |
Add support for receiving Bter UI frames at lapdm.c
Similar to support of sending Bter frame, the same rules apply when
receiving them.
Change-Id: If04115884743455c7bf2b2bc5f7e49e74b6ffb60
Diffstat (limited to 'src/gsm')
| -rw-r--r-- | src/gsm/lapdm.c | 36 |
1 files changed, 25 insertions, 11 deletions
diff --git a/src/gsm/lapdm.c b/src/gsm/lapdm.c index 67e53f83..8ca13427 100644 --- a/src/gsm/lapdm.c +++ b/src/gsm/lapdm.c @@ -57,6 +57,7 @@ #define LAPDm_ADDR_SAPI(addr) (((addr) >> 2) & 0x7) #define LAPDm_ADDR_CR(addr) (((addr) >> 1) & 0x1) #define LAPDm_ADDR_EA(addr) ((addr) & 0x1) +#define LAPDm_ADDR_SHORT_L2(addr) ((addr) & 0x3) /* TS 04.06 Table 3 / Section 3.4.3 */ #define LAPDm_CTRL_I(nr, ns, p) ((((nr) & 0x7) << 5) | (((p) & 0x1) << 4) | (((ns) & 0x7) << 1)) @@ -725,15 +726,24 @@ static int l2_ph_data_ind(struct msgb *msg, struct lapdm_entity *le, if (mctx.link_id & 0x40) { /* It was received from network on SACCH */ - /* If UI on SACCH sent by BTS, lapdm_fmt must be B4 */ - if (le->mode == LAPDM_MODE_MS - && LAPDm_CTRL_is_U(msg->l2h[3]) - && LAPDm_CTRL_U_BITS(msg->l2h[3]) == 0) { + /* A Short L3 header has both bits == 0. */ + if (LAPDm_ADDR_SHORT_L2(msg->l2h[2]) == 0) { + mctx.lapdm_fmt = LAPDm_FMT_Bter; + n201 = N201_Bter_SACCH; + sapi = 0; + } else if (le->mode == LAPDM_MODE_MS + && LAPDm_CTRL_is_U(msg->l2h[3]) + && LAPDm_CTRL_U_BITS(msg->l2h[3]) == 0) { + /* If UI on SACCH sent by BTS, lapdm_fmt must be B4 */ mctx.lapdm_fmt = LAPDm_FMT_B4; n201 = N201_B4; + /* sapi is found after two-btyte L1 header */ + sapi = (msg->l2h[2] >> 2) & 7; } else { mctx.lapdm_fmt = LAPDm_FMT_B; n201 = N201_AB_SACCH; + /* sapi is found after two-btyte L1 header */ + sapi = (msg->l2h[2] >> 2) & 7; } /* SACCH frames have a two-byte L1 header that * OsmocomBB L1 doesn't strip */ @@ -741,11 +751,17 @@ static int l2_ph_data_ind(struct msgb *msg, struct lapdm_entity *le, mctx.ta_ind = msg->l2h[1]; msgb_pull(msg, 2); msg->l2h += 2; - sapi = (msg->l2h[0] >> 2) & 7; } else { - mctx.lapdm_fmt = LAPDm_FMT_B; - n201 = N201_AB_SDCCH; - sapi = (msg->l2h[0] >> 2) & 7; + /* A Short L3 header has both bits == 0. */ + if (LAPDm_ADDR_SHORT_L2(msg->l2h[2]) == 0) { + mctx.lapdm_fmt = LAPDm_FMT_Bter; + n201 = N201_Bter_SDCCH; + sapi = 0; + } else { + mctx.lapdm_fmt = LAPDm_FMT_B; + n201 = N201_AB_SDCCH; + sapi = (msg->l2h[0] >> 2) & 7; + } } } @@ -838,9 +854,7 @@ static int l2_ph_data_ind(struct msgb *msg, struct lapdm_entity *le, rc = lapd_ph_data_ind(msg, &lctx); break; case LAPDm_FMT_Bter: - /* FIXME */ - msgb_free(msg); - break; + /* fall-through */ case LAPDm_FMT_Bbis: /* directly pass up to layer3 */ msg->l3h = msg->l2h; |