diff options
| author | Andreas Eversberg <jolly@eversberg.eu> | 2013-06-12 09:25:27 +0200 |
|---|---|---|
| committer | Harald Welte <laforge@gnumonks.org> | 2013-07-06 23:36:15 +0200 |
| commit | ccc463355d752034db9d380d590d3acc220cf79e (patch) | |
| tree | ec6efd8beef466ee547e8fabe07b60e7a0355bcb | |
| parent | 610517c8bd5f9e87729acdb4529c0870b0b5dced (diff) | |
LAPDm: Fix re-establishment of datalink
If the datalink fails or if handover or assignment to a new channel fails,
it is re-establised by sending SABM again. The length of establish message
is 0 in this case. The length is used to differentiate between
re-establishment and contention resolution, which has to be handled
differently.
See TS 04.06 Chapter 5.4.2.1
| -rw-r--r-- | src/gsm/lapd_core.c | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/src/gsm/lapd_core.c b/src/gsm/lapd_core.c index 116e3116..68b5e784 100644 --- a/src/gsm/lapd_core.c +++ b/src/gsm/lapd_core.c @@ -826,14 +826,23 @@ static int lapd_rx_u(struct msgb *msg, struct lapd_msg_ctx *lctx) * yet received UA or another mobile (collision) tries * to establish connection. The mobile must receive * UA again. */ - if (!dl->cont_res && dl->v_send != dl->v_recv) { - LOGP(DLLAPD, LOGL_INFO, "Remote reestablish\n"); - mdl_error(MDL_CAUSE_SABM_MF, lctx); + /* 5.4.2.1 */ + if (!length) { + /* If no content resolution, this is a + * re-establishment. */ + LOGP(DLLAPD, LOGL_INFO, + "Remote reestablish\n"); break; } + if (!dl->cont_res) { + LOGP(DLLAPD, LOGL_INFO, "SABM command not " + "allowed in this state\n"); + mdl_error(MDL_CAUSE_SABM_MF, lctx); + msgb_free(msg); + return 0; + } /* Ignore SABM if content differs from first SABM. */ - if (dl->mode == LAPD_MODE_NETWORK && length - && dl->cont_res) { + if (dl->mode == LAPD_MODE_NETWORK && length) { #ifdef TEST_CONTENT_RESOLUTION_NETWORK dl->cont_res->data[0] ^= 0x01; #endif |