Review at https://gerrit.osmocom.org/3259
Ensure we don't send dummy UI frames on BCCH for TC=5 When no SI 2bis, nor 2ter, nor 2quater is in use, then the code in bts_sysinfo_get() will return null, causing the transmission of a dummy frame (0303012B2B2B2B2B2B2B2B2B2B2B2B2B2B2B2B2B2B2B2B) instead of a system information message. This is - at least - very odd and might not be backed by the specification. We should simply send any other system information message instead of sending a frame that does not have a valid SI header. While 030301 might be a valid, empty UI frame on a DCCH, it is not a valid frame for the BCCH, where the header is structured differently. In fact, bts_sysinfo_get() should never return NULL and always return a valid BCCH message. This bug was found while developing http://git.osmocom.org/osmo-ttcn3-hacks/tree/sysinfo/Test.ttcn Change-Id: Ifeaed27d1d7ba9994fb8ce67d660648bcc8efece Closes: OS#2365 --- M src/common/sysinfo.c 1 file changed, 7 insertions(+), 1 deletion(-) git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/59/3259/1 diff --git a/src/common/sysinfo.c b/src/common/sysinfo.c index 9276c7b..cf86380 100644 --- a/src/common/sysinfo.c +++ b/src/common/sysinfo.c @@ -129,6 +129,10 @@ else if (GSM_BTS_HAS_SI(bts, SYSINFO_TYPE_2quater) && !GSM_BTS_HAS_SI(bts, SYSINFO_TYPE_2bis) && !GSM_BTS_HAS_SI(bts, SYSINFO_TYPE_2ter)) return get_si2q_inc_index(bts); + + /* simply send SI2 if we have nothing else to send */ + else + return GSM_BTS_SI(bts, SYSINFO_TYPE_2); break; case 6: return GSM_BTS_SI(bts, SYSINFO_TYPE_3); @@ -136,7 +140,9 @@ return GSM_BTS_SI(bts, SYSINFO_TYPE_4); } - return NULL; + /* this should never bve reached. We must transmit a BCCH + * message on the normal BCCH in all cases. */ + OSMO_ASSERT(0); } uint8_t num_agch(struct gsm_bts_trx *trx, const char * arg) -- To view, visit https://gerrit.osmocom.org/3259 To unsubscribe, visit https://gerrit.osmocom.org/settings Gerrit-MessageType: newchange Gerrit-Change-Id: Ifeaed27d1d7ba9994fb8ce67d660648bcc8efece Gerrit-PatchSet: 1 Gerrit-Project: osmo-bts Gerrit-Branch: master Gerrit-Owner: Harald Welte <[email protected]>
