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ftmod_isdn: Handle zero length read correctly.

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ftmod_misdn currently returns len == 0 if the incoming message,
that triggered the read() call, does not contain any data.
Users of ftdm_channel_read() need to handle this case, or they
may possibly end up in an endless loop.

This patch reworks the ftdm_channel_read() handling in ftmod_isdn
and prevents it from entering an endless loop. The read error counter
is reset on first sucessful read w/ data.

Signed-off-by: Stefan Knoblich <stkn@openisdn.net>
This commit is contained in:
Stefan Knoblich 2012-07-24 00:00:01 +02:00
parent 134973187a
commit fc9ea9eab0
1 changed files with 8 additions and 2 deletions
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10
libs/freetdm/src/ftmod/ftmod_isdn/ftmod_isdn.c
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@ -2055,10 +2055,13 @@ static void *ftdm_isdn_run(ftdm_thread_t *me, void *obj)
break; break;
default: default:
{ {
errs = 0;
if (flags & FTDM_READ) { if (flags & FTDM_READ) {
len = sizeof(frame); len = sizeof(frame);
if (ftdm_channel_read(isdn_data->dchan, frame, &len) == FTDM_SUCCESS) { if (ftdm_channel_read(isdn_data->dchan, frame, &len) != FTDM_SUCCESS) {
ftdm_log_chan_msg(isdn_data->dchan, FTDM_LOG_ERROR, "Failed to read from D-Channel\n");
continue;
}
if (len > 0) {
#ifdef HAVE_PCAP #ifdef HAVE_PCAP
if (isdn_pcap_capture_both(isdn_data)) { if (isdn_pcap_capture_both(isdn_data)) {
isdn_pcap_write(isdn_data, frame, len, ISDN_PCAP_INCOMING); isdn_pcap_write(isdn_data, frame, len, ISDN_PCAP_INCOMING);
@ -2066,6 +2069,9 @@ static void *ftdm_isdn_run(ftdm_thread_t *me, void *obj)
#endif #endif
Q921QueueHDLCFrame(&isdn_data->q921, frame, (int)len); Q921QueueHDLCFrame(&isdn_data->q921, frame, (int)len);
Q921Rx12(&isdn_data->q921); Q921Rx12(&isdn_data->q921);
/* Successful read, reset error counter */
errs = 0;
} }
} else { } else {
ftdm_log(FTDM_LOG_DEBUG, "No Read FLAG!\n"); ftdm_log(FTDM_LOG_DEBUG, "No Read FLAG!\n");