From db63cdd38ba7afbb9307b5a794a8ae52b74df79f Mon Sep 17 00:00:00 2001
From: Harald Welte <laforge@osmocom.org>
Date: Sun, 16 Oct 2022 17:31:47 +0200
Subject: [PATCH] actually trigger start + stop of B-channel recordings

---
 src/isdntap.c | 41 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/src/isdntap.c b/src/isdntap.c
index c936262..cf769f0 100644
--- a/src/isdntap.c
+++ b/src/isdntap.c
@@ -153,6 +153,34 @@ static void calltbl_delete_callref_on_chan_id(struct isdntap_line *line, const s
  * Q.931 processing
  ***********************************************************************/
 
+/* Resolve the B-channel data structure based on a decoded Q.931 Channel ID */
+static struct isdntap_ts *get_bchan_ts(struct isdntap_line *line, const struct q931_channel_id *chan_id)
+{
+	if (!chan_id->exclusive) {
+		return NULL;
+	}
+	if (chan_id->d_channel) {
+		return NULL;
+	}
+	if (chan_id->b_channel < 1) {
+		return NULL;
+	}
+	if (chan_id->b_channel >= ARRAY_SIZE(line->ts)) {
+		return NULL;
+	}
+
+	return &line->ts[chan_id->b_channel];
+}
+
+static void gen_chan_label(char *out, size_t out_len, const struct q931_call_state *cstate)
+{
+	char tmbuf[64];
+	/* convert starting time to a string */
+	strftime(tmbuf, sizeof(tmbuf), "%Y%m%d-%H%M%s", localtime(&cstate->create_time));
+	snprintf(out, out_len, "%s-%s-%s", cstate->calling_party.digits, cstate->called_party.digits,
+		 tmbuf);
+}
+
 /* append additional digits received (overlap dialling) to called party number */
 static void append_called_digits(struct q931_party_number *out, const uint8_t *buf, size_t len)
 {
@@ -204,6 +232,7 @@ static int isdntap_q931_rx(struct isdntap_line *line, bool net2user, const uint8
 {
 	struct q931_msg_parsed parsed;
 	struct q931_call_state *cstate;
+	struct isdntap_ts *ts_b = NULL;
 	int rc;
 
 	rc = q931_msg_parse(&parsed, buf, len);
@@ -280,7 +309,13 @@ static int isdntap_q931_rx(struct isdntap_line *line, bool net2user, const uint8
 				return rc;
 			if (cstate->chan_id.exclusive && !cstate->chan_id.d_channel) {
 				/* now we know the exact B channel used */
-				/* TODO: start capturing */
+				/* start B-channel capturing */
+				ts_b = get_bchan_ts(line, &cstate->chan_id);
+				if (!ts_b)
+					break;
+				char strbuf[256];
+				gen_chan_label(strbuf, sizeof(strbuf), cstate);
+				isdntap_ts_start_bchan(ts_b, strbuf);
 			}
 		}
 		break;
@@ -289,6 +324,10 @@ static int isdntap_q931_rx(struct isdntap_line *line, bool net2user, const uint8
 		/* forget about the call */
 		calltbl_delete_callref(cstate);
 		cstate = NULL;
+		/* stop B channel capture */
+		ts_b = get_bchan_ts(line, &cstate->chan_id);
+		if (ts_b)
+			isdntap_ts_stop_bchan(ts_b);
 		break;
 	default:
 		break;