From f7476bce41c8efbfc8239c2c239e5a2cee8a7bcf Mon Sep 17 00:00:00 2001
From: Andreas Eversberg <jolly@eversberg.eu>
Date: Sun, 8 Oct 2017 17:10:03 +0200
Subject: NMT-900: Handle channels >= 1025 correctly

---
 src/nmt/frame.c |  8 ++++----
 src/nmt/nmt.c   | 10 ++++++++--
 2 files changed, 12 insertions(+), 6 deletions(-)

(limited to 'src/nmt')

diff --git a/src/nmt/frame.c b/src/nmt/frame.c
index e25698a..ace9d1f 100644
--- a/src/nmt/frame.c
+++ b/src/nmt/frame.c
@@ -47,8 +47,8 @@ uint64_t nmt_encode_channel(int nmt_system, int channel, int power)
 		value |= power << 9;
 	} else {
 		/* interleaved channels are indicated in traffic area */
-		if (value > 1000)
-			value -= 1000;
+		if (value >= 1024)
+			value -= 1024;
 		value |= channel;
 		/* if channel >= 512, set upper bit */
 		if (value & 0x200)
@@ -132,7 +132,7 @@ uint64_t nmt_encode_traffic_area(int nmt_system, int channel, uint8_t traffic_ar
 	} else {
 		/* upper bit is used for indication of interleaved channel */
 		value = traffic_area & 0x7f;
-		if (channel > 1000)
+		if (channel >= 1024)
 			value |= 0x80;
 	}
 
@@ -487,7 +487,7 @@ static const char *param_ta_900(uint64_t value, int __attribute__((unused)) ndig
 	static char result[32];
 
 	if ((value & 0x80))
-		sprintf(result, "%" PRIu64 " (Channel No. + 1000)", value & 0x7f);
+		sprintf(result, "%" PRIu64 " (Channel No. + 1024)", value & 0x7f);
 	else
 		sprintf(result, "%" PRIu64, value);
 
diff --git a/src/nmt/nmt.c b/src/nmt/nmt.c
index b5aec38..40d8727 100644
--- a/src/nmt/nmt.c
+++ b/src/nmt/nmt.c
@@ -490,10 +490,16 @@ static void nmt_page(transaction_t *trans, int try)
 static int match_channel(nmt_t *nmt, frame_t *frame)
 {
 	int channel, power;
+	int rc;
 
 	/* check channel match */
-	nmt_decode_channel(nmt->sysinfo.system, frame->channel_no, &channel, &power);
-	if ((channel & 0x3ff) != (nmt->sender.kanal & 0x3ff)) {
+	rc = nmt_decode_channel(nmt->sysinfo.system, frame->channel_no, &channel, &power);
+	if (rc < 0) {
+		PDEBUG_CHAN(DNMT, DEBUG_NOTICE, "Frame with illegal encoded channel received, ignoring.\n");
+		return 0;
+	}
+	/* in case of interleaved channel, ignore the missing upper bit */
+	if ((channel % 1024) != (nmt->sender.kanal % 1024)) {
 		PDEBUG_CHAN(DNMT, DEBUG_NOTICE, "Frame for different channel %d received, ignoring.\n", channel);
 		return 0;
 	}
-- 
cgit v1.2.3