Fix test_monitor_tshark.sh to always show counters

- Add message that capture may take time
- Always display packet and PLCP counts
- Better parsing of tshark output
- Separate warnings/errors from packet data
- Show note if packets captured but no PLCP headers

Co-authored-by: Cursor <cursoragent@cursor.com>

test_monitor_tshark.sh

@@ -80,15 +80,35 @@ iw dev "$INTERFACE" info | grep -E "(type|channel)" || echo "Could not verify"
 # Check DLT with tshark (capture for 1 second)
 echo ""
 echo "Checking Data Link Type (1 second test capture)..."
-TEST_OUTPUT=$(timeout 1 tshark -i "$INTERFACE" -T fields -e frame.number -e radiotap.present 2>&1)
-PACKET_COUNT=$(echo "$TEST_OUTPUT" | grep -E '^[0-9]+' | wc -l || echo "0")
-PLCP_COUNT=$(echo "$TEST_OUTPUT" | grep -E '^[0-9]+.*[0-9]' | wc -l || echo "0")
-echo "$TEST_OUTPUT" | tail -5 || true
-echo "Captured $PACKET_COUNT packet(s) in 1 second"
-if [ "$PLCP_COUNT" -gt 0 ]; then
-    echo "PLCP headers: $PLCP_COUNT (radiotap present)"
-else
-    echo "PLCP headers: 0 (no radiotap headers detected)"
+echo "(This may take up to 2 seconds if no packets are present)"
+
+# Use timeout with -c to limit packets and avoid hanging
+# Capture both stdout and stderr
+TEST_OUTPUT=$(timeout 2 tshark -i "$INTERFACE" -c 100 -T fields -e frame.number -e radiotap.present 2>&1 || true)
+TEST_EXIT_CODE=${PIPESTATUS[0]}
+
+# Show any warnings/errors from tshark (but not packet data)
+echo "$TEST_OUTPUT" | grep -E "(Running as|tshark:|Warning|Error|Capturing)" || true
+
+# Count packets (lines starting with a number, excluding error messages)
+PACKET_LINES=$(echo "$TEST_OUTPUT" | grep -E '^[0-9]+' || true)
+PACKET_COUNT=$(echo "$PACKET_LINES" | wc -l || echo "0")
+
+# Count lines with both frame.number and radiotap.present (non-empty second field)
+PLCP_COUNT=$(echo "$PACKET_LINES" | awk -F'\t' 'NF >= 2 && $1 != "" && $2 != "" && $2 != "0" && $2 != "-" {count++} END {print count+0}' || echo "0")
+
+# Show sample output
+if [ "$PACKET_COUNT" -gt 0 ]; then
+    echo "Sample packets:"
+    echo "$PACKET_LINES" | head -3
+fi
+
+echo ""
+echo "Test capture results:"
+echo "  Packets captured: $PACKET_COUNT"
+echo "  PLCP headers: $PLCP_COUNT"
+if [ "$PLCP_COUNT" -eq 0 ] && [ "$PACKET_COUNT" -gt 0 ]; then
+    echo "  Note: Packets captured but no radiotap headers (may be using DLT_IEEE802_11 instead of DLT_IEEE802_11_RADIO)"
 fi
 
 echo ""
@@ -97,6 +117,7 @@ echo "Press Ctrl+C to stop early"
 echo ""
 
 # Capture for specified duration and count packets
+echo "Capturing packets for $DURATION seconds..."
 CAPTURE_OUTPUT=$(timeout "$DURATION" tshark -i "$INTERFACE" -n -T fields \
     -e frame.number \
     -e frame.time \
@@ -107,16 +128,28 @@ CAPTURE_OUTPUT=$(timeout "$DURATION" tshark -i "$INTERFACE" -n -T fields \
     -e wlan.fc.type_subtype \
     -e radiotap.present \
     2>&1)
+CAPTURE_EXIT_CODE=$?
 
-# Display first 50 lines of output
-echo "$CAPTURE_OUTPUT" | head -50
+# Show any warnings/errors
+echo "$CAPTURE_OUTPUT" | grep -E "(tshark:|Warning|Error)" | head -5 || true
 
-# Count total packets captured
+# Display first 50 lines of packet output
+PACKET_LINES=$(echo "$CAPTURE_OUTPUT" | grep -E '^[0-9]+' || true)
+if [ -n "$PACKET_LINES" ]; then
+    echo ""
+    echo "Sample packets (first 20):"
+    echo "$PACKET_LINES" | head -20
+else
+    echo ""
+    echo "(No packets captured)"
+fi
+
+# Count total packets captured (lines starting with a number)
 FINAL_COUNT=$(echo "$CAPTURE_OUTPUT" | grep -E '^[0-9]+' | wc -l || echo "0")
 
 # Count packets with PLCP headers (radiotap present)
 # radiotap.present field is the 8th field (after frame.number, frame.time, wlan.sa, wlan.da, wlan.fc.type, wlan.fc.subtype, wlan.fc.type_subtype)
-PLCP_COUNT=$(echo "$CAPTURE_OUTPUT" | awk -F'\t' 'NF >= 8 && $8 != "" && $8 != "0" && $8 != "-" {count++} END {print count+0}' || echo "0")
+PLCP_COUNT=$(echo "$CAPTURE_OUTPUT" | awk -F'\t' 'NF >= 8 && $1 != "" && $8 != "" && $8 != "0" && $8 != "-" {count++} END {print count+0}' || echo "0")
 
 echo ""
 echo "=== Capture complete ==="