Ensure tcpdump is installed before running capture command.

code/iottb/subcommands/capture.py

@@ -5,7 +5,7 @@ from iottb.definitions import *
 from iottb.models.capture_metadata_model import CaptureMetadata
 from iottb.models.device_metadata_model import DeviceMetadata, dir_contains_device_metadata
 from iottb.utils.capture_utils import get_capture_src_folder, make_capture_src_folder
-
+from iottb.utils.tcpdump_utils import check_installed
 
 def setup_capture_parser(subparsers):
     parser = subparsers.add_parser('sniff', help='Sniff packets with tcpdump')
@@ -74,6 +74,7 @@ def run_tcpdump(cmd):
         p = subprocess.run(cmd, capture_output=True, text=True, check=True)
         if p.returncode != 0:
             print(f'Error running tcpdump {p.stderr}')
+            # TODO add logging
         else:
             print(f'tcpdump run successfully\n: {p.stdout}')
     except KeyboardInterrupt:
@@ -81,6 +82,9 @@ def run_tcpdump(cmd):
 
 
 def handle_capture(args):
+    if not check_installed():
+        print('Please install tcpdump first')
+        exit(ReturnCodes.ABORTED)
     assert args.device_root is not None, f'Device root directory is required'
     assert dir_contains_device_metadata(args.device_root), f'Device metadata file \'{args.device_root}\' does not exist'
     # get device metadata