Refactor download_headless.py

- Support usage as a library
- Optionally get license from a environment variable
- Quiet output option

scripts/download_headless.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python3
 '''Note that this script will only function for headless licenses at this time.'''
-import argparse
 import json
 import os
 import requests
@@ -9,46 +8,106 @@
 
 from pathlib import Path
 
+class DownloadException(Exception):
+    pass
+
 url='https://master.binary.ninja/headless-download'
+env_lic = 'HEADLESS_LICENSE'
+min_download = 8192
+
+def get_system_license_path() -> Path:
+	"""Returns the default path to the Binary Ninja license.dat on the current platform
 
-if sys.platform == "darwin":
-	userpath = Path.home() / 'Library' / 'Application Support' / 'Binary Ninja'
-elif sys.platform.startswith("linux"):
-	userpath = Path.home() / '.binaryninja'
-else:
-	userpath = Path.home() / 'AppData' / 'Roaming' / 'Binary Ninja'
-
-serial = ''
-parser = argparse.ArgumentParser(description='Download a Binary Ninja installer with a headless license')
-parser.add_argument("--serial", help="serial number")
-parser.add_argument('--dev', dest='dev', default=False, action='store_true')
-args = parser.parse_args()
-
-if args.serial:
-	serial = args.serial
-elif userpath.is_dir():
-	if (userpath / 'license.dat').is_file():
-		with open(userpath / 'license.dat') as f:
-			licenses = json.load(f)
-			for license in licenses:
-				if 'headless' in license['product']:
-					serial = license['serial']
-
-if serial == '':
-	parser.print_help()
-	sys.exit(-1)
-
-params = {'serial': serial, 'dev': str(args.dev).lower()}
-
-r = requests.get(url, params)
-results = json.loads(r.text)
-if results['ok']:
-	url = results['url']
-	r = requests.get(url, allow_redirects=True)
-	filename = os.path.basename(urllib.parse.urlparse(url).path)
-	if len(r.content) < 2**13:
-		print(f'Error downloading from {url}')
+	:return: Path object to the license.dat file.
+	:rtype: Path
+	"""
+	if sys.platform == "darwin":
+		return Path.home() / 'Library' / 'Application Support' / 'Binary Ninja' / 'license.dat'
+	elif sys.platform.startswith("linux"):
+		return Path.home() / '.binaryninja' / 'license.dat'
 	else:
-		open(filename, 'wb').write(r.content)
-else:
-	print('Download failed.')
+		return Path.home() / 'AppData' / 'Roaming' / 'Binary Ninja' / 'license.dat'
+
+
+def get_serial_from_license(path: str) -> str:
+	"""Extracts the serial number from the license specified in path
+
+	:param path: path to license file
+	:type path: str
+	:raises ValueError: When no headless license is found in the provided license.dat
+	:return: returns the serial number of the headless license
+	:rtype: str
+	"""
+	with open(path) as f:
+		for license in [l for l in json.load(f) if 'Headless' in l['product']]:
+			return license['serial']
+		raise ValueError(f'No "computer" license in {path}')
+
+
+def get_serial_from_environment(env: str='HEADLESS_LICENSE') -> str:
+	"""Extracts the serial number from the license file referenced by the env
+
+	:param env: environment variable containing headless license path, defaults to 'HEADLESS_LICENSE'
+	:type env: str, optional
+	:raises ValueError: When provided envronment variable doesn't exist or license doesn't contain a headless license.
+	:return: the serial number
+	:rtype: str
+	"""
+	if env not in os.environ:
+		raise ValueError(f'Please add an environment variable {env} pointing to your headless Binary Ninja license')
+
+	return get_serial_from_license(os.environ[env])
+
+
+def download_headless(serial: str, output_path: str=None, dev: bool=False) -> str:
+	"""Downloads the headless Binary Ninja installation binaries.
+
+	:param serial: Serial number for verification
+	:type serial: str
+	:param output_path: path to write the binaries to, defaults to None
+	:type output_path: str, optional
+	:param dev: set to True if you wish to download 'dev' branch, defaults to False
+	:type dev: bool, optional
+	:raises DownloadException: On failure to download the requested binaries.
+	"""
+	r = requests.get(url, {'serial': serial, 'dev': str(dev).lower()})
+	results = json.loads(r.text)
+	if not results['ok']:
+		raise DownloadException('Download failed.')
+
+	req_url = results['url']
+	content = requests.get(req_url, allow_redirects=True)
+	if len(content.content) < min_download:
+		raise DownloadException(f'Error downloading from {req_url}')
+
+	if output_path is None:
+		output_path = os.path.basename(urllib.parse.urlparse(req_url).path)
+	with open(output_path, 'wb') as f:
+		f.write(content.content)
+	return output_path
+
+if __name__ == '__main__':
+	import argparse
+	parser = argparse.ArgumentParser(description='Download a Binary Ninja installer given a headless license')
+	parser.add_argument('--serial', default=None, help='serial number')
+	parser.add_argument('--env', default=False, action='store_true', help='will extract serial from enviroment variable "HEADLESS_LICENSE" if not specfied')
+	parser.add_argument('--dev', default=False, action='store_true', help='download the development branch')
+	parser.add_argument('--output', default=None, help='path to write the file to (defaults to current directory)')
+	parser.add_argument('-q', '--quiet', default=False, action='store_true', help='Don\'t show any output')
+	args = parser.parse_args()
+
+	try:
+		if args.serial is None:
+			if args.env:
+				args.serial = get_serial_from_environment()
+			else:
+				args.serial = get_serial_from_license(get_system_license_path())
+
+		download_path = download_headless(args.serial, args.output, args.dev)
+		if not args.quiet:
+			print(f"Successfully downloaded to: {download_path}")
+		sys.exit(0)
+	except Exception as e:
+		if not args.quiet:
+			print(e)
+		sys.exit(1)