Merge #14756: Improve rpcauth.py by using argparse and getpass modules

d6cde007db9d3e6ee93bd98a9bbfdce9bfa9b15b rpcauth: Improve by using argparse and getpass modules (João Barbosa)

Pull request description:

  This PR improves argument handling in `rpcauth.py` script by using `argparse` module. Specifying `-` as password makes it prompt securely with `getpass` module which prevents leaking passwords to bash history.

Tree-SHA512: 489d66c95f66b5618cb75fd8f07ea5647281226ab9e32b03051eb43f758b9334ac19b7c82c2ed4f8c7ffbb0bee949b3d389e1564ec7a6e372f2864233bc7cb88

2 files changed, 28 insertions, 22 deletions

diff --git a/share/rpcauth/README.md b/share/rpcauth/README.md
index 20d16f0a97..6f627b867b 100644
--- a/share/rpcauth/README.md
+++ b/share/rpcauth/README.md
@@ -3,12 +3,16 @@ RPC Tools
 
 ### [RPCAuth](/share/rpcauth) ###
 
-Create login credentials for a JSON-RPC user.
+```
+usage: rpcauth.py [-h] username [password]
 
-Usage:
+Create login credentials for a JSON-RPC user
 
-    ./rpcauth.py <username>
+positional arguments:
+  username    the username for authentication
+  password    leave empty to generate a random password or specify "-" to
+              prompt for password
 
-in which case the script will generate a password. To specify a custom password do:
-
-    ./rpcauth.py <username> <password>
+optional arguments:
+  -h, --help  show this help message and exit
+  ```
diff --git a/share/rpcauth/rpcauth.py b/share/rpcauth/rpcauth.py
index cecc6c30a4..b14c80171e 100755
--- a/share/rpcauth/rpcauth.py
+++ b/share/rpcauth/rpcauth.py
@@ -3,42 +3,44 @@
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-import sys
-import os
-import base64
+from argparse import ArgumentParser
+from base64 import urlsafe_b64encode
 from binascii import hexlify
+from getpass import getpass
+from os import urandom
+
 import hmac
 
 def generate_salt(size):
     """Create size byte hex salt"""
-    return hexlify(os.urandom(size)).decode()
+    return hexlify(urandom(size)).decode()
 
 def generate_password():
     """Create 32 byte b64 password"""
-    return base64.urlsafe_b64encode(os.urandom(32)).decode('utf-8')
+    return urlsafe_b64encode(urandom(32)).decode('utf-8')
 
 def password_to_hmac(salt, password):
     m = hmac.new(bytearray(salt, 'utf-8'), bytearray(password, 'utf-8'), 'SHA256')
     return m.hexdigest()
 
 def main():
-    if len(sys.argv) < 2:
-        sys.stderr.write('Please include username (and an optional password, will generate one if not provided) as an argument.\n')
-        sys.exit(0)
+    parser = ArgumentParser(description='Create login credentials for a JSON-RPC user')
+    parser.add_argument('username', help='the username for authentication')
+    parser.add_argument('password', help='leave empty to generate a random password or specify "-" to prompt for password', nargs='?')
+    args = parser.parse_args()
 
-    username = sys.argv[1]
+    if not args.password:
+        args.password = generate_password()
+    elif args.password == '-':
+        args.password = getpass()
 
     # Create 16 byte hex salt
     salt = generate_salt(16)
-    if len(sys.argv) > 2:
-        password = sys.argv[2]
-    else:
-        password = generate_password()
-    password_hmac = password_to_hmac(salt, password)
+    password_hmac = password_to_hmac(salt, args.password)
 
     print('String to be appended to bitcoin.conf:')
-    print('rpcauth={0}:{1}${2}'.format(username, salt, password_hmac))
-    print('Your password:\n{0}'.format(password))
+    print('rpcauth={0}:{1}${2}'.format(args.username, salt, password_hmac))
+    print('Your password:\n{0}'.format(args.password))
 
 if __name__ == '__main__':
     main()