openpgp: Support specifying connection timeout

Support specifying connection timeout for key refresh operations.  Set
the default to 3 minutes.  This affects both WKD requests (via
requests, supports sub-second timeouts) and GPG requests (via dirmngr,
supports second precision).

Closes: #26
Signed-off-by: Michał Górny <mgorny@gentoo.org>

gemato/cli.py

@@ -99,12 +99,20 @@ def __init__(self):
     def add_options(self, subp):
         super().add_options(subp)
 
+        default_timeout = 180
+
         subp.add_argument(
             '-K', '--openpgp-key',
             help='Use only the OpenPGP key(s) from a specific file')
         subp.add_argument(
             '--proxy',
             help='Use HTTP proxy')
+        subp.add_argument(
+            "--timeout",
+            default=default_timeout,
+            type=float,
+            help="Connection timeout (for WKD requests, in seconds, "
+                 f"default: {default_timeout})")
 
     def parse_args(self, args, argp):
         super().parse_args(args, argp)
@@ -116,7 +124,8 @@ def parse_args(self, args, argp):
         else:
             env_class = OpenPGPSystemEnvironment
         self.openpgp_env = env_class(debug=args.log_level == logging.DEBUG,
-                                     proxy=args.proxy)
+                                     proxy=args.proxy,
+                                     timeout=args.timeout)
 
         if args.openpgp_key is not None:
             with open(args.openpgp_key, 'rb') as f:

gemato/openpgp.py

@@ -10,6 +10,7 @@
 import errno
 import hashlib
 import logging
+import math
 import os
 import os.path
 import shutil
@@ -112,7 +113,7 @@ class SystemGPGEnvironment:
     (user's home directory or GNUPGHOME).
     """
 
-    def __init__(self, debug=False, proxy=None):
+    def __init__(self, debug=False, proxy=None, timeout=None):
         self.debug = debug
         self._trusted_keys = set()
 
@@ -402,9 +403,10 @@ class IsolatedGPGEnvironment(SystemGPGEnvironment):
     or use as a context manager (via 'with').
     """
 
-    def __init__(self, debug=False, proxy=None):
+    def __init__(self, debug=False, proxy=None, timeout=None):
         super().__init__(debug=debug)
         self.proxy = proxy
+        self.timeout = timeout
         self._home = tempfile.mkdtemp(prefix='gemato.')
 
         with open(os.path.join(self._home, 'dirmngr.conf'), 'w') as f:
@@ -423,6 +425,19 @@ def __init__(self, debug=False, proxy=None):
 log-file {os.path.join(self._home, 'dirmngr.log')}
 debug-level guru
 ''')
+
+            if timeout is not None:
+                # GPG doesn't accept sub-second timeouts
+                gpg_timeout = math.ceil(timeout)
+                f.write(f"""
+# respect user-specified timeouts
+resolver-timeout {gpg_timeout}
+connect-timeout {gpg_timeout}
+""")
+
+        with open(os.path.join(self._home, 'dirmngr.conf'), 'r') as f:
+            print(f.read())
+
         with open(os.path.join(self._home, 'gpg.conf'), 'w') as f:
             f.write('''# autogenerated by gemato
 
@@ -445,7 +460,8 @@ def __exit__(self, exc_type, exc_value, exc_cb):
             self.close()
 
     def clone(self):
-        return IsolatedGPGEnvironment(debug=self.debug, proxy=self.proxy)
+        return IsolatedGPGEnvironment(debug=self.debug, proxy=self.proxy,
+                                      timeout=self.timeout)
 
     def close(self):
         if self._home is not None:
@@ -573,7 +589,7 @@ def refresh_keys_wkd(self):
         for a in addrs:
             url = get_wkd_url(a)
             try:
-                resp = requests.get(url, proxies=proxies)
+                resp = requests.get(url, proxies=proxies, timeout=self.timeout)
                 resp.raise_for_status()
             except (requests.exceptions.ConnectionError,
                     requests.exceptions.HTTPError,
@@ -660,7 +676,7 @@ class PGPyEnvironment:
 
     __slots__ = ['debug', 'keyring', 'proxy']
 
-    def __init__(self, debug=False, proxy=None):
+    def __init__(self, debug=False, proxy=None, timeout=None):
         if pgpy is None:
             raise OpenPGPNoImplementation('install PGPy')
         self.debug = debug