Allow Xmlstream.ca_certs to be an iterable

Signed-off-by: Maxime “pep” Buquet <pep@bouah.net>

slixmpp/xmlstream/xmlstream.py

@@ -15,6 +15,7 @@ from typing import (
     Coroutine,
     Callable,
     Iterator,
+    Iterable,
     List,
     Optional,
     Set,
@@ -33,7 +34,6 @@ import socket as Socket
 import ssl
 import weakref
 import uuid
-from pathlib import Path
 
 from contextlib import contextmanager
 import xml.etree.ElementTree as ET
@@ -47,6 +47,7 @@ from asyncio import (
     iscoroutinefunction,
     wait,
 )
+from pathlib import Path
 
 from slixmpp.types import FilterString
 from slixmpp.xmlstream.tostring import tostring
@@ -75,6 +76,15 @@ class NotConnectedError(Exception):
     """
 
 
+class InvalidCABundle(Exception):
+    """
+        Exception raised when the CA Bundle file hasn't been found.
+    """
+
+    def __init__(self, path: Optional[Path]):
+        self.path = path
+
+
 _T = TypeVar('_T', str, ElementBase, StanzaBase)
 
 
@@ -162,7 +172,7 @@ class XMLStream(asyncio.BaseProtocol):
     #:
     #:     On Mac OS X, certificates in the system keyring will
     #:     be consulted, even if they are not in the provided file.
-    ca_certs: Optional[Path]
+    ca_certs: Optional[Union[Path, Iterable[Path]]]
 
     #: Path to a file containing a client certificate to use for
     #: authenticating via SASL EXTERNAL. If set, there must also
@@ -760,8 +770,20 @@ class XMLStream(asyncio.BaseProtocol):
                 log.debug('Loaded cert file %s and key file %s',
                           self.certfile, self.keyfile)
         if self.ca_certs is not None:
+            ca_cert: Optional[Path] = None
+            if isinstance(self.ca_certs, Path):
+                if self.ca_certs.is_file():
+                    ca_cert = self.ca_certs
+            else:
+                for bundle in self.ca_certs:
+                    if bundle.is_file():
+                        ca_cert = bundle
+                        break
+            if ca_cert is None:
+                raise InvalidCABundle(ca_cert)
+
             self.ssl_context.verify_mode = ssl.CERT_REQUIRED
-            self.ssl_context.load_verify_locations(cafile=self.ca_certs)
+            self.ssl_context.load_verify_locations(cafile=ca_cert)
 
         return self.ssl_context