qt: fix: bip70 pay reqs need x509 verification

regression from https://github.com/spesmilo/electrum/pull/8462

- pr.verify() was called in qml, but not in qt gui
- we now call pr.verify() in get_payment_request(), to make the API less error-prone
- it is now ok to call pr.verify() multiple times, the result is cached

electrum/contacts.py

@@ -21,7 +21,7 @@
 # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 import re
-from typing import Optional, Tuple
+from typing import Optional, Tuple, Dict, Any
 
 import dns
 import threading
@@ -30,10 +30,13 @@ from dns.exception import DNSException
 from . import bitcoin
 from . import dnssec
 from .util import read_json_file, write_json_file, to_string
-from .logging import Logger
+from .logging import Logger, get_logger
 from .util import trigger_callback
 
 
+_logger = get_logger(__name__)
+
+
 class AliasNotFoundException(Exception):
     pass
 
@@ -90,7 +93,13 @@ class Contacts(dict, Logger):
                     'address': addr,
                     'type': 'contact'
                 }
-        out = self.resolve_openalias(k)
+        if openalias := self.resolve_openalias(k):
+            return openalias
+        raise AliasNotFoundException("Invalid Bitcoin address or alias", k)
+
+    @classmethod
+    def resolve_openalias(cls, url: str) -> Dict[str, Any]:
+        out = cls._resolve_openalias(url)
         if out:
             address, name, validated = out
             return {
@@ -99,7 +108,7 @@ class Contacts(dict, Logger):
                 'type': 'openalias',
                 'validated': validated
             }
-        raise AliasNotFoundException("Invalid Bitcoin address or alias", k)
+        return {}
 
     def by_name(self, name):
         for k in self.keys():
@@ -118,33 +127,35 @@ class Contacts(dict, Logger):
         if alias:
             alias = str(alias)
             def f():
-                self.alias_info = self.resolve_openalias(alias)
+                self.alias_info = self._resolve_openalias(alias)
                 trigger_callback('alias_received')
             t = threading.Thread(target=f)
             t.daemon = True
             t.start()
 
-    def resolve_openalias(self, url: str) -> Optional[Tuple[str, str, bool]]:
+    @classmethod
+    def _resolve_openalias(cls, url: str) -> Optional[Tuple[str, str, bool]]:
         # support email-style addresses, per the OA standard
         url = url.replace('@', '.')
         try:
             records, validated = dnssec.query(url, dns.rdatatype.TXT)
         except DNSException as e:
-            self.logger.info(f'Error resolving openalias: {repr(e)}')
+            _logger.info(f'Error resolving openalias: {repr(e)}')
             return None
         prefix = 'btc'
         for record in records:
             string = to_string(record.strings[0], 'utf8')
             if string.startswith('oa1:' + prefix):
-                address = self.find_regex(string, r'recipient_address=([A-Za-z0-9]+)')
-                name = self.find_regex(string, r'recipient_name=([^;]+)')
+                address = cls.find_regex(string, r'recipient_address=([A-Za-z0-9]+)')
+                name = cls.find_regex(string, r'recipient_name=([^;]+)')
                 if not name:
                     name = address
                 if not address:
                     continue
                 return address, name, validated
 
-    def find_regex(self, haystack, needle):
+    @staticmethod
+    def find_regex(haystack, needle):
         regex = re.compile(needle)
         try:
             return regex.search(haystack).groups()[0]