fix: work around a bug in netifaces that crashes on Android

src/flockwave/networking/interfaces.py

@@ -1,13 +1,15 @@
 """Generic networking-related utility functions."""
 
+import sys
+
 from ipaddress import (
     ip_address,
     ip_network,
     IPv4Network,
     IPv6Address,
     IPv6Network,
 )
-from netifaces import AF_INET, AF_INET6, AF_LINK, ifaddresses, interfaces
+from netifaces import AF_INET, AF_INET6, AF_LINK, ifaddresses, interfaces as _interfaces
 from typing import Optional, Sequence, Union
 
 from .addressing import canonicalize_mac_address
@@ -19,9 +21,23 @@
     "get_all_ipv4_addresses",
     "get_broadcast_address_of_network_interface",
     "get_link_layer_address_mapping",
+    "list_network_interfaces",
     "resolve_network_interface_or_address",
 )
 
+_is_android = hasattr(sys, "getandroidapilevel")
+
+
+if _is_android:
+
+    def list_network_interfaces() -> Sequence[str]:
+        """Lists all the network interfaces of the system."""
+        # rmnet and r_rmnet interfaces on Android seem to cause a crash with
+        # netifaces.ifaddresses() so we pretend they do not exist
+        return [iface for iface in _interfaces() if "rmnet" not in iface]
+else:
+    list_network_interfaces = _interfaces
+
 
 def find_interfaces_with_address(
     address: str,
@@ -44,7 +60,7 @@ def find_interfaces_with_address(
         family = AF_INET
 
     candidates: list[tuple[str, Union[IPv4Network, IPv6Network]]] = []
-    for interface in interfaces():
+    for interface in list_network_interfaces():
         specs = ifaddresses(interface).get(family) or []
         ip_addresses_in_network = (
             (spec.get("addr"), spec.get("netmask")) for spec in specs
@@ -79,7 +95,7 @@ def find_interfaces_in_network(
         family = AF_INET
 
     candidates: list[tuple[str, str, Optional[str]]] = []
-    for interface in interfaces():
+    for interface in list_network_interfaces():
         specs = ifaddresses(interface).get(family) or []
         ip_addresses_in_network = (
             (spec.get("addr") or "", spec.get("netmask"))
@@ -130,7 +146,7 @@ def get_address_of_network_interface(value: str, family: int = AF_INET) -> str:
 def get_all_ipv4_addresses() -> Sequence[str]:
     """Returns all IPv4 addresses of the current machine."""
     result = []
-    for iface in interfaces():
+    for iface in list_network_interfaces():
         addresses = ifaddresses(iface)
         if AF_INET in addresses:
             result.append(addresses[AF_INET][0]["addr"])
@@ -169,7 +185,7 @@ def get_link_layer_address_mapping() -> dict[str, str]:
     We assume that one interface may have only one link-layer address.
     """
     result = {}
-    for iface in interfaces():
+    for iface in list_network_interfaces():
         addresses = ifaddresses(iface)
         if AF_LINK in addresses:
             result[iface] = canonicalize_mac_address(addresses[AF_LINK][0]["addr"])
@@ -190,6 +206,10 @@ def resolve_network_interface_or_address(value: str) -> str:
 
     Returns:
         the IPv4 address of the interface.
+
+    Raises:
+        ValueError: if the value seems to be a network interface name but it has
+            no IPv4 address
     """
     try:
         return str(ip_address(value))

src/flockwave/networking/scanner.py

@@ -3,7 +3,7 @@
 from enum import Enum
 from functools import partial
 from ipaddress import ip_address
-from netifaces import AF_INET, AF_LINK, ifaddresses, interfaces
+from netifaces import AF_INET, AF_LINK, ifaddresses
 from typing import (
     Callable,
     Iterable,
@@ -12,6 +12,7 @@
     Sequence,
 )
 
+from .interfaces import list_network_interfaces
 from .utils import aclosing
 from .wired import is_carrier_detected, is_maybe_wired_or_wireless
 from .wireless import get_connected_access_point_name, is_likely_wireless
@@ -166,7 +167,7 @@ def _find_relevant_interfaces(
             its IPv4 addresses (or an empty list if the interface has no IPv4
             address)
         """
-        for interface in interfaces():
+        for interface in list_network_interfaces():
             addresses = ifaddresses(interface)
             ipv4_addresses = addresses.get(AF_INET)
             if not ipv4_addresses:

src/flockwave/networking/sockets.py

@@ -4,9 +4,11 @@
 from contextlib import closing
 from errno import EADDRINUSE
 from ipaddress import ip_address, ip_network
-from netifaces import AF_INET, gateways, ifaddresses, interfaces
+from netifaces import AF_INET, gateways, ifaddresses
 from typing import Any, Optional
 
+from .interfaces import list_network_interfaces
+
 __all__ = (
     "can_bind_to_tcp_address",
     "can_bind_to_udp_address",
@@ -187,7 +189,7 @@ def get_socket_address(
             remote_host = None
 
         if remote_host:
-            for interface in interfaces():
+            for interface in list_network_interfaces():
                 # We are currently interested only in IPv4 addresses
                 specs = ifaddresses(interface).get(AF_INET)
                 if not specs: