Orders ipv6 addresses before v4 in resolution.

When performing  mdns or dns resolution for a given hostname v4
addresses are always returned for the connection over v6 when an address
supports dual stacks.

This allows for ipv6 transitioning and testing in a dual stack
environment. It also follows common practice when picking the right
address to try first.

Not addressed by this commit is the ability to fall back to other
resolved addresses should the first address fail. This feature is
addressed by other todo's in the project.

aioesphomeapi/host_resolver.py

@@ -99,7 +99,10 @@ async def _async_resolve_host_zeroconf(
         return []
 
     addrs: List[AddrInfo] = []
-    for raw in info.addresses_by_version(zeroconf.IPVersion.All):
+    rawAddrs = info.addresses_by_version(
+        zeroconf.IPVersion.V6Only
+    ) + info.addresses_by_version(zeroconf.IPVersion.V4Only)
+    for raw in rawAddrs:
         is_ipv6 = len(raw) == 16
         sockaddr: Sockaddr
         if is_ipv6:
@@ -135,7 +138,8 @@ async def _async_resolve_host_getaddrinfo(host: str, port: int) -> List[AddrInfo
     except OSError as err:
         raise APIConnectionError(f"Error resolving IP address: {err}")
 
-    addrs: List[AddrInfo] = []
+    addrsV4: List[AddrInfo] = []
+    addrsV6: List[AddrInfo] = []
     for family, type_, proto, _, raw in res:
         sockaddr: Sockaddr
         if family == socket.AF_INET:
@@ -152,10 +156,13 @@ async def _async_resolve_host_getaddrinfo(host: str, port: int) -> List[AddrInfo
             # Unknown family
             continue
 
-        addrs.append(
-            AddrInfo(family=family, type=type_, proto=proto, sockaddr=sockaddr)
-        )
-    return addrs
+        addrInfo = AddrInfo(family=family, type=type_, proto=proto, sockaddr=sockaddr)
+        if family == socket.AF_INET6:
+            addrsV6.append(addrInfo)
+        else:
+            addrsV4.append(addrInfo)
+
+    return addrsV6 + addrsV4
 
 
 def _async_ip_address_to_addrs(host: str, port: int) -> List[AddrInfo]:

tests/test_host_resolver.py

@@ -1,7 +1,9 @@
 import asyncio
 import socket
+from typing import List
 
 import pytest
+import zeroconf
 from mock import AsyncMock, MagicMock, patch
 
 import aioesphomeapi.host_resolver as hr
@@ -17,12 +19,6 @@ def async_zeroconf():
 @pytest.fixture
 def addr_infos():
     return [
-        hr.AddrInfo(
-            family=socket.AF_INET,
-            type=socket.SOCK_STREAM,
-            proto=socket.IPPROTO_TCP,
-            sockaddr=hr.IPv4Sockaddr(address="10.0.0.42", port=6052),
-        ),
         hr.AddrInfo(
             family=socket.AF_INET6,
             type=socket.SOCK_STREAM,
@@ -34,16 +30,28 @@ def addr_infos():
                 scope_id=0,
             ),
         ),
+        hr.AddrInfo(
+            family=socket.AF_INET,
+            type=socket.SOCK_STREAM,
+            proto=socket.IPPROTO_TCP,
+            sockaddr=hr.IPv4Sockaddr(address="10.0.0.42", port=6052),
+        ),
     ]
 
 
 @pytest.mark.asyncio
 async def test_resolve_host_zeroconf(async_zeroconf, addr_infos):
+    def address_for_version(version: zeroconf.IPVersion) -> List[bytes]:
+        if version == zeroconf.IPVersion.V6Only:
+            return [
+                b"\x20\x01\x0d\xb8\x85\xa3\x00\x00\x00\x00\x8a\x2e\x03\x70\x73\x34",
+            ]
+        return [
+            b"\x0A\x00\x00\x2A",
+        ]
+
     info = MagicMock()
-    info.addresses_by_version.return_value = [
-        b"\n\x00\x00*",
-        b" \x01\r\xb8\x85\xa3\x00\x00\x00\x00\x8a.\x03ps4",
-    ]
+    info.addresses_by_version.side_effect = address_for_version
     async_zeroconf.async_get_service_info = AsyncMock(return_value=info)
     async_zeroconf.async_close = AsyncMock()
 
@@ -71,18 +79,18 @@ async def test_resolve_host_getaddrinfo(event_loop, addr_infos):
     with patch.object(event_loop, "getaddrinfo") as mock:
         mock.return_value = [
             (
-                socket.AF_INET,
+                socket.AF_INET6,
                 socket.SOCK_STREAM,
                 socket.IPPROTO_TCP,
-                "canon1",
-                ("10.0.0.42", 6052),
+                "canon2",
+                ("2001:db8:85a3::8a2e:370:7334", 6052, 0, 0),
             ),
             (
-                socket.AF_INET6,
+                socket.AF_INET,
                 socket.SOCK_STREAM,
                 socket.IPPROTO_TCP,
-                "canon2",
-                ("2001:db8:85a3::8a2e:370:7334", 6052, 0, 0),
+                "canon1",
+                ("10.0.0.42", 6052),
             ),
             (-1, socket.SOCK_STREAM, socket.IPPROTO_TCP, "canon3", ("10.0.0.42", 6052)),
         ]