Upgrade libuv to v1.48.0 (#600)

* Fix for libuv 1.48
* Fix for macOS (resolve empty host string as "localhost")
* Add test

---------

Co-authored-by: Fantix King <fantix.king@gmail.com>

Author: niklasr22

Diff for: tests/test_dns.py

@@ -31,13 +31,13 @@ def _test_getaddrinfo(self, *args, _patch=False, **kwargs):
                 a1 = patched_getaddrinfo(*args, **kwargs)
             else:
                 a1 = socket.getaddrinfo(*args, **kwargs)
-        except socket.gaierror as ex:
+        except (socket.gaierror, UnicodeError) as ex:
             err = ex
 
         try:
             a2 = self.loop.run_until_complete(
                 self.loop.getaddrinfo(*args, **kwargs))
-        except socket.gaierror as ex:
+        except (socket.gaierror, UnicodeError) as ex:
             if err is not None:
                 self.assertEqual(ex.args, err.args)
             else:
@@ -187,6 +187,18 @@ def test_getaddrinfo_20(self):
         self._test_getaddrinfo('127.0.0.1', 80, type=socket.SOCK_STREAM,
                                flags=socket.AI_CANONNAME, _patch=patch)
 
+    # https://github.com/libuv/libuv/security/advisories/GHSA-f74f-cvh7-c6q6
+    # See also: https://github.com/MagicStack/uvloop/pull/600
+    def test_getaddrinfo_21(self):
+        payload = f'0x{"0" * 246}7f000001.example.com'.encode('ascii')
+        self._test_getaddrinfo(payload, 80)
+        self._test_getaddrinfo(payload, 80, type=socket.SOCK_STREAM)
+
+    def test_getaddrinfo_22(self):
+        payload = f'0x{"0" * 246}7f000001.example.com'
+        self._test_getaddrinfo(payload, 80)
+        self._test_getaddrinfo(payload, 80, type=socket.SOCK_STREAM)
+
     ######
 
     def test_getnameinfo_1(self):

Diff for: uvloop/dns.pyx

@@ -348,6 +348,11 @@ cdef class AddrInfoRequest(UVRequest):
 
         if host is None:
             chost = NULL
+        elif host == b'' and sys.platform == 'darwin':
+            # It seems `getaddrinfo("", ...)` on macOS is equivalent to
+            # `getaddrinfo("localhost", ...)`. This is inconsistent with
+            # libuv 1.48 which treats empty nodename as EINVAL.
+            chost = <char*>'localhost'
         else:
             chost = <char*>host
 
@@ -356,13 +361,6 @@ cdef class AddrInfoRequest(UVRequest):
         else:
             cport = <char*>port
 
-        if cport is NULL and chost is NULL:
-            self.on_done()
-            msg = system.gai_strerror(socket_EAI_NONAME).decode('utf-8')
-            ex = socket_gaierror(socket_EAI_NONAME, msg)
-            callback(ex)
-            return
-
         memset(&self.hints, 0, sizeof(system.addrinfo))
         self.hints.ai_flags = flags
         self.hints.ai_family = family
@@ -382,7 +380,17 @@ cdef class AddrInfoRequest(UVRequest):
 
         if err < 0:
             self.on_done()
-            callback(convert_error(err))
+            try:
+                if err == uv.UV_EINVAL:
+                    # Convert UV_EINVAL to EAI_NONAME to match libc behavior
+                    msg = system.gai_strerror(socket_EAI_NONAME).decode('utf-8')
+                    ex = socket_gaierror(socket_EAI_NONAME, msg)
+                else:
+                    ex = convert_error(err)
+            except Exception as ex:
+                callback(ex)
+            else:
+                callback(ex)
 
 
 cdef class NameInfoRequest(UVRequest):