CI: fix unstable test \ext\sockets\tests\socket_recvfrom_afpacket_no_port.phpt

ext/sockets/tests/socket_recvfrom_afpacket_no_port.phpt

@@ -29,10 +29,30 @@ $ethertype = pack("n", 0x9000);
 $payload = "no port test";
 $frame = str_pad($dst_mac . $src_mac . $ethertype . $payload, 60, "\x00");
 
+// ETH_P_ALL sockets on loopback can observe unrelated localhost traffic from
+// the parallel test runner. Read until we see our own frame, then validate the
+// address returned by recvfrom() without the optional port argument.
+function recv_matching(Socket $s, string $header, int $maxlen = 65536, ?string &$addr = null, &$bytes = null): string|false {
+    socket_set_nonblock($s);
+    $deadline = microtime(true) + 5.0;
+    while (microtime(true) < $deadline) {
+        $recvBytes = @socket_recvfrom($s, $buf, $maxlen, 0, $addr);
+        if ($recvBytes !== false && is_string($buf) && str_starts_with($buf, $header)) {
+            $bytes = $recvBytes;
+            return $buf;
+        }
+        if ($recvBytes === false) {
+            usleep(1000);
+        }
+    }
+    return false;
+}
+
 socket_sendto($s_send, $frame, strlen($frame), 0, "lo", 1);
 
 // recvfrom without the optional 6th argument (port/ifindex).
-$bytes = socket_recvfrom($s_recv, $buf, 65536, 0, $addr);
+$bytes = 0;
+$buf = recv_matching($s_recv, $dst_mac . $src_mac . $ethertype, 65536, $addr, $bytes);
 var_dump($bytes >= 60);
 var_dump($addr === 'lo');