tests/functional: Move the code for testing HTTP downloads to a common function

We are going to use this code in other tests, too, so let's move it
to the qemu_test module to be able to re-use it more easily.

Message-ID: <20250227103915.19795-2-thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/functional/qemu_test/linuxkernel.py

@@ -3,8 +3,12 @@
 # This work is licensed under the terms of the GNU GPL, version 2 or
 # later.  See the COPYING file in the top-level directory.
 
+import hashlib
+import urllib.request
+
+from .cmd import wait_for_console_pattern, exec_command_and_wait_for_pattern
 from .testcase import QemuSystemTest
-from .cmd import wait_for_console_pattern
+from .utils import get_usernet_hostfwd_port
 
 
 class LinuxKernelTest(QemuSystemTest):
@@ -26,3 +30,23 @@ class LinuxKernelTest(QemuSystemTest):
         self.vm.launch()
         if wait_for:
                 self.wait_for_console_pattern(wait_for)
+
+    def check_http_download(self, filename, hashsum, guestport=8080,
+                            pythoncmd='python3 -m http.server'):
+        exec_command_and_wait_for_pattern(self,
+                        f'{pythoncmd} {guestport} & sleep 1',
+                        f'Serving HTTP on 0.0.0.0 port {guestport}')
+        hl = hashlib.sha256()
+        hostport = get_usernet_hostfwd_port(self.vm)
+        url = f'http://localhost:{hostport}{filename}'
+        self.log.info(f'Downloading {url} ...')
+        with urllib.request.urlopen(url) as response:
+            while True:
+                chunk = response.read(1 << 20)
+                if not chunk:
+                    break
+                hl.update(chunk)
+
+        digest = hl.hexdigest()
+        self.log.info(f'sha256sum of download is {digest}.')
+        self.assertEqual(digest, hashsum)