fix(build): tag regex should allow ports (#3196)

Update the regex and add test cases.

(There are some xfails here for cases that the regex is not currently
handling. It's too strict for IPv6 domains at the moment.)

Closes: #3195
Related: opencontainers/distribution-spec#498

Signed-off-by: Sven Kieske <kieske@osism.tech>
Signed-off-by: Milas Bowman <milas.bowman@docker.com>
Co-authored-by: Milas Bowman <milas.bowman@docker.com>

Author: artificial-intelligence

docker/utils/build.py

@@ -10,8 +10,9 @@
 
 _SEP = re.compile('/|\\\\') if IS_WINDOWS_PLATFORM else re.compile('/')
 _TAG = re.compile(
-    r"^[a-z0-9]+((\.|_|__|-+)[a-z0-9]+)*(\/[a-z0-9]+((\.|_|__|-+)[a-z0-9]+)*)*" \
-        + "(:[a-zA-Z0-9_][a-zA-Z0-9._-]{0,127})?$"
+    r"^[a-z0-9]+((\.|_|__|-+)[a-z0-9]+)*"
+    r"(?::[0-9]+)?(/[a-z0-9]+((\.|_|__|-+)[a-z0-9]+)*)*"
+    r"(:[a-zA-Z0-9_][a-zA-Z0-9._-]{0,127})?$"
 )
 
 

tests/unit/utils_build_test.py

@@ -6,11 +6,10 @@
 import tempfile
 import unittest
 
+import pytest
 
 from docker.constants import IS_WINDOWS_PLATFORM
-from docker.utils import exclude_paths, tar
-
-import pytest
+from docker.utils import exclude_paths, tar, match_tag
 
 from ..helpers import make_tree
 
@@ -489,3 +488,51 @@ def test_tar_directory_link(self):
                 assert member in names
             assert 'a/c/b' in names
             assert 'a/c/b/utils.py' not in names
+
+
+# selected test cases from https://github.com/distribution/reference/blob/8507c7fcf0da9f570540c958ea7b972c30eeaeca/reference_test.go#L13-L328
+@pytest.mark.parametrize("tag,expected", [
+    ("test_com", True),
+    ("test.com:tag", True),
+    # N.B. this implicitly means "docker.io/library/test.com:5000"
+    # i.e. the `5000` is a tag, not a port here!
+    ("test.com:5000", True),
+    ("test.com/repo:tag", True),
+    ("test:5000/repo", True),
+    ("test:5000/repo:tag", True),
+    ("test:5000/repo", True),
+    ("", False),
+    (":justtag", False),
+    ("Uppercase:tag", False),
+    ("test:5000/Uppercase/lowercase:tag", False),
+    ("lowercase:Uppercase", True),
+    # length limits not enforced
+    pytest.param("a/"*128 + "a:tag", False, marks=pytest.mark.xfail),
+    ("a/"*127 + "a:tag-puts-this-over-max", True),
+    ("aa/asdf$$^/aa", False),
+    ("sub-dom1.foo.com/bar/baz/quux", True),
+    ("sub-dom1.foo.com/bar/baz/quux:some-long-tag", True),
+    ("b.gcr.io/test.example.com/my-app:test.example.com", True),
+    ("xn--n3h.com/myimage:xn--n3h.com", True),
+    ("foo_bar.com:8080", True),
+    ("foo/foo_bar.com:8080", True),
+    ("192.168.1.1", True),
+    ("192.168.1.1:tag", True),
+    ("192.168.1.1:5000", True),
+    ("192.168.1.1/repo", True),
+    ("192.168.1.1:5000/repo", True),
+    ("192.168.1.1:5000/repo:5050", True),
+    # regex does not properly handle ipv6
+    pytest.param("[2001:db8::1]", False, marks=pytest.mark.xfail),
+    ("[2001:db8::1]:5000", False),
+    pytest.param("[2001:db8::1]/repo", True, marks=pytest.mark.xfail),
+    pytest.param("[2001:db8:1:2:3:4:5:6]/repo:tag", True, marks=pytest.mark.xfail),
+    pytest.param("[2001:db8::1]:5000/repo", True, marks=pytest.mark.xfail),
+    pytest.param("[2001:db8::1]:5000/repo:tag", True, marks=pytest.mark.xfail),
+    pytest.param("[2001:db8::]:5000/repo", True, marks=pytest.mark.xfail),
+    pytest.param("[::1]:5000/repo", True, marks=pytest.mark.xfail),
+    ("[fe80::1%eth0]:5000/repo", False),
+    ("[fe80::1%@invalidzone]:5000/repo", False),
+])
+def test_match_tag(tag: str, expected: bool):
+    assert match_tag(tag) == expected