Answer 404 for Maven paths too short to hold a coordinate

internal/handler/maven.go

@@ -221,14 +221,11 @@ func (h *MavenHandler) handleDownload(w http.ResponseWriter, r *http.Request, so
 	// e.g., com/google/guava/guava/32.1.3-jre/guava-32.1.3-jre.jar
 	group, artifact, version, filename := h.parsePath(urlPath)
 	if artifact == "" {
-		if strings.Count(urlPath, "/") >= minMavenParts-1 {
-			// A dot or colon in a group directory, or a colon in the
-			// artifact, which the Maven layout never has. Proxied, the
-			// file would skip the denylist, scan and cooldown.
-			http.NotFound(w, r)
-			return
-		}
-		h.proxyUpstream(w, r, source, urlPath)
+		// Too few segments to hold a coordinate, or a dot or colon in a
+		// group directory, or a colon in the artifact, which the Maven
+		// layout never has. Proxied, the file would skip the denylist,
+		// scan and cooldown.
+		http.NotFound(w, r)
 		return
 	}
 

internal/handler/maven_repositories_test.go

@@ -139,15 +139,17 @@ func TestMavenRepositoryRepointedServesTheNewUpstream(t *testing.T) {
 	}
 }
 
-// TestMavenDottedGroupDirectoryNotCachedAsGroup checks that a file whose
-// group directories contain dots or colons, which the Maven layout never
-// has, is not served: it would either share the cache entry of the group
-// the dots spell or be proxied past the denylist, scan and cooldown.
+// TestMavenDottedGroupDirectoryNotCachedAsGroup checks that a file outside
+// the Maven layout is not served: a group directory with a dot or a colon,
+// which the layout never has and which would share the cache entry of the
+// group the dots spell, and a path too short to hold a coordinate. Proxied,
+// they would skip the denylist, scan and cooldown.
 func TestMavenDottedGroupDirectoryNotCachedAsGroup(t *testing.T) {
 	const standard = "/org/foo/bar/1.0/bar-1.0.jar"
 	odd := []string{
 		"/org.foo/bar/1.0/bar-1.0.jar", "/org.foo/bar/1.0/bar-1.0-linux.exe",
 		"/org/foo:x/bar/1.0/bar-1.0.jar", "/org/foo/b:ar/1.0/b:ar-1.0.jar",
+		"/bar/1.0/bar-1.0.jar", "/bar-1.0.jar",
 	}
 	central, requests := mavenRepoUpstream(t, "central", append([]string{standard}, odd...)...)
 	portal, _ := mavenRepoUpstream(t, "portal")