feat: glob matching for redirect domains (#1084)

* feat: glob matching for redirect domains

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore: spelling

Signed-off-by: Xe Iaso <me@xeiaso.net>

* docs: update CHANGELOG

Signed-off-by: Xe Iaso <me@xeiaso.net>

---------

Signed-off-by: Xe Iaso <me@xeiaso.net>

internal/glob/glob.go

@@ -0,0 +1,61 @@
+package glob
+
+import "strings"
+
+const GLOB = "*"
+
+const maxGlobParts = 5
+
+// Glob will test a string pattern, potentially containing globs, against a
+// subject string. The result is a simple true/false, determining whether or
+// not the glob pattern matched the subject text.
+func Glob(pattern, subj string) bool {
+	// Empty pattern can only match empty subject
+	if pattern == "" {
+		return subj == pattern
+	}
+
+	// If the pattern _is_ a glob, it matches everything
+	if pattern == GLOB {
+		return true
+	}
+
+	parts := strings.Split(pattern, GLOB)
+
+	if len(parts) > maxGlobParts {
+		return false // Pattern is too complex, reject it.
+	}
+
+	if len(parts) == 1 {
+		// No globs in pattern, so test for equality
+		return subj == pattern
+	}
+
+	leadingGlob := strings.HasPrefix(pattern, GLOB)
+	trailingGlob := strings.HasSuffix(pattern, GLOB)
+	end := len(parts) - 1
+
+	// Go over the leading parts and ensure they match.
+	for i := 0; i < end; i++ {
+		idx := strings.Index(subj, parts[i])
+
+		switch i {
+		case 0:
+			// Check the first section. Requires special handling.
+			if !leadingGlob && idx != 0 {
+				return false
+			}
+		default:
+			// Check that the middle parts match.
+			if idx < 0 {
+				return false
+			}
+		}
+
+		// Trim evaluated text from subj as we loop over the pattern.
+		subj = subj[idx+len(parts[i]):]
+	}
+
+	// Reached the last section. Requires special handling.
+	return trailingGlob || strings.HasSuffix(subj, parts[end])
+}