general: add unit tests for >80% coverage

Includes a few minor fixes:
- frontend: support setting port for WHOIS server
- proxy: fix handling of very long lines
- proxy: refactor IP allowlist logic, parse allow IP list at startup

frontend/dn42_test.go

@@ -28,3 +28,79 @@ func TestDN42WhoisFilterUnneeded(t *testing.T) {
 		t.Errorf("Output doesn't match expected: %s", result)
 	}
 }
+
+func TestShortenWhoisFilterShorterMode(t *testing.T) {
+	input := `
+Information line that will be removed
+
+# Comment that will be removed
+Name: Redacted for privacy
+Descr: This is a vvvvvvvvvvvvvvvvvvvvvvveeeeeeeeeeeeeeeeeeeerrrrrrrrrrrrrrrrrrrrrrrryyyyyyyyyyyyyyyyyyy long line that will be skipped.
+Looooooooooooooooooooooong key: this line will be skipped.
+
+Preserved1: this line isn't removed.
+Preserved2: this line isn't removed.
+Preserved3: this line isn't removed.
+Preserved4: this line isn't removed.
+Preserved5: this line isn't removed.
+
+`
+
+	result := shortenWhoisFilter(input)
+
+	expectedResult := `Preserved1: this line isn't removed.
+Preserved2: this line isn't removed.
+Preserved3: this line isn't removed.
+Preserved4: this line isn't removed.
+Preserved5: this line isn't removed.
+
+3 line(s) skipped.
+`
+
+	if result != expectedResult {
+		t.Errorf("Output doesn't match expected: %s", result)
+	}
+}
+
+func TestShortenWhoisFilterLongerMode(t *testing.T) {
+	input := `
+Information line that will be removed
+
+# Comment that will be removed
+Name: Redacted for privacy
+Descr: This is a vvvvvvvvvvvvvvvvvvvvvvveeeeeeeeeeeeeeeeeeeerrrrrrrrrrrrrrrrrrrrrrrryyyyyyyyyyyyyyyyyyy long line that will be skipped.
+Looooooooooooooooooooooong key: this line will be skipped.
+
+Preserved1: this line isn't removed.
+
+`
+
+	result := shortenWhoisFilter(input)
+
+	expectedResult := `Information line that will be removed
+Descr: This is a vvvvvvvvvvvvvvvvvvvvvvveeeeeeeeeeeeeeeeeeeerrrrrrrrrrrrrrrrrrrrrrrryyyyyyyyyyyyyyyyyyy long line that will be skipped.
+Looooooooooooooooooooooong key: this line will be skipped.
+Preserved1: this line isn't removed.
+
+7 line(s) skipped.
+`
+
+	if result != expectedResult {
+		t.Errorf("Output doesn't match expected: %s", result)
+	}
+}
+
+func TestShortenWhoisFilterSkipNothing(t *testing.T) {
+	input := `Preserved1: this line isn't removed.
+Preserved2: this line isn't removed.
+Preserved3: this line isn't removed.
+Preserved4: this line isn't removed.
+Preserved5: this line isn't removed.
+`
+
+	result := shortenWhoisFilter(input)
+
+	if result != input {
+		t.Errorf("Output doesn't match expected: %s", result)
+	}
+}