[Web Payments] Common Payments validation

components/payments/payments_validators.cc

Index: components/payments/payments_validators.cc
diff --git a/components/payments/payments_validators.cc b/components/payments/payments_validators.cc
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+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/payments/payments_validators.h"
+
+#include "third_party/re2/src/re2/re2.h"
+
+namespace payments {
+
+// We limit the maximum length of the currency code to 2048 bytes for security
+// reasons.
+static const int maxCurrencyCodeLength = 2048;
+
+bool PaymentsValidators::isValidCurrencyCodeFormat(
+    const std::string& code,
+    const std::string& system,
+    std::string* optionalErrorMessage) {
+  if (system == "urn:iso:std:iso:4217") {
+    if (RE2::FullMatch(code, "[A-Z]{3}"))
+      return true;
+
+    if (optionalErrorMessage)
+      *optionalErrorMessage = "'" + code +
+                              "' is not a valid ISO 4217 currency code, should "
+                              "be 3 upper case letters [A-Z]";
+
+    return false;
+  }
+
+  if (code.size() <= maxCurrencyCodeLength)
+    return true;
+
+  if (optionalErrorMessage)
+    *optionalErrorMessage =
+        "The currency code should be at most 2048 characters long";
+
+  return false;
+}
+
+bool PaymentsValidators::isValidAmountFormat(
+    const std::string& amount,
+    std::string* optionalErrorMessage) {
+  if (RE2::FullMatch(amount, "-?[0-9]+(\\.[0-9]+)?"))
+    return true;
+
+  if (optionalErrorMessage)
+    *optionalErrorMessage = "'" + amount + "' is not a valid amount format";
+
+  return false;
+}
+
+}  // namespace payments