Add rlz_utils as a new build target to rlz/

rlz/lib/net_response_check.cc

Index: rlz/lib/net_response_check.cc
diff --git a/rlz/lib/net_response_check.cc b/rlz/lib/net_response_check.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e018176d00a55a88f02f1bf5d95c47195cb6150c
--- /dev/null
+++ b/rlz/lib/net_response_check.cc
@@ -0,0 +1,67 @@
+// Copyright 2017 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 "rlz/lib/net_response_check.h"
+
+#include "base/strings/string_util.h"
+#include "rlz/lib/assert.h"
+#include "rlz/lib/crc32.h"
+#include "rlz/lib/string_utils.h"
+
+// Checksum validation convenience call for RLZ responses.
+namespace rlz_lib {
+
+bool IsPingResponseValid(const char* response, int* checksum_idx) {
+  if (!response || !response[0])
+    return false;
+
+  if (checksum_idx)
+    *checksum_idx = -1;
+
+  if (strlen(response) > kMaxPingResponseLength) {
+    ASSERT_STRING("IsPingResponseValid: response is too long to parse.");
+    return false;
+  }
+
+  // Find the checksum line.
+  std::string response_string(response);
+
+  std::string checksum_param("\ncrc32: ");
+  int calculated_crc;
+  int checksum_index = response_string.find(checksum_param);
+  if (checksum_index >= 0) {
+    // Calculate checksum of message preceeding checksum line.
+    // (+ 1 to include the \n)
+    std::string message(response_string.substr(0, checksum_index + 1));
+    if (!Crc32(message.c_str(), &calculated_crc))
+      return false;
+  } else {
+    checksum_param = "crc32: ";  // Empty response case.
+    if (!base::StartsWith(response_string, checksum_param,
+                          base::CompareCase::SENSITIVE))
+      return false;
+
+    checksum_index = 0;
+    if (!Crc32("", &calculated_crc))
+      return false;
+  }
+
+  // Find the checksum value on the response.
+  int checksum_end = response_string.find("\n", checksum_index + 1);
+  if (checksum_end < 0)
+    checksum_end = response_string.size();
+
+  int checksum_begin = checksum_index + checksum_param.size();
+  std::string checksum =
+      response_string.substr(checksum_begin, checksum_end - checksum_begin + 1);
+  base::TrimWhitespaceASCII(checksum, base::TRIM_ALL, &checksum);
+
+  if (checksum_idx)
+    *checksum_idx = checksum_index;
+
+  return calculated_crc == HexStringToInteger(checksum.c_str());
+}
+
+}  // namespace rlz_lib