IOTSDK-24021: Fix parsing of server DateTime

std::get_time does not claim support of time zones in the string
parameter, and seems to be subject of locale set on the system. An
example is a following result on linux:

ParseTime(Thu, 1 Jan 1970 0:00:00 GMT)=-2209075200

::strptime is also a subject to the time zones of locale, but it also
claim support for parsing a time zone from the passed string. Thus,
additional logic incorporated to offset parsed DataTime to the local
timezone.

Signed-off-by: Mykhailo Diachenko <ext-mykhailo.z.diachenko@here.com>

Author: diachenko-mischa

olp-cpp-sdk-authentication/src/AuthenticationClientUtils.cpp

@@ -32,6 +32,7 @@
 #include "ResponseFromJsonBuilder.h"
 #include "olp/core/http/NetworkResponse.h"
 #include "olp/core/http/NetworkUtils.h"
+#include "olp/core/logging/Log.h"
 #include "olp/core/utils/Base64.h"
 #include "olp/core/utils/Url.h"
 
@@ -55,6 +56,7 @@ constexpr auto kOauthTimestamp = "oauth_timestamp";
 constexpr auto kOauthSignatureMethod = "oauth_signature_method";
 constexpr auto kVersion = "1.0";
 constexpr auto kHmac = "HMAC-SHA256";
+constexpr auto kLogTag = "AuthenticationClientUtils";
 
 std::string Base64Encode(const Crypto::Sha256Digest& digest) {
   std::string ret = olp::utils::Base64Encode(digest.data(), digest.size());
@@ -98,13 +100,28 @@ constexpr auto kDate = "date";
 #define timegm _mkgmtime
 #endif
 
-std::time_t ParseTime(const std::string& value) {
+std::time_t doParseTime(const std::string& value) {
   std::tm tm = {};
   std::istringstream ss(value);
-  ss >> std::get_time(&tm, "%a, %d %b %Y %H:%M:%S %z");
+  const auto format = "%a, %d %b %Y %H:%M:%S %Z";
+  const auto r = ::strptime(value.c_str(), format, &tm);
+  if (r != value.c_str() + value.size()) {
+    OLP_SDK_LOG_WARNING(kLogTag, "Timestamp is not fully parsed" << value);
+  }
   return timegm(&tm);
 }
 
+std::time_t gmtEpochOffset() {
+  const auto epochAsDateTime = "Thu, 1 Jan 1970 0:00:00 GMT";
+  return doParseTime(epochAsDateTime);
+}
+
+std::time_t ParseTime(const std::string& value) {
+  const auto time = doParseTime(value);
+  const auto offset = gmtEpochOffset();
+  return time - offset;
+}
+
 boost::optional<std::time_t> GetTimestampFromHeaders(
     const olp::http::Headers& headers) {
   auto it =