Based my previous post on SAS Token Expiry I wrote a test harness to better understand DateTimeOffset
using System;
namespace UnixEpochTester
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine($"DIY {new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)}");
Console.WriteLine($"DateTime.UnixEpoch {DateTime.UnixEpoch} {DateTime.UnixEpoch.Kind}");
Console.WriteLine();
TimeSpan fromUnixEpochNow = DateTime.UtcNow - DateTime.UnixEpoch;
Console.WriteLine($"Epoc now {fromUnixEpochNow} {fromUnixEpochNow.TotalSeconds.ToString("f0")} sec");
Console.WriteLine();
TimeSpan fromUnixEpochFixed = new DateTime(2019, 11, 30, 2, 0, 0, DateTimeKind.Utc) - DateTime.UnixEpoch;
Console.WriteLine($"Epoc {fromUnixEpochFixed} {fromUnixEpochFixed.TotalSeconds.ToString("f0")} sec");
Console.WriteLine();
DateTimeOffset dateTimeOffset = new DateTimeOffset( new DateTime( 2019,11,30,2,0,0, DateTimeKind.Utc));
Console.WriteLine($"Epoc DateTimeOffset {fromUnixEpochFixed} {dateTimeOffset.ToUnixTimeSeconds()}");
Console.WriteLine();
TimeSpan fromEpochStart = new DateTime(2019, 11, 30, 2, 0, 0, DateTimeKind.Utc) - DateTime.UnixEpoch;
Console.WriteLine($"Epoc DateTimeOffset {fromEpochStart} {fromEpochStart.TotalSeconds.ToString("F0")}");
Console.WriteLine();
// https://www.epochconverter.com/ matches
// https://www.unixtimestamp.com/index.php matches
Console.WriteLine("Press ENTER to exit");
Console.ReadLine();
}
}
}
I validated my numbers against a couple of online calculators and they matched which was a good start.
As I was testing my Azure MQTT Test Client I had noticed some oddness with MQTT connection timeouts.
string token = generateSasToken($"{server}/devices/{clientId}", password, "", new TimeSpan(0,5,0));
1/12/2019 1:29:52 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.391","OfficeHumidity":"93"}]
1/12/2019 1:30:22 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.29","OfficeHumidity":"64"}]
...
1/12/2019 1:43:56 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.591","OfficeHumidity":"98"}]
1/12/2019 1:44:26 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.754","OfficeHumidity":"68"}]
string token = generateSasToken($"{server}/devices/{clientId}", password, "", new TimeSpan(0,5,0));
1/12/2019 1:29:52 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.391","OfficeHumidity":"93"}]
1/12/2019 1:30:22 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.29","OfficeHumidity":"64"}]
...
1/12/2019 2:01:37 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.334","OfficeHumidity":"79"}]
1/12/2019 2:02:07 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.503","OfficeHumidity":"49"}]
string token = generateSasToken($"{server}/devices/{clientId}", password, "", new TimeSpan(0,5,0));
2/12/2019 9:27:21 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.196","OfficeHumidity":"61"}]
2/12/2019 9:27:51 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.788","OfficeHumidity":"91"}]
...
2/12/2019 9:36:24 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.670","OfficeHumidity":"64"}]
2/12/2019 9:36:54 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.836","OfficeHumidity":"94"}]
string token = generateSasToken($"{server}/devices/{clientId}", password, "", new TimeSpan(0,5,0));
2/12/2019 9:40:52 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.46","OfficeHumidity":"92"}]
2/12/2019 9:41:22 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.443","OfficeHumidity":"62"}]
...
2/12/2019 9:50:55 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.742","OfficeHumidity":"95"}]
string token = generateSasToken($"{server}/devices/{clientId}", password, "", new TimeSpan(0,10,0));
approx 15min as only 30 sec resolution
1/12/2019 12:50:23 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.630","OfficeHumidity":"65"}]
1/12/2019 12:50:53 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.798","OfficeHumidity":"95"}]
...
1/12/2019 1:03:59 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.677","OfficeHumidity":"41"}]
1/12/2019 1:04:30 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.26","OfficeHumidity":"72"}]
string token = generateSasToken($"{server}/devices/{clientId}", password, "", new TimeSpan(0,10,0));
approx 15min as only 30 sec resolution
1/12/2019 1:09:30 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.106","OfficeHumidity":"72"}]
1/12/2019 1:10:00 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.463","OfficeHumidity":"42"}]
...
1/12/2019 1:23:35 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.366","OfficeHumidity":"77"}]
1/12/2019 1:24:05 PM> Device: [MQTTLoRa915MHz], Data:[{"OfficeTemperature":"22.537","OfficeHumidity":"47"}]
The dataset with the 5 minute expiry which remained connected for approximately 30 mins was hopefully a configuration issue.
The updated SAS Token code not uses ToUnixTimeSeconds to eliminate the scope for local vs. UTC issues.
public static string generateSasToken(string resourceUri, string key, string policyName, TimeSpan timeToLive)
{
DateTimeOffset expiryDateTimeOffset = new DateTimeOffset(DateTime.UtcNow.Add(timeToLive));
string expiryEpoch = expiryDateTimeOffset.ToUnixTimeSeconds().ToString();
string stringToSign = WebUtility.UrlEncode(resourceUri) + "\n" + expiryEpoch;
HMACSHA256 hmac = new HMACSHA256(Convert.FromBase64String(key));
string signature = Convert.ToBase64String(hmac.ComputeHash(Encoding.UTF8.GetBytes(stringToSign)));
string token = $"SharedAccessSignature sr={WebUtility.UrlEncode(resourceUri)}&sig={WebUtility.UrlEncode(signature)}&se={expiryEpoch}";
if (!String.IsNullOrEmpty(policyName))
{
token += "&skn=" + policyName;
}
return token;
}
I need to test the expiry of my SAS Tokens some more especially with the client running on my development machine (NZT which is currently UTC+13) and in Azure (UTC timezone)
