I use GitHub Copilot with Visual Studio 2020 and I wanted to see if I could write a simple application only using “Ask Copilot”. Retrieving a static image from a security camera (like my HiLook IPC-T250H) felt like a reasonable challenge.
please write a console application that uses an HttpClient to retrieve an image from a security camera
static async Task Main(string[] args)
{
string cameraUrl = "http://your-security-camera-url/image.jpg";
string savePath = "downloaded_image.jpg";
using (HttpClient client = new HttpClient())
{
try
{
HttpResponseMessage response = await client.GetAsync(cameraUrl);
response.EnsureSuccessStatusCode();
byte[] imageBytes = await response.Content.ReadAsByteArrayAsync();
await File.WriteAllBytesAsync(savePath, imageBytes);
Console.WriteLine("Image downloaded successfully.");
}
catch (Exception ex)
{
Console.WriteLine($"An error occurred: {ex.Message}");
}
}
}
}
The Github Copilot generated code compiled first time and looked reasonable for a Proof of Concept (PoC). After changing the “cameraUrl” the program could retrieve an image from one of my cameras when I disabled authentication.
please write a console application that uses an httpclient to retrieve an image from a security camera. The security camera needs a username and password
static async Task Main(string[] args)
{
string cameraUrl = "http://your-security-camera-url/image";
string username = "your-username";
string password = "your-password";
using (HttpClient client = new HttpClient())
{
var byteArray = new System.Text.ASCIIEncoding().GetBytes($"{username}:{password}");
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", Convert.ToBase64String(byteArray));
HttpResponseMessage response = await client.GetAsync(cameraUrl);
response.EnsureSuccessStatusCode();
byte[] imageBytes = await response.Content.ReadAsByteArrayAsync();
File.WriteAllBytes("camera_image.jpg", imageBytes);
Console.WriteLine("Image retrieved and saved as camera_image.jpg");
}
Github Copilot had taken my request literally and implemented Hypertext Transfer Protocol (HTTP/1.1): Authentication (RFC7235). My HiLook IPC-T250H only supports Digest Authentication(RFC2617) so I tried
please modify the security code to support Digest authentication
static async Task Main(string[] args)
{
string cameraUrl = "http://your-security-camera-url/image";
string username = "your-username";
string password = "your-password";
using (HttpClient client = new HttpClient())
{
HttpResponseMessage response = await client.GetAsync(cameraUrl);
if (response.StatusCode == System.Net.HttpStatusCode.Unauthorized)
{
var wwwAuthenticateHeader = response.Headers.WwwAuthenticate.FirstOrDefault();
if (wwwAuthenticateHeader != null && wwwAuthenticateHeader.Scheme == "Digest")
{
var digestHeader = wwwAuthenticateHeader.Parameter;
var digestResponse = CreateDigestHeader(digestHeader, cameraUrl, username, password, "GET");
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Digest", digestResponse);
response = await client.GetAsync(cameraUrl);
response.EnsureSuccessStatusCode();
byte[] imageBytes = await response.Content.ReadAsByteArrayAsync();
File.WriteAllBytes("camera_image.jpg", imageBytes);
Console.WriteLine("Image retrieved and saved as camera_image.jpg");
}
}
}
}
private static string CreateDigestHeader(string digestHeader, string url, string username, string password, string method)
{
var headerValues = digestHeader.Split(',').Select(v => v.Trim().Split('=')).ToDictionary(v => v[0], v => v[1].Trim('"'));
string ha1 = CalculateMD5Hash($"{username}:{headerValues["realm"]}:{password}");
string ha2 = CalculateMD5Hash($"{method}:{url}");
string response = CalculateMD5Hash($"{ha1}:{headerValues["nonce"]}:{headerValues["nc"]}:{headerValues["cnonce"]}:{headerValues["qop"]}:{ha2}");
return $"username=\"{username}\", realm=\"{headerValues["realm"]}\", nonce=\"{headerValues["nonce"]}\", uri=\"{url}\", qop={headerValues["qop"]}, nc={headerValues["nc"]}, cnonce=\"{headerValues["cnonce"]}\", response=\"{response}\", opaque=\"{headerValues["opaque"]}\"";
}
private static string CalculateMD5Hash(string input)
{
using (MD5 md5 = MD5.Create())
{
byte[] inputBytes = Encoding.ASCII.GetBytes(input);
byte[] hashBytes = md5.ComputeHash(inputBytes);
return BitConverter.ToString(hashBytes).Replace("-", "").ToLower();
}
}
Github Copilot had taken my request literally and implemented Digest Authentication(RFC2617) so I did some “research”. The Copilot desktop application suggested using NetworkCredential which supports Basic, and digest (also NTLM, and Kerberos) authentication.
modify the code to use a NetworkCredential to authenticate with the security camera
using System.Net;
namespace SecurityCameraClient
{
internal class Program
{
static async Task Main(string[] args)
{
string cameraUrl = "http://your-security-camera-url/image.jpg";
string savePath = "downloaded_image.jpg";
string username = "your-username";
string password = "your-password";
using (HttpClientHandler handler = new HttpClientHandler { Credentials = new NetworkCredential(username, password) })
using (HttpClient client = new HttpClient(handler))
{
try
{
HttpResponseMessage response = await client.GetAsync(cameraUrl);
response.EnsureSuccessStatusCode();
byte[] imageBytes = await response.Content.ReadAsByteArrayAsync();
await File.WriteAllBytesAsync(savePath, imageBytes);
Console.WriteLine("Image downloaded successfully.");
}
catch (Exception ex)
{
Console.WriteLine($"An error occurred: {ex.Message}");
}
}
}
}
}
The Github Copilot generated code compiled and after changing the “cameraUrl”, “username” and “password” the program could retrieve an image from each of my cameras.
I wanted the application to retrieve images regularly, but the first Github Copilot generated code was pretty ugly (it used a System.Timers.Timer). After “consulting” the Copilot desktop application
modify the code to use a System.Threading Timer so an image is retrieved every 1000mSec
using System.Net;
namespace SecurityCameraClient
{
internal class Program
{
private static Timer _timer;
private static HttpClient _client;
private static string _cameraUrl = "http://your-security-camera-url/image.jpg";
string savePath = "downloaded_image.jpg";
static void Main(string[] args)
{
string username = "your-username";
string password = "your-password";
HttpClientHandler handler = new HttpClientHandler { Credentials = new NetworkCredential(username, password) };
_client = new HttpClient(handler, disposeHandler: true);
_timer = new Timer(async _ => await RetrieveImageAsync(), null, 0, 1000);
Console.WriteLine("Press any key to exit...");
Console.ReadKey();
_timer.Dispose();
_client.Dispose();
}
private static async Task RetrieveImageAsync()
{
try
{
HttpResponseMessage response = await _client.GetAsync(_cameraUrl);
response.EnsureSuccessStatusCode();
byte[] imageBytes = await response.Content.ReadAsByteArrayAsync();
await File.WriteAllBytesAsync(_savePath, imageBytes);
Console.WriteLine("Image downloaded successfully.");
}
catch (Exception ex)
{
Console.WriteLine($"An error occurred: {ex.Message}");
}
}
}
}
By this stage I was an elite “prompt engineer” and after a couple of revisions of my Github Copilot prompt to released unmanaged resources (the initial version used .Dispose and was a bit ugly).
modify the code to dispose of the HttpClientHandler, HttpClient and Timer with “using” statements
The application had a reentrancy issue when retrieving an image from a camera took too long
modify the code to stop RetrieveImageAsync getting called while an image is already being retrieved
I then decided to try a “cosmetic” change
modify the code _timer does not have to be class level variable
The savePath was a constant and I wanted to store a series of images
modify the code to use String.Format to generate the savepath
For the final version I modified the program adding a Console.Writeline to display the build type, retrieving the SavePath, dueTime, and period from the appsettings.json. The Microsoft.Configuration.UserSecrets configuration source was used for the CameraUrl, UserName, and Password.
using System.Net;
using Microsoft.Extensions.Configuration;
namespace SecurityCameraClient
{
internal class Program
{
private static HttpClient _client;
private static bool _isRetrievingImage = false;
private static ApplicationSettings _applicationSettings;
static void Main(string[] args)
{
Console.WriteLine($"{DateTime.UtcNow:yy-MM-dd HH:mm:ss} SecurityCameraClient starting");
#if RELEASE
Console.WriteLine("RELEASE");
#else
Console.WriteLine("DEBUG");
#endif
var configuration = new ConfigurationBuilder()
.AddJsonFile("appsettings.json", false, true)
.AddUserSecrets<Program>()
.Build();
_applicationSettings = configuration.GetSection("ApplicationSettings").Get<ApplicationSettings>();
using (HttpClientHandler handler = new HttpClientHandler { Credentials = new NetworkCredential(_applicationSettings.Username, _applicationSettings.Password) })
using (_client = new HttpClient(handler))
using (var timer = new Timer(async _ => await RetrieveImageAsync(), null, _applicationSettings.TimerDue, _applicationSettings.TimerPeriod))
{
Console.WriteLine("Press any key to exit...");
Console.ReadKey();
}
}
private static async Task RetrieveImageAsync()
{
if (_isRetrievingImage) return;
_isRetrievingImage = true;
try
{
HttpResponseMessage response = await _client.GetAsync(_applicationSettings.CameraUrl);
response.EnsureSuccessStatusCode();
byte[] imageBytes = await response.Content.ReadAsByteArrayAsync();
string savePath = string.Format(_applicationSettings.SavePath, DateTime.UtcNow);
await File.WriteAllBytesAsync(savePath, imageBytes);
Console.WriteLine("Image downloaded successfully.");
}
catch (Exception ex)
{
Console.WriteLine($"An error occurred: {ex.Message}");
}
finally
{
_isRetrievingImage = false;
}
}
}
public class ApplicationSettings
{
public string CameraUrl { get; set; } = "";
public string SavePath { get; set; } = "";
public string Username { get; set; } = "";
public string Password { get; set; } = "";
public TimeSpan TimerDue { get; set; } = TimeSpan.Zero;
public TimeSpan TimerPeriod { get; set; } = TimeSpan.Zero;
}
}
Overall, my Github Copilot experience was pretty good, and got better as my “prompt engineering” improved.
The Github Copilot “decision” to implement Hypertext Transfer Protocol (HTTP/1.1): Authentication (RFC7235) and Digest Authentication(RFC2617) was “sub optimal”
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