Missing files + start working on offline patcher

SafeExamBrowser.Server/Requests/Request.cs

@@ -0,0 +1,216 @@
+/*
+ * Copyright (c) 2025 ETH Zürich, IT Services
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+using System;
+using System.Collections.Generic;
+using System.Net;
+using System.Net.Http;
+using System.Net.Http.Headers;
+using System.Text;
+using System.Threading.Tasks;
+using SafeExamBrowser.Logging.Contracts;
+using SafeExamBrowser.Server.Data;
+using SafeExamBrowser.Settings.Server;
+
+namespace SafeExamBrowser.Server.Requests
+{
+	internal abstract class Request
+	{
+		private static string connectionToken;
+		private static string oauth2Token;
+
+		private readonly HttpClient httpClient;
+
+		private bool hadException;
+
+		protected readonly Api api;
+		protected readonly ILogger logger;
+		protected readonly Parser parser;
+		protected readonly ServerSettings settings;
+
+		protected (string, string) Authorization => (Header.AUTHORIZATION, $"Bearer {oauth2Token}");
+		protected (string, string) Token => (Header.CONNECTION_TOKEN, connectionToken);
+
+		internal static string ConnectionToken
+		{
+			get { return connectionToken; }
+			set { connectionToken = value; }
+		}
+
+		internal static string Oauth2Token
+		{
+			get { return oauth2Token; }
+			set { oauth2Token = value; }
+		}
+
+		protected Request(Api api, HttpClient httpClient, ILogger logger, Parser parser, ServerSettings settings)
+		{
+			this.api = api;
+			this.httpClient = httpClient;
+			this.logger = logger;
+			this.parser = parser;
+			this.settings = settings;
+		}
+
+		protected bool TryExecute(
+			HttpMethod method,
+			string url,
+			out HttpResponseMessage response,
+			string content = default,
+			string contentType = default,
+			params (string name, string value)[] headers)
+		{
+			response = default;
+
+			for (var attempt = 0; attempt < settings.RequestAttempts && (response == default || !response.IsSuccessStatusCode); attempt++)
+			{
+				var request = BuildRequest(method, url, content, contentType, headers);
+
+				try
+				{
+					response = httpClient.SendAsync(request).GetAwaiter().GetResult();
+
+					if (PerformLoggingFor(request))
+					{
+						logger.Debug($"Completed request: {request.Method} '{request.RequestUri}' -> {response.ToLogString()}");
+					}
+
+					if (response.StatusCode == HttpStatusCode.Unauthorized && parser.IsTokenExpired(response.Content))
+					{
+						logger.Info("OAuth2 token has expired, attempting to retrieve new one...");
+
+						if (TryRetrieveOAuth2Token(out var message))
+						{
+							headers = UpdateOAuth2Token(headers);
+						}
+					}
+				}
+				catch (TaskCanceledException)
+				{
+					if (PerformLoggingFor(request))
+					{
+						logger.Warn($"Request {request.Method} '{request.RequestUri}' did not complete within {settings.RequestTimeout}ms!");
+					}
+
+					break;
+				}
+				catch (Exception e)
+				{
+					if (PerformLoggingFor(request) && IsFirstException())
+					{
+						logger.Warn($"Request {request.Method} '{request.RequestUri}' has failed: {e.ToSummary()}!");
+					}
+				}
+			}
+
+			return response != default && response.IsSuccessStatusCode;
+		}
+
+		protected bool TryRetrieveConnectionToken(HttpResponseMessage response)
+		{
+			var success = parser.TryParseConnectionToken(response, out connectionToken);
+
+			if (success)
+			{
+				logger.Info("Successfully retrieved connection token.");
+			}
+			else
+			{
+				logger.Error("Failed to retrieve connection token!");
+			}
+
+			return success;
+		}
+
+		protected bool TryRetrieveOAuth2Token(out string message)
+		{
+			var secret = Convert.ToBase64String(Encoding.UTF8.GetBytes($"{settings.ClientName}:{settings.ClientSecret}"));
+			var authorization = (Header.AUTHORIZATION, $"Basic {secret}");
+			var content = "grant_type=client_credentials&scope=read write";
+			var success = TryExecute(HttpMethod.Post, api.AccessTokenEndpoint, out var response, content, ContentType.URL_ENCODED, authorization);
+
+			message = response.ToLogString();
+
+			if (success && parser.TryParseOauth2Token(response.Content, out oauth2Token))
+			{
+				logger.Info("Successfully retrieved OAuth2 token.");
+			}
+			else
+			{
+				logger.Error("Failed to retrieve OAuth2 token!");
+			}
+
+			return success;
+		}
+
+		private HttpRequestMessage BuildRequest(
+			HttpMethod method,
+			string url,
+			string content = default,
+			string contentType = default,
+			params (string name, string value)[] headers)
+		{
+			var request = new HttpRequestMessage(method, url);
+
+			if (content != default)
+			{
+				request.Content = new StringContent(content, Encoding.UTF8);
+
+				if (contentType != default)
+				{
+					request.Content.Headers.ContentType = MediaTypeHeaderValue.Parse(contentType);
+				}
+			}
+
+			request.Headers.Add(Header.ACCEPT, "application/json, */*");
+
+			foreach (var (name, value) in headers)
+			{
+				request.Headers.Add(name, value);
+			}
+
+			return request;
+		}
+
+		private bool IsFirstException()
+		{
+			var isFirst = !hadException;
+
+			hadException = true;
+
+			return isFirst;
+		}
+
+		private bool PerformLoggingFor(HttpRequestMessage request)
+		{
+			var path = request.RequestUri.AbsolutePath.TrimStart('/');
+			var perform = path != api.LogEndpoint && path != api.PingEndpoint;
+
+			return perform;
+		}
+
+		private (string name, string value)[] UpdateOAuth2Token((string name, string value)[] headers)
+		{
+			var result = new List<(string name, string value)>();
+
+			foreach (var header in headers)
+			{
+				if (header.name == Header.AUTHORIZATION)
+				{
+					result.Add((Header.AUTHORIZATION, $"Bearer {oauth2Token}"));
+				}
+				else
+				{
+					result.Add(header);
+				}
+			}
+
+			return result.ToArray();
+		}
+	}
+}