Endpoint/Configuration/Model/Admin.cs

@@ -1,5 +1,6 @@
 using Mirea.Api.Endpoint.Common.Services;
 using Mirea.Api.Security.Common.Domain;
+using System.Collections.Generic;
 using System.IO;
 using System.Text.Json;
 using System.Text.Json.Serialization;
@@ -20,6 +21,8 @@ public class Admin : ISaveSettings
     public TwoFactorAuthenticator TwoFactorAuthenticator { get; set; } = TwoFactorAuthenticator.None;
     public string? Secret { get; set; }
 
+    public Dictionary<OAuthProvider, OAuthUser>? OAuthProviders { get; set; }
+
     public void SaveSetting()
     {
         File.WriteAllText(FilePath, JsonSerializer.Serialize(this));

Endpoint/Controllers/V1/AuthController.cs

@@ -13,6 +13,7 @@ using Mirea.Api.Endpoint.Configuration.Model;
 using Mirea.Api.Security.Common.Domain;
 using Mirea.Api.Security.Services;
 using System;
+using System.Collections.Generic;
 using System.Threading.Tasks;
 
 namespace Mirea.Api.Endpoint.Controllers.V1;
@@ -47,7 +48,8 @@ public class AuthController(IOptionsSnapshot<Admin> user, AuthService auth, Pass
                 PasswordHash = userEntity.PasswordHash,
                 Salt = userEntity.Salt,
                 TwoFactorAuthenticator = userEntity.TwoFactorAuthenticator,
-                SecondFactorToken = userEntity.Secret
+                SecondFactorToken = userEntity.Secret,
+                OAuthProviders = userEntity.OAuthProviders
             },
             HttpContext, request.Password);
 

Security/Common/Domain/OAuth2/OAuthProviderUrisData.cs

@@ -0,0 +1,13 @@
+using System;
+
+namespace Mirea.Api.Security.Common.Domain.OAuth2;
+
+internal struct OAuthProviderUrisData
+{
+    public string RedirectUrl { get; init; }
+    public string TokenUrl { get; init; }
+    public string UserInfoUrl { get; init; }
+    public string AuthHeader { get; init; }
+    public string Scope { get; init; }
+    public Type UserInfoType { get; init; }
+}

Security/Common/Domain/OAuth2/OAuthTokenResponse.cs

@@ -0,0 +1,12 @@
+using System.Text.Json.Serialization;
+
+namespace Mirea.Api.Security.Common.Domain.OAuth2;
+
+public class OAuthTokenResponse
+{
+    [JsonPropertyName("access_token")]
+    public required string AccessToken { get; set; }
+
+    [JsonPropertyName("expires_in")]
+    public int ExpiresIn { get; set; }
+}

Security/Common/Domain/OAuth2/UserInfo/GoogleUserInfo.cs

@@ -0,0 +1,38 @@
+using Mirea.Api.Security.Common.Interfaces;
+using System.Text.Json.Serialization;
+
+namespace Mirea.Api.Security.Common.Domain.OAuth2.UserInfo;
+
+internal class GoogleUserInfo : IUserInfo
+{
+    [JsonPropertyName("id")]
+    public required string Id { get; set; }
+
+    [JsonPropertyName("email")]
+    public required string Email { get; set; }
+
+    [JsonPropertyName("given_name")]
+    public required string GivenName { get; set; }
+
+    [JsonPropertyName("family_name")]
+    public required string FamilyName { get; set; }
+
+    [JsonPropertyName("name")]
+    public required string Name { get; set; }
+
+    [JsonPropertyName("picture")]
+    public required string Picture { get; set; }
+
+    [JsonPropertyName("verified_email")]
+    public bool? VerifiedEmail { get; set; }
+
+    public OAuthUser MapToInternalUser() =>
+        new()
+        {
+            Id = Id,
+            Email = VerifiedEmail.HasValue && VerifiedEmail.Value ? Email : null,
+            FirstName = GivenName,
+            LastName = FamilyName,
+            IconUri = Picture
+        };
+}

Security/Common/Domain/OAuth2/UserInfo/MailRuUserInfo.cs

@@ -0,0 +1,36 @@
+using Mirea.Api.Security.Common.Interfaces;
+using System.Text.Json.Serialization;
+
+namespace Mirea.Api.Security.Common.Domain.OAuth2.UserInfo;
+
+internal class MailRuUserInfo : IUserInfo
+{
+    [JsonPropertyName("id")]
+    public required string Id { get; set; }
+
+    [JsonPropertyName("email")]
+    public required string Email { get; set; }
+
+    [JsonPropertyName("first_name")]
+    public required string FirstName { get; set; }
+
+    [JsonPropertyName("last_name")]
+    public required string LastName { get; set; }
+
+    [JsonPropertyName("nickname")]
+    public required string Username { get; set; }
+
+    [JsonPropertyName("image")]
+    public string? Image { get; set; }
+
+    public OAuthUser MapToInternalUser() =>
+        new()
+        {
+            Id = Id,
+            Email = Email,
+            FirstName = FirstName,
+            LastName = LastName,
+            Username = Username,
+            IconUri = Image
+        };
+}

Security/Common/Domain/OAuth2/UserInfo/YandexUserInfo.cs

@@ -0,0 +1,41 @@
+using Mirea.Api.Security.Common.Interfaces;
+using System.Text.Json.Serialization;
+
+namespace Mirea.Api.Security.Common.Domain.OAuth2.UserInfo;
+
+internal class YandexUserInfo : IUserInfo
+{
+    [JsonPropertyName("id")]
+    public required string Id { get; set; }
+
+    [JsonPropertyName("login")]
+    public required string Login { get; set; }
+
+    [JsonPropertyName("default_email")]
+    public required string DefaultEmail { get; set; }
+
+    [JsonPropertyName("first_name")]
+    public string? FirstName { get; set; }
+
+    [JsonPropertyName("last_name")]
+    public string? LastName { get; set; }
+
+
+    [JsonPropertyName("is_avatar_empty")]
+    public bool IsAvatarEmpty { get; set; }
+
+    [JsonPropertyName("default_avatar_id")]
+    public string? DefaultAvatarId { get; set; }
+
+    public OAuthUser MapToInternalUser() =>
+        new()
+        {
+            Id = Id,
+            Email = DefaultEmail,
+            FirstName = FirstName,
+            LastName = LastName,
+            IconUri =
+                IsAvatarEmpty ? null : $"https://avatars.yandex.net/get-yapic/{DefaultAvatarId}/islands-retina-50",
+            Username = Login
+        };
+}

Security/Common/Domain/OAuthProvider.cs

@@ -0,0 +1,8 @@
+namespace Mirea.Api.Security.Common.Domain;
+
+public enum OAuthProvider
+{
+    Google,
+    Yandex,
+    MailRu
+}

Security/Common/Domain/OAuthUser.cs

@@ -0,0 +1,11 @@
+namespace Mirea.Api.Security.Common.Domain;
+
+public class OAuthUser
+{
+    public required string Id { get; set; }
+    public string? Username { get; set; }
+    public string? Email { get; set; }
+    public string? FirstName { get; set; }
+    public string? LastName { get; set; }
+    public string? IconUri { get; set; }
+}

Security/Common/Domain/User.cs

@@ -1,4 +1,6 @@
-namespace Mirea.Api.Security.Common.Domain;
+using System.Collections.Generic;
+
+namespace Mirea.Api.Security.Common.Domain;
 
 public class User
 {
@@ -9,4 +11,5 @@ public class User
     public required string Salt { get; set; }
     public required TwoFactorAuthenticator TwoFactorAuthenticator { get; set; }
     public string? SecondFactorToken { get; set; }
+    public Dictionary<OAuthProvider, OAuthUser>? OAuthProviders { get; set; }
 }

Security/Common/Interfaces/IUserInfo.cs

@@ -0,0 +1,8 @@
+using Mirea.Api.Security.Common.Domain;
+
+namespace Mirea.Api.Security.Common.Interfaces;
+
+internal interface IUserInfo
+{
+    OAuthUser MapToInternalUser();
+}

Security/DependencyInjection.cs

@@ -1,9 +1,11 @@
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
+using Mirea.Api.Security.Common.Domain;
 using Mirea.Api.Security.Common.Interfaces;
 using Mirea.Api.Security.Services;
 using System;
+using System.Collections.Generic;
 
 namespace Mirea.Api.Security;
 
@@ -45,6 +47,22 @@ public static class DependencyInjection
             };
         });
 
+        var providers = new Dictionary<OAuthProvider, (string ClientId, string Secret)>();
+
+        foreach (var provider in Enum.GetValues<OAuthProvider>())
+        {
+            var providerName = Enum.GetName(provider)!.ToUpper();
+            var clientId = configuration[$"{providerName}_CLIENT_ID"];
+            var secret = configuration[$"{providerName}_CLIENT_SECRET"];
+
+            if (string.IsNullOrEmpty(clientId) || string.IsNullOrEmpty(secret))
+                continue;
+
+            providers.Add(provider, (clientId, secret));
+        }
+
+        services.AddSingleton(provider => new OAuthService(provider.GetRequiredService<ILogger<OAuthService>>(), providers));
+
         return services;
     }
 }

Security/Services/AuthService.cs

@@ -23,7 +23,7 @@ public class AuthService(ICacheService cache, IAccessToken accessTokenService, I
         accessTokenService.GenerateToken(userId);
 
     private static string GetAuthCacheKey(string fingerprint) => $"{fingerprint}_auth_token";
-    internal static string GetFirstAuthCacheKey(string fingerprint) => $"{fingerprint}_auth_token_first";
+    private static string GetFirstAuthCacheKey(string fingerprint) => $"{fingerprint}_auth_token_first";
 
     private Task SetAuthTokenDataToCache(AuthToken data, CancellationToken cancellation) =>
         cache.SetAsync(
@@ -32,6 +32,18 @@ public class AuthService(ICacheService cache, IAccessToken accessTokenService, I
             slidingExpiration: Lifetime,
             cancellationToken: cancellation);
 
+    private Task CreateFirstAuthTokenToCache(User data, RequestContextInfo requestContext, CancellationToken cancellation) =>
+        cache.SetAsync(
+            GetFirstAuthCacheKey(requestContext.Fingerprint),
+            JsonSerializer.SerializeToUtf8Bytes(new FirstAuthToken(requestContext)
+            {
+                UserId = data.Id,
+                Secret = data.SecondFactorToken,
+                TwoFactorAuthenticator = data.TwoFactorAuthenticator
+            }),
+            slidingExpiration: LifetimeFirstAuth,
+            cancellationToken: cancellation);
+
     private Task RevokeAccessToken(string token) =>
         revokedToken.AddTokenToRevokedAsync(token, accessTokenService.GetExpireDateTime(token));
 
@@ -94,6 +106,21 @@ public class AuthService(ICacheService cache, IAccessToken accessTokenService, I
             authToken.Fingerprint);
     }
 
+    public async Task<TwoFactorAuthenticator> LoginOAuthAsync(CookieOptionsParameters cookieOptions, HttpContext context, User user, OAuthProvider provider, CancellationToken cancellation = default)
+    {
+        var requestContext = new RequestContextInfo(context, cookieOptions);
+
+        if (user.TwoFactorAuthenticator == TwoFactorAuthenticator.None)
+        {
+            await GenerateAuthTokensAsync(cookieOptions, context, requestContext, user.Id, cancellation);
+            return TwoFactorAuthenticator.None;
+        }
+
+        await CreateFirstAuthTokenToCache(user, requestContext, cancellation);
+
+        return user.TwoFactorAuthenticator;
+    }
+
     public async Task<bool> LoginAsync(CookieOptionsParameters cookieOptions, HttpContext context, TwoFactorAuthenticator authenticator, string code, CancellationToken cancellation = default)
     {
         var requestContext = new RequestContextInfo(context, cookieOptions);
@@ -116,8 +143,6 @@ public class AuthService(ICacheService cache, IAccessToken accessTokenService, I
                         throw new SecurityException("Invalid verification code. Please try again.");
                 }
                 break;
-            case TwoFactorAuthenticator.None:
-                break;
             default:
                 throw new InvalidOperationException("Unsupported authorization method.");
         }
@@ -138,14 +163,7 @@ public class AuthService(ICacheService cache, IAccessToken accessTokenService, I
             return TwoFactorAuthenticator.None;
         }
 
-        var firstAuthToken = new FirstAuthToken(requestContext)
-        {
-            UserId = user.Id,
-            Secret = user.SecondFactorToken,
-            TwoFactorAuthenticator = user.TwoFactorAuthenticator
-        };
-
-        await cache.SetAsync(GetFirstAuthCacheKey(requestContext.Fingerprint), firstAuthToken, absoluteExpirationRelativeToNow: LifetimeFirstAuth, cancellationToken: cancellation);
+        await CreateFirstAuthTokenToCache(user, requestContext, cancellation);
 
         return user.TwoFactorAuthenticator;
     }

Security/Services/OAuthService.cs

@@ -0,0 +1,166 @@
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Logging;
+using Mirea.Api.Security.Common.Domain;
+using Mirea.Api.Security.Common.Domain.OAuth2;
+using Mirea.Api.Security.Common.Domain.OAuth2.UserInfo;
+using Mirea.Api.Security.Common.Interfaces;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net.Http;
+using System.Net.Http.Headers;
+using System.Security;
+using System.Text.Json;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Mirea.Api.Security.Services;
+
+public class OAuthService(ILogger<OAuthService> logger, Dictionary<OAuthProvider, (string ClientId, string Secret)> providers)
+{
+    private static readonly Dictionary<OAuthProvider, OAuthProviderUrisData> ProviderData = new()
+    {
+        [OAuthProvider.Google] = new OAuthProviderUrisData
+        {
+            RedirectUrl = "https://accounts.google.com/o/oauth2/v2/auth",
+            TokenUrl = "https://oauth2.googleapis.com/token",
+            UserInfoUrl = "https://www.googleapis.com/oauth2/v2/userinfo",
+            Scope = "openid email profile",
+            AuthHeader = "Bearer",
+            UserInfoType = typeof(GoogleUserInfo)
+        },
+        [OAuthProvider.Yandex] = new OAuthProviderUrisData
+        {
+            RedirectUrl = "https://oauth.yandex.ru/authorize",
+            TokenUrl = "https://oauth.yandex.ru/token",
+            UserInfoUrl = "https://login.yandex.ru/info?format=json",
+            Scope = "login:email login:info login:avatar",
+            AuthHeader = "OAuth",
+            UserInfoType = typeof(YandexUserInfo)
+        },
+        [OAuthProvider.MailRu] = new OAuthProviderUrisData
+        {
+            RedirectUrl = "https://oauth.mail.ru/login",
+            TokenUrl = "https://oauth.mail.ru/token",
+            UserInfoUrl = "https://oauth.mail.ru/userinfo",
+            AuthHeader = "",
+            Scope = "",
+            UserInfoType = typeof(MailRuUserInfo)
+        }
+    };
+
+    private static async Task<OAuthTokenResponse?> ExchangeCodeForTokensAsync(string requestUri, string redirectUrl, string code, string clientId, string secret, CancellationToken cancellation)
+    {
+        var tokenRequest = new HttpRequestMessage(HttpMethod.Post, requestUri)
+        {
+            Content = new FormUrlEncodedContent(new Dictionary<string, string>
+            {
+                { "code", code },
+                { "client_id", clientId },
+                { "client_secret", secret },
+                { "redirect_uri", redirectUrl},
+                { "grant_type", "authorization_code" }
+            })
+        };
+
+        using var httpClient = new HttpClient();
+        httpClient.DefaultRequestHeaders.UserAgent.ParseAdd("MireaSchedule/1.0 (Winsomnia)");
+
+        var response = await httpClient.SendAsync(tokenRequest, cancellation);
+        var data = await response.Content.ReadAsStringAsync(cancellation);
+
+        if (!response.IsSuccessStatusCode)
+            throw new HttpRequestException(data);
+
+        return JsonSerializer.Deserialize<OAuthTokenResponse>(data);
+    }
+
+    private static async Task<OAuthUser?> GetUserProfileAsync(string requestUri, string authHeader, string accessToken, OAuthProvider provider, CancellationToken cancellation)
+    {
+        var request = new HttpRequestMessage(HttpMethod.Get, requestUri);
+
+        if (string.IsNullOrEmpty(authHeader))
+            request.RequestUri = new Uri(request.RequestUri?.AbsoluteUri + "?access_token=" + accessToken);
+        else
+            request.Headers.Authorization = new AuthenticationHeaderValue(authHeader, accessToken);
+
+        using var httpClient = new HttpClient();
+        httpClient.DefaultRequestHeaders.UserAgent.ParseAdd("MireaSchedule/1.0 (Winsomnia)");
+
+        var response = await httpClient.SendAsync(request, cancellation);
+        var data = await response.Content.ReadAsStringAsync(cancellation);
+
+        if (!response.IsSuccessStatusCode)
+            throw new HttpRequestException(data);
+
+        var userInfo = JsonSerializer.Deserialize(data, ProviderData[provider].UserInfoType) as IUserInfo;
+        return userInfo?.MapToInternalUser();
+    }
+
+    public (OAuthProvider Provider, Uri Redirect)[] GetAvailableProviders(HttpContext context, CookieOptionsParameters cookieOptions, string redirectUrl)
+    {
+        var redirectUri = "?client_id={0}" +
+                                "&response_type=code" +
+                                $"&redirect_uri={redirectUrl}" +
+                                "&scope={1}" +
+                                $"&state={new RequestContextInfo(context, cookieOptions).Fingerprint}_{{2}}";
+
+        return providers.Select(x => (x.Key, new Uri(ProviderData[x.Key].RedirectUrl.TrimEnd('/') +
+                                                     string.Format(redirectUri,
+                                                         x.Value.ClientId,
+                                                         ProviderData[x.Key].Scope,
+                                                         Enum.GetName(x.Key))))
+        ).ToArray();
+    }
+
+    public async Task<(OAuthProvider provider, OAuthUser User)> LoginOAuth(HttpContext context, CookieOptionsParameters cookieOptions, string redirectUrl, string code, string state, CancellationToken cancellation = default)
+    {
+        var requestContext = new RequestContextInfo(context, cookieOptions);
+
+        var partsState = state.Split('_');
+
+        if (!Enum.TryParse<OAuthProvider>(partsState.Last(), true, out var provider) ||
+            !providers.TryGetValue(provider, out var providerInfo) ||
+            !ProviderData.TryGetValue(provider, out var currentProviderStruct))
+        {
+            logger.LogWarning("Failed to parse OAuth provider from state: {State}", state);
+            throw new InvalidOperationException("Invalid authorization request.");
+        }
+
+        var fingerprint = string.Join("_", partsState.SkipLast(1));
+
+        if (requestContext.Fingerprint != fingerprint)
+        {
+            logger.LogWarning("Fingerprint mismatch. Possible CSRF attack detected.");
+            throw new SecurityException("Suspicious activity detected. Please try again.");
+        }
+
+        OAuthTokenResponse? accessToken = null;
+        try
+        {
+            accessToken = await ExchangeCodeForTokensAsync(currentProviderStruct.TokenUrl, redirectUrl, code, providerInfo.ClientId, providerInfo.Secret, cancellation);
+        }
+        catch (Exception ex)
+        {
+            logger.LogWarning(ex, "Failed to exchange authorization code for tokens with provider {Provider}", provider);
+        }
+
+        if (accessToken == null)
+            throw new SecurityException("Unable to complete authorization with the provider. Please try again later.");
+
+        OAuthUser? result = null;
+        try
+        {
+            result = await GetUserProfileAsync(currentProviderStruct.UserInfoUrl, currentProviderStruct.AuthHeader, accessToken.AccessToken, provider, cancellation);
+        }
+        catch (Exception ex)
+        {
+            logger.LogWarning(ex, "Failed to retrieve user information from provider {Provider}", provider);
+        }
+
+        if (result == null)
+            throw new SecurityException("Unable to retrieve user information. Please check the details and try again.");
+
+        return (provider, result);
+    }
+}