From 94a153c3853315085bfbd2fe2cc6887b5d8ff18b Mon Sep 17 00:00:00 2001
From: itsokto <picnet9@gmail.com>
Date: Sat, 23 May 2020 02:30:31 +0300
Subject: [PATCH] =?UTF-8?q?AuthorizationFormHtmlParser:=20=D1=83=D0=BB?=
 =?UTF-8?q?=D1=83=D1=87=D1=88=D0=B8=D1=82=D1=8C=20=D0=BE=D0=B1=D1=80=D0=B0?=
 =?UTF-8?q?=D0=B1=D0=BE=D1=82=D0=BA=D1=83=20=D0=BE=D1=88=D0=B8=D0=B1=D0=BE?=
 =?UTF-8?q?=D0=BA?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

#625
---
 .../AuthorizationFormHtmlParser.cs            | 11 +++++
 VkNet/Model/VkAuthError.cs                    | 42 +++++++++++++++++++
 VkNet/Utils/Utilities.cs                      | 21 ++++++++++
 3 files changed, 74 insertions(+)
 create mode 100644 VkNet/Model/VkAuthError.cs

diff --git a/VkNet/Infrastructure/Authorization/ImplicitFlow/AuthorizationFormHtmlParser.cs b/VkNet/Infrastructure/Authorization/ImplicitFlow/AuthorizationFormHtmlParser.cs
index 1dbd9d00b..64456a493 100644
--- a/VkNet/Infrastructure/Authorization/ImplicitFlow/AuthorizationFormHtmlParser.cs
+++ b/VkNet/Infrastructure/Authorization/ImplicitFlow/AuthorizationFormHtmlParser.cs
@@ -6,6 +6,7 @@
 using JetBrains.Annotations;
 using VkNet.Abstractions.Utils;
 using VkNet.Exception;
+using VkNet.Model;
 using VkNet.Utils;
 
 namespace VkNet.Infrastructure.Authorization.ImplicitFlow
@@ -30,6 +31,16 @@ public async Task<VkHtmlFormResult> GetFormAsync(Uri url)
 		{
 			var response = await _restClient.PostAsync(url, Enumerable.Empty<KeyValuePair<string, string>>());
 
+			if (!response.IsSuccess)
+			{
+				throw new VkAuthorizationException(response.Message);
+			}
+
+			if (Utilities.TryDeserializeObject<VkAuthError>(response.Value, out var authError))
+			{
+				throw new VkAuthorizationException(authError.ErrorDescription);
+			}
+
 			var doc = new HtmlDocument();
 			doc.LoadHtml(response.Value);
 			var formNode = GetFormNode(doc);
diff --git a/VkNet/Model/VkAuthError.cs b/VkNet/Model/VkAuthError.cs
new file mode 100644
index 000000000..49b244b53
--- /dev/null
+++ b/VkNet/Model/VkAuthError.cs
@@ -0,0 +1,42 @@
+using System;
+using Newtonsoft.Json;
+
+namespace VkNet.Model
+{
+	/// <summary>
+	/// Authorization error.
+	/// </summary>
+	[Serializable]
+	public class VkAuthError
+	{
+		/// <summary>
+		/// Error.
+		/// </summary>
+		[JsonProperty("error")]
+		public string Error { get; set; }
+
+		/// <summary>
+		/// Error type.
+		/// </summary>
+		[JsonProperty("error_type")]
+		public string ErrorType { get; set; }
+
+		/// <summary>
+		/// Error description.
+		/// </summary>
+		[JsonProperty("error_description")]
+		public string ErrorDescription { get; set; }
+
+		/// <summary>
+		/// Captcha id.
+		/// </summary>
+		[JsonProperty("captcha_sid")]
+		public ulong? CaptchaSid { get; set; }
+
+		/// <summary>
+		/// Captcha image Uri.
+		/// </summary>
+		[JsonProperty("captcha_img")]
+		public Uri CaptchaImg { get; set; }
+	}
+}
\ No newline at end of file
diff --git a/VkNet/Utils/Utilities.cs b/VkNet/Utils/Utilities.cs
index 8155f4463..dda2f2d0d 100644
--- a/VkNet/Utils/Utilities.cs
+++ b/VkNet/Utils/Utilities.cs
@@ -118,5 +118,26 @@ public static string SerializeToJson<T>(T @object)
 
 			return result == "null" ? null : result;
 		}
+
+		/// <summary>
+		/// Deserializes JSON for the specified .NET type. A return value indicates whether deserialization succeeded.
+		/// </summary>
+		/// <param name="json"> The JSON to deserialize. </param>
+		/// <param name="result"> Deserialized object. </param>
+		/// <typeparam name="T"> Type for deserialization. </typeparam>
+		/// <returns></returns>
+		public static bool TryDeserializeObject<T>(string json, out T result)
+		{
+			try
+			{
+				result = JsonConvert.DeserializeObject<T>(json);
+				return true;
+			}
+			catch
+			{
+				result = default;
+				return false;
+			}
+		}
 	}
 }
\ No newline at end of file