[dotnet] Parse response before deserialization (SeleniumHQ#15268)

* [dotnet] Parse response before deserialization

* Handle if `value.sessionId` is `null`

* null check instead

Author: RenderMichael

dotnet/src/webdriver/Response.cs

@@ -19,27 +19,21 @@
 
 using OpenQA.Selenium.Internal;
 using System;
-using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.Text.Json;
+using System.Text.Json.Nodes;
 using System.Text.Json.Serialization;
 
 #nullable enable
 
 namespace OpenQA.Selenium
 {
     /// <summary>
-    /// Handles reponses from the browser
+    /// Handles responses from the browser
     /// </summary>
     public class Response
     {
-        private static readonly JsonSerializerOptions s_jsonSerializerOptions = new()
-        {
-            TypeInfoResolver = ResponseJsonSerializerContext.Default,
-            Converters = { new ResponseValueJsonConverter() } // we still need it to make `Object` as `Dictionary`
-        };
-
         /// <summary>
         /// Initializes a new instance of the <see cref="Response"/> class
         /// </summary>
@@ -62,18 +56,18 @@ public Response(string? sessionId, object? value, WebDriverResult status)
         /// <exception cref="JsonException">If <paramref name="value"/> is not a valid JSON object.</exception>
         public static Response FromJson(string value)
         {
-            Dictionary<string, object?> rawResponse = JsonSerializer.Deserialize<Dictionary<string, object?>>(value, s_jsonSerializerOptions)
-                ?? throw new WebDriverException("JSON success response returned \"null\" value");
+            JsonObject rawResponse = JsonNode.Parse(value) as JsonObject
+                ?? throw new WebDriverException($"JSON success response did not return a dictionary{Environment.NewLine}{value}");
 
-            object? contents;
+            JsonNode? contents;
             string? sessionId = null;
 
-            if (rawResponse.TryGetValue("sessionId", out object? s) && s is not null)
+            if (rawResponse.TryGetPropertyValue("sessionId", out JsonNode? s) && s is not null)
             {
                 sessionId = s.ToString();
             }
 
-            if (rawResponse.TryGetValue("value", out object? valueObj))
+            if (rawResponse.TryGetPropertyValue("value", out JsonNode? valueObj))
             {
                 contents = valueObj;
             }
@@ -87,7 +81,7 @@ public static Response FromJson(string value)
 
                 // Special-case for the new session command, where the "capabilities"
                 // property of the response is the actual value we're interested in.
-                if (rawResponse.TryGetValue("capabilities", out object? capabilities))
+                if (rawResponse.TryGetPropertyValue("capabilities", out JsonNode? capabilities))
                 {
                     contents = capabilities;
                 }
@@ -97,14 +91,14 @@ public static Response FromJson(string value)
                 }
             }
 
-            if (contents is Dictionary<string, object?> valueDictionary)
+            if (contents is JsonObject valueDictionary)
             {
                 // Special case code for the new session command. If the response contains
                 // sessionId and capabilities properties, fix up the session ID and value members.
-                if (valueDictionary.TryGetValue("sessionId", out object? session))
+                if (valueDictionary.TryGetPropertyValue("sessionId", out JsonNode? session))
                 {
-                    sessionId = session.ToString();
-                    if (valueDictionary.TryGetValue("capabilities", out object? capabilities))
+                    sessionId = session?.ToString();
+                    if (valueDictionary.TryGetPropertyValue("capabilities", out JsonNode? capabilities))
                     {
                         contents = capabilities;
                     }
@@ -115,7 +109,9 @@ public static Response FromJson(string value)
                 }
             }
 
-            return new Response(sessionId, contents, WebDriverResult.Success);
+            var contentsDictionary = JsonSerializer.Deserialize(contents, ResponseJsonSerializerContext.Default.Object);
+
+            return new Response(sessionId, contentsDictionary, WebDriverResult.Success);
         }
 
         /// <summary>
@@ -143,29 +139,30 @@ public static Response FromJson(string value)
         /// <exception cref="WebDriverException">If the JSON dictionary is not in the expected state, per spec.</exception>
         public static Response FromErrorJson(string value)
         {
-            Dictionary<string, object?> deserializedResponse = JsonSerializer.Deserialize<Dictionary<string, object?>>(value, s_jsonSerializerOptions)
-                ?? throw new WebDriverException("JSON error response returned \"null\" value");
+            JsonObject responseObject = JsonNode.Parse(value) as JsonObject
+                ?? throw new WebDriverException($"JSON error response did not return an object{Environment.NewLine}{value}");
 
-            if (!deserializedResponse.TryGetValue("value", out object? valueObject))
+            if (!responseObject.TryGetPropertyValue("value", out JsonNode? valueNode))
             {
-                throw new WebDriverException($"The 'value' property was not found in the response:{Environment.NewLine}{value}");
+                throw new WebDriverException($"The 'value' property was not found in the response{Environment.NewLine}{value}");
             }
 
-            if (valueObject is not Dictionary<string, object?> valueDictionary)
+            if (valueNode is not JsonObject valueObject)
             {
-                throw new WebDriverException($"The 'value' property is not a dictionary of <string, object>{Environment.NewLine}{value}");
+                throw new WebDriverException($"The 'value' property is not a dictionary{Environment.NewLine}{value}");
             }
 
-            if (!valueDictionary.TryGetValue("error", out object? errorObject))
+            if (!valueObject.TryGetPropertyValue("error", out JsonNode? errorObject))
             {
-                throw new WebDriverException($"The 'value > error' property was not found in the response:{Environment.NewLine}{value}");
+                throw new WebDriverException($"The 'value > error' property was not found in the response{Environment.NewLine}{value}");
             }
 
-            if (errorObject is not string errorString)
+            if (errorObject is not JsonValue errorValue || !errorValue.TryGetValue(out string? errorString))
             {
                 throw new WebDriverException($"The 'value > error' property is not a string{Environment.NewLine}{value}");
             }
 
+            var valueDictionary = JsonSerializer.Deserialize(valueObject, ResponseJsonSerializerContext.Default.Object);
             WebDriverResult status = WebDriverError.ResultFromError(errorString);
 
             return new Response(sessionId: null, valueDictionary, status);
@@ -205,6 +202,7 @@ public override string ToString()
         }
     }
 
-    [JsonSerializable(typeof(Dictionary<string, object>))]
+    [JsonSerializable(typeof(object))]
+    [JsonSourceGenerationOptions(Converters = [typeof(ResponseValueJsonConverter)])] // we still need it to make `Object` as `Dictionary`
     internal sealed partial class ResponseJsonSerializerContext : JsonSerializerContext;
 }