小心 HttpClient 中 FormUrlEncodeContent 的 bug

Intro

最近发现活动室预约项目里的上传图片有时候会有问题，周末找时间测试了一下，发现小图片的上传没问题，大图片上传会有问题，而且异常信息还很奇怪，System.UriFormatException: Invalid URI: The Uri string is too long 看这个错误的信息还以为是请求的 url 过长导致的，但是实际请求的 url 很短，诡异的异常信息

测试示例

为了方便大家了解和测试这个bug，我在 Github 上提供了一个示例 https://github.com/WeihanLi/SamplesInPractice/blob/master/HttpClientTest/FormUrlEncodeContentTest.cs

HttpClient 示例代码：

public class FormUrlEncodeContentTest
{
    private const string TestUrl = "https://cnblogs.com";

    public static async Task FormUrlEncodedContentLengthTest()
    {
        using (var httpClient = new HttpClient(new NoProxyHttpClientHandler()))
        {
            using (var response = await httpClient.PostAsync(TestUrl, new FormUrlEncodedContent(new Dictionary<string, string>()
            {
                {"bigContent", new string('a', 65535)},
            })))
            {
                Console.WriteLine($"response status code:{response.StatusCode}");
            }
        }
    }

    public static async Task ByteArrayContentLengthTest()
    {
        using (var httpClient = new HttpClient(new NoProxyHttpClientHandler()))
        {
            var postContent = $"bigContent={new string('a', 65535)}";
            using (var response = await httpClient.PostAsync(TestUrl, new ByteArrayContent(postContent.GetBytes())))
            {
                Console.WriteLine($"response status code:{response.StatusCode}");
            }
        }
    }

    public static async Task StringContentLengthTest()
    {
        using (var httpClient = new HttpClient(new NoProxyHttpClientHandler()))
        {
            var postContent = $"bigContent={new string('a', 65535)}";
            using (var response = await httpClient.PostAsync(TestUrl, new StringContent(postContent)))
            {
                Console.WriteLine($"response status code:{response.StatusCode}");
            }
        }
    }
}

测试代码：

InvokeHelper.OnInvokeException = Console.WriteLine;

await InvokeHelper.TryInvokeAsync(FormUrlEncodeContentTest.FormUrlEncodedContentLengthTest);
Console.WriteLine();
await InvokeHelper.TryInvokeAsync(FormUrlEncodeContentTest.StringContentLengthTest);
Console.WriteLine();
await InvokeHelper.TryInvokeAsync(FormUrlEncodeContentTest.ByteArrayContentLengthTest);

Console.WriteLine("Completed!");

输出结果如下：