RestSharp 107+版本multipart/form-data文件传输失败问题求助

我将RestSharp版本从104升级到108后，其他application/json接口运行正常，但使用multipart/form-data传输文件时服务器无法接收到文件。测试发现104.4.0、106.15.0版本可正常工作，而107.3.0、108.0.3版本无法正常传输文件。以下是不同版本的实现代码、请求捕获信息及Nginx错误日志，请问使用107及以上版本传输文件还需进行哪些额外操作？

版本106.15.0 实现代码 #

var client = new RestClient("https://192.168.0.1/");
client.Timeout = -1;

var request = new RestRequest("file", Method.POST);
request.AlwaysMultipartFormData = true;

request.AddHeader("Authorization", "Auth-Token" + token);
request.AddHeader("Content-Type", "multipart/form-data");
request.AddHeader("Accept", "application/json");
request.AddFile("file", path);

System.Net.ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };

var response = client.Execute(request);
Console.WriteLine(response.Content);

Postman控制台捕获的请求信息 #

POST /file HTTP/1.1
Authorization: Auth-Token ----
Postman-Token: ecff7025-298c-4b29-8b15-ebd0d679aad8
Host: 192.168.0.1
Content-Type: multipart/form-data; boundary=--------------------------077067924352348455764323
Content-Length: 2409
 
----------------------------077067924352348455764323
Content-Disposition: form-data; name="file"; filename="filename.txt"
<filename.txt>
----------------------------077067924352348455764323--

版本107.3.0 实现代码 #

var options = new RestClientOptions("https://192.168.0.1/")
{
        RemoteCertificateValidationCallback = (sender, certificate, chain, sslPolicyErrors) => true,
        ConfigureMessageHandler = handler =>
            new HttpTracerHandler(handler, new ConsoleLogger(), HttpMessageParts.All),
};

var client = new RestClient(options);

var request = new RestRequest("file", Method.Post);
request.AlwaysMultipartFormData = true;

request.AddHeader("Authorization", "Auth-Token" + token);
request.AddHeader("Content-Type", "multipart/form-data");
request.AddHeader("Accept", "application/json");
request.AddFile("file", path);

var response = client.ExecuteAsync(request).Result;
Console.WriteLine(response.Content);

HttpTracer捕获的请求信息 #

==================== HTTP REQUEST: [POST] ====================
POST https://192.168.0.1/file
Authorization: Auth-Token ----
Accept: application/json
User-Agent: RestSharp/0.0.0.0
--94000a34-a3fa-4eeb-b803-52eea1c7cbc9
Content-Type: application/octet-stream
Content-Disposition: form-data; name="file"; filename="filename.txt"

/////////////////////////////////

File contents ...

/////////////////////////////////

--94000a34-a3fa-4eeb-b803-52eea1c7cbc9--

Nginx错误日志 #

upstream timed out (110: Connection timed out) while reading response header from upstream

问题分析与解决步骤 #

从请求捕获信息对比可发现核心差异：

1. 107+版本的请求缺少全局的Content-Type: multipart/form-data; boundary=xxx请求头，手动添加的该头未生效；
2. 文件部分被自动添加了Content-Type: application/octet-stream，可能导致服务器解析异常；
3. 新版本未设置超时，默认超时时间较短，匹配Nginx的超时日志。

对应的解决操作：

• 移除手动添加的Content-Type头：RestSharp 107+会自动生成包含boundary的multipart/form-data请求头，手动添加会干扰框架的自动处理逻辑；
• 添加超时配置：在RestClientOptions中设置无超时或足够长的超时时间，对齐旧版本的Timeout = -1：

  var options = new RestClientOptions("https://192.168.0.1/")
  {
      Timeout = TimeSpan.FromMilliseconds(-1), // 无超时
      // 其他配置...
  };
  

• 指定文件MIME类型：使用AddFile的重载明确设置文件的Content-Type，避免框架默认的application/octet-stream：

  request.AddFile("file", path, "text/plain"); // 根据实际文件类型调整，如image/jpeg等
  

• 避免使用.Result同步阻塞：推荐用await调用异步方法，防止死锁问题：

  var response = await client.ExecuteAsync(request);
  

修改后的示例代码 #

var options = new RestClientOptions("https://192.168.0.1/")
{
    RemoteCertificateValidationCallback = (sender, certificate, chain, sslPolicyErrors) => true,
    Timeout = TimeSpan.FromMilliseconds(-1),
    ConfigureMessageHandler = handler =>
        new HttpTracerHandler(handler, new ConsoleLogger(), HttpMessageParts.All),
};

var client = new RestClient(options);

var request = new RestRequest("file", Method.Post);
request.AlwaysMultipartFormData = true;

request.AddHeader("Authorization", "Auth-Token" + token);
request.AddHeader("Accept", "application/json");
request.AddFile("file", path, "text/plain");

var response = await client.ExecuteAsync(request);
Console.WriteLine(response.Content);

内容的提问来源于stack exchange，提问作者Bap