c# – 使用HttpClient异步NancyFX – fbcdn的GetAsync返回403 fo

我假设您正在向南希发送请求,例如：

http://localhost/?url= …

因此对于Facebook,它将是：

http://localhost/?url=https://scontent.xx.fbcdn.net/v/t1.0-1/c15.0.50.50/p50x50/10354686_10150004552801856_220367501106153455_n.jpg?oh=6c801f82cd5a32fd6e5a4258ce00a314&oe=589AAD2F

但对于这个url字符串url = Request.Query [“url”].Value.ToString();是不完整的并且缺少最后一部分(& oe = 589AAD2F),因此服务器响应Forbidden.

以下是演示此问题的简单更改：

private async Task<Response> GetResult(dynamic parameters,CancellationToken ct)
{
    var client = new HttpClient();
    var req = Request.Url.ToString();
    var queryStart = req.IndexOf("url=");
    if (queryStart == -1)
        return Nancy.HttpStatusCode.BadRequest;

    var url = req.Substring(queryStart + 4);
    if (string.IsNullOrEmpty(url))
        return Nancy.HttpStatusCode.BadRequest;

    client.DefaultRequestHeaders.Add("Access-Control-Allow-Origin","*");
    client.DefaultRequestHeaders.Add("User-Agent",like Gecko) Chrome/54.0.2840.71 Safari/537.36");
    client.DefaultRequestHeaders.Add("Upgrade-Insecure-Requests","1");
    client.DefaultRequestHeaders.Add("Accept",*/*;q=0.8");
    client.DefaultRequestHeaders.Add("Accept-Encoding",br");
    client.DefaultRequestHeaders.Add("Accept-Language",ru;q=0.6");
    var response = await client.GetAsync(url,ct);

    ct.ThrowIfCancellationRequested();


    switch (response.StatusCode)
    {
        case System.Net.HttpStatusCode.OK:
            var stream = await response.Content.ReadAsStreamAsync();

            return Response.FromStream(stream,response.Content.Headers.ContentType != null
                ? response.Content.Headers.ContentType.ToString()
                : "application/octet-stream");

        default:
            return Response.AsText("nError " + response.StatusCode);
    }
}

解

我们实际上可以在发送之前对URL进行编码,Nancy将自动为我们解码URL,因此无需更改任何服务器端.

这是使用HttpUtility.UrlEncode生成的链接示例

https://scontent.xx.fbcdn.net/v/t1.0-1/c15.0.50.50/p50x50/10354686_10150004552801856_220367501106153455_n.jpg?oh=6c801f82cd5a32fd6e5a4258ce00a314&oe=589AAD2F

结果：

https://scontent.xx.fbcdn.net/v/t1.0-1/c15.0.50.50/p50x50/10354686_10150004552801856_220367501106153455_n.jpg?oh=6c801f82cd5a32fd6e5a4258ce00a314u0026oe=589AAD2F

并且对此特定链接的实际请求将是：

http://localhost:9876/?url=https%3a%2f%2fscontent.xx.fbcdn.net%2fv%2ft1.0-1%2fc15.0.50.50%2fp50x50%2f10354686_10150004552801856_220367501106153455_n.jpg%3foh%3d6c801f82cd5a32fd6e5a4258ce00a314%26oe%3d589AAD2F

替代解决方案

在这种情况下我个人更喜欢POST而不是GET,所以这里是：

public class ReverseProxyController : NancyModule
{
    class ProxyRequest
    {
        public string Url { get; set; }
    }

    public ReverseProxyController()
    {
        Post["/",CancellationToken ct)
    {
        var pReq = this.Bind<ProxyRequest>();
        var url = pReq.Url;
        if (string.IsNullOrEmpty(url))
            return null;

        var client = new HttpClient();
        client.DefaultRequestHeaders.Add("Access-Control-Allow-Origin",ct);

        ct.ThrowIfCancellationRequested();


        switch (response.StatusCode)
        {
            case System.Net.HttpStatusCode.OK:
                var stream = await response.Content.ReadAsStreamAsync();

                return Response.FromStream(stream,response.Content.Headers.ContentType != null
                    ? response.Content.Headers.ContentType.ToString()
                    : "application/octet-stream");

            default:
                return Response.AsText("nError " + response.StatusCode);
        }
    }
}