我想从fbcdn获取这个图像：
https://scontent.xx.fbcdn.net/v/t1.0-1/c15.0.50.50/p50x50/10354686_10150004552801856_220367501106153455_n.jpg?oh=6c801f82cd5a32fd6e5a4258ce00a314&oe=589AAD2F
浏览器得到它就好了.这是我的代码：
public class ReverseProxyController : NancyModule
{
public ReverseProxyController()
{
Get["/",true] = async (parameters,ct) =>
{
var result = await GetResult(parameters,ct);
return result;
};
}
private async Task<Response> GetResult(dynamic parameters,CancellationToken ct)
{
var client = new HttpClient();
string url = Request.Query["url"].Value.ToString();
if (url == null) return null;
client.DefaultRequestHeaders.Add("Access-Control-Allow-Origin","*");
client.DefaultRequestHeaders.Add("User-Agent","Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML,like Gecko) Chrome/54.0.2840.71 Safari/537.36");
client.DefaultRequestHeaders.Add("Upgrade-Insecure-Requests","1");
client.DefaultRequestHeaders.Add("Accept","text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8");
client.DefaultRequestHeaders.Add("Accept-Encoding","gzip,deflate,sdch,br");
client.DefaultRequestHeaders.Add("Accept-Language","en-US,en;q=0.8,ru;q=0.6");
var response = await client.GetAsync(url,ct);
ct.ThrowIfCancellationRequested();
switch (response.StatusCode)
{
case 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);
}
}
}
我每次都得到403 Forbidden响应.我认为添加标题会使它工作但不会去.
此代码适用于其他主机上的其他图像,如下所示：
https://s-media-cache-ak0.pinimg.com/564x/ff/f0/c9/fff0c988a4516659d4009f60e0694cb6.jpg
解决方法
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=6c801f82cd5a32fd6e5a4258ce00a314\u0026oe=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);
}
}
}