通过Webrequest调用时，Api返回403错误，但在邮递员中调用时有效

Question

I can successfully run the following OpenStreetMap api from Postman:
https://nominatim.openstreetmap.org/reverse?format=json&lat=30.32736&lon=56.91912

Postman request:

GET /reverse?format=json& lat=30.32736& lon=56.91912 HTTP/1.1
Host: nominatim.openstreetmap.org
cache-control: no-cache
Postman-Token: 92646056-107c-4011-b35f-85858ec715bd

But when trying to call it in c# using this code:

            HttpWebRequest objRequest = (HttpWebRequest)WebRequest
            .Create("https://nominatim.openstreetmap.org/reverse?format=json&lat=30.32736&lon=56.91912");
            objRequest.Method = "GET";
            objRequest.Headers.Add("User-Agent: Other");

            WebResponse response = (WebResponse)objRequest.GetResponse();
            HttpWebResponse objResponse = (HttpWebResponse)objRequest.GetResponse();
            string result = "";
            using (StreamReader responseStream = new StreamReader(objResponse.GetResponseStream()))
            {
                result = responseStream.ReadToEnd();
                responseStream.Close();
            }

I get the following error:

System.Net.WebException: 'The remote server returned an error: (403) Forbidden.'

On line:

HttpWebResponse objResponse = (HttpWebResponse)objRequest.GetResponse();

After I did a search, I found the following header suggested to be added to the request:

objRequest.Headers.Add("User-Agent: SomeName");

But still not working.

Answer 1

Actually, when I run your code, I get an ArgumentException "The 'User-Agent' header must be modified using the appropriate property or method."

Removing the line also yields the 403 error. But, you are already on the right track: Replace your objRequest.Headers.Add("User-Agent: SomeName"); line with:

objRequest.UserAgent = "SomeName";

Then, it works fine for me.