Search code examples
c#urlsslhttps

Accessing HTTPS URL from Console Application using C#

I want my application to hit the HTTPS URL specified and download the CSV file from that URL.

I have the following code:

Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Net.Security;
using System.IO;

namespace httpWebRequest_Test
{
    class Program
    {
        static void Main(string[] args)
        {
            var webAddr = "https://SFTP URL/xyz.csv";
            var httpWebRequest = (HttpWebRequest) WebRequest.Create(webAddr);
            httpWebRequest.ContentType = "text/csv";
            httpWebRequest.Method = "POST";
            var httpResponse = (HttpWebResponse) httpWebRequest.GetResponse();
            //ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };
            ServicePointManager.ServerCertificateValidationCallback = new System.Net.Security.RemoteCertificateValidationCallback(AcceptAllCertifications);
            Stream resStream = httpResponse.GetResponseStream();
        }

        AcceptAllCertification aac = new AcceptAllCertification();

        public static RemoteCertificateValidationCallback AcceptAllCertifications { get; set; }
    }
}

AcceptAllCertifications.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace httpWebRequest_Test
{
    class AcceptAllCertification
    {
        public bool AcceptAllCertifications(object sender, System.Security.Cryptography.X509Certificates.X509Certificate certification, System.Security.Cryptography.X509Certificates.X509Chain chain, System.Net.Security.SslPolicyErrors sslPolicyErrors)
        {
            return true;
        }
    }
}

I am not receiving any error at compile time. But at run time, I am seeing the following error:

The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel

How do I overcome this error?

Edit 1:

I tried to access the same URL from the browser and it is showing me the following screen:

enter image description here

Only after adding exception am I able to continue.

Edit 2:

After following answer's by @AndrewSilver and @Übercoder, I am seeing the following error:

The remote server returned an error: (411) Length Required

Thereafter I added httpWebRequest.ContentLength = 0;, which led me to the following error:

The remote server returned an error: (405) Method Not Allowed.

Thereafter I added httpWebRequest.ContentLength = 100;, which led me to the following error:

ProtocolViolationException: You must provide a request body if you set ContentLength>0 or SendChunked==true. Do this by calling [Begin]GetRequestStream before [Begin]GetResponse.

NOTE: Anyone who improves my answer by providing a solution without bypassing Certificate validation will be marked as accepted.

Solution

  • This code did the trick for me:

    using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.IO;

namespace ReadCSVFromURL
{
    class Program
    {
        static void Main(string[] args)
        {
            SplitCSV();
        }

        public static string GetCSV(string url)
        {

            ServicePointManager.ServerCertificateValidationCallback = 
            (object a, System.Security.Cryptography.X509Certificates.X509Certificate b, System.Security.Cryptography.X509Certificates.X509Chain c, System.Net.Security.SslPolicyErrors d) => { return true; };            

            HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);
            HttpWebResponse resp = (HttpWebResponse)req.GetResponse();
            StreamReader sr = new StreamReader(resp.GetResponseStream());
            string results = sr.ReadToEnd();
            sr.Close();

            return results;
        }
        public static void SplitCSV()
        {
            List<string> splitted = new List<string>();
            string fileList = GetCSV("URL");
            string[] tempStr;
            tempStr = fileList.Split(',');
            foreach (string item in tempStr)
            {
                if (!string.IsNullOrWhiteSpace(item))
                {
                    splitted.Add(item);
                } 
            }
        }
    }
}