Excel Add-in, connecting to a web service through both http and https protocol - authentication

Question

I'm making changes to a Excel Add-in that reads data from a server through a web service interface. Previously the servers where the data is read from didn't support https protocol. In the future they will, but some servers for the same purpose may not be changed to support https for a long time.
So, I would like to maintain flexible logging into the server: I would like that the user doesn't need to make choice between protocols. The user could be totally unaware of the protocol and needs only to give credentials and server name. However, the default protocol would be https. If the server, where data is read, doesn't support that, then http would be used.
The current implementation for logging in is approximately like this:
public partial class AuthenticationService : System.Web.Services.Protocols.SoapHttpClientProtocol {
public AuthenticationService() {
this.Url = global::ExcelAddInExtension.Base.Properties.Settings.Default.ExcelAddInExtension_Base_ServiceReference_AuthenticationService;
if ((this.IsLocalFileSystemWebService(this.Url) == true)) {
this.UseDefaultCredentials = true;
this.useDefaultCredentialsSetExplicitly = false;
}
else {
this.useDefaultCredentialsSetExplicitly = true;
}
}
public new string Url {
get {
return base.Url;
}
set {
if ((((this.IsLocalFileSystemWebService(base.Url) == true)
&& (this.useDefaultCredentialsSetExplicitly == false))
&& (this.IsLocalFileSystemWebService(value) == false))) {
base.UseDefaultCredentials = false;
}
base.Url = value;
}
}
[System.Web.Services.Protocols.SoapDocumentMethodAttribute("http://asp.net/ApplicationServices/v200/AuthenticationService/Login", RequestNamespace="http://asp.net/ApplicationServices/v200", ResponseNamespace="http://asp.net/ApplicationServices/v200", Use=System.Web.Services.Description.SoapBindingUse.Literal, ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped)]
public void Login([System.Xml.Serialization.XmlElementAttribute(IsNullable=true)] string username, [System.Xml.Serialization.XmlElementAttribute(IsNullable=true)] string password, [System.Xml.Serialization.XmlElementAttribute(IsNullable=true)] string customCredential, bool isPersistent, [System.Xml.Serialization.XmlIgnoreAttribute()] bool isPersistentSpecified, out bool LoginResult, [System.Xml.Serialization.XmlIgnoreAttribute()] out bool LoginResultSpecified) {
object[] results = this.Invoke("Login", new object[] {
username,
password,
customCredential,
isPersistent,
isPersistentSpecified});
LoginResult = ((bool)(results[0]));
LoginResultSpecified = ((bool)(results[1]));
}
}
The actual login is done like this:
using (var authenticationService = new ServiceReference.AuthenticationService())
{
authenticationService.Url = "https://server/AuthenticationService.svc";
authenticationService.CookieContainer = new CookieContainer();
bool loginResult;
bool loginResultSpecified;
try
{
authenticationService.Login(userName, password, "", true, true, out loginResult, out loginResultSpecified);
}
catch (Exception ex)
{
Debug.Write(string.Format("Authentication failed, Error message: {0}, \r\nerror inner exception \r\n{1}, \r\nerror stack trace \r\n{2}.", ex.Message, ex.InnerException, ex.StackTrace)));
loginResult = false;
}
}
So, when trying to login to a server that doesn't support https, I get error
System.Net.Sockets.SocketException (0x80004005): No connection could be made because the target machine actively refused it server_ip_number:443.
This is understandable.
My approach was to retry login using http -protocol in the catch block.
authenticationService.Url = "http://server/AuthenticationService.svc";
authenticationService.Login(userName, password, "", true, true, out loginResult, out loginResultSpecified);
Unfortunately I get the same error
System.Net.Sockets.SocketException (0x80004005): No connection could be made because the target machine actively refused it server_ip_number:443.
Seems like the authenticationService object keeps the port number after the first attempt somewhere.
How to refresh or reinitialize that? Or, what kind of approach do you suggest?
The login itself works regardless of the protocol (to a server that supports https or if I try logging in first through http to a server that doesn't support https).
EDIT:
I'm almost ashamed about my question, and specially not understanding that the error message I got second time was actually from the first exception.
Anyway, I solved my problem. Solution below as an answer.

Answer 1

So, I solved my problem by checking first if the server I'm contacting from Excel Add-In is capable of using https-protocol. Then, according to the result, I used either http or https -protocol in the actual authentication.
The solution is originally provided here: How can I check if a server has ssl enable or not
private bool DetectSslSupport(string url)
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.Timeout = 5000;
try
{
using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
{
//some sites like stackoverflow will perform a service side redirect to the http site before the browser/request can throw an errror.
return response.ResponseUri.Scheme == "https";
}
}
catch (WebException webex)//"The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel."}
{
return false;
}
}