How to: Perform Custom Authentication Using SOAP Headers
This topic is specific to a legacy technology. XML Web services and XML Web service clients should now be created using Windows Communication Foundation.
The following custom solution is built using ASP.NET to provide an authentication mechanism using SOAP headers. The solution involves a custom IHttpModule on the Web server that executes the following steps:
The HTTP Module parses HTTP messages to check whether they are SOAP messages.
If the HTTP Module detects a SOAP message, it reads the SOAP headers.
If the SOAP message has the SOAP header with authentication credentials, HTTP Module raises a custom global.asax event.
In the sample provided, the HTTP Module authenticates the user and sets Context properties that a Web service can use to decide whether the client is authorized access to the Web service.
Note
In this sample, the text is sent over the network in clearly readable text (it is not encrypted). If clear text is not secure enough for your application, add an encryption algorithm.
Example
The following code example is an HTTP Module that parses HTTP messages for SOAP requests. If the HTTP message is a SOAP message, the custom WebServiceAuthenticationEvent is raised.
using System;
using System.Web;
using System.IO;
using System.Xml;
using System.Xml.XPath;
using System.Text;
using System.Web.Services.Protocols;
namespace Microsoft.WebServices.Security {
public sealed class WebServiceAuthenticationModule : IHttpModule
{
private WebServiceAuthenticationEventHandler
_eventHandler = null;
public event WebServiceAuthenticationEventHandler Authenticate
{
add { _eventHandler += value;}
remove {_eventHandler -= value;}
}
public void Dispose()
{
}
public void Init(HttpApplication app)
{
app.AuthenticateRequest += new
EventHandler(this.OnEnter);
}
private void OnAuthenticate(WebServiceAuthenticationEvent e)
{
if (_eventHandler == null)
return;
_eventHandler(this, e);
if (e.User != null)
e.Context.User = e.Principal;
}
public string ModuleName
{
get{ return "WebServiceAuthentication"; }
}
void OnEnter(Object source, EventArgs eventArgs) {
HttpApplication app = (HttpApplication)source;
HttpContext context = app.Context;
Stream HttpStream = context.Request.InputStream;
// Save the current position of stream.
long posStream = HttpStream.Position;
// If the request contains an HTTP_SOAPACTION
// header, look at this message.
if (context.Request.ServerVariables["HTTP_SOAPACTION"]
== null)
return;
// Load the body of the HTTP message
// into an XML document.
XmlDocument dom = new XmlDocument();
string soapUser;
string soapPassword;
try
{
dom.Load(HttpStream);
// Reset the stream position.
HttpStream.Position = posStream;
// Bind to the Authentication header.
soapUser =
dom.GetElementsByTagName("User").Item(0).InnerText;
soapPassword =
dom.GetElementsByTagName("Password").Item(0).InnerText;
}
catch (Exception e)
{
// Reset the position of stream.
HttpStream.Position = posStream;
// Throw a SOAP exception.
XmlQualifiedName name = new
XmlQualifiedName("Load");
SoapException soapException = new SoapException(
"Unable to read SOAP request", name, e);
throw soapException;
}
// Raise the custom global.asax event.
OnAuthenticate(new WebServiceAuthenticationEvent (context, soapUser, soapPassword));
return;
}
}
}
Public NotInheritable Class WebServiceAuthenticationModule
Implements IHttpModule
Public Delegate Sub WebServiceAuthenticationEventHandler(ByVal sender As [Object], ByVal e As WebServiceAuthenticationEvent)
Private _eventHandler As WebServiceAuthenticationEventHandler = Nothing
Public Custom Event Authenticate As
WebServiceAuthenticationEventHandler
AddHandler(ByVal value As
WebServiceAuthenticationEventHandler)
_eventHandler = value
End AddHandler
RemoveHandler(ByVal value As
WebServiceAuthenticationEventHandler)
_eventHandler = value
End RemoveHandler
RaiseEvent(ByVal sender As Object,
ByVal e As WebServiceAuthenticationEvent)
End RaiseEvent
End Event
Public Sub Dispose() Implements System.Web.IHttpModule.Dispose
End Sub 'Dispose
Public Sub Init(ByVal app As HttpApplication) Implements System.Web.IHttpModule.Init
AddHandler app.AuthenticateRequest, AddressOf Me.OnEnter
End Sub 'Init
Private Sub OnAuthenticate(ByVal e As WebServiceAuthenticationEvent)
If _eventHandler Is Nothing Then
Return
End If
_eventHandler(Me, e)
If Not (e.User Is Nothing) Then
e.Context.User = e.Principal
End If
End Sub 'OnAuthenticate
Public ReadOnly Property ModuleName() As String
Get
Return "WebServiceAuthentication"
End Get
End Property
Sub OnEnter(ByVal [source] As [Object], ByVal eventArgs As EventArgs)
Dim app As HttpApplication = CType([source], HttpApplication)
Dim context As HttpContext = app.Context
Dim HttpStream As Stream = context.Request.InputStream
' Save the current position of stream.
Dim posStream As Long = HttpStream.Position
' If the request contains an HTTP_SOAPACTION
' header, look at this message.
If context.Request.ServerVariables("HTTP_SOAPACTION") Is Nothing Then
Return
End If
' Load the body of the HTTP message
' into an XML document.
Dim dom As New XmlDocument()
Dim soapUser As String
Dim soapPassword As String
Try
dom.Load(HttpStream)
' Reset the stream position.
HttpStream.Position = posStream
' Bind to the Authentication header.
soapUser = dom.GetElementsByTagName("User").Item(0).InnerText
soapPassword = dom.GetElementsByTagName("Password").Item(0).InnerText
Catch e As Exception
' Reset the position of stream.
HttpStream.Position = posStream
' Throw a SOAP exception.
Dim name As New XmlQualifiedName("Load")
Dim soapException As New SoapException("Unable to read SOAP request", name, e)
Throw soapException
End Try
' Raise the custom global.asax event.
OnAuthenticate(New WebServiceAuthenticationEvent(context, soapUser, soapPassword))
Return
End Sub 'OnEnter
End Class 'WebServiceAuthenticationModule
The following code example is the custom authentication event that is raised by the HTTP Module, if a SOAP request is received.
namespace Microsoft.WebServices.Security {
using System;
using System.Web;
using System.Security.Principal;
public class WebServiceAuthenticationEvent : EventArgs {
private Iprincipal _IPrincipalUser;
private HttpContext _Context;
private string _User;
private string _Password;
public WebServiceAuthenticationEvent(HttpContext context)
{
_Context = context;
}
public WebServiceAuthenticationEvent(HttpContext context,
string user, string password)
{
_Context = context;
_User = user;
_Password = password;
}
public HttpContext Context
{
get { return _Context;}
}
public IPrincipal Principal
{
get { return _IPrincipalUser;}
set { _IPrincipalUser = value;}
}
public void Authenticate()
{
GenericIdentity i = new GenericIdentity(User);
this.Principal = new GenericPrincipal(i, new String[0]);
}
public void Authenticate(string[] roles)
{
GenericIdentity i = new GenericIdentity(User);
this.Principal = new GenericPrincipal(i, roles);
}
public string User
{
get { return _User; }
set { _User = value; }
}
public string Password
{
get { return _Password; }
set { _Password = value; }
}
public bool HasCredentials {
get
{
if ((_User == null) || (_Password == null))
return false;
return true;
}
}
}
}
Imports System
Imports System.Web
Imports System.Security.Principal
Public Class WebServiceAuthenticationEvent
Inherits EventArgs
Private _IPrincipalUser As Iprincipal
Private _Context As HttpContext
Private _User As String
Private _Password As String
Public Sub New(ByVal context As HttpContext)
_Context = context
End Sub 'New
Public Sub New(ByVal context As HttpContext, ByVal user As String, ByVal password As String)
_Context = context
_User = user
_Password = password
End Sub 'New
Public ReadOnly Property Context() As HttpContext
Get
Return _Context
End Get
End Property
Public Property Principal() As IPrincipal
Get
Return _IPrincipalUser
End Get
Set
_IPrincipalUser = value
End Set
End Property
Overloads Public Sub Authenticate()
Dim i As New GenericIdentity(User)
Me.Principal = New GenericPrincipal(i, New String(-1) {})
End Sub 'Authenticate
Overloads Public Sub Authenticate(ByVal roles() As String)
Dim i As New GenericIdentity(User)
Me.Principal = New GenericPrincipal(i, roles)
End Sub 'Authenticate
Public Property User() As String
Get
Return _User
End Get
Set
_User = value
End Set
End Property
Public Property Password() As String
Get
Return _Password
End Get
Set
_Password = value
End Set
End Property
Public ReadOnly Property HasCredentials() As Boolean
Get
If _User Is Nothing OrElse _Password Is Nothing Then
Return False
End If
Return True
End Get
End Property
End Class 'WebServiceAuthenticationEvent
The following code example is the delegate for the custom WebServiceAuthenticationEvent event.
namespace Microsoft.WebServices.Security
{
using System;
public delegate void WebServiceAuthenticationEventHandler(Object sender, WebServiceAuthenticationEvent e);
}
Imports System
Public Delegate Sub WebServiceAuthenticationEventHandler(ByVal sender As [Object], ByVal e As WebServiceAuthenticationEvent)
The following code example is a Web service that defines the Authentication SOAP header that a client must pass. The Web service does not have to do the authentication. Rather, it can inspect the User.Identity.IsAuthenticated property to determine if the HTTP Module has authenticated the user.
<%@ WebService Language="C#" Class="SecureWebService" %>
using System;
using System.Web.Services;
using System.Web.Services.Protocols;
public class Authentication : SoapHeader {
public string User;
public string Password;
}
public class SecureWebService : WebService{
public Authentication authentication;
[WebMethod]
[SoapHeader("authentication")]
public string ValidUser(){
if (User.IsInRole("Customer"))
return "User is in role customer";
if (User.Identity.IsAuthenticated)
return "User is a valid user";
return "not authenticated";
}
}
<%@ WebService Language="VB" Class="SecureWebService" %>
Imports System
Imports System.Web.Services
Imports System.Web.Services.Protocols
Public Class Authentication
Inherits SoapHeader
Public User As String
Public Password As String
End Class 'Authentication
Public Class SecureWebService
Inherits WebService
Public authentication As Authentication
<WebMethod(), SoapHeader("authentication")> _
Public Function ValidUser() As String
If User.IsInRole("Customer") Then
Return "User is in role customer"
End If
If User.Identity.IsAuthenticated Then
Return "User is a valid user"
End If
Return "not authenticated"
End Function 'ValidUser
End Class 'SecureWebService
The following code example is a Web service client that passes the necessary credentials for a custom SOAP header authentication mechanism within an Authentication SOAP header.
// Create a new instance of a Web service proxy class.
SecureWebService s = new SecureWebService();
// Create the Authentication SOAP header and set values.
Authentication a = new Authentication();
a.User = user.Value;
a.Password = password.Value;
// Assign the Header.
s.AuthenticationValue = a;
string result = s.ValidUser();
span1.InnerHtml = result;
' Create a new instance of a Web service proxy class.
Dim s As New SecureWebService()
' Create the Authentication SOAP header and set values.
Dim a As New Authentication()
a.User = user.Value
a.Password = password.Value
Assign the Header.
s.AuthenticationValue = a
Dim result As String = s.ValidUser()
span1.InnerHtml = result
See Also
Tasks
How to: Configure an XML Web Service for Windows Authentication
Reference
NetworkCredential
CredentialCache
X509Certificate
Concepts
Securing XML Web Services Created Using ASP.NET
Other Resources
Securing ASP.NET Web Applications
XML Web Services Using ASP.NET