//
// System.Net.DigestClient.cs
//
// Authors:
// Greg Reinacker (gregr@rassoc.com)
// Sebastien Pouliot (spouliot@motus.com)
// Gonzalo Paniagua Javier (gonzalo@ximian.com
//
// Copyright 2002-2003 Greg Reinacker, Reinacker & Associates, Inc. All rights reserved.
// Portions (C) 2003 Motus Technologies Inc. (http://www.motus.com)
// (c) 2003 Novell, Inc. (http://www.novell.com)
//
// Original (server-side) source code available at
// http://www.rassoc.com/gregr/weblog/stories/2002/07/09/webServicesSecurityHttpDigestAuthenticationWithoutActiveDirectory.html
//
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;
using System.Collections;
using System.Collections.Specialized;
using System.IO;
using System.Net;
using System.Security.Cryptography;
using System.Text;
namespace System.Net{
//
// This works with apache mod_digest
//TODO:
// MD5-sess
// qop (auth-int)
//
// See RFC 2617 for details.
//
class DigestHeaderParser
{
string header;
int length;
int pos;
static string [] keywords = { "realm", "opaque", "nonce", "algorithm", "qop" };
string [] values = new string [keywords.Length];
public DigestHeaderParser (string header)
{
this.header = header.Trim ();
}
public string Realm {
get { return values [0]; }
}
public string Opaque {
get { return values [1]; }
}
public string Nonce {
get { return values [2]; }
}
public string Algorithm {
get { return values [3]; }
}
public string QOP {
get { return values [4]; }
}
public bool Parse ()
{
if (!header.ToLower ().StartsWith ("digest "))
return false;
pos = 6;
length = this.header.Length;
while (pos < length) {
string key, value;
if (!GetKeywordAndValue (out key, out value))
return false;
SkipWhitespace ();
if (pos < length && header [pos] == ',')
pos++;
int idx = Array.IndexOf (keywords, (key));
if (idx == -1)
continue;
if (values [idx] != null)
return false;
values [idx] = value;
}
if (Realm == null || Nonce == null)
return false;
return true;
}
void SkipWhitespace ()
{
char c = ' ';
while (pos < length && (c == ' ' || c == '\t' || c == '\r' || c == '\n')) {
c = header [pos++];
}
pos--;
}
string GetKey ()
{
SkipWhitespace ();
int begin = pos;
while (pos < length && header [pos] != '=') {
pos++;
}
string key = header.Substring (begin, pos - begin).Trim ().ToLower ();
return key;
}
bool GetKeywordAndValue (out string key, out string value)
{
key = null;
value = null;
key = GetKey ();
if (pos >= length)
return false;
SkipWhitespace ();
if (pos + 1 >= length || header [pos++] != '=')
return false;
SkipWhitespace ();
// note: Apache doesn't use " in all case (like algorithm)
if (pos + 1 >= length)
return false;
bool useQuote = false;
if (header [pos] == '"') {
pos++;
useQuote = true;
}
int beginQ = pos;
if (useQuote) {
pos = header.IndexOf ('"', pos);
if (pos == -1)
return false;
} else {
do {
char c = header [pos];
if (c == ',' || c == ' ' || c == '\t' || c == '\r' || c == '\n')
break;
} while (++pos < length);
if (pos >= length && beginQ == pos)
return false;
}
value = header.Substring (beginQ, pos - beginQ);
pos += 2;
return true;
}
}
class DigestSession
{
static RandomNumberGenerator rng;
DateTime lastUse;
static DigestSession ()
{
rng = RandomNumberGenerator.Create ();
}
private int _nc;
private HashAlgorithm hash;
private DigestHeaderParser parser;
private string _cnonce;
public DigestSession ()
{
_nc = 1;
lastUse = DateTime.Now;
}
public string Algorithm {
get { return parser.Algorithm; }
}
public string Realm {
get { return parser.Realm; }
}
public string Nonce {
get { return parser.Nonce; }
}
public string Opaque {
get { return parser.Opaque; }
}
public string QOP {
get { return parser.QOP; }
}
public string CNonce {
get {
if (_cnonce == null) {
// 15 is a multiple of 3 which is better for base64 because it
// wont end with '=' and risk messing up the server parsing
byte[] bincnonce = new byte [15];
rng.GetBytes (bincnonce);
_cnonce = Convert.ToBase64String (bincnonce);
Array.Clear (bincnonce, 0, bincnonce.Length);
}
return _cnonce;
}
}
public bool Parse (string challenge)
{
parser = new DigestHeaderParser (challenge);
if (!parser.Parse ()) {
return false;
}
// build the hash object (only MD5 is defined in RFC2617)
if ((parser.Algorithm == null) || (parser.Algorithm.ToUpper ().StartsWith ("MD5")))
hash = HashAlgorithm.Create ("MD5");
return true;
}
private string HashToHexString (string toBeHashed)
{
if (hash == null)
return null;
hash.Initialize ();
byte[] result = hash.ComputeHash (Encoding.ASCII.GetBytes (toBeHashed));
StringBuilder sb = new StringBuilder ();
foreach (byte b in result)
sb.Append (b.ToString ("x2"));
return sb.ToString ();
}
private string HA1 (string username, string password)
{
string ha1 = String.Format ("{0}:{1}:{2}", username, Realm, password);
if (Algorithm != null && Algorithm.ToLower () == "md5-sess")
ha1 = String.Format ("{0}:{1}:{2}", HashToHexString (ha1), Nonce, CNonce);
return HashToHexString (ha1);
}
private string HA2 (HttpWebRequest webRequest)
{
string ha2 = String.Format ("{0}:{1}", webRequest.Method, webRequest.RequestUri.PathAndQuery);
if (QOP == "auth-int") {
// TODO
// ha2 += String.Format (":{0}", hentity);
}
return HashToHexString (ha2);
}
private string Response (string username, string password, HttpWebRequest webRequest)
{
string response = String.Format ("{0}:{1}:", HA1 (username, password), Nonce);
if (QOP != null)
response += String.Format ("{0}:{1}:{2}:", _nc.ToString ("X8"), CNonce, QOP);
response += HA2 (webRequest);
return HashToHexString (response);
}
public Authorization Authenticate (WebRequest webRequest, ICredentials credentials)
{
if (parser == null)
throw new InvalidOperationException ();
HttpWebRequest request = webRequest as HttpWebRequest;
if (request == null)
return null;
lastUse = DateTime.Now;
NetworkCredential cred = credentials.GetCredential (request.RequestUri, "digest");
if (cred == null)
return null;
string userName = cred.UserName;
if (userName == null || userName == "")
return null;
string password = cred.Password;
StringBuilder auth = new StringBuilder ();
auth.AppendFormat ("Digest username=\"{0}\", ", userName);
auth.AppendFormat ("realm=\"{0}\", ", Realm);
auth.AppendFormat ("nonce=\"{0}\", ", Nonce);
auth.AppendFormat ("uri=\"{0}\", ", request.Address.PathAndQuery);
if (Algorithm != null) { // hash algorithm (only MD5 in RFC2617)
auth.AppendFormat ("algorithm=\"{0}\", ", Algorithm);
}
auth.AppendFormat ("response=\"{0}\", ", Response (userName, password, request));
if (QOP != null) { // quality of protection (server decision)
auth.AppendFormat ("qop=\"{0}\", ", QOP);
}
lock (this) {
// _nc MUST NOT change from here...
// number of request using this nonce
if (QOP != null) {
auth.AppendFormat ("nc={0:X8}, ", _nc);
_nc++;
}
// until here, now _nc can change
}
if (CNonce != null) // opaque value from the client
auth.AppendFormat ("cnonce=\"{0}\", ", CNonce);
if (Opaque != null) // exact same opaque value as received from server
auth.AppendFormat ("opaque=\"{0}\", ", Opaque);
auth.Length -= 2; // remove ", "
return new Authorization (auth.ToString ());
}
public DateTime LastUse {
get { return lastUse; }
}
}
class DigestClient : IAuthenticationModule
{
static readonly Hashtable cache = Hashtable.Synchronized (new Hashtable ());
static Hashtable Cache {
get {
lock (cache.SyncRoot) {
CheckExpired (cache.Count);
}
return cache;
}
}
static void CheckExpired (int count)
{
if (count < 10)
return;
DateTime t = DateTime.MaxValue;
DateTime now = DateTime.Now;
ArrayList list = null;
foreach (int key in cache.Keys) {
DigestSession elem = (DigestSession) cache [key];
if (elem.LastUse < t &&
(elem.LastUse - now).Ticks > TimeSpan.TicksPerMinute * 10) {
t = elem.LastUse;
if (list == null)
list = new ArrayList ();
list.Add (key);
}
}
if (list != null) {
foreach (int k in list)
cache.Remove (k);
}
}
// IAuthenticationModule
public Authorization Authenticate (string challenge, WebRequest webRequest, ICredentials credentials)
{
if (credentials == null || challenge == null)
return null;
string header = challenge.Trim ();
if (header.ToLower ().IndexOf ("digest") == -1)
return null;
HttpWebRequest request = webRequest as HttpWebRequest;
if (request == null)
return null;
int hashcode = request.Address.GetHashCode () ^ credentials.GetHashCode ();
DigestSession ds = (DigestSession) Cache [hashcode];
bool addDS = (ds == null);
if (addDS)
ds = new DigestSession ();
if (!ds.Parse (challenge))
return null;
if (addDS)
Cache.Add (hashcode, ds);
return ds.Authenticate (webRequest, credentials);
}
public Authorization PreAuthenticate (WebRequest webRequest, ICredentials credentials)
{
HttpWebRequest request = webRequest as HttpWebRequest;
if (request == null)
return null;
if (credentials == null)
return null;
int hashcode = request.Address.GetHashCode () ^ credentials.GetHashCode ();
DigestSession ds = (DigestSession) Cache [hashcode];
if (ds == null)
return null;
return ds.Authenticate (webRequest, credentials);
}
public string AuthenticationType {
get { return "Digest"; }
}
public bool CanPreAuthenticate {
get { return true; }
}
}
}
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