Class DigestAuthHandler

java.lang.Object
sunlabs.brazil.handler.DigestAuthHandler
All Implemented Interfaces:
Handler
public class DigestAuthHandler extends Object implements Handler
Perform digest authentication. This is a minimal implementation of RFC 2617 The "optional" qos parameter is required by IE (only qop="auth" is supported). The "password" file is read at startup time, either as a resource or from the file system, and may contain either plain text or digested passwords (see main() below to digest passwords).

Future enhancements

  • Better dynamic operation
  • Optional digest parameter handling
  • Nonce time-to-live checking
Sample auth request header 
  
WWW-Authenticate: Digest
   realm="myrealm",
   qop="auth",                                  [req'd for IE]
   nonce="dcd98b7102dd2f0e8b11d0f600bfb0c093",
   opaque="5ccc069c403ebaf9f0171e9517f40e41",   [optional]
   domain="/foo"                                        [optional]
Sample client return header 
 Authorization: Digest
   username="name",
   realm="foo@bar",
   nonce="mynonce10",
   uri="/da.html",
   response="d58f3f9fa7554da651d3f1901d22ea04",
   qop=auth,
   nc=00000001,
   cnonce="b6ac242cb324c38a"

response algorithm:

A1 = md5(user:realm:pass)
A2 = md5(method:uri)
response=md5(A1:nonce:nonceCount:cnonce:qop:A2)
- all MD5's are represented as hex: [0-9a-f]
- all quotes (") are removed before digesting
prefix, suffix, glob, match
Specify which url's this handler applies to.
realm
The string presented to the user for validation. This must also match any "digested" passwords.
credentials
A java-properties format file of credentials. The keys are the users, the values are either the "A1" values described above, or the user's password.
isDynamic
If set (to anything), when authentication for a user is requested that is not in the credentials table and the credentials table has changed since last read, the table is re-read, in case the user has been added since the credentials were loaded.
allowBogusIE
Internet Explorer does not use the query parameters as part of the "uri" calculation. This is a bug (and a security risk, as it allows replay attacts to other than the url requested). If this variable is set, then it allows IE to work in this case.
username
If the user was validated, this field is filled out by the handler.

  • Constructor Details

    • DigestAuthHandler

      public DigestAuthHandler()

  • Method Details

    • init

      public boolean init(Server server, String propsPrefix)
      Description copied from interface: Handler
      Initializes the handler.
      Specified by:
      init in interface Handler
      Parameters:
      server - The HTTP server that created this Handler. Typical Handlers will use Server.props to obtain run-time configuration information.
      propsPrefix - The handlers name. The string this Handler may prepend to all of the keys that it uses to extract configuration information from Server.props. This is set (by the Server and ChainHandler) to help avoid configuration parameter namespace collisions.
      Returns:
      true if this Handler initialized successfully, false otherwise. If false is returned, this Handler should not be used.

    • respond

      public boolean respond(Request request) throws IOException
      Description copied from interface: Handler
      Responds to an HTTP request.
      Specified by:
      respond in interface Handler
      Parameters:
      request - The Request object that represents the HTTP request.
      Returns:
      true if the request was handled. A request was handled if a response was supplied to the client, typically by calling Request.sendResponse() or Request.sendError.
      Throws:
      IOException - if there was an I/O error while sending the response to the client. Typically, in that case, the Server will (try to) send an error message to the client and then close the client's connection.

      The IOException should not be used to silently ignore problems such as being unable to access some server-side resource (for example getting a FileNotFoundException due to not being able to open a file). In that case, the Handler's duty is to turn that IOException into a HTTP response indicating, in this case, that a file could not be found.

    • responseOk

      public static boolean responseOk(String A1, String method, Properties h)
      Check the digest response string.
      Parameters:
      A1 - The "A1" hash from the RFC
      method - The http request method.
      h - Properties containing all the name=value options from the http authentiation header field (see extractAuth(String)).

    • computeA1

      public static String computeA1(String user, String realm, String pass)
      Compute the A1 parameter as per the RFC.

    • computeA2

      public static String computeA2(String method, String uri)
      Compute the A2 parameter as per the RFC.

    • computeResponse

      public static String computeResponse(String A1, String A2, String nonce, String nc, String cnonce, String qop)
      Compute the expected client response attribute value.

    • genResponseHeader

      public static String genResponseHeader(String request, String user, String pass, String method, String uri, String nc, String cnonce)
      Given the "WWW-Authenticate" header value and additional client info, generate the value of the "Authorization" header. The "request" should contain "realm", "nonce", "qop" and optionally "opaque". This is a convenience method for clients to use to athenticate to this server implementation.
      Parameters:
      request - The string value of the "WWW-Authenticate" header from the server
      user - The userid
      pass - The password associated with this user
      method - "GET", "POST", etc.
      uri - The requested url (e.g. "/index.html")
      nc - The "nonce count", or number of times the client has used The "nonce" presented by the server (e.g. "0000001").
      cnonce - An opaque value provided by the client

    • md5Digest

      public static String md5Digest(String s)
      Compute the md5 digest of a string, returning the digest as a hex string.

    • isMd5Digest

      public static boolean isMd5Digest(String s)
      See if a string is a valid md5 digest.

    • extractAuth

      public static Properties extractAuth(String header)
      Parse an auth header, placing the results into a Properties object. Format is: Digest key=value, key=value, ... values may be in "'s.

    • main

      public static void main(String[] args) throws Exception
      Convert a "plain text" password file into a digested one. Any existing digests are left alone. 
      Usage: DigestAuthHandler [realm]
      The stdin, in Properties format, is emitted on stdout with all plain-text passwords digested. If an entry is already digested, it is left alone.

      Note, this handler will except either plaintext or digested passwords in the credentials file.

      Throws:
      Exception