// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_HTTP_HTTP_AUTH_H_
#define NET_HTTP_HTTP_AUTH_H_

#include "net/http/http_util.h"

template <class T> class scoped_refptr;

namespace net {

class HttpAuthHandler;
class HttpResponseHeaders;

// Utility class for http authentication.
class HttpAuth {
 public:

   // Http authentication can be done the the proxy server, origin server,
   // or both. This enum tracks who the target is.
   enum Target {
     AUTH_NONE = -1,
     // We depend on the valid targets (!= AUTH_NONE) being usable as indexes
     // in an array, so start from 0.
     AUTH_PROXY = 0,
     AUTH_SERVER = 1,
   };

   // Describes where the identity used for authentication came from.
   enum IdentitySource {
     // Came from nowhere -- the identity is not initialized.
     IDENT_SRC_NONE,

     // The identity came from the auth cache, by doing a path-based
     // lookup (premptive authorization).
     IDENT_SRC_PATH_LOOKUP,

     // The identity was extracted from a URL of the form:
     // http://<username>:<password>@host:port
     IDENT_SRC_URL,

     // The identity was retrieved from the auth cache, by doing a
     // realm lookup.
     IDENT_SRC_REALM_LOOKUP,

     // The identity was provided by RestartWithAuth -- it likely
     // came from a prompt (or maybe the password manager).
     IDENT_SRC_EXTERNAL,
   };

   // Helper structure used by HttpNetworkTransaction to track
   // the current identity being used for authorization.
   struct Identity {
     Identity() : source(IDENT_SRC_NONE), invalid(true) { }

     IdentitySource source;
     bool invalid;
     // TODO(wtc): |username| and |password| should be string16.
     std::wstring username;
     std::wstring password;
   };

  // Get the name of the header containing the auth challenge
  // (either WWW-Authenticate or Proxy-Authenticate).
  static std::string GetChallengeHeaderName(Target target);

  // Get the name of the header where the credentials go
  // (either Authorization or Proxy-Authorization).
  static std::string GetAuthorizationHeaderName(Target target);

  // Create a handler to generate credentials for the challenge, and pass
  // it back in |*handler|. If the challenge is unsupported or invalid
  // |*handler| is set to NULL.
  static void CreateAuthHandler(const std::string& challenge,
                                Target target,
                                scoped_refptr<HttpAuthHandler>* handler);

  // Iterate through the challenge headers, and pick the best one that
  // we support. Obtains the implementation class for handling the challenge,
  // and passes it back in |*handler|. If the existing handler in |*handler|
  // should continue to be used (such as for the NTLM authentication scheme),
  // |*handler| is unchanged. If no supported challenge was found, |*handler|
  // is set to NULL.
  //
  // TODO(wtc): Continuing to use the existing handler in |*handler| (for
  // NTLM) is new behavior.  Rename ChooseBestChallenge to fully encompass
  // what it does now.
  static void ChooseBestChallenge(const HttpResponseHeaders* headers,
                                  Target target,
                                  scoped_refptr<HttpAuthHandler>* handler);

  // ChallengeTokenizer breaks up a challenge string into the the auth scheme
  // and parameter list, according to RFC 2617 Sec 1.2:
  //    challenge = auth-scheme 1*SP 1#auth-param
  //
  // Check valid() after each iteration step in case it was malformed.
  // Also note that value() will give whatever is to the right of the equals
  // sign, quotemarks and all. Use unquoted_value() to get the logical value.
  class ChallengeTokenizer {
   public:
    ChallengeTokenizer(std::string::const_iterator begin,
                       std::string::const_iterator end)
        : props_(begin, end, ','), valid_(true) {
      Init(begin, end);
    }

    // Get the auth scheme of the challenge.
    std::string::const_iterator scheme_begin() const { return scheme_begin_; }
    std::string::const_iterator scheme_end() const { return scheme_end_; }
    std::string scheme() const {
      return std::string(scheme_begin_, scheme_end_);
    }

    // Returns false if there was a parse error.
    bool valid() const {
      return valid_;
    }

    // Advances the iterator to the next name-value pair, if any.
    // Returns true if there is none to consume.
    bool GetNext();

    // The name of the current name-value pair.
    std::string::const_iterator name_begin() const { return name_begin_; }
    std::string::const_iterator name_end() const { return name_end_; }
    std::string name() const {
      return std::string(name_begin_, name_end_);
    }

    // The value of the current name-value pair.
    std::string::const_iterator value_begin() const { return value_begin_; }
    std::string::const_iterator value_end() const { return value_end_; }
    std::string value() const {
      return std::string(value_begin_, value_end_);
    }

    // If value() has quotemarks, unquote it.
    std::string unquoted_value() const;

    // True if the name-value pair's value has quote marks.
    bool value_is_quoted() const { return value_is_quoted_; }

   private:
    void Init(std::string::const_iterator begin,
              std::string::const_iterator end);

    HttpUtil::ValuesIterator props_;
    bool valid_;

    std::string::const_iterator scheme_begin_;
    std::string::const_iterator scheme_end_;

    std::string::const_iterator name_begin_;
    std::string::const_iterator name_end_;

    std::string::const_iterator value_begin_;
    std::string::const_iterator value_end_;

    bool value_is_quoted_;
  };
};

}  // namespace net

#endif  // NET_HTTP_HTTP_AUTH_H_