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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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package sun.net.www.protocol.http;

import sun.net.www.*;
import java.util.Collections;
import java.util.Iterator;
import java.util.HashMap;
import java.util.Set;

This class is used to parse the information in WWW-Authenticate: and Proxy-Authenticate: headers. It searches among multiple header lines and within each header line for the best currently supported scheme. It can also return a HeaderParser containing the challenge data for that particular scheme. Some examples: WWW-Authenticate: Basic realm="foo" Digest realm="bar" NTLM Note the realm parameter must be associated with the particular scheme. or WWW-Authenticate: Basic realm="foo" WWW-Authenticate: Digest realm="foo",qop="auth",nonce="thisisanunlikelynonce" WWW-Authenticate: NTLM or WWW-Authenticate: Basic realm="foo" WWW-Authenticate: NTLM ASKAJK9893289889QWQIOIONMNMN The last example shows how NTLM breaks the rules of rfc2617 for the structure of the authentication header. This is the reason why the raw header field is used for ntlm. At present, the class chooses schemes in following order : 1. Negotiate (if supported) 2. Kerberos (if supported) 3. Digest 4. NTLM (if supported) 5. Basic This choice can be modified by setting a system property: -Dhttp.auth.preference="scheme" which in this case, specifies that "scheme" should be used as the auth scheme when offered disregarding the default prioritisation. If scheme is not offered, or explicitly disabled, by disabledSchemes, then the default priority is used. Attention: when http.auth.preference is set as SPNEGO or Kerberos, it's actually "Negotiate with SPNEGO" or "Negotiate with Kerberos", which means the user will prefer the Negotiate scheme with GSS/SPNEGO or GSS/Kerberos mechanism. This also means that the real "Kerberos" scheme can never be set as a preference. /**
 * This class is used to parse the information in WWW-Authenticate: and Proxy-Authenticate:
 * headers. It searches among multiple header lines and within each header line
 * for the best currently supported scheme. It can also return a HeaderParser
 * containing the challenge data for that particular scheme.
 *
 * Some examples:
 *
 * WWW-Authenticate: Basic realm="foo" Digest realm="bar" NTLM
 *  Note the realm parameter must be associated with the particular scheme.
 *
 * or
 *
 * WWW-Authenticate: Basic realm="foo"
 * WWW-Authenticate: Digest realm="foo",qop="auth",nonce="thisisanunlikelynonce"
 * WWW-Authenticate: NTLM
 *
 * or
 *
 * WWW-Authenticate: Basic realm="foo"
 * WWW-Authenticate: NTLM ASKAJK9893289889QWQIOIONMNMN
 *
 * The last example shows how NTLM breaks the rules of rfc2617 for the structure of
 * the authentication header. This is the reason why the raw header field is used for ntlm.
 *
 * At present, the class chooses schemes in following order :
 *      1. Negotiate (if supported)
 *      2. Kerberos (if supported)
 *      3. Digest
 *      4. NTLM (if supported)
 *      5. Basic
 *
 * This choice can be modified by setting a system property:
 *
 *      -Dhttp.auth.preference="scheme"
 *
 * which in this case, specifies that "scheme" should be used as the auth scheme when offered
 * disregarding the default prioritisation. If scheme is not offered, or explicitly
 * disabled, by {@code disabledSchemes}, then the default priority is used.
 *
 * Attention: when http.auth.preference is set as SPNEGO or Kerberos, it's actually "Negotiate
 * with SPNEGO" or "Negotiate with Kerberos", which means the user will prefer the Negotiate
 * scheme with GSS/SPNEGO or GSS/Kerberos mechanism.
 *
 * This also means that the real "Kerberos" scheme can never be set as a preference.
 */

public class AuthenticationHeader {

    MessageHeader rsp; // the response to be parsed
    HeaderParser preferred;
    String preferred_r; // raw Strings
    private final HttpCallerInfo hci;   // un-schemed, need check

    // When set true, do not use Negotiate even if the response
    // headers suggest so.
    boolean dontUseNegotiate = false;
    static String authPref=null;

    public String toString() {
        return "AuthenticationHeader: prefer " + preferred_r;
    }

    static {
        authPref = java.security.AccessController.doPrivileged(
            new sun.security.action.GetPropertyAction("http.auth.preference"));

        // http.auth.preference can be set to SPNEGO or Kerberos.
        // In fact they means "Negotiate with SPNEGO" and "Negotiate with
        // Kerberos" separately, so here they are all translated into
        // Negotiate. Read NegotiateAuthentication.java to see how they
        // were used later.

        if (authPref != null) {
            authPref = authPref.toLowerCase();
            if(authPref.equals("spnego") || authPref.equals("kerberos")) {
                authPref = "negotiate";
            }
        }
    }

    String hdrname; // Name of the header to look for

    
Parses a set of authentication headers and chooses the preferred scheme
that is supported for a given host.
/**
     * Parses a set of authentication headers and chooses the preferred scheme
     * that is supported for a given host.
     */
    public AuthenticationHeader (String hdrname, MessageHeader response,
            HttpCallerInfo hci, boolean dontUseNegotiate) {
        this(hdrname, response, hci, dontUseNegotiate, Collections.<String>emptySet());
    }

    
Parses a set of authentication headers and chooses the preferred scheme
that is supported for a given host.
 The disabledSchemes parameter is a, possibly empty, set of authentication schemes that are disabled. /**
     * Parses a set of authentication headers and chooses the preferred scheme
     * that is supported for a given host.
     *
     * <p> The {@code disabledSchemes} parameter is a, possibly empty, set of
     * authentication schemes that are disabled.
     */
    public AuthenticationHeader(String hdrname,
                                MessageHeader response,
                                HttpCallerInfo hci,
                                boolean dontUseNegotiate,
                                Set<String> disabledSchemes) {
        this.hci = hci;
        this.dontUseNegotiate = dontUseNegotiate;
        this.rsp = response;
        this.hdrname = hdrname;
        this.schemes = new HashMap<>();
        parse(disabledSchemes);
    }

    public HttpCallerInfo getHttpCallerInfo() {
        return hci;
    }
    /* we build up a map of scheme names mapped to SchemeMapValue objects */
    static class SchemeMapValue {
        SchemeMapValue (HeaderParser h, String r) {raw=r; parser=h;}
        String raw;
        HeaderParser parser;
    }

    HashMap<String, SchemeMapValue> schemes;

    /* Iterate through each header line, and then within each line.
     * If multiple entries exist for a particular scheme (unlikely)
     * then the last one will be used. The
     * preferred scheme that we support will be used.
     */
    private void parse(Set<String> disabledSchemes) {
        Iterator<String> iter = rsp.multiValueIterator(hdrname);
        while (iter.hasNext()) {
            String raw = iter.next();
            // HeaderParser lower cases everything, so can be used case-insensitively
            HeaderParser hp = new HeaderParser(raw);
            Iterator<String> keys = hp.keys();
            int i, lastSchemeIndex;
            for (i=0, lastSchemeIndex = -1; keys.hasNext(); i++) {
                keys.next();
                if (hp.findValue(i) == null) { /* found a scheme name */
                    if (lastSchemeIndex != -1) {
                        HeaderParser hpn = hp.subsequence (lastSchemeIndex, i);
                        String scheme = hpn.findKey(0);
                        if (!disabledSchemes.contains(scheme))
                            schemes.put (scheme, new SchemeMapValue (hpn, raw));
                    }
                    lastSchemeIndex = i;
                }
            }
            if (i > lastSchemeIndex) {
                HeaderParser hpn = hp.subsequence (lastSchemeIndex, i);
                String scheme = hpn.findKey(0);
                if (!disabledSchemes.contains(scheme))
                    schemes.put(scheme, new SchemeMapValue (hpn, raw));
            }
        }

        /* choose the best of them, the order is
         * negotiate -> kerberos -> digest -> ntlm -> basic
         */
        SchemeMapValue v = null;
        if (authPref == null || (v=schemes.get (authPref)) == null) {

            if(v == null && !dontUseNegotiate) {
                SchemeMapValue tmp = schemes.get("negotiate");
                if(tmp != null) {
                    if(hci == null || !NegotiateAuthentication.isSupported(new HttpCallerInfo(hci, "Negotiate"))) {
                        tmp = null;
                    }
                    v = tmp;
                }
            }

            if(v == null && !dontUseNegotiate) {
                SchemeMapValue tmp = schemes.get("kerberos");
                if(tmp != null) {
                    // the Kerberos scheme is only observed in MS ISA Server. In
                    // fact i think it's a Kerberos-mechnism-only Negotiate.
                    // Since the Kerberos scheme is always accompanied with the
                    // Negotiate scheme, so it seems impossible to reach this
                    // line. Even if the user explicitly set http.auth.preference
                    // as Kerberos, it means Negotiate with Kerberos, and the code
                    // will still tried to use Negotiate at first.
                    //
                    // The only chance this line get executed is that the server
                    // only suggest the Kerberos scheme.
                    if(hci == null || !NegotiateAuthentication.isSupported(new HttpCallerInfo(hci, "Kerberos"))) {
                        tmp = null;
                    }
                    v = tmp;
                }
            }

            if(v == null) {
                if ((v=schemes.get ("digest")) == null) {
                    if (((v=schemes.get("ntlm"))==null)) {
                        v = schemes.get ("basic");
                    }
                }
            }
        } else {    // authPref != null && it's found in reponses'
            if (dontUseNegotiate && authPref.equals("negotiate")) {
                v = null;
            }
        }

        if (v != null) {
            preferred = v.parser;
            preferred_r = v.raw;
        }
    }

    
return a header parser containing the preferred authentication scheme (only).
The preferred scheme is the strongest of the schemes proposed by the server.
The returned HeaderParser will contain the relevant parameters for that scheme
/**
     * return a header parser containing the preferred authentication scheme (only).
     * The preferred scheme is the strongest of the schemes proposed by the server.
     * The returned HeaderParser will contain the relevant parameters for that scheme
     */
    public HeaderParser headerParser() {
        return preferred;
    }

    
return the name of the preferred scheme
/**
     * return the name of the preferred scheme
     */
    public String scheme() {
        if (preferred != null) {
            return preferred.findKey(0);
        } else {
            return null;
        }
    }

    /* return the raw header field for the preferred/chosen scheme */

    public String raw () {
        return preferred_r;
    }

    
returns true is the header exists and contains a recognised scheme
/**
     * returns true is the header exists and contains a recognised scheme
     */
    public boolean isPresent () {
        return preferred != null;
    }
}