Cookie.java

/*
 * Copyright (c) 1997, 2020 Oracle and/or its affiliates and others.
 * All rights reserved.
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package jakarta.servlet.http;

import java.io.Serializable;
import java.text.MessageFormat;
import java.util.Locale;
import java.util.ResourceBundle;

/**
 *
 * Creates a cookie, a small amount of information sent by a servlet to a Web browser, saved by the browser, and later
 * sent back to the server. A cookie's value can uniquely identify a client, so cookies are commonly used for session
 * management.
 * 
 * <p>
 * A cookie has a name, a single value, and optional attributes such as a comment, path and domain qualifiers, a maximum
 * age, and a version number. Some Web browsers have bugs in how they handle the optional attributes, so use them
 * sparingly to improve the interoperability of your servlets.
 *
 * <p>
 * The servlet sends cookies to the browser by using the {@link HttpServletResponse#addCookie} method, which adds fields
 * to HTTP response headers to send cookies to the browser, one at a time. The browser is expected to support 20 cookies
 * for each Web server, 300 cookies total, and may limit cookie size to 4 KB each.
 * 
 * <p>
 * The browser returns cookies to the servlet by adding fields to HTTP request headers. Cookies can be retrieved from a
 * request by using the {@link HttpServletRequest#getCookies} method. Several cookies might have the same name but
 * different path attributes.
 * 
 * <p>
 * Cookies affect the caching of the Web pages that use them. HTTP 1.0 does not cache pages that use cookies created
 * with this class. This class does not support the cache control defined with HTTP 1.1.
 *
 * <p>
 * This class supports both the Version 0 (by Netscape) and Version 1 (by RFC 2109) cookie specifications. By default,
 * cookies are created using Version 0 to ensure the best interoperability.
 *
 * @author Various
 */
public class Cookie implements Cloneable, Serializable {

    private static final long serialVersionUID = -6454587001725327448L;

    private static final String TSPECIALS;

    private static final String LSTRING_FILE = "jakarta.servlet.http.LocalStrings";

    private static ResourceBundle lStrings = ResourceBundle.getBundle(LSTRING_FILE);

    static {
        if (Boolean.valueOf(System.getProperty("org.glassfish.web.rfc2109_cookie_names_enforced", "true"))
                .booleanValue()) {
            TSPECIALS = "/()<>@,;:\\\"[]?={} \t";
        } else {
            TSPECIALS = ",; ";
        }
    }

    //
    // The value of the cookie itself.
    //

    private String name; // NAME= ... "$Name" style is reserved
    private String value; // value of NAME

    //
    // Attributes encoded in the header's cookie fields.
    //

    private String comment; // ;Comment=VALUE ... describes cookie's use
    // ;Discard ... implied by maxAge < 0
    private String domain; // ;Domain=VALUE ... domain that sees cookie
    private int maxAge = -1; // ;Max-Age=VALUE ... cookies auto-expire
    private String path; // ;Path=VALUE ... URLs that see the cookie
    private boolean secure; // ;Secure ... e.g. use SSL
    private int version = 0; // ;Version=1 ... means RFC 2109++ style
    private boolean isHttpOnly = false;

    /**
     * Constructs a cookie with the specified name and value.
     *
     * <p>
     * The name must conform to RFC 2109. However, vendors may provide a configuration option that allows cookie names
     * conforming to the original Netscape Cookie Specification to be accepted.
     *
     * <p>
     * The name of a cookie cannot be changed once the cookie has been created.
     *
     * <p>
     * The value can be anything the server chooses to send. Its value is probably of interest only to the server. The
     * cookie's value can be changed after creation with the <code>setValue</code> method.
     *
     * <p>
     * By default, cookies are created according to the Netscape cookie specification. The version can be changed with the
     * <code>setVersion</code> method.
     *
     * @param name the name of the cookie
     *
     * @param value the value of the cookie
     *
     * @throws IllegalArgumentException if the cookie name is null or empty or contains any illegal characters (for example,
     * a comma, space, or semicolon) or matches a token reserved for use by the cookie protocol
     *
     * @see #setValue
     * @see #setVersion
     */
    public Cookie(String name, String value) {
        if (name == null || name.length() == 0) {
            throw new IllegalArgumentException(lStrings.getString("err.cookie_name_blank"));
        }
        if (!isToken(name) || name.equalsIgnoreCase("Comment") || // rfc2019
                name.equalsIgnoreCase("Discard") || // 2019++
                name.equalsIgnoreCase("Domain") || name.equalsIgnoreCase("Expires") || // (old cookies)
                name.equalsIgnoreCase("Max-Age") || // rfc2019
                name.equalsIgnoreCase("Path") || name.equalsIgnoreCase("Secure") || name.equalsIgnoreCase("Version")
                || name.startsWith("$")) {
            String errMsg = lStrings.getString("err.cookie_name_is_token");
            Object[] errArgs = new Object[1];
            errArgs[0] = name;
            errMsg = MessageFormat.format(errMsg, errArgs);
            throw new IllegalArgumentException(errMsg);
        }

        this.name = name;
        this.value = value;
    }

    /**
     * Specifies a comment that describes a cookie's purpose. The comment is useful if the browser presents the cookie to
     * the user. Comments are not supported by Netscape Version 0 cookies.
     *
     * @param purpose a <code>String</code> specifying the comment to display to the user
     *
     * @see #getComment
     */
    public void setComment(String purpose) {
        comment = purpose;
    }

    /**
     * Returns the comment describing the purpose of this cookie, or <code>null</code> if the cookie has no comment.
     *
     * @return the comment of the cookie, or <code>null</code> if unspecified
     *
     * @see #setComment
     */
    public String getComment() {
        return comment;
    }

    /**
     *
     * Specifies the domain within which this cookie should be presented.
     *
     * <p>
     * The form of the domain name is specified by RFC 2109. A domain name begins with a dot (<code>.foo.com</code>) and
     * means that the cookie is visible to servers in a specified Domain Name System (DNS) zone (for example,
     * <code>www.foo.com</code>, but not <code>a.b.foo.com</code>). By default, cookies are only returned to the server that
     * sent them.
     *
     * @param domain the domain name within which this cookie is visible; form is according to RFC 2109
     *
     * @see #getDomain
     */
    public void setDomain(String domain) {
        this.domain = domain != null ? domain.toLowerCase(Locale.ENGLISH) : null; // IE allegedly needs this
    }

    /**
     * Gets the domain name of this Cookie.
     *
     * <p>
     * Domain names are formatted according to RFC 2109.
     *
     * @return the domain name of this Cookie
     *
     * @see #setDomain
     */
    public String getDomain() {
        return domain;
    }

    /**
     * Sets the maximum age in seconds for this Cookie.
     *
     * <p>
     * A positive value indicates that the cookie will expire after that many seconds have passed. Note that the value is
     * the <i>maximum</i> age when the cookie will expire, not the cookie's current age.
     *
     * <p>
     * A negative value means that the cookie is not stored persistently and will be deleted when the Web browser exits. A
     * zero value causes the cookie to be deleted.
     *
     * @param expiry an integer specifying the maximum age of the cookie in seconds; if negative, means the cookie is not
     * stored; if zero, deletes the cookie
     *
     * @see #getMaxAge
     */
    public void setMaxAge(int expiry) {
        maxAge = expiry;
    }

    /**
     * Gets the maximum age in seconds of this Cookie.
     *
     * <p>
     * By default, <code>-1</code> is returned, which indicates that the cookie will persist until browser shutdown.
     *
     * @return an integer specifying the maximum age of the cookie in seconds; if negative, means the cookie persists until
     * browser shutdown
     *
     * @see #setMaxAge
     */
    public int getMaxAge() {
        return maxAge;
    }

    /**
     * Specifies a path for the cookie to which the client should return the cookie.
     *
     * <p>
     * The cookie is visible to all the pages in the directory you specify, and all the pages in that directory's
     * subdirectories. A cookie's path must include the servlet that set the cookie, for example, <i>/catalog</i>, which
     * makes the cookie visible to all directories on the server under <i>/catalog</i>.
     *
     * <p>
     * Consult RFC 2109 (available on the Internet) for more information on setting path names for cookies.
     *
     *
     * @param uri a <code>String</code> specifying a path
     *
     * @see #getPath
     */
    public void setPath(String uri) {
        path = uri;
    }

    /**
     * Returns the path on the server to which the browser returns this cookie. The cookie is visible to all subpaths on the
     * server.
     *
     * @return a <code>String</code> specifying a path that contains a servlet name, for example, <i>/catalog</i>
     *
     * @see #setPath
     */
    public String getPath() {
        return path;
    }

    /**
     * Indicates to the browser whether the cookie should only be sent using a secure protocol, such as HTTPS or SSL.
     *
     * <p>
     * The default value is <code>false</code>.
     *
     * @param flag if <code>true</code>, sends the cookie from the browser to the server only when using a secure protocol;
     * if <code>false</code>, sent on any protocol
     *
     * @see #getSecure
     */
    public void setSecure(boolean flag) {
        secure = flag;
    }

    /**
     * Returns <code>true</code> if the browser is sending cookies only over a secure protocol, or <code>false</code> if the
     * browser can send cookies using any protocol.
     *
     * @return <code>true</code> if the browser uses a secure protocol, <code>false</code> otherwise
     *
     * @see #setSecure
     */
    public boolean getSecure() {
        return secure;
    }

    /**
     * Returns the name of the cookie. The name cannot be changed after creation.
     *
     * @return the name of the cookie
     */
    public String getName() {
        return name;
    }

    /**
     * Assigns a new value to this Cookie.
     * 
     * <p>
     * If you use a binary value, you may want to use BASE64 encoding.
     *
     * <p>
     * With Version 0 cookies, values should not contain white space, brackets, parentheses, equals signs, commas, double
     * quotes, slashes, question marks, at signs, colons, and semicolons. Empty values may not behave the same way on all
     * browsers.
     *
     * @param newValue the new value of the cookie
     *
     * @see #getValue
     */
    public void setValue(String newValue) {
        value = newValue;
    }

    /**
     * Gets the current value of this Cookie.
     *
     * @return the current value of this Cookie
     *
     * @see #setValue
     */
    public String getValue() {
        return value;
    }

    /**
     * Returns the version of the protocol this cookie complies with. Version 1 complies with RFC 2109, and version 0
     * complies with the original cookie specification drafted by Netscape. Cookies provided by a browser use and identify
     * the browser's cookie version.
     * 
     * @return 0 if the cookie complies with the original Netscape specification; 1 if the cookie complies with RFC 2109
     *
     * @see #setVersion
     */
    public int getVersion() {
        return version;
    }

    /**
     * Sets the version of the cookie protocol that this Cookie complies with.
     *
     * <p>
     * Version 0 complies with the original Netscape cookie specification. Version 1 complies with RFC 2109.
     *
     * <p>
     * Since RFC 2109 is still somewhat new, consider version 1 as experimental; do not use it yet on production sites.
     *
     * @param v 0 if the cookie should comply with the original Netscape specification; 1 if the cookie should comply with
     * RFC 2109
     *
     * @see #getVersion
     */
    public void setVersion(int v) {
        version = v;
    }

    /*
     * Tests a string and returns true if the string counts as a reserved token in the Java language.
     * 
     * @param value the <code>String</code> to be tested
     *
     * @return <code>true</code> if the <code>String</code> is a reserved token; <code>false</code> otherwise
     */
    private boolean isToken(String value) {
        int len = value.length();
        for (int i = 0; i < len; i++) {
            char c = value.charAt(i);
            if (c < 0x20 || c >= 0x7f || TSPECIALS.indexOf(c) != -1) {
                return false;
            }
        }

        return true;
    }

    /**
     * Overrides the standard <code>java.lang.Object.clone</code> method to return a copy of this Cookie.
     */
    @Override
    public Object clone() {
        try {
            return super.clone();
        } catch (CloneNotSupportedException e) {
            throw new RuntimeException(e.getMessage());
        }
    }

    /**
     * Marks or unmarks this Cookie as <i>HttpOnly</i>.
     *
     * <p>
     * If <tt>isHttpOnly</tt> is set to <tt>true</tt>, this cookie is marked as <i>HttpOnly</i>, by adding the
     * <tt>HttpOnly</tt> attribute to it.
     *
     * <p>
     * <i>HttpOnly</i> cookies are not supposed to be exposed to client-side scripting code, and may therefore help mitigate
     * certain kinds of cross-site scripting attacks.
     *
     * @param isHttpOnly true if this cookie is to be marked as <i>HttpOnly</i>, false otherwise
     *
     * @since Servlet 3.0
     */
    public void setHttpOnly(boolean isHttpOnly) {
        this.isHttpOnly = isHttpOnly;
    }

    /**
     * Checks whether this Cookie has been marked as <i>HttpOnly</i>.
     *
     * @return true if this Cookie has been marked as <i>HttpOnly</i>, false otherwise
     *
     * @since Servlet 3.0
     */
    public boolean isHttpOnly() {
        return isHttpOnly;
    }
}