javax.servlet/src/main/java/javax/servlet/http/Cookie.java

/*
 * Copyright 1999,2005 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 javax.servlet.http;

import java.text.MessageFormat;
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
 * @version	$Version$
 *
 */

// XXX would implement java.io.Serializable too, but can't do that
// so long as sun.servlet.* must run on older JDK 1.02 JVMs which
// don't include that support.

public class Cookie implements Cloneable {

    private static final String LSTRING_FILE =
	"javax.servlet.http.LocalStrings";
    private static ResourceBundle lStrings =
	ResourceBundle.getBundle(LSTRING_FILE);
    
    //
    // 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
    
    

    /**
     * Constructs a cookie with a specified name and value.
     *
     * <p>The name must conform to RFC 2109. That means it can contain 
     * only ASCII alphanumeric characters and cannot contain commas, 
     * semicolons, or white space or begin with a $ character. The cookie's
     * name cannot be changed after creation.
     *
     * <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 			a <code>String</code> specifying the name of the cookie
     *
     * @param value			a <code>String</code> specifying the value of the cookie
     *
     * @throws IllegalArgumentException	if the cookie name contains illegal characters
     *					(for example, a comma, space, or semicolon)
     *					or it is one of the tokens reserved for use
     *					by the cookie protocol
     * @see #setValue
     * @see #setVersion
     *
     */

    public Cookie(String name, String value) {
	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")
	    ) {
	    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			a <code>String</code> containing the comment,
     *				or <code>null</code> if none
     *
     * @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 pattern		a <code>String</code> containing the domain name
     *				within which this cookie is visible;
     *				form is according to RFC 2109
     *
     * @see #getDomain
     *
     */

    public void setDomain(String pattern) {
	domain = pattern.toLowerCase();	// IE allegedly needs this
    }
    
    
    
    

    /**
     * Returns the domain name set for this cookie. The form of 
     * the domain name is set by RFC 2109.
     *
     * @return			a <code>String</code> containing the domain name
     *
     * @see #setDomain
     *
     */ 

    public String getDomain() {
	return domain;
    }




    /**
     * Sets the maximum age of the cookie in seconds.
     *
     * <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;
    }




    /**
     * Returns the maximum age of the cookie, specified in seconds,
     * By default, <code>-1</code> indicating 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 using 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;
     * 			 otherwise, <code>true</code>
     *
     * @see #setSecure
     *
     */

    public boolean getSecure() {
	return secure;
    }





    /**
     * Returns the name of the cookie. The name cannot be changed after
     * creation.
     *
     * @return		a <code>String</code> specifying the cookie's name
     *
     */

    public String getName() {
	return name;
    }





    /**
     *
     * Assigns a new value to a cookie after the cookie is created.
     * 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		a <code>String</code> specifying the new value 
     *
     *
     * @see #getValue
     * @see Cookie
     *
     */

    public void setValue(String newValue) {
	value = newValue;
    }




    /**
     * Returns the value of the cookie.
     *
     * @return			a <code>String</code> containing the cookie's
     *				present value
     *
     * @see #setValue
     * @see Cookie
     *
     */

    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 this cookie complies
     * with. 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;
    }

    // Note -- disabled for now to allow full Netscape compatibility
    // from RFC 2068, token special case characters
    // 
    // private static final String tspecials = "()<>@,;:\\\"/[]?={} \t";

    private static final String tspecials = ",;";
    
    
    

    /*
     * 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>
     *				if it is not			
     */

    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.
     *		
     *
     */

    public Object clone() {
	try {
	    return super.clone();
	} catch (CloneNotSupportedException e) {
	    throw new RuntimeException(e.getMessage());
	}
    }
}