uk.ac.starlink.auth

Class Redirector

java.lang.Object

uk.ac.starlink.auth.Redirector

public abstract class Redirector
extends java.lang.Object

Defines how HTTP 3xx redirects are handled.

Since:

22 Jun 2020

Field Summary

Fields

Modifier and Type	Field and Description
static Redirector	DEFAULT Default instance.
static Redirector	NO_REDIRECT No redirections are performed.

Constructor Summary

Constructors

Constructor and Description
Redirector()

Method Summary

Modifier and Type	Method and Description
static Redirector	createStandardInstance(int[] redirectCodes) Returns an instance that redirects on a given list of 3xx codes.
java.net.URL	getRedirectUrl(java.net.URLConnection conn) Returns a URL to which connections should be redirected from a supplied URL connection, according to this redirector's policy.
abstract boolean	isRedirect(int responseCode) Indicates whether a given HTTP response code should be followed as a redirect.
abstract boolean	willRedirect(java.lang.String fromProto, java.lang.String toProto) Indicates whether HTTP 3xx redirection is permitted between two URL protocols.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT

public static final Redirector DEFAULT

Default instance. Redirects 301, 302, 303, 307 and 308 are followed, and all protocol redirections are permitted except from HTTPS to other (less secure) protocols.

NO_REDIRECT

public static final Redirector NO_REDIRECT

No redirections are performed.

Constructor Detail

Redirector

public Redirector()

Method Detail

isRedirect

public abstract boolean isRedirect(int responseCode)

Indicates whether a given HTTP response code should be followed as a redirect. This will generaly return true for some or all 3xx values and false otherwise. Codes for which true is returned are assumed to imply an accompanying Location header.

Parameters:

responseCode - HTTP response code

Returns:

true iff responseCode should result in following a Location header

willRedirect

public abstract boolean willRedirect(java.lang.String fromProto,
                                     java.lang.String toProto)

Indicates whether HTTP 3xx redirection is permitted between two URL protocols.

The behaviour of the J2SE HttpURLConnection.setInstanceFollowRedirects(boolean) method is that redirection is only permitted beween identical protocols (for instance HTTP->HTTP, but not HTTP->HTTPS), see http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4620571. This is for security reasons, but considerations of the same arguments could reasonably lead to weaker restrictions.

Parameters:

fromProto - protocol part of source URL

toProto - protocol part of destination URL

See Also:

URL.getProtocol()

getRedirectUrl

public java.net.URL getRedirectUrl(java.net.URLConnection conn)
                            throws java.io.IOException

Returns a URL to which connections should be redirected from a supplied URL connection, according to this redirector's policy.

Parameters:

conn - URL connection; will be connected if it is not already

Returns:

URL to which requests should be redirected if any; otherwise null

Throws:

java.io.IOException - if there is a problem with the redirection (for instance missing Location header)

createStandardInstance

public static Redirector createStandardInstance(int[] redirectCodes)

Returns an instance that redirects on a given list of 3xx codes. If the supplied list is empty, no redirection is performed. Redirection between protocols is permitted except from HTTPS to other (less secure) protocols; not this differs from J2SE behaviour.

Parameters:

redirectCodes - list of zero or more 3xx codes which are to be treated as redirects

Returns:

new instance