org.gwtproject.safehtml.shared

Class UriUtils

java.lang.Object

org.gwtproject.safehtml.shared.UriUtils

public final class UriUtils
extends Object

Utility class containing static methods for validating and sanitizing URIs.

Method Summary

Modifier and Type	Method and Description
static String	encode(String uri) Encodes the URL.
static String	encodeAllowEscapes(String uri) Encodes the URL, preserving existing %-escapes.
static String	extractScheme(String uri) Extracts the scheme of a URI.
static SafeUri	fromSafeConstant(String s) Returns a SafeUri constructed from a value that is fully under the control of the program, e.g., a constant.
static SafeUri	fromString(String s) Returns a SafeUri obtained by sanitizing the provided string.
static SafeUri	fromTrustedString(String s) Returns a SafeUri constructed from a trusted string, i.e., without sanitizing the string.
static boolean	isSafeUri(String uri) Determines if a String is safe to use as the value of a URI-valued HTML attribute such as src or href.
static String	sanitizeUri(String uri) Sanitizes a URI.
static SafeUri	unsafeCastFromUntrustedString(String s) Deprecated. This method is intended only for use in APIs that use SafeUri to represent URIs, but for backwards compatibility have methods that accept URI parameters as plain strings.

Methods inherited from class java.lang.Object

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

Method Detail

encode

public static String encode(String uri)

Encodes the URL.

In client code, this method delegates to URL#encode(String) and then unescapes brackets, as they might be used for IPv6 addresses.

Parameters:

uri - the URL to encode

Returns:

the %-escaped URL

encodeAllowEscapes

public static String encodeAllowEscapes(String uri)

Encodes the URL, preserving existing %-escapes.

Parameters:

uri - the URL to encode

Returns:

the %-escaped URL

extractScheme

public static String extractScheme(String uri)

Extracts the scheme of a URI.

Parameters:

uri - the URI to extract the scheme from

Returns:

the URI's scheme, or null if the URI does not have one

fromSafeConstant

public static SafeUri fromSafeConstant(String s)

Returns a SafeUri constructed from a value that is fully under the control of the program, e.g., a constant.

The string is not sanitized and no checks are performed. The assumption that the resulting value adheres to the SafeUri type contract is entirely based on the argument being fully under program control and not being derived from a program input.

Convention of use: This method must only be invoked on values that are fully under the program's control, such as string literals.

Parameters:

s - the input String

Returns:

a SafeUri instance

fromString

public static SafeUri fromString(String s)

Returns a SafeUri obtained by sanitizing the provided string.

The input string is sanitized using sanitizeUri(String).

Parameters:

s - the input String

Returns:

a SafeUri instance

fromTrustedString

public static SafeUri fromTrustedString(String s)

Returns a SafeUri constructed from a trusted string, i.e., without sanitizing the string. No checks are performed. The calling code should be carefully reviewed to ensure the argument meets the SafeUri contract.

Parameters:

s - the input String

Returns:

a SafeUri instance

isSafeUri

public static boolean isSafeUri(String uri)

Determines if a String is safe to use as the value of a URI-valued HTML attribute such as src or href.

In this context, a URI is safe if it can be established that using it as the value of a URI-valued HTML attribute such as src or href cannot result in script execution. Specifically, this method deems a URI safe if it either does not have a scheme, or its scheme is one of http, https, ftp, mailto.

Parameters:

uri - the URI to validate

Returns:

true if uri is safe in the above sense; false otherwise

sanitizeUri

public static String sanitizeUri(String uri)

Sanitizes a URI.

This method returns the URI provided if it is safe to use as the value of a URI-valued HTML attribute according to isSafeUri(java.lang.String), or the URI "#" otherwise.

Parameters:

uri - the URI to sanitize

Returns:

a sanitized String

unsafeCastFromUntrustedString

@Deprecated
public static SafeUri unsafeCastFromUntrustedString(String s)

Deprecated. This method is intended only for use in APIs that use SafeUri to represent URIs, but for backwards compatibility have methods that accept URI parameters as plain strings.

Returns a SafeUri constructed from an untrusted string but without sanitizing it. Despite this method creating a SafeUri instance, no checks are performed, so the returned SafeUri is absolutely NOT guaranteed to be safe!

Parameters:

s - the input String

Returns:

a SafeUri instance