Copyright	(c) 2015 Ben Hamilton
License	BSD-style
Maintainer	bgertzfield@gmail.com
Stability	experimental
Portability	GHC
Safe Haskell	None
Language	Haskell98

Data.Text.ICU.Spoof

Contents

Unicode spoof checking API
Functions

Description

String spoofing (confusability) checks for Unicode, implemented as bindings to the International Components for Unicode (ICU) uspoof library.

See UTR #36 and UTS #39 for detailed information about the underlying algorithms and databases used by this module.

Synopsis

data MSpoof
data OpenFromSourceParseError = OpenFromSourceParseError {
- errFile :: OpenFromSourceParseErrorFile
- parseError :: ParseError
}
data SpoofCheck
- = SingleScriptConfusable
- | MixedScriptConfusable
- | WholeScriptConfusable
- | AnyCase
- | RestrictionLevel
- | Invisible
- | CharLimit
- | MixedNumbers
- | AllChecks
- | AuxInfo
data SpoofCheckResult
- = CheckOK
- | CheckFailed [SpoofCheck]
- | CheckFailedWithRestrictionLevel {
  - failedChecks :: [SpoofCheck]
  - failedLevel :: RestrictionLevel
  }
data RestrictionLevel
data SkeletonTypeOverride
- = SkeletonSingleScript
- | SkeletonAnyCase
open :: IO MSpoof
openFromSerialized :: ByteString -> IO MSpoof
openFromSource :: (ByteString, ByteString) -> IO MSpoof
getSkeleton :: MSpoof -> Maybe SkeletonTypeOverride -> Text -> IO Text
getChecks :: MSpoof -> IO [SpoofCheck]
setChecks :: MSpoof -> [SpoofCheck] -> IO ()
getRestrictionLevel :: MSpoof -> IO (Maybe RestrictionLevel)
setRestrictionLevel :: MSpoof -> RestrictionLevel -> IO ()
getAllowedLocales :: MSpoof -> IO [String]
setAllowedLocales :: MSpoof -> [String] -> IO ()
areConfusable :: MSpoof -> Text -> Text -> IO SpoofCheckResult
spoofCheck :: MSpoof -> Text -> IO SpoofCheckResult
serialize :: MSpoof -> IO ByteString

Unicode spoof checking API

The spoofCheck, areConfusable, and getSkeleton functions analyze Unicode text for visually confusable (or "spoof") characters.

For example, Latin, Cyrillic, and Greek all contain unique Unicode values which appear nearly identical on-screen:

     A    0041    LATIN CAPITAL LETTER A
     Α    0391    GREEK CAPITAL LETTER ALPHA
     А    0410    CYRILLIC CAPITAL LETTER A
     Ꭺ    13AA    CHEROKEE LETTER GO
     ᴀ    1D00    LATIN LETTER SMALL CAPITAL A
     ᗅ    15C5    CANADIAN SYLLABICS CARRIER GHO
     Ａ    FF21    FULLWIDTH LATIN CAPITAL LETTER A
     𐊠    102A0   CARIAN LETTER A
     𝐀    1D400   MATHEMATICAL BOLD CAPITAL A

and so on. To check a string for visually confusable characters:

open an MSpoof
optionally configure it with setChecks, setRestrictionLevel, and/or setAllowedLocales, then
spoofCheck a single string, use areConfusable to check if two strings could be confused for each other, or use getSkeleton to precompute a "skeleton" string (similar to a hash code) which can be cached and re-used to quickly check (using Unicode string comparison) if two strings are confusable.

By default, these methods will use ICU's bundled copy of confusables.txt and confusablesWholeScript.txt, which could be out of date. To provide your own confusables databases, use openFromSource. (To avoid repeatedly parsing these databases, you can then serialize your configured MSpoof and later openFromSerialized to load the pre-parsed databases.)

data MSpoof #

Configurable spoof checker wrapping an opaque handle and optionally wrapping a previously serialized instance.

data OpenFromSourceParseError #

Exception thrown with openFromSource fails to parse one of the input files.

Constructors

OpenFromSourceParseError
Fields errFile :: OpenFromSourceParseErrorFile The file which could not be parsed. parseError :: ParseError Parse error encountered opening a spoof checker from source.

Instances

Instances details

Show OpenFromSourceParseError #
Instance details Defined in Data.Text.ICU.Spoof Methods showsPrec :: Int -> OpenFromSourceParseError -> ShowS # show :: OpenFromSourceParseError -> String # showList :: [OpenFromSourceParseError] -> ShowS #
Exception OpenFromSourceParseError #
Instance details Defined in Data.Text.ICU.Spoof Methods toException :: OpenFromSourceParseError -> SomeException # fromException :: SomeException -> Maybe OpenFromSourceParseError # displayException :: OpenFromSourceParseError -> String #
NFData OpenFromSourceParseError #
Instance details Defined in Data.Text.ICU.Spoof Methods rnf :: OpenFromSourceParseError -> () #

data SpoofCheck #

Constructors

SingleScriptConfusable	Makes `areConfusable` report if both identifiers are both from the same script and are visually confusable. Does not affect `spoofCheck`.
MixedScriptConfusable	Makes `areConfusable` report if both identifiers are visually confusable and at least one identifier contains characters from more than one script. Makes `spoofCheck` report if the identifier contains multiple scripts, and is confusable with some other identifier in a single script.
WholeScriptConfusable	Makes `areConfusable` report if each identifier is of a different single script, and the identifiers are visually confusable.
AnyCase	By default, spoof checks assume the strings have been processed through `toCaseFold` and only check lower-case identifiers. If this is set, spoof checks will check both upper and lower case identifiers.
RestrictionLevel	Checks that identifiers are no looser than the specified level passed to `setRestrictionLevel`.
Invisible	Checks the identifier for the presence of invisible characters, such as zero-width spaces, or character sequences that are likely not to display, such as multiple occurrences of the same non-spacing mark.
CharLimit	Checks whether the identifier contains only characters from a specified set (for example, via `setAllowedLocales`).
MixedNumbers	Checks that the identifier contains numbers from only a single script.
AllChecks	Enables all checks.
AuxInfo	Enables returning a `RestrictionLevel` in the `SpoofCheckResult`.

Instances

Instances details

Bounded SpoofCheck #
Instance details Defined in Data.Text.ICU.Spoof Methods minBound :: SpoofCheck # maxBound :: SpoofCheck #
Enum SpoofCheck #
Instance details Defined in Data.Text.ICU.Spoof Methods succ :: SpoofCheck -> SpoofCheck # pred :: SpoofCheck -> SpoofCheck # toEnum :: Int -> SpoofCheck # fromEnum :: SpoofCheck -> Int # enumFrom :: SpoofCheck -> [SpoofCheck] # enumFromThen :: SpoofCheck -> SpoofCheck -> [SpoofCheck] # enumFromTo :: SpoofCheck -> SpoofCheck -> [SpoofCheck] # enumFromThenTo :: SpoofCheck -> SpoofCheck -> SpoofCheck -> [SpoofCheck] #
Eq SpoofCheck #
Instance details Defined in Data.Text.ICU.Spoof Methods (==) :: SpoofCheck -> SpoofCheck -> Bool # (/=) :: SpoofCheck -> SpoofCheck -> Bool #
Show SpoofCheck #
Instance details Defined in Data.Text.ICU.Spoof Methods showsPrec :: Int -> SpoofCheck -> ShowS # show :: SpoofCheck -> String # showList :: [SpoofCheck] -> ShowS #

data SpoofCheckResult #

Constructors

CheckOK	The string passed all configured spoof checks.
CheckFailed [SpoofCheck]	The string failed one or more spoof checks.
CheckFailedWithRestrictionLevel	The string failed one or more spoof checks, and failed to pass the configured restriction level.
Fields failedChecks :: [SpoofCheck] The spoof checks which the string failed. failedLevel :: RestrictionLevel The restriction level which the string failed to pass.

Instances

Instances details

Eq SpoofCheckResult #
Instance details Defined in Data.Text.ICU.Spoof Methods (==) :: SpoofCheckResult -> SpoofCheckResult -> Bool # (/=) :: SpoofCheckResult -> SpoofCheckResult -> Bool #
Show SpoofCheckResult #
Instance details Defined in Data.Text.ICU.Spoof Methods showsPrec :: Int -> SpoofCheckResult -> ShowS # show :: SpoofCheckResult -> String # showList :: [SpoofCheckResult] -> ShowS #

data RestrictionLevel #

Constructors

ASCII	Checks that the string contains only Unicode values in the range ߝ inclusive.
SingleScriptRestrictive	Checks that the string contains only characters from a single script.
HighlyRestrictive	Checks that the string contains only characters from a single script, or from the combinations (Latin + Han + Hiragana + Katakana), (Latin + Han + Bopomofo), or (Latin + Han + Hangul).
ModeratelyRestrictive	Checks that the string contains only characters from the combinations (Latin + Cyrillic + Greek + Cherokee), (Latin + Han + Hiragana + Katakana), (Latin + Han + Bopomofo), or (Latin + Han + Hangul).
MinimallyRestrictive	Allows arbitrary mixtures of scripts.
Unrestrictive	Allows any valid identifiers, including characters outside of the Identifier Profile.

Instances

Instances details

Bounded RestrictionLevel #
Instance details Defined in Data.Text.ICU.Spoof Methods minBound :: RestrictionLevel # maxBound :: RestrictionLevel #
Enum RestrictionLevel #
Instance details Defined in Data.Text.ICU.Spoof Methods succ :: RestrictionLevel -> RestrictionLevel # pred :: RestrictionLevel -> RestrictionLevel # toEnum :: Int -> RestrictionLevel # fromEnum :: RestrictionLevel -> Int # enumFrom :: RestrictionLevel -> [RestrictionLevel] # enumFromThen :: RestrictionLevel -> RestrictionLevel -> [RestrictionLevel] # enumFromTo :: RestrictionLevel -> RestrictionLevel -> [RestrictionLevel] # enumFromThenTo :: RestrictionLevel -> RestrictionLevel -> RestrictionLevel -> [RestrictionLevel] #
Eq RestrictionLevel #
Instance details Defined in Data.Text.ICU.Spoof Methods (==) :: RestrictionLevel -> RestrictionLevel -> Bool # (/=) :: RestrictionLevel -> RestrictionLevel -> Bool #
Show RestrictionLevel #
Instance details Defined in Data.Text.ICU.Spoof Methods showsPrec :: Int -> RestrictionLevel -> ShowS # show :: RestrictionLevel -> String # showList :: [RestrictionLevel] -> ShowS #

data SkeletonTypeOverride #

Constructors

SkeletonSingleScript	By default, `getSkeleton` builds skeletons which catch visually confusable characters across multiple scripts. Pass this flag to override that behavior and build skeletons which catch visually confusable characters across single scripts.
SkeletonAnyCase	By default, `getSkeleton` assumes the input string has already been passed through `toCaseFold` and is lower-case. Pass this flag to override that behavior and allow upper and lower-case strings.

Instances

Instances details

Bounded SkeletonTypeOverride #
Instance details Defined in Data.Text.ICU.Spoof Methods minBound :: SkeletonTypeOverride # maxBound :: SkeletonTypeOverride #
Enum SkeletonTypeOverride #
Instance details Defined in Data.Text.ICU.Spoof Methods succ :: SkeletonTypeOverride -> SkeletonTypeOverride # pred :: SkeletonTypeOverride -> SkeletonTypeOverride # toEnum :: Int -> SkeletonTypeOverride # fromEnum :: SkeletonTypeOverride -> Int # enumFrom :: SkeletonTypeOverride -> [SkeletonTypeOverride] # enumFromThen :: SkeletonTypeOverride -> SkeletonTypeOverride -> [SkeletonTypeOverride] # enumFromTo :: SkeletonTypeOverride -> SkeletonTypeOverride -> [SkeletonTypeOverride] # enumFromThenTo :: SkeletonTypeOverride -> SkeletonTypeOverride -> SkeletonTypeOverride -> [SkeletonTypeOverride] #
Eq SkeletonTypeOverride #
Instance details Defined in Data.Text.ICU.Spoof Methods (==) :: SkeletonTypeOverride -> SkeletonTypeOverride -> Bool # (/=) :: SkeletonTypeOverride -> SkeletonTypeOverride -> Bool #
Show SkeletonTypeOverride #
Instance details Defined in Data.Text.ICU.Spoof Methods showsPrec :: Int -> SkeletonTypeOverride -> ShowS # show :: SkeletonTypeOverride -> String # showList :: [SkeletonTypeOverride] -> ShowS #

Functions

open :: IO MSpoof #

Open a spoof checker for checking Unicode strings for lookalike security issues with default options (all SpoofChecks except CharLimit).

openFromSerialized :: ByteString -> IO MSpoof #

Open a spoof checker previously serialized to bytes using serialize. The returned MSpoof will retain a reference to the ForeignPtr inside the ByteString, so ensure its contents do not change for the lifetime of the lifetime of the returned value.

openFromSource :: (ByteString, ByteString) -> IO MSpoof #

Open a spoof checker with custom rules given the UTF-8 encoded contents of the confusables.txt and confusablesWholeScript.txt files as described in Unicode UAX #39.

getSkeleton :: MSpoof -> Maybe SkeletonTypeOverride -> Text -> IO Text #

Generates re-usable "skeleton" strings which can be used (via Unicode equality) to check if an identifier is confusable with some large set of existing identifiers.

If you cache the returned strings in storage, you must invalidate your cache any time the underlying confusables database changes (i.e., on ICU upgrade).

By default, assumes all input strings have been passed through toCaseFold and are lower-case. To change this, pass SkeletonAnyCase.

By default, builds skeletons which catch visually confusable characters across multiple scripts. Pass SkeletonSingleScript to override that behavior and build skeletons which catch visually confusable characters across single scripts.

getChecks :: MSpoof -> IO [SpoofCheck] #

Get the checks performed by a spoof checker.

setChecks :: MSpoof -> [SpoofCheck] -> IO () #

Configure the checks performed by a spoof checker.

getRestrictionLevel :: MSpoof -> IO (Maybe RestrictionLevel) #

Get the restriction level of a spoof checker.

setRestrictionLevel :: MSpoof -> RestrictionLevel -> IO () #

Configure the restriction level of a spoof checker.

getAllowedLocales :: MSpoof -> IO [String] #

Get the list of locale names allowed to be used with a spoof checker. (We don't use LocaleName since the root and default locales have no meaning here.)

setAllowedLocales :: MSpoof -> [String] -> IO () #

Get the list of locale names allowed to be used with a spoof checker. (We don't use LocaleName since the root and default locales have no meaning here.)

areConfusable :: MSpoof -> Text -> Text -> IO SpoofCheckResult #

Check if two strings could be confused with each other.

spoofCheck :: MSpoof -> Text -> IO SpoofCheckResult #

Checks if a string could be confused with any other.

serialize :: MSpoof -> IO ByteString #

Serializes the rules in this spoof checker to a byte array, suitable for re-use by openFromSerialized.

Only includes any data provided to openFromSource. Does not include any other state or configuration.