Module: Sprockets::DigestUtils

Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Extended In: `::Sprockets`
Included In: `Base`, `CachedEnvironment`, `Configuration`, `Dependencies`, `Environment`, `Loader`, `PathDigestUtils`
Defined in:	lib/sprockets/digest_utils.rb

Overview

Internal: Hash functions and digest related utilities. Mixed into Environment.

Constant Summary

ADD_VALUE_TO_DIGEST = private
# File 'lib/sprockets/digest_utils.rb', line 36

{
  String     => ->(val, digest) { digest << val },
  FalseClass => ->(val, digest) { digest << 'FalseClass'.freeze },
  TrueClass  => ->(val, digest) { digest << 'TrueClass'.freeze  },
  NilClass   => ->(val, digest) { digest << 'NilClass'.freeze   },

  Symbol => ->(val, digest) {
    digest << 'Symbol'.freeze
    digest << val.to_s
  },
  Integer => ->(val, digest) {
    digest << 'Integer'.freeze
    digest << val.to_s
  },
  Array => ->(val, digest) {
    digest << 'Array'.freeze
    val.each do |element|
      ADD_VALUE_TO_DIGEST[element.class].call(element, digest)
    end
  },
  Hash => ->(val, digest) {
    digest << 'Hash'.freeze
    val.sort.each do |array|
      ADD_VALUE_TO_DIGEST[Array].call(array, digest)
    end
  },
  Set => ->(val, digest) {
    digest << 'Set'.freeze
    ADD_VALUE_TO_DIGEST[Array].call(val, digest)
  },
  Encoding => ->(val, digest) {
    digest << 'Encoding'.freeze
    digest << val.name
  }
}

DIGEST_SIZES =

Internal: Maps digest bytesize to the digest class.

# File 'lib/sprockets/digest_utils.rb', line 20

{
  20 => Digest::SHA1,
  32 => Digest::SHA256,
  48 => Digest::SHA384,
  64 => Digest::SHA512
}

HASH_ALGORITHMS =

Internal: Maps digest class to the CSP hash algorithm name.

# File 'lib/sprockets/digest_utils.rb', line 142

{
  Digest::SHA256 => 'sha256'.freeze,
  Digest::SHA384 => 'sha384'.freeze,
  Digest::SHA512 => 'sha512'.freeze
}

Instance Method Summary

#already_digested?(name) ⇒ Boolean

Internal: Checks an asset name for a valid digest.
#detect_digest_class(bytes)

Internal: Detect digest class hash algorithm for digest bytes.
#digest(obj)

Internal: Generate a hexdigest for a nested JSON serializable object.
#digest_class

Internal: Default digest class.
#hexdigest(obj)

Internal: Generate a hexdigest for a nested JSON serializable object.
#hexdigest_integrity_uri(hexdigest)

Public: Generate hash for use in the integrity attribute of an asset tag as per the subresource integrity specification.
#integrity_uri(digest)

Public: Generate hash for use in the integrity attribute of an asset tag as per the subresource integrity specification.
#pack_base64digest(bin)

Internal: Pack a binary digest to a base64 encoded string.
#pack_hexdigest(bin)

Internal: Pack a binary digest to a hex encoded string.
#pack_urlsafe_base64digest(bin)

Internal: Pack a binary digest to a urlsafe base64 encoded string.
#unpack_hexdigest(hex)

Internal: Unpack a hex encoded digest string into binary bytes.
#build_digest(obj) private

Instance Method Details

#already_digested?(name) ⇒ `Boolean`

Internal: Checks an asset name for a valid digest

name - The name of the asset

Returns true if the name contains a digest like string and .digested before the extension

[ GitHub ]

# File 'lib/sprockets/digest_utils.rb', line 185


def already_digested?(name)
  return name =~ /-([0-9a-zA-Z]{7,128})\.digested/
end

#build_digest(obj) (private)

[ GitHub ]

# File 'lib/sprockets/digest_utils.rb', line 190


def build_digest(obj)
  digest = digest_class.new

  ADD_VALUE_TO_DIGEST[obj.class].call(obj, digest)
  digest
end

#detect_digest_class(bytes)

Internal: Detect digest class hash algorithm for digest bytes.

While not elegant, all the supported digests have a unique bytesize.

Returns Digest::Base or nil.

[ GitHub ]

# File 'lib/sprockets/digest_utils.rb', line 32


def detect_digest_class(bytes)
  DIGEST_SIZES[bytes.bytesize]
end

#digest(obj)

Internal: Generate a hexdigest for a nested JSON serializable object.

This is used for generating cache keys, so its pretty important its wicked fast. Microbenchmarks away!

obj - A JSON serializable object.

Returns a String digest of the object.

[ GitHub ]

# File 'lib/sprockets/digest_utils.rb', line 87


def digest(obj)
  build_digest(obj).digest
end

#digest_class

Internal: Default digest class.

Returns a Digest::Base subclass.

[ GitHub ]

# File 'lib/sprockets/digest_utils.rb', line 15


def digest_class
  Digest::SHA256
end

#hexdigest(obj)

Internal: Generate a hexdigest for a nested JSON serializable object.

The same as pack_hexdigest(digest(obj)).

obj - A JSON serializable object.

Returns a String digest of the object.

[ GitHub ]

# File 'lib/sprockets/digest_utils.rb', line 98


def hexdigest(obj)
  build_digest(obj).hexdigest!
end

#hexdigest_integrity_uri(hexdigest)

Public: Generate hash for use in the integrity attribute of an asset tag as per the subresource integrity specification.

digest - The String hexbyte digest of the asset content.

Returns a String or nil if hash algorithm is incompatible.

[ GitHub ]

# File 'lib/sprockets/digest_utils.rb', line 176


def hexdigest_integrity_uri(hexdigest)
  integrity_uri(unpack_hexdigest(hexdigest))
end

#integrity_uri(digest)

Public: Generate hash for use in the integrity attribute of an asset tag as per the subresource integrity specification.

digest - The String byte digest of the asset content.

Returns a String or nil if hash algorithm is incompatible.

[ GitHub ]

# File 'lib/sprockets/digest_utils.rb', line 154


def integrity_uri(digest)
  case digest
  when Digest::Base
    digest_class = digest.class
    digest = digest.digest
  when String
    digest_class = DIGEST_SIZES[digest.bytesize]
  else
    raise TypeError, "unknown digest: #{digest.inspect}"
  end

  if hash_name = HASH_ALGORITHMS[digest_class]
    "#{hash_name}-#{pack_base64digest(digest)}"
  end
end

#pack_base64digest(bin)

Internal: Pack a binary digest to a base64 encoded string.

bin - String bytes

Returns base64 String.

[ GitHub ]

# File 'lib/sprockets/digest_utils.rb', line 125


def pack_base64digest(bin)
  [bin].pack('m0')
end

#pack_hexdigest(bin)

Internal: Pack a binary digest to a hex encoded string.

bin - String bytes

Returns hex String.

[ GitHub ]

# File 'lib/sprockets/digest_utils.rb', line 107


def pack_hexdigest(bin)
  bin.unpack('H*'.freeze).first
end

#pack_urlsafe_base64digest(bin)

Internal: Pack a binary digest to a urlsafe base64 encoded string.

bin - String bytes

Returns urlsafe base64 String.

[ GitHub ]

# File 'lib/sprockets/digest_utils.rb', line 134


def pack_urlsafe_base64digest(bin)
  str = pack_base64digest(bin)
  str.tr!('+/'.freeze, '-_'.freeze)
  str.tr!('='.freeze, ''.freeze)
  str
end

#unpack_hexdigest(hex)

Internal: Unpack a hex encoded digest string into binary bytes.

hex - String hex

Returns binary String.

[ GitHub ]

# File 'lib/sprockets/digest_utils.rb', line 116


def unpack_hexdigest(hex)
  [hex].pack('H*')
end

Module: Sprockets::DigestUtils

Overview

Constant Summary

Instance Method Summary

Instance Method Details

#already_digested?(name) ⇒ Boolean

#build_digest(obj) (private)

#detect_digest_class(bytes)

#digest(obj)

#digest_class

#hexdigest(obj)

#hexdigest_integrity_uri(hexdigest)

#integrity_uri(digest)

#pack_base64digest(bin)

#pack_hexdigest(bin)

#pack_urlsafe_base64digest(bin)

#unpack_hexdigest(hex)

#already_digested?(name) ⇒ `Boolean`