JezK
Edit File: digest_utils.rb
require 'digest/md5' require 'digest/sha1' require 'digest/sha2' require 'set' module Sprockets # Internal: Hash functions and digest related utilities. Mixed into # Environment. module DigestUtils extend self # Internal: Default digest class. # # Returns a Digest::Base subclass. def digest_class Digest::SHA256 end # Internal: Maps digest bytesize to the digest class. DIGEST_SIZES = { 16 => Digest::MD5, 20 => Digest::SHA1, 32 => Digest::SHA256, 48 => Digest::SHA384, 64 => Digest::SHA512 } # 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. def detect_digest_class(bytes) DIGEST_SIZES[bytes.bytesize] end ADD_VALUE_TO_DIGEST = { 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.to_a, digest) }, Encoding => ->(val, digest) { digest << 'Encoding'.freeze digest << val.name }, } if 0.class != Integer # Ruby < 2.4 ADD_VALUE_TO_DIGEST[Fixnum] = ->(val, digest) { digest << 'Integer'.freeze digest << val.to_s } ADD_VALUE_TO_DIGEST[Bignum] = ->(val, digest) { digest << 'Integer'.freeze digest << val.to_s } end ADD_VALUE_TO_DIGEST.default_proc = ->(_, val) { raise TypeError, "couldn't digest #{ val }" } private_constant :ADD_VALUE_TO_DIGEST # 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. def digest(obj) digest = digest_class.new ADD_VALUE_TO_DIGEST[obj.class].call(obj, digest) digest.digest end # Internal: Pack a binary digest to a hex encoded string. # # bin - String bytes # # Returns hex String. def pack_hexdigest(bin) bin.unpack('H*').first end # Internal: Unpack a hex encoded digest string into binary bytes. # # hex - String hex # # Returns binary String. def unpack_hexdigest(hex) [hex].pack('H*') end # Internal: Pack a binary digest to a base64 encoded string. # # bin - String bytes # # Returns base64 String. def pack_base64digest(bin) [bin].pack('m0') end # Internal: Pack a binary digest to a urlsafe base64 encoded string. # # bin - String bytes # # Returns urlsafe base64 String. def pack_urlsafe_base64digest(bin) str = pack_base64digest(bin) str.tr!('+/'.freeze, '-_'.freeze) str.tr!('='.freeze, ''.freeze) str end # Internal: Maps digest class to the CSP hash algorithm name. HASH_ALGORITHMS = { Digest::SHA256 => 'sha256'.freeze, Digest::SHA384 => 'sha384'.freeze, Digest::SHA512 => 'sha512'.freeze } # 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. 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 # 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. def hexdigest_integrity_uri(hexdigest) integrity_uri(unpack_hexdigest(hexdigest)) end end end