Module: Ethereum::ABI

Extended by:
ABI
Includes:
Constant
Included in:
ABI
Defined in:
lib/ethereum/abi.rb,
lib/ethereum/abi/type.rb,
lib/ethereum/abi/version.rb,
lib/ethereum/abi/constant.rb,
lib/ethereum/abi/contract_translator.rb

Overview

Contract ABI encoding and decoding.

See Also:

Defined Under Namespace

Modules: Constant Classes: ContractTranslator, DecodingError, EncodingError, Type, ValueOutOfBounds

Constant Summary collapse

VERSION = 
"0.0.1"

Constants included from Constant

Constant::BYTE_EMPTY, Constant::BYTE_ONE, Constant::BYTE_ZERO, Constant::HASH_ZERO, Constant::INT_MAX, Constant::INT_MIN, Constant::PRIVKEY_ZERO, Constant::PRIVKEY_ZERO_HEX, Constant::PUBKEY_ZERO, Constant::TT256, Constant::TT32, Constant::TT64M1, Constant::UINT_MAX, Constant::UINT_MIN

Instance Method Summary collapse

Instance Method Details

#decode_abi(types, data) ⇒ Object Also known as: decode

Decodes multiple arguments using the head/tail mechanism.

Raises:



170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
 
# File 'lib/ethereum/abi.rb', line 170

def decode_abi(types, data)
  parsed_types = types.map {|t| Type.parse(t) }

  outputs = [nil] * types.size
  start_positions = [nil] * types.size + [data.size]

  # TODO: refactor, a reverse iteration will be better
  pos = 0
  parsed_types.each_with_index do |t, i|
    # If a type is static, grab the data directly, otherwise record its
    # start position
    if t.dynamic?
      start_positions[i] = Utils.big_endian_to_int(data[pos, 32])

      j = i - 1
      while j >= 0 && start_positions[j].nil?
        start_positions[j] = start_positions[i]
        j -= 1
      end

      pos += 32
    else
      outputs[i] = data[pos, t.size]
      pos += t.size
    end
  end

  # We add a start position equal to the length of the entire data for
  # convenience.
  j = types.size - 1
  while j >= 0 && start_positions[j].nil?
    start_positions[j] = start_positions[types.size]
    j -= 1
  end

  raise DecodingError, "Not enough data for head" unless pos <= data.size

  parsed_types.each_with_index do |t, i|
    if t.dynamic?
      offset, next_offset = start_positions[i, 2]
      outputs[i] = data[offset...next_offset]
    end
  end

  parsed_types.zip(outputs).map {|(type, out)| decode_type(type, out) }
end

#decode_primitive_type(type, data) ⇒ Object 



252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
 
# File 'lib/ethereum/abi.rb', line 252

def decode_primitive_type(type, data)
  case type.base
  when 'address'
    Utils.encode_hex data[12..-1]
  when 'string', 'bytes'
    if type.sub.empty? # dynamic
      size = Utils.big_endian_to_int data[0,32]
      data[32..-1][0,size]
    else # fixed
      data[0, type.sub.to_i]
    end
  when 'hash'
    data[(32 - type.sub.to_i), type.sub.to_i]
  when 'uint'
    Utils.big_endian_to_int data
  when 'int'
    u = Utils.big_endian_to_int data
    u >= 2**(type.sub.to_i-1) ? (u - 2**type.sub.to_i) : u
  when 'ureal', 'ufixed'
    high, low = type.sub.split('x').map(&:to_i)
    Utils.big_endian_to_int(data) * 1.0 / 2**low
  when 'real', 'fixed'
    high, low = type.sub.split('x').map(&:to_i)
    u = Utils.big_endian_to_int data
    i = u >= 2**(high+low-1) ? (u - 2**(high+low)) : u
    i * 1.0 / 2**low
  when 'bool'
    data[-1] == BYTE_ONE
  else
    raise DecodingError, "Unknown primitive type: #{type.base}"
  end
end

#decode_type(type, arg) ⇒ Object 



218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
 
# File 'lib/ethereum/abi.rb', line 218

def decode_type(type, arg)
  if %w(string bytes).include?(type.base) && type.sub.empty?
    l = Utils.big_endian_to_int arg[0,32]
    data = arg[32..-1]

    raise DecodingError, "Wrong data size for string/bytes object" unless data.size == Utils.ceil32(l)

    data[0, l]
  elsif type.dynamic?
    l = Utils.big_endian_to_int arg[0,32]
    subtype = type.subtype

    if subtype.dynamic?
      raise DecodingError, "Not enough data for head" unless arg.size >= 32 + 32*l

      start_positions = (1..l).map {|i| Utils.big_endian_to_int arg[32*i, 32] }
      start_positions.push arg.size

      outputs = (0...l).map {|i| arg[start_positions[i]...start_positions[i+1]] }

      outputs.map {|out| decode_type(subtype, out) }
    else
      (0...l).map {|i| decode_type(subtype, arg[32 + subtype.size*i, subtype.size]) }
    end
  elsif !type.dims.empty? # static-sized arrays
    l = type.dims.last[0]
    subtype = type.subtype

    (0...l).map {|i| decode_type(subtype, arg[subtype.size*i, subtype.size]) }
  else
    decode_primitive_type type, arg
  end
end

#encode_abi(types, args) ⇒ Object Also known as: encode

Encodes multiple arguments using the head/tail mechanism.



27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
 
# File 'lib/ethereum/abi.rb', line 27

def encode_abi(types, args)
  parsed_types = types.map {|t| Type.parse(t) }

  head_size = (0...args.size)
    .map {|i| parsed_types[i].size || 32 }
    .reduce(0, &:+)

  head, tail = '', ''
  args.each_with_index do |arg, i|
    if parsed_types[i].dynamic?
      head += encode_type(Type.size_type, head_size + tail.size)
      tail += encode_type(parsed_types[i], arg)
    else
      head += encode_type(parsed_types[i], arg)
    end
  end

  "#{head}#{tail}"
end

#encode_primitive_type(type, arg) ⇒ Object 



95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
 
# File 'lib/ethereum/abi.rb', line 95

def encode_primitive_type(type, arg)
  case type.base
  when 'uint'
    real_size = type.sub.to_i
    i = get_uint arg

    raise ValueOutOfBounds, arg unless i >= 0 && i < 2**real_size
    Utils.zpad_int i
  when 'bool'
    raise ArgumentError, "arg is not bool: #{arg}" unless arg.instance_of?(TrueClass) || arg.instance_of?(FalseClass)
    Utils.zpad_int(arg ? 1: 0)
  when 'int'
    real_size = type.sub.to_i
    i = get_int arg

    raise ValueOutOfBounds, arg unless i >= -2**(real_size-1) && i < 2**(real_size-1)
    Utils.zpad_int(i % 2**type.sub.to_i)
  when 'ureal', 'ufixed'
    high, low = type.sub.split('x').map(&:to_i)

    raise ValueOutOfBounds, arg unless arg >= 0 && arg < 2**high
    Utils.zpad_int((arg * 2**low).to_i)
  when 'real', 'fixed'
    high, low = type.sub.split('x').map(&:to_i)

    raise ValueOutOfBounds, arg unless arg >= -2**(high - 1) && arg < 2**(high - 1)

    i = (arg * 2**low).to_i
    Utils.zpad_int(i % 2**(high+low))
  when 'string', 'bytes'
    raise EncodingError, "Expecting string: #{arg}" unless arg.instance_of?(String)

    if type.sub.empty? # variable length type
      size = Utils.zpad_int arg.size
      padding = BYTE_ZERO * (Utils.ceil32(arg.size) - arg.size)
      "#{size}#{arg}#{padding}"
    else # fixed length type
      raise ValueOutOfBounds, arg unless arg.size <= type.sub.to_i

      padding = BYTE_ZERO * (32 - arg.size)
      "#{arg}#{padding}"
    end
  when 'hash'
    size = type.sub.to_i
    raise EncodingError, "too long: #{arg}" unless size > 0 && size <= 32

    if arg.is_a?(Integer)
      Utils.zpad_int(arg)
    elsif arg.size == size
      Utils.zpad arg, 32
    elsif arg.size == size * 2
      Utils.zpad_hex arg
    else
      raise EncodingError, "Could not parse hash: #{arg}"
    end
  when 'address'
    if arg.is_a?(Integer)
      Utils.zpad_int arg
    elsif arg.size == 20
      Utils.zpad arg, 32
    elsif arg.size == 40
      Utils.zpad_hex arg
    elsif arg.size == 42 && arg[0,2] == '0x'
      Utils.zpad_hex arg[2..-1]
    else
      raise EncodingError, "Could not parse address: #{arg}"
    end
  else
    raise EncodingError, "Unhandled type: #{type.base} #{type.sub}"
  end
end

#encode_type(type, arg) ⇒ String

Encodes a single value (static or dynamic).

Parameters:

Returns:

  • (String) —

    encoded bytes



56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
 
# File 'lib/ethereum/abi.rb', line 56

def encode_type(type, arg)
  if %w(string bytes).include?(type.base) && type.sub.empty?
    raise ArgumentError, "arg must be a string" unless arg.instance_of?(String)

    size = encode_type Type.size_type, arg.size
    padding = BYTE_ZERO * (Utils.ceil32(arg.size) - arg.size)

    "#{size}#{arg}#{padding}"
  elsif type.dynamic?
    raise ArgumentError, "arg must be an array" unless arg.instance_of?(Array)

    head, tail = '', ''
    if type.dims.last == 0
      head += encode_type(Type.size_type, arg.size)
    else
      raise ArgumentError, "Wrong array size: found #{arg.size}, expecting #{type.dims.last}" unless arg.size == type.dims.last
    end

    sub_type = type.subtype
    sub_size = type.subtype.size
    arg.size.times do |i|
      if sub_size.nil?
        head += encode_type(Type.size_type, 32*arg.size + tail.size)
        tail += encode_type(sub_type, arg[i])
      else
        head += encode_type(sub_type, arg[i])
      end
    end

    "#{head}#{tail}"
  else # static type
    if type.dims.empty?
      encode_primitive_type type, arg
    else
      arg.map {|x| encode_type(type.subtype, x) }.join
    end
  end
end