rlp-decode.js 3.3 KB

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  1. "use strict";
  2. //See: https://github.com/ethereum/wiki/wiki/RLP
  3. Object.defineProperty(exports, "__esModule", { value: true });
  4. exports.decodeRlp = void 0;
  5. const data_js_1 = require("./data.js");
  6. const errors_js_1 = require("./errors.js");
  7. const data_js_2 = require("./data.js");
  8. function hexlifyByte(value) {
  9. let result = value.toString(16);
  10. while (result.length < 2) {
  11. result = "0" + result;
  12. }
  13. return "0x" + result;
  14. }
  15. function unarrayifyInteger(data, offset, length) {
  16. let result = 0;
  17. for (let i = 0; i < length; i++) {
  18. result = (result * 256) + data[offset + i];
  19. }
  20. return result;
  21. }
  22. function _decodeChildren(data, offset, childOffset, length) {
  23. const result = [];
  24. while (childOffset < offset + 1 + length) {
  25. const decoded = _decode(data, childOffset);
  26. result.push(decoded.result);
  27. childOffset += decoded.consumed;
  28. (0, errors_js_1.assert)(childOffset <= offset + 1 + length, "child data too short", "BUFFER_OVERRUN", {
  29. buffer: data, length, offset
  30. });
  31. }
  32. return { consumed: (1 + length), result: result };
  33. }
  34. // returns { consumed: number, result: Object }
  35. function _decode(data, offset) {
  36. (0, errors_js_1.assert)(data.length !== 0, "data too short", "BUFFER_OVERRUN", {
  37. buffer: data, length: 0, offset: 1
  38. });
  39. const checkOffset = (offset) => {
  40. (0, errors_js_1.assert)(offset <= data.length, "data short segment too short", "BUFFER_OVERRUN", {
  41. buffer: data, length: data.length, offset
  42. });
  43. };
  44. // Array with extra length prefix
  45. if (data[offset] >= 0xf8) {
  46. const lengthLength = data[offset] - 0xf7;
  47. checkOffset(offset + 1 + lengthLength);
  48. const length = unarrayifyInteger(data, offset + 1, lengthLength);
  49. checkOffset(offset + 1 + lengthLength + length);
  50. return _decodeChildren(data, offset, offset + 1 + lengthLength, lengthLength + length);
  51. }
  52. else if (data[offset] >= 0xc0) {
  53. const length = data[offset] - 0xc0;
  54. checkOffset(offset + 1 + length);
  55. return _decodeChildren(data, offset, offset + 1, length);
  56. }
  57. else if (data[offset] >= 0xb8) {
  58. const lengthLength = data[offset] - 0xb7;
  59. checkOffset(offset + 1 + lengthLength);
  60. const length = unarrayifyInteger(data, offset + 1, lengthLength);
  61. checkOffset(offset + 1 + lengthLength + length);
  62. const result = (0, data_js_1.hexlify)(data.slice(offset + 1 + lengthLength, offset + 1 + lengthLength + length));
  63. return { consumed: (1 + lengthLength + length), result: result };
  64. }
  65. else if (data[offset] >= 0x80) {
  66. const length = data[offset] - 0x80;
  67. checkOffset(offset + 1 + length);
  68. const result = (0, data_js_1.hexlify)(data.slice(offset + 1, offset + 1 + length));
  69. return { consumed: (1 + length), result: result };
  70. }
  71. return { consumed: 1, result: hexlifyByte(data[offset]) };
  72. }
  73. /**
  74. * Decodes %%data%% into the structured data it represents.
  75. */
  76. function decodeRlp(_data) {
  77. const data = (0, data_js_2.getBytes)(_data, "data");
  78. const decoded = _decode(data, 0);
  79. (0, errors_js_1.assertArgument)(decoded.consumed === data.length, "unexpected junk after rlp payload", "data", _data);
  80. return decoded.result;
  81. }
  82. exports.decodeRlp = decodeRlp;
  83. //# sourceMappingURL=rlp-decode.js.map