index.js 6.3 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156
  1. import { encodePacket, encodePacketToBinary } from "./encodePacket.js";
  2. import { decodePacket } from "./decodePacket.js";
  3. import { ERROR_PACKET, } from "./commons.js";
  4. const SEPARATOR = String.fromCharCode(30); // see https://en.wikipedia.org/wiki/Delimiter#ASCII_delimited_text
  5. const encodePayload = (packets, callback) => {
  6. // some packets may be added to the array while encoding, so the initial length must be saved
  7. const length = packets.length;
  8. const encodedPackets = new Array(length);
  9. let count = 0;
  10. packets.forEach((packet, i) => {
  11. // force base64 encoding for binary packets
  12. encodePacket(packet, false, (encodedPacket) => {
  13. encodedPackets[i] = encodedPacket;
  14. if (++count === length) {
  15. callback(encodedPackets.join(SEPARATOR));
  16. }
  17. });
  18. });
  19. };
  20. const decodePayload = (encodedPayload, binaryType) => {
  21. const encodedPackets = encodedPayload.split(SEPARATOR);
  22. const packets = [];
  23. for (let i = 0; i < encodedPackets.length; i++) {
  24. const decodedPacket = decodePacket(encodedPackets[i], binaryType);
  25. packets.push(decodedPacket);
  26. if (decodedPacket.type === "error") {
  27. break;
  28. }
  29. }
  30. return packets;
  31. };
  32. export function createPacketEncoderStream() {
  33. return new TransformStream({
  34. transform(packet, controller) {
  35. encodePacketToBinary(packet, (encodedPacket) => {
  36. const payloadLength = encodedPacket.length;
  37. let header;
  38. // inspired by the WebSocket format: https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API/Writing_WebSocket_servers#decoding_payload_length
  39. if (payloadLength < 126) {
  40. header = new Uint8Array(1);
  41. new DataView(header.buffer).setUint8(0, payloadLength);
  42. }
  43. else if (payloadLength < 65536) {
  44. header = new Uint8Array(3);
  45. const view = new DataView(header.buffer);
  46. view.setUint8(0, 126);
  47. view.setUint16(1, payloadLength);
  48. }
  49. else {
  50. header = new Uint8Array(9);
  51. const view = new DataView(header.buffer);
  52. view.setUint8(0, 127);
  53. view.setBigUint64(1, BigInt(payloadLength));
  54. }
  55. // first bit indicates whether the payload is plain text (0) or binary (1)
  56. if (packet.data && typeof packet.data !== "string") {
  57. header[0] |= 0x80;
  58. }
  59. controller.enqueue(header);
  60. controller.enqueue(encodedPacket);
  61. });
  62. },
  63. });
  64. }
  65. let TEXT_DECODER;
  66. function totalLength(chunks) {
  67. return chunks.reduce((acc, chunk) => acc + chunk.length, 0);
  68. }
  69. function concatChunks(chunks, size) {
  70. if (chunks[0].length === size) {
  71. return chunks.shift();
  72. }
  73. const buffer = new Uint8Array(size);
  74. let j = 0;
  75. for (let i = 0; i < size; i++) {
  76. buffer[i] = chunks[0][j++];
  77. if (j === chunks[0].length) {
  78. chunks.shift();
  79. j = 0;
  80. }
  81. }
  82. if (chunks.length && j < chunks[0].length) {
  83. chunks[0] = chunks[0].slice(j);
  84. }
  85. return buffer;
  86. }
  87. export function createPacketDecoderStream(maxPayload, binaryType) {
  88. if (!TEXT_DECODER) {
  89. TEXT_DECODER = new TextDecoder();
  90. }
  91. const chunks = [];
  92. let state = 0 /* State.READ_HEADER */;
  93. let expectedLength = -1;
  94. let isBinary = false;
  95. return new TransformStream({
  96. transform(chunk, controller) {
  97. chunks.push(chunk);
  98. while (true) {
  99. if (state === 0 /* State.READ_HEADER */) {
  100. if (totalLength(chunks) < 1) {
  101. break;
  102. }
  103. const header = concatChunks(chunks, 1);
  104. isBinary = (header[0] & 0x80) === 0x80;
  105. expectedLength = header[0] & 0x7f;
  106. if (expectedLength < 126) {
  107. state = 3 /* State.READ_PAYLOAD */;
  108. }
  109. else if (expectedLength === 126) {
  110. state = 1 /* State.READ_EXTENDED_LENGTH_16 */;
  111. }
  112. else {
  113. state = 2 /* State.READ_EXTENDED_LENGTH_64 */;
  114. }
  115. }
  116. else if (state === 1 /* State.READ_EXTENDED_LENGTH_16 */) {
  117. if (totalLength(chunks) < 2) {
  118. break;
  119. }
  120. const headerArray = concatChunks(chunks, 2);
  121. expectedLength = new DataView(headerArray.buffer, headerArray.byteOffset, headerArray.length).getUint16(0);
  122. state = 3 /* State.READ_PAYLOAD */;
  123. }
  124. else if (state === 2 /* State.READ_EXTENDED_LENGTH_64 */) {
  125. if (totalLength(chunks) < 8) {
  126. break;
  127. }
  128. const headerArray = concatChunks(chunks, 8);
  129. const view = new DataView(headerArray.buffer, headerArray.byteOffset, headerArray.length);
  130. const n = view.getUint32(0);
  131. if (n > Math.pow(2, 53 - 32) - 1) {
  132. // the maximum safe integer in JavaScript is 2^53 - 1
  133. controller.enqueue(ERROR_PACKET);
  134. break;
  135. }
  136. expectedLength = n * Math.pow(2, 32) + view.getUint32(4);
  137. state = 3 /* State.READ_PAYLOAD */;
  138. }
  139. else {
  140. if (totalLength(chunks) < expectedLength) {
  141. break;
  142. }
  143. const data = concatChunks(chunks, expectedLength);
  144. controller.enqueue(decodePacket(isBinary ? data : TEXT_DECODER.decode(data), binaryType));
  145. state = 0 /* State.READ_HEADER */;
  146. }
  147. if (expectedLength === 0 || expectedLength > maxPayload) {
  148. controller.enqueue(ERROR_PACKET);
  149. break;
  150. }
  151. }
  152. },
  153. });
  154. }
  155. export const protocol = 4;
  156. export { encodePacket, encodePayload, decodePacket, decodePayload, };