parser.js (7539B)
1 /* 2 * Copyright (c) 2018 Deepak Kumar 3 * 4 * MIT License 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: 7 * 8 * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 11 * 12 * https://github.com/stomp-js/stompjs 13 * https://github.com/stomp-js/stompjs/blob/develop/src/parser.ts 14 */ 15 16 "use strict"; 17 18 /** 19 * @internal 20 */ 21 const NULL = 0; 22 /** 23 * @internal 24 */ 25 const LF = 10; 26 /** 27 * @internal 28 */ 29 const CR = 13; 30 /** 31 * @internal 32 */ 33 const COLON = 58; 34 /** 35 * This is an evented, rec descent parser. 36 * A stream of Octets can be passed and whenever it recognizes 37 * a complete Frame or an incoming ping it will invoke the registered callbacks. 38 * 39 * All incoming Octets are fed into _onByte function. 40 * Depending on current state the _onByte function keeps changing. 41 * Depending on the state it keeps accumulating into _token and _results. 42 * State is indicated by current value of _onByte, all states are named as _collect. 43 * 44 * STOMP standards https://stomp.github.io/stomp-specification-1.2.html 45 * imply that all lengths are considered in bytes (instead of string lengths). 46 * So, before actual parsing, if the incoming data is String it is converted to Octets. 47 * This allows faithful implementation of the protocol and allows NULL Octets to be present in the body. 48 * 49 * There is no peek function on the incoming data. 50 * When a state change occurs based on an Octet without consuming the Octet, 51 * the Octet, after state change, is fed again (_reinjectByte). 52 * This became possible as the state change can be determined by inspecting just one Octet. 53 * 54 * There are two modes to collect the body, if content-length header is there then it by counting Octets 55 * otherwise it is determined by NULL terminator. 56 * 57 * Following the standards, the command and headers are converted to Strings 58 * and the body is returned as Octets. 59 * Headers are returned as an array and not as Hash - to allow multiple occurrence of an header. 60 * 61 * This parser does not use Regular Expressions as that can only operate on Strings. 62 * 63 * It handles if multiple STOMP frames are given as one chunk, a frame is split into multiple chunks, or 64 * any combination there of. The parser remembers its state (any partial frame) and continues when a new chunk 65 * is pushed. 66 * 67 * Typically the higher level function will convert headers to Hash, handle unescaping of header values 68 * (which is protocol version specific), and convert body to text. 69 * 70 * Check the parser.spec.js to understand cases that this parser is supposed to handle. 71 * 72 * Part of `@stomp/stompjs`. 73 * 74 * @internal 75 */ 76 class Parser { 77 constructor(onFrame, onIncomingPing) { 78 this.onFrame = onFrame; 79 this.onIncomingPing = onIncomingPing; 80 this._encoder = new TextEncoder(); 81 this._decoder = new TextDecoder(); 82 this._token = []; 83 this._initState(); 84 } 85 parseChunk(segment, appendMissingNULLonIncoming = false) { 86 let chunk; 87 if (segment instanceof ArrayBuffer) { 88 chunk = new Uint8Array(segment); 89 } else { 90 chunk = this._encoder.encode(segment); 91 } 92 // See https://github.com/stomp-js/stompjs/issues/89 93 // Remove when underlying issue is fixed. 94 // 95 // Send a NULL byte, if the last byte of a Text frame was not NULL.F 96 if (appendMissingNULLonIncoming && chunk[chunk.length - 1] !== 0) { 97 const chunkWithNull = new Uint8Array(chunk.length + 1); 98 chunkWithNull.set(chunk, 0); 99 chunkWithNull[chunk.length] = 0; 100 chunk = chunkWithNull; 101 } 102 // tslint:disable-next-line:prefer-for-of 103 for (let i = 0; i < chunk.length; i++) { 104 const byte = chunk[i]; 105 this._onByte(byte); 106 } 107 } 108 // The following implements a simple Rec Descent Parser. 109 // The grammar is simple and just one byte tells what should be the next state 110 _collectFrame(byte) { 111 if (byte === NULL) { 112 // Ignore 113 return; 114 } 115 if (byte === CR) { 116 // Ignore CR 117 return; 118 } 119 if (byte === LF) { 120 // Incoming Ping 121 this.onIncomingPing(); 122 return; 123 } 124 this._onByte = this._collectCommand; 125 this._reinjectByte(byte); 126 } 127 _collectCommand(byte) { 128 if (byte === CR) { 129 // Ignore CR 130 return; 131 } 132 if (byte === LF) { 133 this._results.command = this._consumeTokenAsUTF8(); 134 this._onByte = this._collectHeaders; 135 return; 136 } 137 this._consumeByte(byte); 138 } 139 _collectHeaders(byte) { 140 if (byte === CR) { 141 // Ignore CR 142 return; 143 } 144 if (byte === LF) { 145 this._setupCollectBody(); 146 return; 147 } 148 this._onByte = this._collectHeaderKey; 149 this._reinjectByte(byte); 150 } 151 _reinjectByte(byte) { 152 this._onByte(byte); 153 } 154 _collectHeaderKey(byte) { 155 if (byte === COLON) { 156 this._headerKey = this._consumeTokenAsUTF8(); 157 this._onByte = this._collectHeaderValue; 158 return; 159 } 160 this._consumeByte(byte); 161 } 162 _collectHeaderValue(byte) { 163 if (byte === CR) { 164 // Ignore CR 165 return; 166 } 167 if (byte === LF) { 168 this._results.headers.push([this._headerKey, this._consumeTokenAsUTF8()]); 169 this._headerKey = undefined; 170 this._onByte = this._collectHeaders; 171 return; 172 } 173 this._consumeByte(byte); 174 } 175 _setupCollectBody() { 176 const contentLengthHeader = this._results.headers.filter(header => { 177 return header[0] === "content-length"; 178 })[0]; 179 if (contentLengthHeader) { 180 this._bodyBytesRemaining = parseInt(contentLengthHeader[1], 10); 181 this._onByte = this._collectBodyFixedSize; 182 } else { 183 this._onByte = this._collectBodyNullTerminated; 184 } 185 } 186 _collectBodyNullTerminated(byte) { 187 if (byte === NULL) { 188 this._retrievedBody(); 189 return; 190 } 191 this._consumeByte(byte); 192 } 193 _collectBodyFixedSize(byte) { 194 // It is post decrement, so that we discard the trailing NULL octet 195 if (this._bodyBytesRemaining-- === 0) { 196 this._retrievedBody(); 197 return; 198 } 199 this._consumeByte(byte); 200 } 201 _retrievedBody() { 202 this._results.binaryBody = this._consumeTokenAsRaw(); 203 this.onFrame(this._results); 204 this._initState(); 205 } 206 // Rec Descent Parser helpers 207 _consumeByte(byte) { 208 this._token.push(byte); 209 } 210 _consumeTokenAsUTF8() { 211 return this._decoder.decode(this._consumeTokenAsRaw()); 212 } 213 _consumeTokenAsRaw() { 214 const rawResult = new Uint8Array(this._token); 215 this._token = []; 216 return rawResult; 217 } 218 _initState() { 219 this._results = { 220 command: undefined, 221 headers: [], 222 binaryBody: undefined, 223 }; 224 this._token = []; 225 this._headerKey = undefined; 226 this._onByte = this._collectFrame; 227 } 228 } 229 230 module.exports = { Parser };