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Diffstat (limited to 'vanilla/node_modules/undici/lib/web/eventsource/eventsource-stream.js')
| -rw-r--r-- | vanilla/node_modules/undici/lib/web/eventsource/eventsource-stream.js | 399 |
1 files changed, 399 insertions, 0 deletions
diff --git a/vanilla/node_modules/undici/lib/web/eventsource/eventsource-stream.js b/vanilla/node_modules/undici/lib/web/eventsource/eventsource-stream.js new file mode 100644 index 0000000..d24e8f6 --- /dev/null +++ b/vanilla/node_modules/undici/lib/web/eventsource/eventsource-stream.js @@ -0,0 +1,399 @@ +'use strict' +const { Transform } = require('node:stream') +const { isASCIINumber, isValidLastEventId } = require('./util') + +/** + * @type {number[]} BOM + */ +const BOM = [0xEF, 0xBB, 0xBF] +/** + * @type {10} LF + */ +const LF = 0x0A +/** + * @type {13} CR + */ +const CR = 0x0D +/** + * @type {58} COLON + */ +const COLON = 0x3A +/** + * @type {32} SPACE + */ +const SPACE = 0x20 + +/** + * @typedef {object} EventSourceStreamEvent + * @type {object} + * @property {string} [event] The event type. + * @property {string} [data] The data of the message. + * @property {string} [id] A unique ID for the event. + * @property {string} [retry] The reconnection time, in milliseconds. + */ + +/** + * @typedef eventSourceSettings + * @type {object} + * @property {string} [lastEventId] The last event ID received from the server. + * @property {string} [origin] The origin of the event source. + * @property {number} [reconnectionTime] The reconnection time, in milliseconds. + */ + +class EventSourceStream extends Transform { + /** + * @type {eventSourceSettings} + */ + state + + /** + * Leading byte-order-mark check. + * @type {boolean} + */ + checkBOM = true + + /** + * @type {boolean} + */ + crlfCheck = false + + /** + * @type {boolean} + */ + eventEndCheck = false + + /** + * @type {Buffer|null} + */ + buffer = null + + pos = 0 + + event = { + data: undefined, + event: undefined, + id: undefined, + retry: undefined + } + + /** + * @param {object} options + * @param {boolean} [options.readableObjectMode] + * @param {eventSourceSettings} [options.eventSourceSettings] + * @param {(chunk: any, encoding?: BufferEncoding | undefined) => boolean} [options.push] + */ + constructor (options = {}) { + // Enable object mode as EventSourceStream emits objects of shape + // EventSourceStreamEvent + options.readableObjectMode = true + + super(options) + + this.state = options.eventSourceSettings || {} + if (options.push) { + this.push = options.push + } + } + + /** + * @param {Buffer} chunk + * @param {string} _encoding + * @param {Function} callback + * @returns {void} + */ + _transform (chunk, _encoding, callback) { + if (chunk.length === 0) { + callback() + return + } + + // Cache the chunk in the buffer, as the data might not be complete while + // processing it + // TODO: Investigate if there is a more performant way to handle + // incoming chunks + // see: https://github.com/nodejs/undici/issues/2630 + if (this.buffer) { + this.buffer = Buffer.concat([this.buffer, chunk]) + } else { + this.buffer = chunk + } + + // Strip leading byte-order-mark if we opened the stream and started + // the processing of the incoming data + if (this.checkBOM) { + switch (this.buffer.length) { + case 1: + // Check if the first byte is the same as the first byte of the BOM + if (this.buffer[0] === BOM[0]) { + // If it is, we need to wait for more data + callback() + return + } + // Set the checkBOM flag to false as we don't need to check for the + // BOM anymore + this.checkBOM = false + + // The buffer only contains one byte so we need to wait for more data + callback() + return + case 2: + // Check if the first two bytes are the same as the first two bytes + // of the BOM + if ( + this.buffer[0] === BOM[0] && + this.buffer[1] === BOM[1] + ) { + // If it is, we need to wait for more data, because the third byte + // is needed to determine if it is the BOM or not + callback() + return + } + + // Set the checkBOM flag to false as we don't need to check for the + // BOM anymore + this.checkBOM = false + break + case 3: + // Check if the first three bytes are the same as the first three + // bytes of the BOM + if ( + this.buffer[0] === BOM[0] && + this.buffer[1] === BOM[1] && + this.buffer[2] === BOM[2] + ) { + // If it is, we can drop the buffered data, as it is only the BOM + this.buffer = Buffer.alloc(0) + // Set the checkBOM flag to false as we don't need to check for the + // BOM anymore + this.checkBOM = false + + // Await more data + callback() + return + } + // If it is not the BOM, we can start processing the data + this.checkBOM = false + break + default: + // The buffer is longer than 3 bytes, so we can drop the BOM if it is + // present + if ( + this.buffer[0] === BOM[0] && + this.buffer[1] === BOM[1] && + this.buffer[2] === BOM[2] + ) { + // Remove the BOM from the buffer + this.buffer = this.buffer.subarray(3) + } + + // Set the checkBOM flag to false as we don't need to check for the + this.checkBOM = false + break + } + } + + while (this.pos < this.buffer.length) { + // If the previous line ended with an end-of-line, we need to check + // if the next character is also an end-of-line. + if (this.eventEndCheck) { + // If the the current character is an end-of-line, then the event + // is finished and we can process it + + // If the previous line ended with a carriage return, we need to + // check if the current character is a line feed and remove it + // from the buffer. + if (this.crlfCheck) { + // If the current character is a line feed, we can remove it + // from the buffer and reset the crlfCheck flag + if (this.buffer[this.pos] === LF) { + this.buffer = this.buffer.subarray(this.pos + 1) + this.pos = 0 + this.crlfCheck = false + + // It is possible that the line feed is not the end of the + // event. We need to check if the next character is an + // end-of-line character to determine if the event is + // finished. We simply continue the loop to check the next + // character. + + // As we removed the line feed from the buffer and set the + // crlfCheck flag to false, we basically don't make any + // distinction between a line feed and a carriage return. + continue + } + this.crlfCheck = false + } + + if (this.buffer[this.pos] === LF || this.buffer[this.pos] === CR) { + // If the current character is a carriage return, we need to + // set the crlfCheck flag to true, as we need to check if the + // next character is a line feed so we can remove it from the + // buffer + if (this.buffer[this.pos] === CR) { + this.crlfCheck = true + } + + this.buffer = this.buffer.subarray(this.pos + 1) + this.pos = 0 + if ( + this.event.data !== undefined || this.event.event || this.event.id !== undefined || this.event.retry) { + this.processEvent(this.event) + } + this.clearEvent() + continue + } + // If the current character is not an end-of-line, then the event + // is not finished and we have to reset the eventEndCheck flag + this.eventEndCheck = false + continue + } + + // If the current character is an end-of-line, we can process the + // line + if (this.buffer[this.pos] === LF || this.buffer[this.pos] === CR) { + // If the current character is a carriage return, we need to + // set the crlfCheck flag to true, as we need to check if the + // next character is a line feed + if (this.buffer[this.pos] === CR) { + this.crlfCheck = true + } + + // In any case, we can process the line as we reached an + // end-of-line character + this.parseLine(this.buffer.subarray(0, this.pos), this.event) + + // Remove the processed line from the buffer + this.buffer = this.buffer.subarray(this.pos + 1) + // Reset the position as we removed the processed line from the buffer + this.pos = 0 + // A line was processed and this could be the end of the event. We need + // to check if the next line is empty to determine if the event is + // finished. + this.eventEndCheck = true + continue + } + + this.pos++ + } + + callback() + } + + /** + * @param {Buffer} line + * @param {EventSourceStreamEvent} event + */ + parseLine (line, event) { + // If the line is empty (a blank line) + // Dispatch the event, as defined below. + // This will be handled in the _transform method + if (line.length === 0) { + return + } + + // If the line starts with a U+003A COLON character (:) + // Ignore the line. + const colonPosition = line.indexOf(COLON) + if (colonPosition === 0) { + return + } + + let field = '' + let value = '' + + // If the line contains a U+003A COLON character (:) + if (colonPosition !== -1) { + // Collect the characters on the line before the first U+003A COLON + // character (:), and let field be that string. + // TODO: Investigate if there is a more performant way to extract the + // field + // see: https://github.com/nodejs/undici/issues/2630 + field = line.subarray(0, colonPosition).toString('utf8') + + // Collect the characters on the line after the first U+003A COLON + // character (:), and let value be that string. + // If value starts with a U+0020 SPACE character, remove it from value. + let valueStart = colonPosition + 1 + if (line[valueStart] === SPACE) { + ++valueStart + } + // TODO: Investigate if there is a more performant way to extract the + // value + // see: https://github.com/nodejs/undici/issues/2630 + value = line.subarray(valueStart).toString('utf8') + + // Otherwise, the string is not empty but does not contain a U+003A COLON + // character (:) + } else { + // Process the field using the steps described below, using the whole + // line as the field name, and the empty string as the field value. + field = line.toString('utf8') + value = '' + } + + // Modify the event with the field name and value. The value is also + // decoded as UTF-8 + switch (field) { + case 'data': + if (event[field] === undefined) { + event[field] = value + } else { + event[field] += `\n${value}` + } + break + case 'retry': + if (isASCIINumber(value)) { + event[field] = value + } + break + case 'id': + if (isValidLastEventId(value)) { + event[field] = value + } + break + case 'event': + if (value.length > 0) { + event[field] = value + } + break + } + } + + /** + * @param {EventSourceStreamEvent} event + */ + processEvent (event) { + if (event.retry && isASCIINumber(event.retry)) { + this.state.reconnectionTime = parseInt(event.retry, 10) + } + + if (event.id !== undefined && isValidLastEventId(event.id)) { + this.state.lastEventId = event.id + } + + // only dispatch event, when data is provided + if (event.data !== undefined) { + this.push({ + type: event.event || 'message', + options: { + data: event.data, + lastEventId: this.state.lastEventId, + origin: this.state.origin + } + }) + } + } + + clearEvent () { + this.event = { + data: undefined, + event: undefined, + id: undefined, + retry: undefined + } + } +} + +module.exports = { + EventSourceStream +} |