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/* eslint-disable no-fallthrough */
/* eslint-disable no-bitwise */
/* eslint-disable no-plusplus */
/* eslint-disable no-underscore-dangle */
'use strict';
const { Transform } = require('stream');
const errors = require('../FormidableError.js');
const { FormidableError } = errors;
let s = 0;
const STATE = {
PARSER_UNINITIALIZED: s++,
START: s++,
START_BOUNDARY: s++,
HEADER_FIELD_START: s++,
HEADER_FIELD: s++,
HEADER_VALUE_START: s++,
HEADER_VALUE: s++,
HEADER_VALUE_ALMOST_DONE: s++,
HEADERS_ALMOST_DONE: s++,
PART_DATA_START: s++,
PART_DATA: s++,
PART_END: s++,
END: s++,
};
let f = 1;
const FBOUNDARY = { PART_BOUNDARY: f, LAST_BOUNDARY: (f *= 2) };
const LF = 10;
const CR = 13;
const SPACE = 32;
const HYPHEN = 45;
const COLON = 58;
const A = 97;
const Z = 122;
function lower(c) {
return c | 0x20;
}
exports.STATES = {};
Object.keys(STATE).forEach((stateName) => {
exports.STATES[stateName] = STATE[stateName];
});
class MultipartParser extends Transform {
constructor(options = {}) {
super({ readableObjectMode: true });
this.boundary = null;
this.boundaryChars = null;
this.lookbehind = null;
this.bufferLength = 0;
this.state = STATE.PARSER_UNINITIALIZED;
this.globalOptions = { ...options };
this.index = null;
this.flags = 0;
}
_flush(done) {
if (
(this.state === STATE.HEADER_FIELD_START && this.index === 0) ||
(this.state === STATE.PART_DATA && this.index === this.boundary.length)
) {
this._handleCallback('partEnd');
this._handleCallback('end');
done();
} else if (this.state !== STATE.END) {
done(
new FormidableError(
`MultipartParser.end(): stream ended unexpectedly: ${this.explain()}`,
errors.malformedMultipart,
400,
),
);
}
}
initWithBoundary(str) {
this.boundary = Buffer.from(`\r\n--${str}`);
this.lookbehind = Buffer.alloc(this.boundary.length + 8);
this.state = STATE.START;
this.boundaryChars = {};
for (let i = 0; i < this.boundary.length; i++) {
this.boundaryChars[this.boundary[i]] = true;
}
}
// eslint-disable-next-line max-params
_handleCallback(name, buf, start, end) {
if (start !== undefined && start === end) {
return;
}
this.push({ name, buffer: buf, start, end });
}
// eslint-disable-next-line max-statements
_transform(buffer, _, done) {
let i = 0;
let prevIndex = this.index;
let { index, state, flags } = this;
const { lookbehind, boundary, boundaryChars } = this;
const boundaryLength = boundary.length;
const boundaryEnd = boundaryLength - 1;
this.bufferLength = buffer.length;
let c = null;
let cl = null;
const setMark = (name, idx) => {
this[`${name}Mark`] = typeof idx === 'number' ? idx : i;
};
const clearMarkSymbol = (name) => {
delete this[`${name}Mark`];
};
const dataCallback = (name, shouldClear) => {
const markSymbol = `${name}Mark`;
if (!(markSymbol in this)) {
return;
}
if (!shouldClear) {
this._handleCallback(name, buffer, this[markSymbol], buffer.length);
setMark(name, 0);
} else {
this._handleCallback(name, buffer, this[markSymbol], i);
clearMarkSymbol(name);
}
};
for (i = 0; i < this.bufferLength; i++) {
c = buffer[i];
switch (state) {
case STATE.PARSER_UNINITIALIZED:
return i;
case STATE.START:
index = 0;
state = STATE.START_BOUNDARY;
case STATE.START_BOUNDARY:
if (index === boundary.length - 2) {
if (c === HYPHEN) {
flags |= FBOUNDARY.LAST_BOUNDARY;
} else if (c !== CR) {
return i;
}
index++;
break;
} else if (index - 1 === boundary.length - 2) {
if (flags & FBOUNDARY.LAST_BOUNDARY && c === HYPHEN) {
this._handleCallback('end');
state = STATE.END;
flags = 0;
} else if (!(flags & FBOUNDARY.LAST_BOUNDARY) && c === LF) {
index = 0;
this._handleCallback('partBegin');
state = STATE.HEADER_FIELD_START;
} else {
return i;
}
break;
}
if (c !== boundary[index + 2]) {
index = -2;
}
if (c === boundary[index + 2]) {
index++;
}
break;
case STATE.HEADER_FIELD_START:
state = STATE.HEADER_FIELD;
setMark('headerField');
index = 0;
case STATE.HEADER_FIELD:
if (c === CR) {
clearMarkSymbol('headerField');
state = STATE.HEADERS_ALMOST_DONE;
break;
}
index++;
if (c === HYPHEN) {
break;
}
if (c === COLON) {
if (index === 1) {
// empty header field
return i;
}
dataCallback('headerField', true);
state = STATE.HEADER_VALUE_START;
break;
}
cl = lower(c);
if (cl < A || cl > Z) {
return i;
}
break;
case STATE.HEADER_VALUE_START:
if (c === SPACE) {
break;
}
setMark('headerValue');
state = STATE.HEADER_VALUE;
case STATE.HEADER_VALUE:
if (c === CR) {
dataCallback('headerValue', true);
this._handleCallback('headerEnd');
state = STATE.HEADER_VALUE_ALMOST_DONE;
}
break;
case STATE.HEADER_VALUE_ALMOST_DONE:
if (c !== LF) {
return i;
}
state = STATE.HEADER_FIELD_START;
break;
case STATE.HEADERS_ALMOST_DONE:
if (c !== LF) {
return i;
}
this._handleCallback('headersEnd');
state = STATE.PART_DATA_START;
break;
case STATE.PART_DATA_START:
state = STATE.PART_DATA;
setMark('partData');
case STATE.PART_DATA:
prevIndex = index;
if (index === 0) {
// boyer-moore derrived algorithm to safely skip non-boundary data
i += boundaryEnd;
while (i < this.bufferLength && !(buffer[i] in boundaryChars)) {
i += boundaryLength;
}
i -= boundaryEnd;
c = buffer[i];
}
if (index < boundary.length) {
if (boundary[index] === c) {
if (index === 0) {
dataCallback('partData', true);
}
index++;
} else {
index = 0;
}
} else if (index === boundary.length) {
index++;
if (c === CR) {
// CR = part boundary
flags |= FBOUNDARY.PART_BOUNDARY;
} else if (c === HYPHEN) {
// HYPHEN = end boundary
flags |= FBOUNDARY.LAST_BOUNDARY;
} else {
index = 0;
}
} else if (index - 1 === boundary.length) {
if (flags & FBOUNDARY.PART_BOUNDARY) {
index = 0;
if (c === LF) {
// unset the PART_BOUNDARY flag
flags &= ~FBOUNDARY.PART_BOUNDARY;
this._handleCallback('partEnd');
this._handleCallback('partBegin');
state = STATE.HEADER_FIELD_START;
break;
}
} else if (flags & FBOUNDARY.LAST_BOUNDARY) {
if (c === HYPHEN) {
this._handleCallback('partEnd');
this._handleCallback('end');
state = STATE.END;
flags = 0;
} else {
index = 0;
}
} else {
index = 0;
}
}
if (index > 0) {
// when matching a possible boundary, keep a lookbehind reference
// in case it turns out to be a false lead
lookbehind[index - 1] = c;
} else if (prevIndex > 0) {
// if our boundary turned out to be rubbish, the captured lookbehind
// belongs to partData
this._handleCallback('partData', lookbehind, 0, prevIndex);
prevIndex = 0;
setMark('partData');
// reconsider the current character even so it interrupted the sequence
// it could be the beginning of a new sequence
i--;
}
break;
case STATE.END:
break;
default:
return i;
}
}
dataCallback('headerField');
dataCallback('headerValue');
dataCallback('partData');
this.index = index;
this.state = state;
this.flags = flags;
done();
return this.bufferLength;
}
explain() {
return `state = ${MultipartParser.stateToString(this.state)}`;
}
}
// eslint-disable-next-line consistent-return
MultipartParser.stateToString = (stateNumber) => {
// eslint-disable-next-line no-restricted-syntax, guard-for-in
for (const stateName in STATE) {
const number = STATE[stateName];
if (number === stateNumber) return stateName;
}
};
module.exports = Object.assign(MultipartParser, { STATES: exports.STATES });