'use strict'
const { bufferToLowerCasedHeaderName } = require('../../core/util')
const { HTTP_TOKEN_CODEPOINTS } = require('./data-url')
const { makeEntry } = require('./formdata')
const { webidl } = require('../webidl')
const assert = require('node:assert')
const { isomorphicDecode } = require('../infra')
const dd = Buffer.from('--')
const decoder = new TextDecoder()
const decoderIgnoreBOM = new TextDecoder('utf-8', { ignoreBOM: true })
/**
* @param {string} chars
*/
function isAsciiString (chars) {
for (let i = 0; i < chars.length; ++i) {
if ((chars.charCodeAt(i) & ~0x7F) !== 0) {
return false
}
}
return true
}
/**
* @see https://andreubotella.github.io/multipart-form-data/#multipart-form-data-boundary
* @param {string} boundary
*/
function validateBoundary (boundary) {
const length = boundary.length
// - its length is greater or equal to 27 and lesser or equal to 70, and
if (length < 27 || length > 70) {
return false
}
// - it is composed by bytes in the ranges 0x30 to 0x39, 0x41 to 0x5A, or
// 0x61 to 0x7A, inclusive (ASCII alphanumeric), or which are 0x27 ('),
// 0x2D (-) or 0x5F (_).
for (let i = 0; i < length; ++i) {
const cp = boundary.charCodeAt(i)
if (!(
(cp >= 0x30 && cp <= 0x39) ||
(cp >= 0x41 && cp <= 0x5a) ||
(cp >= 0x61 && cp <= 0x7a) ||
cp === 0x27 ||
cp === 0x2d ||
cp === 0x5f
)) {
return false
}
}
return true
}
/**
* @see https://andreubotella.github.io/multipart-form-data/#multipart-form-data-parser
* @param {Buffer} input
* @param {ReturnType<import('./data-url')['parseMIMEType']>} mimeType
*/
function multipartFormDataParser (input, mimeType) {
// 1. Assert: mimeType’s essence is "multipart/form-data".
assert(mimeType !== 'failure' && mimeType.essence === 'multipart/form-data')
const boundaryString = mimeType.parameters.get('boundary')
// 2. If mimeType’s parameters["boundary"] does not exist, return failure.
// Otherwise, let boundary be the result of UTF-8 decoding mimeType’s
// parameters["boundary"].
if (boundaryString === undefined) {
throw parsingError('missing boundary in content-type header')
}
const boundary = Buffer.from(`--${boundaryString}`, 'utf8')
// 3. Let entry list be an empty entry list.
const entryList = []
// 4. Let position be a pointer to a byte in input, initially pointing at
// the first byte.
const position = { position: 0 }
// Note: Per RFC 2046 Section 5.1.1, we must ignore anything before the
// first boundary delimiter line (preamble). Search for the first boundary.
const firstBoundaryIndex = input.indexOf(boundary)
if (firstBoundaryIndex === -1) {
throw parsingError('no boundary found in multipart body')
}
// Start parsing from the first boundary, ignoring any preamble
position.position = firstBoundaryIndex
// 5. While true:
while (true) {
// 5.1. If position points to a sequence of bytes starting with 0x2D 0x2D
// (`--`) followed by boundary, advance position by 2 + the length of
// boundary. Otherwise, return failure.
// Note: boundary is padded with 2 dashes already, no need to add 2.
if (input.subarray(position.position, position.position + boundary.length).equals(boundary)) {
position.position += boundary.length
} else {
throw parsingError('expected a value starting with -- and the boundary')
}
// 5.2. If position points to the sequence of bytes 0x2D 0x2D 0x0D 0x0A
// (`--` followed by CR LF) followed by the end of input, return entry list.
// Note: Per RFC 2046 Section 5.1.1, we must ignore anything after the
// final boundary delimiter (epilogue). Check for -- or --CRLF and return
// regardless of what follows.
if (bufferStartsWith(input, dd, position)) {
// Found closing boundary delimiter (--), ignore any epilogue
return entryList
}
// 5.3. If position does not point to a sequence of bytes starting with 0x0D
// 0x0A (CR LF), return failure.
if (input[position.position] !== 0x0d || input[position.position + 1] !== 0x0a) {
throw parsingError('expected CRLF')
}
// 5.4. Advance position by 2. (This skips past the newline.)
position.position += 2
// 5.5. Let name, filename and contentType be the result of parsing
// multipart/form-data headers on input and position, if the result
// is not failure. Otherwise, return failure.
const result = parseMultipartFormDataHeaders(input, position)
let { name, filename, contentType, encoding } = result
// 5.6. Advance position by 2. (This skips past the empty line that marks
// the end of the headers.)
position.position += 2
// 5.7. Let body be the empty byte sequence.
let body
// 5.8. Body loop: While position is not past the end of input:
// TODO: the steps here are completely wrong
{
const boundaryIndex = input.indexOf(boundary.subarray(2), position.position)
if (boundaryIndex === -1) {
throw parsingError('expected boundary after body')
}
body = input.subarray(position.position, boundaryIndex - 4)
position.position += body.length
// Note: position must be advanced by the body's length before being
// decoded, otherwise the parsing will fail.
if (encoding === 'base64') {
body = Buffer.from(body.toString(), 'base64')
}
}
// 5.9. If position does not point to a sequence of bytes starting with
// 0x0D 0x0A (CR LF), return failure. Otherwise, advance position by 2.
if (input[position.position] !== 0x0d || input[position.position + 1] !== 0x0a) {
throw parsingError('expected CRLF')
} else {
position.position += 2
}
// 5.10. If filename is not null:
let value
if (filename !== null) {
// 5.10.1. If contentType is null, set contentType to "text/plain".
contentType ??= 'text/plain'
// 5.10.2. If contentType is not an ASCII string, set contentType to the empty string.
// Note: `buffer.isAscii` can be used at zero-cost, but converting a string to a buffer is a high overhead.
// Content-Type is a relatively small string, so it is faster to use `String#charCodeAt`.
if (!isAsciiString(contentType)) {
contentType = ''
}
// 5.10.3. Let value be a new File object with name filename, type contentType, and body body.
value = new File([body], filename, { type: contentType })
} else {
// 5.11. Otherwise:
// 5.11.1. Let value be the UTF-8 decoding without BOM of body.
value = decoderIgnoreBOM.decode(Buffer.from(body))
}
// 5.12. Assert: name is a scalar value string and value is either a scalar value string or a File object.
assert(webidl.is.USVString(name))
assert((typeof value === 'string' && webidl.is.USVString(value)) || webidl.is.File(value))
// 5.13. Create an entry with name and value, and append it to entry list.
entryList.push(makeEntry(name, value, filename))
}
}
/**
* Parses content-disposition attributes (e.g., name="value" or filename*=utf-8''encoded)
* @param {Buffer} input
* @param {{ position: number }} position
* @returns {{ name: string, value: string, extended: boolean } | null}
*/
function parseContentDispositionAttribute (input, position) {
// Skip leading semicolon and whitespace
if (input[position.position] === 0x3b /* ; */) {
position.position++
}
// Skip whitespace
collectASequenceOfBytes(
(char) => char === 0x20 || char === 0x09,
input,
position
)
// Collect attribute name (token characters)
const attributeName = collectASequenceOfBytes(
(char) => isToken(char) && char !== 0x3d && char !== 0x2a, // not = or *
input,
position
)
if (attributeName.length === 0) {
return null
}
const attrNameStr = attributeName.toString('ascii').toLowerCase()
// Check for extended notation (attribute*)
const isExtended = input[position.position] === 0x2a /* * */
if (isExtended) {
position.position++ // skip *
}
// Expect = sign
if (input[position.position] !== 0x3d /* = */) {
return null
}
position.position++ // skip =
// Skip whitespace
collectASequenceOfBytes(
(char) => char === 0x20 || char === 0x09,
input,
position
)
let value
if (isExtended) {
// Extended attribute format: charset'language'encoded-value
const headerValue = collectASequenceOfBytes(
(char) => char !== 0x20 && char !== 0x0d && char !== 0x0a && char !== 0x3b, // not space, CRLF, or ;
input,
position
)
// Check for utf-8'' prefix (case insensitive)
if (
(headerValue[0] !== 0x75 && headerValue[0] !== 0x55) || // u or U
(headerValue[1] !== 0x74 && headerValue[1] !== 0x54) || // t or T
(headerValue[2] !== 0x66 && headerValue[2] !== 0x46) || // f or F
headerValue[3] !== 0x2d || // -
headerValue[4] !== 0x38 // 8
) {
throw parsingError('unknown encoding, expected utf-8\'\'')
}
// Skip utf-8'' and decode the rest
value = decodeURIComponent(decoder.decode(headerValue.subarray(7)))
} else if (input[position.position] === 0x22 /* " */) {
// Quoted string
position.position++ // skip opening quote
const quotedValue = collectASequenceOfBytes(
(char) => char !== 0x0a && char !== 0x0d && char !== 0x22, // not LF, CR, or "
input,
position
)
if (input[position.position] !== 0x22) {
throw parsingError('Closing quote not found')
}
position.position++ // skip closing quote
value = decoder.decode(quotedValue)
.replace(/%0A/ig, '\n')
.replace(/%0D/ig, '\r')
.replace(/%22/g, '"')
} else {
// Token value (no quotes)
const tokenValue = collectASequenceOfBytes(
(char) => isToken(char) && char !== 0x3b, // not ;
input,
position
)
value = decoder.decode(tokenValue)
}
return { name: attrNameStr, value, extended: isExtended }
}
/**
* @see https://andreubotella.github.io/multipart-form-data/#parse-multipart-form-data-headers
* @param {Buffer} input
* @param {{ position: number }} position
*/
function parseMultipartFormDataHeaders (input, position) {
// 1. Let name, filename and contentType be null.
let name = null
let filename = null
let contentType = null
let encoding = null
// 2. While true:
while (true) {
// 2.1. If position points to a sequence of bytes starting with 0x0D 0x0A (CR LF):
if (input[position.position] === 0x0d && input[position.position + 1] === 0x0a) {
// 2.1.1. If name is null, return failure.
if (name === null) {
throw parsingError('header name is null')
}
// 2.1.2. Return name, filename and contentType.
return { name, filename, contentType, encoding }
}
// 2.2. Let header name be the result of collecting a sequence of bytes that are
// not 0x0A (LF), 0x0D (CR) or 0x3A (:), given position.
let headerName = collectASequenceOfBytes(
(char) => char !== 0x0a && char !== 0x0d && char !== 0x3a,
input,
position
)
// 2.3. Remove any HTTP tab or space bytes from the start or end of header name.
headerName = removeChars(headerName, true, true, (char) => char === 0x9 || char === 0x20)
// 2.4. If header name does not match the field-name token production, return failure.
if (!HTTP_TOKEN_CODEPOINTS.test(headerName.toString())) {
throw parsingError('header name does not match the field-name token production')
}
// 2.5. If the byte at position is not 0x3A (:), return failure.
if (input[position.position] !== 0x3a) {
throw parsingError('expected :')
}
// 2.6. Advance position by 1.
position.position++
// 2.7. Collect a sequence of bytes that are HTTP tab or space bytes given position.
// (Do nothing with those bytes.)
collectASequenceOfBytes(
(char) => char === 0x20 || char === 0x09,
input,
position
)
// 2.8. Byte-lowercase header name and switch on the result:
switch (bufferToLowerCasedHeaderName(headerName)) {
case 'content-disposition': {
name = filename = null
// Track whether filename was set from the extended (RFC 5987) form so
// a subsequent legacy `filename` attribute does not override it.
let filenameIsExtended = false
// Collect the disposition type (should be "form-data")
const dispositionType = collectASequenceOfBytes(
(char) => isToken(char),
input,
position
)
if (dispositionType.toString('ascii').toLowerCase() !== 'form-data') {
throw parsingError('expected form-data for content-disposition header')
}
// Parse attributes recursively until CRLF
while (
position.position < input.length &&
(input[position.position] !== 0x0d ||
input[position.position + 1] !== 0x0a)
) {
const attribute = parseContentDispositionAttribute(input, position)
if (!attribute) {
break
}
if (attribute.name === 'name') {
name = attribute.value
} else if (attribute.name === 'filename') {
// Per RFC 5987 §4.1, when both legacy and extended forms of the
// same parameter are present, the extended (filename*) form takes
// precedence regardless of the order they appear in.
if (attribute.extended) {
filename = attribute.value
filenameIsExtended = true
} else if (!filenameIsExtended) {
filename = attribute.value
}
}
}
if (name === null) {
throw parsingError('name attribute is required in content-disposition header')
}
break
}
case 'content-type': {
// 1. Let header value be the result of collecting a sequence of bytes that are
// not 0x0A (LF) or 0x0D (CR), given position.
let headerValue = collectASequenceOfBytes(
(char) => char !== 0x0a && char !== 0x0d,
input,
position
)
// 2. Remove any HTTP tab or space bytes from the end of header value.
headerValue = removeChars(headerValue, false, true, (char) => char === 0x9 || char === 0x20)
// 3. Set contentType to the isomorphic decoding of header value.
contentType = isomorphicDecode(headerValue)
break
}
case 'content-transfer-encoding': {
let headerValue = collectASequenceOfBytes(
(char) => char !== 0x0a && char !== 0x0d,
input,
position
)
headerValue = removeChars(headerValue, false, true, (char) => char === 0x9 || char === 0x20)
encoding = isomorphicDecode(headerValue)
break
}
default: {
// Collect a sequence of bytes that are not 0x0A (LF) or 0x0D (CR), given position.
// (Do nothing with those bytes.)
collectASequenceOfBytes(
(char) => char !== 0x0a && char !== 0x0d,
input,
position
)
}
}
// 2.9. If position does not point to a sequence of bytes starting with 0x0D 0x0A
// (CR LF), return failure. Otherwise, advance position by 2 (past the newline).
if (input[position.position] !== 0x0d || input[position.position + 1] !== 0x0a) {
throw parsingError('expected CRLF')
} else {
position.position += 2
}
}
}
/**
* @param {(char: number) => boolean} condition
* @param {Buffer} input
* @param {{ position: number }} position
*/
function collectASequenceOfBytes (condition, input, position) {
let start = position.position
while (start < input.length && condition(input[start])) {
++start
}
return input.subarray(position.position, (position.position = start))
}
/**
* @param {Buffer} buf
* @param {boolean} leading
* @param {boolean} trailing
* @param {(charCode: number) => boolean} predicate
* @returns {Buffer}
*/
function removeChars (buf, leading, trailing, predicate) {
let lead = 0
let trail = buf.length - 1
if (leading) {
while (lead < buf.length && predicate(buf[lead])) lead++
}
if (trailing) {
while (trail > 0 && predicate(buf[trail])) trail--
}
return lead === 0 && trail === buf.length - 1 ? buf : buf.subarray(lead, trail + 1)
}
/**
* Checks if {@param buffer} starts with {@param start}
* @param {Buffer} buffer
* @param {Buffer} start
* @param {{ position: number }} position
*/
function bufferStartsWith (buffer, start, position) {
if (buffer.length < start.length) {
return false
}
for (let i = 0; i < start.length; i++) {
if (start[i] !== buffer[position.position + i]) {
return false
}
}
return true
}
function parsingError (cause) {
return new TypeError('Failed to parse body as FormData.', { cause: new TypeError(cause) })
}
/**
* CTL = <any US-ASCII control character
* (octets 0 - 31) and DEL (127)>
* @param {number} char
*/
function isCTL (char) {
return char <= 0x1f || char === 0x7f
}
/**
* tspecials := "(" / ")" / "<" / ">" / "@" /
* "," / ";" / ":" / "\" / <">
* "/" / "[" / "]" / "?" / "="
* ; Must be in quoted-string,
* ; to use within parameter values
* @param {number} char
*/
function isTSpecial (char) {
return (
char === 0x28 || // (
char === 0x29 || // )
char === 0x3c || // <
char === 0x3e || // >
char === 0x40 || // @
char === 0x2c || // ,
char === 0x3b || // ;
char === 0x3a || // :
char === 0x5c || // \
char === 0x22 || // "
char === 0x2f || // /
char === 0x5b || // [
char === 0x5d || // ]
char === 0x3f || // ?
char === 0x3d // +
)
}
/**
* token := 1*<any (US-ASCII) CHAR except SPACE, CTLs,
* or tspecials>
* @param {number} char
*/
function isToken (char) {
return (
char <= 0x7f && // ascii
char !== 0x20 && // space
char !== 0x09 &&
!isCTL(char) &&
!isTSpecial(char)
)
}
module.exports = {
multipartFormDataParser,
validateBoundary
}