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feat: add support for multipart/form-data #1606

Merged
merged 10 commits into from
Sep 28, 2022
45 changes: 43 additions & 2 deletions lib/fetch/body.js
Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
'use strict'

const Busboy = require('busboy')
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const util = require('../core/util')
const { ReadableStreamFrom, toUSVString, isBlobLike } = require('./util')
const { FormData } = require('./formdata')
Expand All @@ -8,9 +9,9 @@ const { webidl } = require('./webidl')
const { Blob } = require('buffer')
const { kBodyUsed } = require('../core/symbols')
const assert = require('assert')
const { NotSupportedError } = require('../core/errors')
const { isErrored } = require('../core/util')
const { isUint8Array, isArrayBuffer } = require('util/types')
const { File } = require('./file')

let ReadableStream

Expand Down Expand Up @@ -397,7 +398,47 @@ function bodyMixinMethods (instance) {

// If mimeType’s essence is "multipart/form-data", then:
if (/multipart\/form-data/.test(contentType)) {
throw new NotSupportedError('multipart/form-data not supported')
const headers = {}
for (const [key, value] of this.headers) headers[key.toLowerCase()] = value

const responseFormData = new FormData()

let busboy
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try {
busboy = Busboy({ headers })
} catch (err) {
// Error due to headers:
throw Object.assign(new TypeError(), { cause: err })
}

busboy.on('field', (name, value) => {
responseFormData.append(name, value)
})
busboy.on('file', (name, value, info) => {
const { filename, encoding, mimeType } = info
const base64 = encoding.toLowerCase() === 'base64'
const chunks = []
value.on('data', (chunk) => {
if (base64) chunk = Buffer.from(chunk.toString(), 'base64')
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@repsac-by repsac-by Sep 4, 2022

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You can't just decrypt a base64 chunk, because the length of the base64 chunk must be a multiple of 4 characters.

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I don't understand.

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@repsac-by repsac-by Sep 4, 2022

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const data = Buffer.from(Buffer.from('hello world').toString('base64'));

const chunks1 = [];
const chunks2 = [];
for (let offset = 0, step = 6; offset < data.length; offset += step) {
	const chunk = data.subarray(offset, offset + step);

	// Decode each chunk
	chunks1.push(Buffer.from(chunk.toString(), 'base64'));

	// Here we collect as is
	chunks2.push(chunk);
}

// Decode after the transfer is completed
const buffer = Buffer.from(Buffer.concat(chunks2).toString(), 'base64');

// hell�v�ld
console.log(await new Blob(chunks1).text());

// hello world
console.log(await new Blob([buffer]).text());

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We have the https://nodejs.org/api/string_decoder.html for this purpose.

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@mcollina does string decoder need to be applied somewhere in this code explicitly, or it will be called down the line automatically?

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@cameron-robey see what @repsac-by is suggesting, plus test to cover that case. inlining the code should be fine

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What's the problem exactly? You need 4 bytes to decode base64 at minimum, so why don't you accumulate until you have 4 bytes of multiples?

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@mcollina I'm assuming that you mean: push chunks until the total length of unprocessed data is divisible by 4, then decode and clear the chunk array, and repeat with the next pieces of data. Accumulating like that seems unreliable, since it cannot be known when that multiple of 4 will be reached. It might happen only after a huge number of chunks. The streaming method suggested above is superior because the number of unprocessed bytes that are kept in memory never exceeds 3.

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The one in the comment also looks good.

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@cameron-robey Do you need any help with the remaining part?

chunks.push(chunk)
})
value.on('end', () => {
const file = new File(chunks, filename, { type: mimeType })
responseFormData.append(name, file)
})
})
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const busboyResolve = new Promise((resolve, reject) => {
busboy.on('finish', resolve)
busboy.on('error', (err) => reject(err))
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})

if (this.body !== null) for await (const chunk of consumeBody(this[kState].body)) busboy.write(chunk)
busboy.end()
await busboyResolve

return responseFormData
} else if (/application\/x-www-form-urlencoded/.test(contentType)) {
// Otherwise, if mimeType’s essence is "application/x-www-form-urlencoded", then:

Expand Down
4 changes: 3 additions & 1 deletion package.json
Original file line number Diff line number Diff line change
Expand Up @@ -68,7 +68,6 @@
"@types/node": "^17.0.29",
"abort-controller": "^3.0.0",
"atomic-sleep": "^1.0.0",
"busboy": "^1.6.0",
"chai": "^4.3.4",
"chai-as-promised": "^7.1.1",
"chai-iterator": "^3.0.2",
Expand Down Expand Up @@ -122,5 +121,8 @@
"testMatch": [
"<rootDir>/test/jest/**"
]
},
"dependencies": {
"busboy": "^1.6.0"
}
}
92 changes: 84 additions & 8 deletions test/fetch/client-fetch.js
Original file line number Diff line number Diff line change
Expand Up @@ -165,21 +165,97 @@ test('unsupported formData 1', (t) => {
})
})

test('unsupported formData 2', (t) => {
test('multipart formdata not base64', async (t) => {
t.plan(2)

// Construct example form data, with text and blob fields
const formData = new FormData()
formData.append('field1', 'value1')
const blob = new Blob(['example\ntext file'], { type: 'text/plain' })
formData.append('field2', blob, 'file.txt')

const tempRes = new Response(formData)
const boundary = tempRes.headers.get('content-type').split('boundary=')[1]
const formRaw = await tempRes.text()

const server = createServer((req, res) => {
res.setHeader('content-type', 'multipart/form-data; boundary=' + boundary)
res.write(formRaw)
res.end()
})
t.teardown(server.close.bind(server))

await new Promise((resolve) => {
server.listen(0, async () => {
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const response = await fetch(`http://localhost:${server.address().port}`)
const form = await response.formData()

// Text field
const field1 = form.get('field1')
t.equal(field1, 'value1')

// Blob field
const field2 = form.get('field2')
const field2Text = await field2.text()
t.equal(field2Text, 'example\ntext file')
resolve()
})
})
})

test('busboy emit error', async (t) => {
t.plan(1)

const formData = new FormData()
formData.append('field1', 'value1')

const tempRes = new Response(formData)
const formRaw = await tempRes.text()

const server = createServer((req, res) => {
res.setHeader('content-type', 'multipart/form-data')
res.setHeader('content-type', 'multipart/form-data; boundary=wrongboundary')
res.write(formRaw)
res.end()
})
t.teardown(server.close.bind(server))

server.listen(0, () => {
fetch(`http://localhost:${server.address().port}`)
.then(res => res.formData())
.catch(err => {
t.equal(err.name, 'NotSupportedError')
})
await new Promise((resolve) => {
server.listen(0, async () => {
const response = await fetch(`http://localhost:${server.address().port}`)

try {
await response.formData()
} catch (err) {
t.equal(err.message, 'Unexpected end of form')
}

resolve()
})
})
})

test('multipart formdata base64', async (t) => {
t.plan(1)

// Example form data with base64 encoding
const formRaw = '------formdata-undici-0.5786922755719377\r\nContent-Disposition: form-data; name="key"; filename="test.txt"\r\nContent-Type: text/plain\r\nContent-Transfer-Encoding: base64\r\n\r\ndmFsdWU=\r\n------formdata-undici-0.5786922755719377--'
const server = createServer((req, res) => {
res.setHeader('content-type', 'multipart/form-data; boundary=----formdata-undici-0.5786922755719377')
res.write(formRaw)
res.end()
})
t.teardown(server.close.bind(server))

await new Promise((resolve) => {
server.listen(0, async () => {
const response = await fetch(`http://localhost:${server.address().port}`)
const form = await response.formData()

const text = await form.get('key').text()
console.log(text)
t.equal(text, 'value')
resolve()
})
})
})

Expand Down