implement sync formdata parsser

lib/web/fetch/body.js

@@ -577,5 +577,6 @@ module.exports = {
   extractBody,
   safelyExtractBody,
   cloneBody,
-  mixinBody
+  mixinBody,
+  utf8DecodeBytes
 }

lib/web/fetch/data-url.js

@@ -738,5 +738,6 @@ module.exports = {
   collectAnHTTPQuotedString,
   serializeAMimeType,
   removeChars,
-  minimizeSupportedMimeType
+  minimizeSupportedMimeType,
+  HTTP_TOKEN_CODEPOINTS
 }

lib/web/fetch/formdata-parser.js

@@ -0,0 +1,379 @@
+'use strict'
+
+const { webidl } = require('./webidl')
+const { utf8DecodeBytes } = require('./body')
+const { collectASequenceOfCodePoints, removeChars, HTTP_TOKEN_CODEPOINTS } = require('./data-url')
+const { isFileLike, File: UndiciFile } = require('./file')
+const { makeEntry } = require('./formdata')
+const assert = require('node:assert')
+const { isAscii } = require('node:buffer')
+
+const File = globalThis.File ?? UndiciFile
+
+/**
+ * @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 < boundary.length; i++) {
+    const cp = boundary.charCodeAt(i)
+
+    if (!(
+      (cp >= 0x30 && cp <= 0x39) ||
+      (cp >= 0x41 && cp <= 0x5a) ||
+      (cp >= 0x61 && cp <= 0x7a) ||
+      cp === 0x27 ||
+      cp === 0x3d ||
+      cp === 0x5f
+    )) {
+      return false
+    }
+  }
+
+  return true
+}
+
+/**
+ * @see https://andreubotella.github.io/multipart-form-data/#escape-a-multipart-form-data-name
+ * @param {string} name
+ * @param {string?} encoding
+ * @param {boolean?} isFilename
+ */
+function escapeFormDataName (name, encoding = 'utf-8', isFilename = false) {
+  // 1. If isFilename is true:
+  if (isFilename) {
+    // 1.1. Set name to the result of converting name into a scalar value string.
+    name = webidl.converters.USVString(name)
+  } else {
+    // 2. Otherwise:
+
+    // 2.1. Assert: name is a scalar value string.
+    assert(name === webidl.converters.USVString(name))
+
+    // 2.2. Replace every occurrence of U+000D (CR) not followed by U+000A (LF),
+    //      and every occurrence of U+000A (LF) not preceded by U+000D (CR), in
+    //      name, by a string consisting of U+000D (CR) and U+000A (LF).
+    name = name.replace(/\r\n?|\r?\n/g, '\r\n')
+  }
+
+  // 3. Let encoded be the result of encoding name with encoding.
+  assert(Buffer.isEncoding(encoding))
+
+  // 4. Replace every 0x0A (LF) bytes in encoded with the byte sequence `%0A`,
+  //    0x0D (CR) with `%0D` and 0x22 (") with `%22`.
+  name = name
+    .replace(/\n/g, '%0A')
+    .replace(/\r/g, '%0D')
+    .replace(/"/g, '%22')
+
+  // 5. Return encoded.
+  return Buffer.from(name, encoding) // encoded
+}
+
+/**
+ * @see https://andreubotella.github.io/multipart-form-data/#multipart-form-data-parser
+ * @param {string} 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')
+
+  // 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 (!mimeType.parameters.has('boundary')) {
+    return 'failure'
+  }
+
+  const boundary = utf8DecodeBytes(Buffer.from(mimeType.parameters.get('boundary')))
+
+  // 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 }
+
+  // 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.
+    if (input.slice(position.position, position.position + 2 + boundary.length) === `--${boundary}`) {
+      position.position += 2 + boundary.length
+    } else {
+      return 'failure'
+    }
+
+    // 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.
+    // TODO: a FormData body doesn't need to end with CRLF?
+    if (position.position === input.length - 2 && input.endsWith('--')) {
+      return entryList
+    }
+
+    // 5.3. If position does not point to a sequence of bytes starting with 0x0D
+    //      0x0A (CR LF), return failure.
+    if (input.charCodeAt(position.position) !== 0x0d || input.charCodeAt(position.position + 1) !== 0x0a) {
+      return 'failure'
+    }
+
+    // 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)
+
+    if (result === 'failure') {
+      return 'failure'
+    }
+
+    let { name, filename, contentType } = 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, position.position)
+
+      if (boundaryIndex === -1) {
+        return 'failure'
+      }
+
+      body = input.slice(position.position, boundaryIndex - 4)
+
+      position.position += body.length
+    }
+
+    // 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.charCodeAt(position.position) !== 0x0d || input.charCodeAt(position.position + 1) !== 0x0a) {
+      return 'failure'
+    } 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.
+      if (!isAscii(Buffer.from(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 = utf8DecodeBytes(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(name === webidl.converters.USVString(name))
+    assert((typeof value === 'string' && value === webidl.converters.USVString(value)) || isFileLike(value))
+
+    // 5.13. Create an entry with name and value, and append it to entry list.
+    entryList.push(makeEntry(name, value, filename))
+  }
+}
+
+/**
+ * @see https://andreubotella.github.io/multipart-form-data/#parse-multipart-form-data-headers
+ * @param {string} 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
+
+  // 2. While true:
+  while (true) {
+    // 2.1. If position points to a sequence of bytes starting with 0x0D 0x0A (CR LF):
+    if (input.charCodeAt(position.position) === 0x0d && input.charCodeAt(position.position + 1) === 0x0a) {
+      // 2.1.1. If name is null, return failure.
+      if (name === null) {
+        return 'failure'
+      }
+
+      // 2.1.2. Return name, filename and contentType.
+      return { name, filename, contentType }
+    }
+
+    // 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 = collectASequenceOfCodePoints(
+      (char) => char !== '\n' && char !== '\n' && char !== ':',
+      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)) {
+      return 'failure'
+    }
+
+    // 2.5. If the byte at position is not 0x3A (:), return failure.
+    if (input.charCodeAt(position.position) !== 0x3a) {
+      return 'failure'
+    }
+
+    // 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.)
+    collectASequenceOfCodePoints(
+      (char) => char === ' ' || char === '\t',
+      input,
+      position
+    )
+
+    // 2.8. Byte-lowercase header name and switch on the result:
+    switch (headerName.toLowerCase()) {
+      case 'content-disposition': {
+        // 1. Set name and filename to null.
+        name = filename = null
+
+        // 2. If position does not point to a sequence of bytes starting with
+        //    `form-data; name="`, return failure.
+        if (!input.slice(position.position).startsWith('form-data; name="')) {
+          return 'failure'
+        }
+
+        // 3. Advance position so it points at the byte after the next 0x22 (")
+        //    byte (the one in the sequence of bytes matched above).
+        position.position += 17
+
+        // 4. Set name to the result of parsing a multipart/form-data name given
+        //    input and position, if the result is not failure. Otherwise, return
+        //    failure.
+        name = parseMultipartFormDataName(input, position)
+
+        if (name === false) {
+          return 'failure'
+        }
+
+        // 5. If position points to a sequence of bytes starting with `; filename="`:
+        if (input.slice(position.position).startsWith('; filename="')) {
+          // 1. Advance position so it points at the byte after the next 0x22 (") byte
+          //    (the one in the sequence of bytes matched above).
+          position.position += 13
+
+          // 2. Set filename to the result of parsing a multipart/form-data name given
+          //    input and position, if the result is not failure. Otherwise, return failure.
+          filename = parseMultipartFormDataName(input, position)
+
+          if (filename === false) {
+            return 'failure'
+          }
+        }
+
+        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 = collectASequenceOfCodePoints(
+          (char) => char !== '\r' && char !== '\n',
+          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 = headerValue
+
+        break
+      }
+      default: {
+        // Collect a sequence of bytes that are not 0x0A (LF) or 0x0D (CR), given position.
+        // (Do nothing with those bytes.)
+        collectASequenceOfCodePoints(
+          (char) => char !== '\n' && char !== '\r',
+          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.charCodeAt(position.position) !== 0x0d && input.charCodeAt(position.position + 1) !== 0x0a) {
+      return 'failure'
+    } else {
+      position.position += 2
+    }
+  }
+}
+
+/**
+ * @see https://andreubotella.github.io/multipart-form-data/#parse-a-multipart-form-data-name
+ * @param {string} input
+ * @param {{ position: number }} position
+ */
+function parseMultipartFormDataName (input, position) {
+  // 1. Assert: The byte at (position - 1) is 0x22 (").
+  assert(input.charCodeAt(position.position - 1) === 0x22)
+
+  // 2. Let name be the result of collecting a sequence of bytes that are not 0x0A (LF), 0x0D (CR) or 0x22 ("), given position.
+  let name = collectASequenceOfCodePoints(
+    (char) => char !== '\n' && char !== '\r' && char !== '"',
+    input,
+    position
+  )
+
+  // 3. If the byte at position is not 0x22 ("), return failure. Otherwise, advance position by 1.
+  if (input.charCodeAt(position.position) !== 0x22) {
+    return false // name could be 'failure'
+  } else {
+    position.position++
+  }
+
+  // 4. Replace any occurrence of the following subsequences in name with the given byte:
+  // - `%0A`: 0x0A (LF)
+  // - `%0D`: 0x0D (CR)
+  // - `%22`: 0x22 (")
+  name = name
+    .replace(/%0A/i, '\n')
+    .replace(/%0D/i, '\r')
+    .replace(/%22/, '"')
+
+  // 5. Return the UTF-8 decoding without BOM of name.
+  return Buffer.from(name, 'utf-8').toString('utf-8')
+}
+
+module.exports = {
+  multipartFormDataParser
+}