参考地址
https://www.jianshu.com/p/29e38bcc8a1d

multipart/form-data

  • 基本形态
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--cc51ab821e27f5818ba3662ab706787e6bcc6e4d
Content-Disposition: form-data; name="appid"
Content-Length: 20

8ovpzwzBKFzz88y60N22
--cc51ab821e27f5818ba3662ab706787e6bcc6e4d
Content-Disposition: form-data; name="file2"; filename="upfile.txt"
Content-Length: 6
Content-Type: text/plain

upfile
--cc51ab821e27f5818ba3662ab706787e6bcc6e4d
Content-Disposition: form-data; name="file3"; filename="upfile.txt"
Content-Length: 6
Content-Type: text/plain

upfile
--cc51ab821e27f5818ba3662ab706787e6bcc6e4d--

关键代码

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class MultipartFormDataParser
{
/**
* Returns the maximum size of an uploaded file as configured in php.ini.
*
* @return int The maximum size of an uploaded file in bytes
*/
public static function getMaxFilesize()
{
$sizePostMax = self::parseFilesize(ini_get('post_max_size'));
$sizeUploadMax = self::parseFilesize(ini_get('upload_max_filesize'));

return min($sizePostMax ?: PHP_INT_MAX, $sizeUploadMax ?: PHP_INT_MAX);
}

/**
* Returns the given size from an ini value in bytes.
*/
private static function parseFilesize($size): int
{
if ('' === $size) {
return 0;
}

$size = strtolower($size);

$max = ltrim($size, '+');
if (0 === strpos($max, '0x')) {
$max = \intval($max, 16);
} elseif (0 === strpos($max, '0')) {
$max = \intval($max, 8);
} else {
$max = (int) $max;
}

switch (substr($size, -1)) {
case 't':$max *= 1024;
// no break
case 'g':$max *= 1024;
// no break
case 'm':$max *= 1024;
// no break
case 'k':$max *= 1024;
}

return $max;
}

/**
* @var int upload file max size in bytes.
*/
private $uploadFileMaxSize;

/**
* @var int maximum upload files count.
*/
private $uploadFileMaxCount;

/**
* @var resource[] resources for temporary file, created during request parsing.
*/
private $tmpFileResources = [];

/**
* @return int upload file max size in bytes.
*/
public function getUploadFileMaxSize(): int
{
if ($this->uploadFileMaxSize === null) {
$this->uploadFileMaxSize = static::getMaxFilesize();
}

return $this->uploadFileMaxSize;
}

/**
* @param int $uploadFileMaxSize upload file max size in bytes.
* @return static self reference.
*/
public function setUploadFileMaxSize(int $uploadFileMaxSize): self
{
$this->uploadFileMaxSize = $uploadFileMaxSize;

return $this;
}
/**
* @return int maximum upload files count.
*/
public function getUploadFileMaxCount(): int
{
if ($this->uploadFileMaxCount === null) {
$this->uploadFileMaxCount = ini_get('max_file_uploads');
}

return $this->uploadFileMaxCount;
}
/**
* @param int $uploadFileMaxCount maximum upload files count.
* @return static self reference.
*/
public function setUploadFileMaxCount(int $uploadFileMaxCount): self
{
$this->uploadFileMaxCount = $uploadFileMaxCount;

return $this;
}

/**
* Parses given request in case it holds 'multipart/form-data' content.
* This method is immutable: it leaves passed request object intact, creating new one for parsed results.
* This method returns original request in case it does not hold appropriate content type or has empty body.
*/
public function parse(array $headers, string $rawBody)
{
$contentType = $headers['content-type'] ?? '';
if (stripos($contentType, 'multipart/form-data') === false) {
return false;
}
if (!preg_match('/boundary=(.*)$/is', $contentType, $matches)) {
return false;
}
$boundary = $matches[1];

if (empty($rawBody)) {
return false;
}

$bodyParts = preg_split('/\\R?-+' . preg_quote($boundary, '/') . '/s', $rawBody);
array_pop($bodyParts); // last block always has no data, contains boundary ending like `--`

$bodyParams = [];
$uploadedFiles = [];
$filesCount = 0;
foreach ($bodyParts as $bodyPart) {
if (empty($bodyPart)) {
continue;
}

[$headers, $value] = preg_split('/\\R\\R/', $bodyPart, 2);
$headers = $this->parseHeaders($headers);

if (!isset($headers['content-disposition']['name'])) {
continue;
}

if (isset($headers['content-disposition']['filename'])) {
// file upload:
if ($filesCount >= $this->getUploadFileMaxCount()) {
continue;
}

$clientFilename = $headers['content-disposition']['filename'];
$clientMediaType = $headers['content-type'] ?? 'application/octet-stream';
$size = mb_strlen($value, '8bit');
$error = UPLOAD_ERR_OK;
$tempFilename = '';

if ($size > $this->getUploadFileMaxSize()) {
$error = UPLOAD_ERR_INI_SIZE;
} else {
$tmpResource = tmpfile();

if ($tmpResource === false) {
$error = UPLOAD_ERR_CANT_WRITE;
} else {
$tmpResourceMetaData = stream_get_meta_data($tmpResource);
$tmpFileName = $tmpResourceMetaData['uri'];

if (empty($tmpFileName)) {
$error = UPLOAD_ERR_CANT_WRITE;
@fclose($tmpResource);
} else {
fwrite($tmpResource, $value);
$tempFilename = $tmpFileName;
$this->tmpFileResources[] = $tmpResource; // save file resource, otherwise it will be deleted
}
}
}

$this->addValue(
$uploadedFiles,
$headers['content-disposition']['name'],
$this->createUploadedFile(
$tempFilename,
$clientFilename,
$clientMediaType,
$error
)
);

$filesCount++;
} else {
// regular parameter:
$this->addValue($bodyParams, $headers['content-disposition']['name'], $value);
}
}

return $this->newRequest($bodyParams, $uploadedFiles);
}
/**
* Creates new request instance from original one with parsed body parameters and uploaded files.
* This method is called only in case original request has been successfully parsed as 'multipart/form-data'.
*
* @param \Illuminate\Http\Request $originalRequest original request instance being parsed.
* @param array $bodyParams parsed body parameters.
* @param array $uploadedFiles parsed uploaded files.
* @return \Illuminate\Http\Request new request instance.
*/
protected function newRequest(array $bodyParams, array $uploadedFiles)
{
$request = [];
$request['files'] = $uploadedFiles;
$request['params'] = $bodyParams;
return $request;
}
/**
* Creates new uploaded file instance.
*
* @param string $tempFilename the full temporary path to the file.
* @param string $clientFilename the filename sent by the client.
* @param string|null $clientMediaType the media type sent by the client.
* @param int|null $error the error associated with the uploaded file.
*/
protected function createUploadedFile(string $tempFilename, string $clientFilename, string $clientMediaType = null, int $error = null)
{
return [
'name' => $clientFilename,
'type' => $clientMediaType,
'tmp_name' => $tempFilename,
'error' => $error,
'size' => (new \SplFileInfo($tempFilename))->getSize(),
];
}

/**
* Parses content part headers.
*
* @param string $headerContent headers source content
* @return array parsed headers.
*/
private function parseHeaders(string $headerContent): array
{
$headers = [];
$headerParts = preg_split('/\\R/s', $headerContent, -1, PREG_SPLIT_NO_EMPTY);

foreach ($headerParts as $headerPart) {
if (strpos($headerPart, ':') === false) {
continue;
}

[$headerName, $headerValue] = explode(':', $headerPart, 2);
$headerName = strtolower(trim($headerName));
$headerValue = trim($headerValue);

if (strpos($headerValue, ';') === false) {
$headers[$headerName] = $headerValue;
} else {
$headers[$headerName] = [];
foreach (explode(';', $headerValue) as $part) {
$part = trim($part);
if (strpos($part, '=') === false) {
$headers[$headerName][] = $part;
} else {
[$name, $value] = explode('=', $part, 2);
$name = strtolower(trim($name));
$value = trim(trim($value), '"');
$headers[$headerName][$name] = $value;
}
}
}
}

return $headers;
}

/**
* Adds value to the array by input name, e.g. `Item[name]`.
*
* @param array $array array which should store value.
* @param string $name input name specification.
* @param mixed $value value to be added.
*/
private function addValue(&$array, $name, $value): void
{
$nameParts = preg_split('/\\]\\[|\\[/s', $name);
$current = &$array;
foreach ($nameParts as $namePart) {
$namePart = trim($namePart, ']');
if ($namePart === '') {
$current[] = [];
$keys = array_keys($current);
$lastKey = array_pop($keys);
$current = &$current[$lastKey];
} else {
if (!isset($current[$namePart])) {
$current[$namePart] = [];
}
$current = &$current[$namePart];
}
}
$current = $value;
}
/**
* Closes all temporary files associated with this parser instance.
*
* @return static self instance.
*/
public function closeTmpFiles(): self
{
foreach ($this->tmpFileResources as $resource) {
@fclose($resource);
}

$this->tmpFileResources = [];

return $this;
}
/**
* Destructor.
* Ensures all possibly created during parsing temporary files are gracefully closed and removed.
*/
public function __destruct()
{
$this->closeTmpFiles();
}
}

// $body = <<<EOF
// --cc51ab821e27f5818ba3662ab706787e6bcc6e4d
// Content-Disposition: form-data; name="appid"
// Content-Length: 20

// 8ovpzwzBKFzz88y60N22
// --cc51ab821e27f5818ba3662ab706787e6bcc6e4d
// Content-Disposition: form-data; name="file2"; filename="upfile.txt"
// Content-Length: 6
// Content-Type: text/plain

// upfile
// --cc51ab821e27f5818ba3662ab706787e6bcc6e4d
// Content-Disposition: form-data; name="file3"; filename="upfile.txt"
// Content-Length: 6
// Content-Type: text/plain

// upfile
// --cc51ab821e27f5818ba3662ab706787e6bcc6e4d--

// EOF;

// $header = [
// "content-length" => "516",
// "content-type" => "multipart/form-data; boundary=cc51ab821e27f5818ba3662ab706787e6bcc6e4d",
// ];

// (new MultipartFormDataParser)->parse($header, $body);