PhpZip\IO\Filter\Cipher\WinZipAes\WinZipAesDecryptionStreamFilter::filter()

Complexity

Conditions	15
Paths	45

Size

Total Lines	87
Code Lines	51

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	47
CRAP Score	15.1084

Importance

Changes	1
Bugs	0	Features	1

<?php
    public function filter($in, $out, &$consumed, $closing)
    {
        while ($bucket = stream_bucket_make_writeable($in)) {
            $this->buffer .= $bucket->data;
            $this->readLength += $bucket->datalen;

            if ($this->readLength > $this->entry->getCompressedSize()) {
                $this->buffer = substr($this->buffer, 0, $this->entry->getCompressedSize() - $this->readLength);
            }

            // read header
            if ($this->context === null) {
                /**
                 * @var WinZipAesExtraField|null $winZipExtra
                 */
                $winZipExtra = $this->entry->getExtraField(WinZipAesExtraField::HEADER_ID);

                if ($winZipExtra === null) {
                    throw new RuntimeException('$winZipExtra is null');
                }
                $saltSize = $winZipExtra->getSaltSize();
                $headerSize = $saltSize + WinZipAesContext::PASSWORD_VERIFIER_SIZE;

                if (\strlen($this->buffer) < $headerSize) {
                    return \PSFS_FEED_ME;
                }

                $salt = substr($this->buffer, 0, $saltSize);
                $passwordVerifier = substr($this->buffer, $saltSize, WinZipAesContext::PASSWORD_VERIFIER_SIZE);
                $password = $this->entry->getPassword();

                if ($password === null) {
                    throw new RuntimeException('$password is null');
                }
                $this->context = new WinZipAesContext($winZipExtra->getEncryptionStrength(), $password, $salt);
                unset($password);

                // Verify password.
                if ($passwordVerifier !== $this->context->getPasswordVerifier()) {
                    throw new ZipAuthenticationException('Invalid password');
                }

                $this->encBlockPosition = 0;
                $this->encBlockLength = $this->entry->getCompressedSize() - $headerSize - WinZipAesContext::FOOTER_SIZE;

                $this->buffer = substr($this->buffer, $headerSize);
            }

            // encrypt data
            $plainText = '';
            $offset = 0;
            $len = \strlen($this->buffer);
            $remaining = $this->encBlockLength - $this->encBlockPosition;

            if ($remaining >= WinZipAesContext::BLOCK_SIZE && $len < WinZipAesContext::BLOCK_SIZE) {
                return \PSFS_FEED_ME;
            }
            $limit = min($len, $remaining);

            if ($remaining > $limit && ($limit % WinZipAesContext::BLOCK_SIZE) !== 0) {
                $limit -= ($limit % WinZipAesContext::BLOCK_SIZE);
            }

            while ($offset < $limit) {
                $this->context->updateIv();
                $length = min(WinZipAesContext::BLOCK_SIZE, $limit - $offset);
                $data = substr($this->buffer, 0, $length);
                $plainText .= $this->context->decryption($data);
                $offset += $length;
                $this->buffer = substr($this->buffer, $length);
            }
            $this->encBlockPosition += $offset;

            if (
                $this->encBlockPosition === $this->encBlockLength &&
                \strlen($this->buffer) === WinZipAesContext::FOOTER_SIZE
            ) {
                $this->authenticationCode = $this->buffer;
                $this->buffer = '';
            }

            $bucket->data = $plainText;
            $consumed += $bucket->datalen;
            stream_bucket_append($out, $bucket);
        }

        return \PSFS_PASS_ON;
    }