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https://github.com/phpseclib/phpseclib.git
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Improve performance of File\ASN1->_decode_ber() for large data
This removes the use of _string_shift() which copies the (potentially large) latter part of the input data repeatedly, in favor of maintaining a position var and using string indexing or substr() to only copy the (relatively small) current data as it is parsed.
This commit is contained in:
John Sterling
terrafrost
parent
c788ec574f
commit
a1e16797ca
@ -285,14 +285,15 @@ class File_ASN1
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*
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* @param string $encoded
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* @param int $start
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* @param int $encoded_pos
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* @return array
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* @access private
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*/
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function _decode_ber($encoded, $start = 0)
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function _decode_ber($encoded, $start = 0, $encoded_pos = 0)
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{
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$current = array('start' => $start);
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$type = ord($this->_string_shift($encoded));
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$type = ord($encoded[$encoded_pos++]);
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$start++;
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$constructed = ($type >> 5) & 1;
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@ -304,23 +305,24 @@ class File_ASN1
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do {
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$loop = ord($encoded[0]) >> 7;
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$tag <<= 7;
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$tag |= ord($this->_string_shift($encoded)) & 0x7F;
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$tag |= ord($encoded[$encoded_pos++]) & 0x7F;
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$start++;
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} while ($loop);
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}
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// Length, as discussed in paragraph 8.1.3 of X.690-0207.pdf#page=13
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$length = ord($this->_string_shift($encoded));
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$length = ord($encoded[$encoded_pos++]);
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$start++;
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if ($length == 0x80) { // indefinite length
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// "[A sender shall] use the indefinite form (see 8.1.3.6) if the encoding is constructed and is not all
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// immediately available." -- paragraph 8.1.3.2.c
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$length = strlen($encoded);
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$length = strlen($encoded) - $encoded_pos;
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} elseif ($length & 0x80) { // definite length, long form
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// technically, the long form of the length can be represented by up to 126 octets (bytes), but we'll only
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// support it up to four.
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$length&= 0x7F;
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$temp = $this->_string_shift($encoded, $length);
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$temp = substr($encoded, $encoded_pos, $length);
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$encoded_pos += $length;
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// tags of indefinte length don't really have a header length; this length includes the tag
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$current+= array('headerlength' => $length + 2);
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$start+= $length;
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@ -329,11 +331,12 @@ class File_ASN1
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$current+= array('headerlength' => 2);
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}
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if ($length > strlen($encoded)) {
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if ($length > (strlen($encoded) - $encoded_pos)) {
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return false;
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}
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$content = $this->_string_shift($encoded, $length);
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$content = substr($encoded, $encoded_pos, $length);
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$content_pos = 0;
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// at this point $length can be overwritten. it's only accurate for definite length things as is
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@ -366,7 +369,7 @@ class File_ASN1
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$temp = $this->_decode_ber($content, $start);
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$length = $temp['length'];
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// end-of-content octets - see paragraph 8.1.5
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if (substr($content, $length, 2) == "\0\0") {
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if (substr($content, $content_pos + $length, 2) == "\0\0") {
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$length+= 2;
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$start+= $length;
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$newcontent[] = $temp;
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@ -375,7 +378,7 @@ class File_ASN1
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$start+= $length;
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$remainingLength-= $length;
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$newcontent[] = $temp;
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$this->_string_shift($content, $length);
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$content_pos += $length;
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}
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return array(
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@ -399,11 +402,11 @@ class File_ASN1
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//if (strlen($content) != 1) {
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// return false;
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//}
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$current['content'] = (bool) ord($content[0]);
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$current['content'] = (bool) ord($content[$content_pos]);
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break;
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case FILE_ASN1_TYPE_INTEGER:
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case FILE_ASN1_TYPE_ENUMERATED:
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$current['content'] = new Math_BigInteger($content, -256);
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$current['content'] = new Math_BigInteger(substr($content, $content_pos), -256);
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break;
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case FILE_ASN1_TYPE_REAL: // not currently supported
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return false;
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@ -412,10 +415,10 @@ class File_ASN1
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// the number of unused bits in the final subsequent octet. The number shall be in the range zero to
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// seven.
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if (!$constructed) {
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$current['content'] = $content;
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$current['content'] = substr($content, $content_pos);
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} else {
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$temp = $this->_decode_ber($content, $start);
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$length-= strlen($content);
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$temp = $this->_decode_ber($content, $start, $content_pos);
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$length-= (strlen($content) - $content_pos);
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$last = count($temp) - 1;
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for ($i = 0; $i < $last; $i++) {
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// all subtags should be bit strings
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@ -433,13 +436,13 @@ class File_ASN1
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break;
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case FILE_ASN1_TYPE_OCTET_STRING:
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if (!$constructed) {
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$current['content'] = $content;
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$current['content'] = substr($content, $content_pos);
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} else {
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$current['content'] = '';
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$length = 0;
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while (substr($content, 0, 2) != "\0\0") {
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$temp = $this->_decode_ber($content, $length + $start);
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$this->_string_shift($content, $temp['length']);
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while (substr($content, $content_pos, 2) != "\0\0") {
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$temp = $this->_decode_ber($content, $length + $start, $content_pos);
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$content_pos += $temp['length'];
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// all subtags should be octet strings
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//if ($temp['type'] != FILE_ASN1_TYPE_OCTET_STRING) {
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// return false;
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@ -447,7 +450,7 @@ class File_ASN1
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$current['content'].= $temp['content'];
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$length+= $temp['length'];
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}
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if (substr($content, 0, 2) == "\0\0") {
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if (substr($content, $content_pos, 2) == "\0\0") {
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$length+= 2; // +2 for the EOC
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}
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}
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@ -462,26 +465,28 @@ class File_ASN1
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case FILE_ASN1_TYPE_SET:
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$offset = 0;
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$current['content'] = array();
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while (strlen($content)) {
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$content_len = strlen($content);
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while ($content_pos < $content_len) {
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// if indefinite length construction was used and we have an end-of-content string next
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// see paragraphs 8.1.1.3, 8.1.3.2, 8.1.3.6, 8.1.5, and (for an example) 8.6.4.2
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if (!isset($current['headerlength']) && substr($content, 0, 2) == "\0\0") {
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if (!isset($current['headerlength']) && substr($content, $content_pos, 2) == "\0\0") {
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$length = $offset + 2; // +2 for the EOC
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break 2;
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}
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$temp = $this->_decode_ber($content, $start + $offset);
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$this->_string_shift($content, $temp['length']);
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$temp = $this->_decode_ber($content, $start + $offset, $content_pos);
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$content_pos += $temp['length'];
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$current['content'][] = $temp;
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$offset+= $temp['length'];
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}
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break;
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case FILE_ASN1_TYPE_OBJECT_IDENTIFIER:
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$temp = ord($this->_string_shift($content));
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$temp = ord($content[$content_pos++]);
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$current['content'] = sprintf('%d.%d', floor($temp / 40), $temp % 40);
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$valuen = 0;
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// process septets
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while (strlen($content)) {
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$temp = ord($this->_string_shift($content));
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$content_len = strlen($content);
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while ($content_pos < $content_len) {
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$temp = ord($content[$content_pos++]);
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$valuen <<= 7;
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$valuen |= $temp & 0x7F;
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if (~$temp & 0x80) {
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@ -522,11 +527,11 @@ class File_ASN1
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case FILE_ASN1_TYPE_UTF8_STRING:
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// ????
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case FILE_ASN1_TYPE_BMP_STRING:
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$current['content'] = $content;
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$current['content'] = substr($content, $content_pos);
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break;
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case FILE_ASN1_TYPE_UTC_TIME:
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case FILE_ASN1_TYPE_GENERALIZED_TIME:
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$current['content'] = $this->_decodeTime($content, $tag);
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$current['content'] = $this->_decodeTime(substr($content, $content_pos), $tag);
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default:
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}
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