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authorplegall <plg@piwigo.org>2016-04-26 11:07:44 +0200
committerplegall <plg@piwigo.org>2016-04-26 11:07:44 +0200
commitf51ee90c66527fd7ff634f3e8d414cb670da068d (patch)
tree2550f0753f14ed594dbf99cb65675fa02b49fe21 /include/random_compat/random_bytes_dev_urandom.php
parenta3c46de7511cb5b66f59375d225b1f0fb66ae988 (diff)
bug #470, use a dedicated lib to generate random bytes
Diffstat (limited to 'include/random_compat/random_bytes_dev_urandom.php')
-rw-r--r--include/random_compat/random_bytes_dev_urandom.php148
1 files changed, 148 insertions, 0 deletions
diff --git a/include/random_compat/random_bytes_dev_urandom.php b/include/random_compat/random_bytes_dev_urandom.php
new file mode 100644
index 000000000..db93b0757
--- /dev/null
+++ b/include/random_compat/random_bytes_dev_urandom.php
@@ -0,0 +1,148 @@
+<?php
+/**
+ * Random_* Compatibility Library
+ * for using the new PHP 7 random_* API in PHP 5 projects
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2015 Paragon Initiative Enterprises
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+if (!defined('RANDOM_COMPAT_READ_BUFFER')) {
+ define('RANDOM_COMPAT_READ_BUFFER', 8);
+}
+
+/**
+ * Unless open_basedir is enabled, use /dev/urandom for
+ * random numbers in accordance with best practices
+ *
+ * Why we use /dev/urandom and not /dev/random
+ * @ref http://sockpuppet.org/blog/2014/02/25/safely-generate-random-numbers
+ *
+ * @param int $bytes
+ *
+ * @throws Exception
+ *
+ * @return string
+ */
+function random_bytes($bytes)
+{
+ static $fp = null;
+ /**
+ * This block should only be run once
+ */
+ if (empty($fp)) {
+ /**
+ * We use /dev/urandom if it is a char device.
+ * We never fall back to /dev/random
+ */
+ $fp = fopen('/dev/urandom', 'rb');
+ if (!empty($fp)) {
+ $st = fstat($fp);
+ if (($st['mode'] & 0170000) !== 020000) {
+ fclose($fp);
+ $fp = false;
+ }
+ }
+
+ if (!empty($fp)) {
+ /**
+ * stream_set_read_buffer() does not exist in HHVM
+ *
+ * If we don't set the stream's read buffer to 0, PHP will
+ * internally buffer 8192 bytes, which can waste entropy
+ *
+ * stream_set_read_buffer returns 0 on success
+ */
+ if (function_exists('stream_set_read_buffer')) {
+ stream_set_read_buffer($fp, RANDOM_COMPAT_READ_BUFFER);
+ }
+ if (function_exists('stream_set_chunk_size')) {
+ stream_set_chunk_size($fp, RANDOM_COMPAT_READ_BUFFER);
+ }
+ }
+ }
+
+ try {
+ $bytes = RandomCompat_intval($bytes);
+ } catch (TypeError $ex) {
+ throw new TypeError(
+ 'random_bytes(): $bytes must be an integer'
+ );
+ }
+
+ if ($bytes < 1) {
+ throw new Error(
+ 'Length must be greater than 0'
+ );
+ }
+
+ /**
+ * This if() block only runs if we managed to open a file handle
+ *
+ * It does not belong in an else {} block, because the above
+ * if (empty($fp)) line is logic that should only be run once per
+ * page load.
+ */
+ if (!empty($fp)) {
+ $remaining = $bytes;
+ $buf = '';
+
+ /**
+ * We use fread() in a loop to protect against partial reads
+ */
+ do {
+ $read = fread($fp, $remaining);
+ if ($read === false) {
+ /**
+ * We cannot safely read from the file. Exit the
+ * do-while loop and trigger the exception condition
+ */
+ $buf = false;
+ break;
+ }
+ /**
+ * Decrease the number of bytes returned from remaining
+ */
+ $remaining -= RandomCompat_strlen($read);
+ $buf .= $read;
+ } while ($remaining > 0);
+
+ /**
+ * Is our result valid?
+ */
+ if ($buf !== false) {
+ if (RandomCompat_strlen($buf) === $bytes) {
+ /**
+ * Return our random entropy buffer here:
+ */
+ return $buf;
+ }
+ }
+ }
+
+ /**
+ * If we reach here, PHP has failed us.
+ */
+ throw new Exception(
+ 'Error reading from source device'
+ );
+}