Merge branch 'u2_10_12_branch' of git://git.code.sf.net/p/undernet-ircu/ircu2

[ircu2.10.12-pk.git] / ircd / random.c

diff --git a/ircd/random.c b/ircd/random.c
new file mode 100644 (file)
index 0000000..7727dbb
--- /dev/null
+++ b/ircd/random.c
@@ -0,0 +1,109 @@
+/*
+ * IRC - Internet Relay Chat, ircd/random.c
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 1, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+/** @file
+ * @brief 32-bit pseudo-random number generator implementation.
+ * @version $Id$
+ */
+#include "config.h"
+
+#include "random.h"
+#include "client.h"
+#include "ircd_log.h"
+#include "ircd_md5.h"
+#include "ircd_reply.h"
+#include "send.h"
+
+#include <string.h>
+#include <sys/time.h>
+
+/** Pseudo-random number generator state. */
+static struct MD5Context localkey;
+/** Next byte position in #localkey to insert at. */
+static unsigned int localkey_pos;
+
+/** Add bytes to #localkey.
+ * This should be fairly resistant to adding non-random bytes, but the
+ * more random the bytes are, the harder it is for an attacker to
+ * guess the internal state.
+ * @param[in] buf Buffer of bytes to add.
+ * @param[in] count Number of bytes to add.
+ */
+static void
+random_add_entropy(const char *buf, unsigned int count)
+{
+  while (count--) {
+    localkey.in[localkey_pos++] ^= *buf++;
+    if (localkey_pos >= sizeof(localkey.in))
+      localkey_pos = 0;
+  }
+}
+
+/** Seed the PRNG with a string.
+ * @param[in] from Client setting the seed (may be NULL).
+ * @param[in] fields Input arguments (fields[0] is used).
+ * @param[in] count Number of input arguments.
+ * @return Non-zero on success, zero on error.
+ */
+int
+random_seed_set(struct Client* from, const char* const* fields, int count)
+{
+  if (count < 1) {
+    if (from) /* send an error */
+      return need_more_params(from, "SET");
+    else {
+      log_write(LS_CONFIG, L_ERROR, 0, "Not enough fields in F line");
+      return 0;
+    }
+  }
+
+  random_add_entropy(fields[0], strlen(fields[0]));
+  return 1;
+}
+
+/** Generate a pseudo-random number.
+ * This uses the #localkey structure plus current time as input to
+ * MD5, feeding most of the MD5 output back to #localkey and using one
+ * output words as the pseudo-random output.
+ * @return A 32-bit pseudo-random number.
+ */
+unsigned int ircrandom(void)
+{
+  struct timeval tv;
+  char usec[3];
+
+  /* Add some randomness to the pool. */
+  gettimeofday(&tv, 0);
+  usec[0] = tv.tv_usec;
+  usec[1] = tv.tv_usec >> 8;
+  usec[2] = tv.tv_usec >> 16;
+  random_add_entropy(usec, 3);
+
+  /* Perform MD5 step. */
+  localkey.buf[0] = 0x67452301;
+  localkey.buf[1] = 0xefcdab89;
+  localkey.buf[2] = 0x98badcfe;
+  localkey.buf[3] = 0x10325476;
+  MD5Transform(localkey.buf, (uint32*)localkey.in);
+
+  /* Feed back 12 bytes of hash value into randomness pool. */
+  random_add_entropy((char*)localkey.buf, 12);
+
+  /* Return the final word of hash, which should not provide any
+   * useful insight into current pool contents. */
+  return localkey.buf[3];
+}