Imported Upstream version 2.2.1upstream/2.2.1

1 files changed, 215 insertions, 0 deletions

diff --git a/gremlin.c b/gremlin.c
new file mode 100644
index 0000000..c7c0206
--- /dev/null
+++ b/gremlin.c
@@ -0,0 +1,215 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  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 (see the file COPYING included with this
+ *  distribution); if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+/*
+ * Test protocol robustness by simulating dropped packets and
+ * network outages when the --gremlin option is used.
+ */
+
+#include "syshead.h"
+
+#ifdef ENABLE_DEBUG
+
+#include "error.h"
+#include "common.h"
+#include "misc.h"
+#include "otime.h"
+#include "gremlin.h"
+
+#include "memdbg.h"
+
+/*
+ * Parameters for packet corruption and droppage.
+ * Each parameter has 4 possible levels, 0 = disabled,
+ * while 1, 2, and 3 are enumerated in the below arrays.
+ * The parameter is a 2-bit field within the --gremlin
+ * parameter.
+ */
+
+/*
+ * Probability that we will drop a packet is 1 / n
+ */
+static const int drop_freq[] = { 500, 100, 50 };
+
+/*
+ * Probability that we will corrupt a packet is 1 / n
+ */
+static const int corrupt_freq[] = { 500, 100, 50 };
+
+/*
+ * When network goes up, it will be up for between
+ * UP_LOW and UP_HIGH seconds.
+ */
+static const int up_low[] =  {  60, 10,  5 };
+static const int up_high[] = { 600, 60, 10 };
+
+/*
+ * When network goes down, it will be down for between
+ * DOWN_LOW and DOWN_HIGH seconds.
+ */
+static const int down_low[] =  {  5, 10,  10 };
+static const int down_high[] = { 10, 60, 120 };
+
+/*
+ * Packet flood levels:
+ *  { number of packets, packet size }
+ */
+static const struct packet_flood_parms packet_flood_data[] =
+  {{10, 100}, {10, 1500}, {100, 1500}};
+
+struct packet_flood_parms
+get_packet_flood_parms (int level)
+{
+  ASSERT (level > 0 && level < 4);
+  return packet_flood_data [level - 1];
+}
+
+/*
+ * Return true with probability 1/n
+ */
+static bool flip(int n) {
+  return (get_random() % n) == 0;
+}
+
+/*
+ * Return uniformly distributed random number between
+ * low and high.
+ */
+static int roll(int low, int high) {
+  int ret;
+  ASSERT (low <= high);
+  ret = low + (get_random() % (high - low + 1));
+  ASSERT (ret >= low && ret <= high);
+  return ret;
+}
+
+static bool initialized; /* GLOBAL */
+static bool up;          /* GLOBAL */
+static time_t next;      /* GLOBAL */
+
+/*
+ * Return false if we should drop a packet.
+ */
+bool
+ask_gremlin (int flags)
+{
+  const int up_down_level = GREMLIN_UP_DOWN_LEVEL (flags);
+  const int drop_level = GREMLIN_DROP_LEVEL (flags);
+
+  if (!initialized)
+    {
+      initialized = true;
+
+      if (up_down_level)
+	up = false;
+      else
+	up = true;
+
+      next = now;
+    }
+
+  if (up_down_level) /* change up/down state? */
+    {
+      if (now >= next)
+	{
+	  int delta;
+	  if (up)
+	    {
+	      delta = roll (down_low[up_down_level-1], down_high[up_down_level-1]);
+	      up = false;
+	    }
+	  else
+	    {
+	      delta = roll (up_low[up_down_level-1], up_high[up_down_level-1]);
+	      up = true;
+	    }
+      
+	  msg (D_GREMLIN,
+	       "GREMLIN: CONNECTION GOING %s FOR %d SECONDS",
+	       (up ? "UP" : "DOWN"),
+	       delta);
+	  next = now + delta;
+	}
+    }
+
+  if (drop_level)
+    {
+      if (up && flip (drop_freq[drop_level-1]))
+	{
+	  dmsg (D_GREMLIN_VERBOSE, "GREMLIN: Random packet drop");
+	  return false;
+	}
+    }
+
+  return up;
+}
+
+/*
+ * Possibly corrupt a packet.
+ */
+void corrupt_gremlin (struct buffer *buf, int flags) {
+  const int corrupt_level = GREMLIN_CORRUPT_LEVEL (flags);
+  if (corrupt_level)
+    {
+      if (flip (corrupt_freq[corrupt_level-1]))
+	{
+	  do
+	    {
+	      if (buf->len > 0)
+		{
+		  uint8_t r = roll (0, 255);
+		  int method = roll (0, 5);
+
+		  switch (method) {
+		  case 0: /* corrupt the first byte */
+		    *BPTR (buf) = r;
+		    break;
+		  case 1: /* corrupt the last byte */
+		    *(BPTR (buf) + buf->len - 1) = r;
+		    break;
+		  case 2: /* corrupt a random byte */
+		    *(BPTR(buf) + roll (0, buf->len - 1)) = r;
+		    break;
+		  case 3: /* append a random byte */
+		    buf_write (buf, &r, 1);
+		    break;
+		  case 4: /* reduce length by 1 */
+		    --buf->len;
+		    break;
+		  case 5: /* reduce length by a random amount */
+		    buf->len -= roll (0, buf->len - 1);
+		    break;
+		  }
+		  dmsg (D_GREMLIN_VERBOSE, "GREMLIN: Packet Corruption, method=%d", method);
+		}
+	      else
+		break;
+	    } while (flip (2)); /* a 50% chance we will corrupt again */
+	}
+    }
+}
+
+#else
+static void dummy(void) {}
+#endif