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-rw-r--r--gremlin.c215
1 files changed, 0 insertions, 215 deletions
diff --git a/gremlin.c b/gremlin.c
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--- a/gremlin.c
+++ /dev/null
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-/*
- * 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