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-rw-r--r--reliable.c700
1 files changed, 700 insertions, 0 deletions
diff --git a/reliable.c b/reliable.c
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+++ b/reliable.c
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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) 2002-2005 OpenVPN Solutions LLC <info@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
+ */
+
+/*
+ * These routines implement a reliability layer on top of UDP,
+ * so that SSL/TLS can be run over UDP.
+ */
+
+#ifdef WIN32
+#include "config-win32.h"
+#else
+#include "config.h"
+#endif
+
+#if defined(USE_CRYPTO) && defined(USE_SSL)
+
+#include "syshead.h"
+
+#include "buffer.h"
+#include "error.h"
+#include "common.h"
+#include "reliable.h"
+
+#include "memdbg.h"
+
+/* check if a particular packet_id is present in ack */
+static inline bool
+reliable_ack_packet_id_present (struct reliable_ack *ack, packet_id_type pid)
+{
+ int i;
+ for (i = 0; i < ack->len; ++i)
+ if (ack->packet_id[i] == pid)
+ return true;
+ return false;
+}
+
+/* get a packet_id from buf */
+bool
+reliable_ack_read_packet_id (struct buffer *buf, packet_id_type *pid)
+{
+ packet_id_type net_pid;
+
+ if (buf_read (buf, &net_pid, sizeof (net_pid)))
+ {
+ *pid = ntohpid (net_pid);
+ dmsg (D_REL_DEBUG, "ACK read ID " packet_id_format " (buf->len=%d)",
+ (packet_id_print_type)*pid, buf->len);
+ return true;
+ }
+
+ dmsg (D_REL_LOW, "ACK read ID FAILED (buf->len=%d)", buf->len);
+ return false;
+}
+
+/* acknowledge a packet_id by adding it to a struct reliable_ack */
+bool
+reliable_ack_acknowledge_packet_id (struct reliable_ack *ack, packet_id_type pid)
+{
+ if (!reliable_ack_packet_id_present (ack, pid) && ack->len < RELIABLE_ACK_SIZE)
+ {
+ ack->packet_id[ack->len++] = pid;
+ dmsg (D_REL_DEBUG, "ACK acknowledge ID " packet_id_format " (ack->len=%d)",
+ (packet_id_print_type)pid, ack->len);
+ return true;
+ }
+
+ dmsg (D_REL_LOW, "ACK acknowledge ID " packet_id_format " FAILED (ack->len=%d)",
+ (packet_id_print_type)pid, ack->len);
+ return false;
+}
+
+/* read a packet ID acknowledgement record from buf into ack */
+bool
+reliable_ack_read (struct reliable_ack * ack,
+ struct buffer * buf, const struct session_id * sid)
+{
+ struct gc_arena gc = gc_new ();
+ int i;
+ uint8_t count;
+ packet_id_type net_pid;
+ packet_id_type pid;
+ struct session_id session_id_remote;
+
+ if (!buf_read (buf, &count, sizeof (count)))
+ goto error;
+ for (i = 0; i < count; ++i)
+ {
+ if (!buf_read (buf, &net_pid, sizeof (net_pid)))
+ goto error;
+ if (ack->len >= RELIABLE_ACK_SIZE)
+ goto error;
+ pid = ntohpid (net_pid);
+ ack->packet_id[ack->len++] = pid;
+ }
+ if (count)
+ {
+ if (!session_id_read (&session_id_remote, buf))
+ goto error;
+ if (!session_id_defined (&session_id_remote) ||
+ !session_id_equal (&session_id_remote, sid))
+ {
+ dmsg (D_REL_LOW,
+ "ACK read BAD SESSION-ID FROM REMOTE, local=%s, remote=%s",
+ session_id_print (sid, &gc), session_id_print (&session_id_remote, &gc));
+ goto error;
+ }
+ }
+ gc_free (&gc);
+ return true;
+
+error:
+ gc_free (&gc);
+ return false;
+}
+
+#define ACK_SIZE(n) (sizeof (uint8_t) + ((n) ? SID_SIZE : 0) + sizeof (packet_id_type) * (n))
+
+/* write a packet ID acknowledgement record to buf, */
+/* removing all acknowledged entries from ack */
+bool
+reliable_ack_write (struct reliable_ack * ack,
+ struct buffer * buf,
+ const struct session_id * sid, int max, bool prepend)
+{
+ int i, j;
+ uint8_t n;
+ struct buffer sub;
+
+ n = ack->len;
+ if (n > max)
+ n = max;
+ sub = buf_sub (buf, ACK_SIZE(n), prepend);
+ if (!BDEF (&sub))
+ goto error;
+ ASSERT (buf_write (&sub, &n, sizeof (n)));
+ for (i = 0; i < n; ++i)
+ {
+ packet_id_type pid = ack->packet_id[i];
+ packet_id_type net_pid = htonpid (pid);
+ ASSERT (buf_write (&sub, &net_pid, sizeof (net_pid)));
+ dmsg (D_REL_DEBUG, "ACK write ID " packet_id_format " (ack->len=%d, n=%d)", (packet_id_print_type)pid, ack->len, n);
+ }
+ if (n)
+ {
+ ASSERT (session_id_defined (sid));
+ ASSERT (session_id_write (sid, &sub));
+ for (i = 0, j = n; j < ack->len;)
+ ack->packet_id[i++] = ack->packet_id[j++];
+ ack->len = i;
+ }
+
+ return true;
+
+error:
+ return false;
+}
+
+/* add to extra_frame the maximum number of bytes we will need for reliable_ack_write */
+void
+reliable_ack_adjust_frame_parameters (struct frame* frame, int max)
+{
+ frame_add_to_extra_frame (frame, ACK_SIZE (max));
+}
+
+/* print a reliable ACK record coming off the wire */
+const char *
+reliable_ack_print (struct buffer *buf, bool verbose, struct gc_arena *gc)
+{
+ int i;
+ uint8_t n_ack;
+ struct session_id sid_ack;
+ packet_id_type pid;
+ struct buffer out = alloc_buf_gc (256, gc);
+
+ buf_printf (&out, "[");
+ if (!buf_read (buf, &n_ack, sizeof (n_ack)))
+ goto done;
+ for (i = 0; i < n_ack; ++i)
+ {
+ if (!buf_read (buf, &pid, sizeof (pid)))
+ goto done;
+ pid = ntohpid (pid);
+ buf_printf (&out, " " packet_id_format, (packet_id_print_type)pid);
+ }
+ if (n_ack)
+ {
+ if (!session_id_read (&sid_ack, buf))
+ goto done;
+ if (verbose)
+ buf_printf (&out, " sid=%s", session_id_print (&sid_ack, gc));
+ }
+
+ done:
+ buf_printf (&out, " ]");
+ return BSTR (&out);
+}
+
+/*
+ * struct reliable member functions.
+ */
+
+void
+reliable_init (struct reliable *rel, int buf_size, int offset, int array_size)
+{
+ int i;
+
+ CLEAR (*rel);
+ ASSERT (array_size > 0 && array_size <= RELIABLE_CAPACITY);
+ rel->size = array_size;
+ rel->offset = offset;
+ for (i = 0; i < rel->size; ++i)
+ {
+ struct reliable_entry *e = &rel->array[i];
+ e->buf = alloc_buf (buf_size);
+ ASSERT (buf_init (&e->buf, offset));
+ }
+}
+
+void
+reliable_free (struct reliable *rel)
+{
+ int i;
+ for (i = 0; i < rel->size; ++i)
+ {
+ struct reliable_entry *e = &rel->array[i];
+ free_buf (&e->buf);
+ }
+}
+
+/* no active buffers? */
+bool
+reliable_empty (const struct reliable *rel)
+{
+ int i;
+ for (i = 0; i < rel->size; ++i)
+ {
+ const struct reliable_entry *e = &rel->array[i];
+ if (e->active)
+ return false;
+ }
+ return true;
+}
+
+/* del acknowledged items from send buf */
+void
+reliable_send_purge (struct reliable *rel, struct reliable_ack *ack)
+{
+ int i, j;
+ for (i = 0; i < ack->len; ++i)
+ {
+ packet_id_type pid = ack->packet_id[i];
+ for (j = 0; j < rel->size; ++j)
+ {
+ struct reliable_entry *e = &rel->array[j];
+ if (e->active && e->packet_id == pid)
+ {
+ dmsg (D_REL_DEBUG,
+ "ACK received for pid " packet_id_format ", deleting from send buffer",
+ (packet_id_print_type)pid);
+#if 0
+ /* DEBUGGING -- how close were we timing out on ACK failure and resending? */
+ {
+ if (e->next_try)
+ {
+ const interval_t wake = e->next_try - now;
+ msg (M_INFO, "ACK " packet_id_format ", wake=%d", pid, wake);
+ }
+ }
+#endif
+ e->active = false;
+ break;
+ }
+ }
+ }
+}
+
+/* print the current sequence of active packet IDs */
+static const char *
+reliable_print_ids (const struct reliable *rel, struct gc_arena *gc)
+{
+ struct buffer out = alloc_buf_gc (256, gc);
+ int i;
+
+ buf_printf (&out, "[" packet_id_format "]", (packet_id_print_type)rel->packet_id);
+ for (i = 0; i < rel->size; ++i)
+ {
+ const struct reliable_entry *e = &rel->array[i];
+ if (e->active)
+ buf_printf (&out, " " packet_id_format, (packet_id_print_type)e->packet_id);
+ }
+ return BSTR (&out);
+}
+
+/* true if at least one free buffer available */
+bool
+reliable_can_get (const struct reliable *rel)
+{
+ struct gc_arena gc = gc_new ();
+ int i;
+ for (i = 0; i < rel->size; ++i)
+ {
+ const struct reliable_entry *e = &rel->array[i];
+ if (!e->active)
+ return true;
+ }
+ dmsg (D_REL_LOW, "ACK no free receive buffer available: %s", reliable_print_ids (rel, &gc));
+ gc_free (&gc);
+ return false;
+}
+
+/* make sure that incoming packet ID isn't a replay */
+bool
+reliable_not_replay (const struct reliable *rel, packet_id_type id)
+{
+ struct gc_arena gc = gc_new ();
+ int i;
+ if (id < rel->packet_id)
+ goto bad;
+ for (i = 0; i < rel->size; ++i)
+ {
+ const struct reliable_entry *e = &rel->array[i];
+ if (e->active && e->packet_id == id)
+ goto bad;
+ }
+ gc_free (&gc);
+ return true;
+
+ bad:
+ dmsg (D_REL_DEBUG, "ACK " packet_id_format " is a replay: %s", (packet_id_print_type)id, reliable_print_ids (rel, &gc));
+ gc_free (&gc);
+ return false;
+}
+
+/* make sure that incoming packet ID won't deadlock the receive buffer */
+bool
+reliable_wont_break_sequentiality (const struct reliable *rel, packet_id_type id)
+{
+ struct gc_arena gc = gc_new ();
+ int ret;
+
+ if ((int)id < (int)rel->packet_id + rel->size)
+ {
+ ret = true;
+ }
+ else
+ {
+ dmsg (D_REL_LOW, "ACK " packet_id_format " breaks sequentiality: %s",
+ (packet_id_print_type)id, reliable_print_ids (rel, &gc));
+ ret = false;
+ }
+ gc_free (&gc);
+ return ret;
+}
+
+/* grab a free buffer */
+struct buffer *
+reliable_get_buf (struct reliable *rel)
+{
+ int i;
+ for (i = 0; i < rel->size; ++i)
+ {
+ struct reliable_entry *e = &rel->array[i];
+ if (!e->active)
+ {
+ ASSERT (buf_init (&e->buf, rel->offset));
+ return &e->buf;
+ }
+ }
+ return NULL;
+}
+
+/* grab a free buffer, fail if buffer clogged by unacknowledged low packet IDs */
+struct buffer *
+reliable_get_buf_output_sequenced (struct reliable *rel)
+{
+ struct gc_arena gc = gc_new ();
+ int i;
+ packet_id_type min_id = 0;
+ bool min_id_defined = false;
+ struct buffer *ret = NULL;
+
+ /* find minimum active packet_id */
+ for (i = 0; i < rel->size; ++i)
+ {
+ const struct reliable_entry *e = &rel->array[i];
+ if (e->active)
+ {
+ if (!min_id_defined || e->packet_id < min_id)
+ {
+ min_id_defined = true;
+ min_id = e->packet_id;
+ }
+ }
+ }
+
+ if (!min_id_defined || (int)(rel->packet_id - min_id) < rel->size)
+ {
+ ret = reliable_get_buf (rel);
+ }
+ else
+ {
+ dmsg (D_REL_LOW, "ACK output sequence broken: %s", reliable_print_ids (rel, &gc));
+ }
+ gc_free (&gc);
+ return ret;
+}
+
+/* get active buffer for next sequentially increasing key ID */
+struct buffer *
+reliable_get_buf_sequenced (struct reliable *rel)
+{
+ int i;
+ for (i = 0; i < rel->size; ++i)
+ {
+ struct reliable_entry *e = &rel->array[i];
+ if (e->active && e->packet_id == rel->packet_id)
+ {
+ return &e->buf;
+ }
+ }
+ return NULL;
+}
+
+/* return true if reliable_send would return a non-NULL result */
+bool
+reliable_can_send (const struct reliable *rel)
+{
+ struct gc_arena gc = gc_new ();
+ int i;
+ int n_active = 0, n_current = 0;
+ for (i = 0; i < rel->size; ++i)
+ {
+ const struct reliable_entry *e = &rel->array[i];
+ if (e->active)
+ {
+ ++n_active;
+ if (now >= e->next_try)
+ ++n_current;
+ }
+ }
+ dmsg (D_REL_DEBUG, "ACK reliable_can_send active=%d current=%d : %s",
+ n_active,
+ n_current,
+ reliable_print_ids (rel, &gc));
+
+ gc_free (&gc);
+ return n_current > 0;
+}
+
+/* return a unique point-in-time to trigger retry */
+static time_t
+reliable_unique_retry (struct reliable *rel, time_t retry)
+{
+ int i;
+ while (true)
+ {
+ for (i = 0; i < rel->size; ++i)
+ {
+ struct reliable_entry *e = &rel->array[i];
+ if (e->active && e->next_try == retry)
+ goto again;
+ }
+ break;
+ again:
+ ++retry;
+ }
+ return retry;
+}
+
+/* return next buffer to send to remote */
+struct buffer *
+reliable_send (struct reliable *rel, int *opcode)
+{
+ int i;
+ struct reliable_entry *best = NULL;
+ const time_t local_now = now;
+
+ for (i = 0; i < rel->size; ++i)
+ {
+ struct reliable_entry *e = &rel->array[i];
+ if (e->active && local_now >= e->next_try)
+ {
+ if (!best || e->packet_id < best->packet_id)
+ best = e;
+ }
+ }
+ if (best)
+ {
+#ifdef EXPONENTIAL_BACKOFF
+ /* exponential backoff */
+ best->next_try = reliable_unique_retry (rel, local_now + best->timeout);
+ best->timeout *= 2;
+#else
+ /* constant timeout, no backoff */
+ best->next_try = local_now + best->timeout;
+#endif
+ *opcode = best->opcode;
+ dmsg (D_REL_DEBUG, "ACK reliable_send ID " packet_id_format " (size=%d to=%d)",
+ (packet_id_print_type)best->packet_id, best->buf.len,
+ (int)(best->next_try - local_now));
+ return &best->buf;
+ }
+ return NULL;
+}
+
+/* schedule all pending packets for immediate retransmit */
+void
+reliable_schedule_now (struct reliable *rel)
+{
+ int i;
+ dmsg (D_REL_DEBUG, "ACK reliable_schedule_now");
+ for (i = 0; i < rel->size; ++i)
+ {
+ struct reliable_entry *e = &rel->array[i];
+ if (e->active)
+ {
+ e->next_try = now;
+ e->timeout = rel->initial_timeout;
+ }
+ }
+}
+
+/* in how many seconds should we wake up to check for timeout */
+/* if we return BIG_TIMEOUT, nothing to wait for */
+interval_t
+reliable_send_timeout (const struct reliable *rel)
+{
+ struct gc_arena gc = gc_new ();
+ interval_t ret = BIG_TIMEOUT;
+ int i;
+ const time_t local_now = now;
+
+ for (i = 0; i < rel->size; ++i)
+ {
+ const struct reliable_entry *e = &rel->array[i];
+ if (e->active)
+ {
+ if (e->next_try <= local_now)
+ {
+ ret = 0;
+ break;
+ }
+ else
+ {
+ ret = min_int (ret, e->next_try - local_now);
+ }
+ }
+ }
+
+ dmsg (D_REL_DEBUG, "ACK reliable_send_timeout %d %s",
+ (int) ret,
+ reliable_print_ids (rel, &gc));
+
+ gc_free (&gc);
+ return ret;
+}
+
+/*
+ * Enable an incoming buffer previously returned by a get function as active.
+ */
+
+void
+reliable_mark_active_incoming (struct reliable *rel, struct buffer *buf,
+ packet_id_type pid, int opcode)
+{
+ int i;
+ for (i = 0; i < rel->size; ++i)
+ {
+ struct reliable_entry *e = &rel->array[i];
+ if (buf == &e->buf)
+ {
+ e->active = true;
+
+ /* packets may not arrive in sequential order */
+ e->packet_id = pid;
+
+ /* check for replay */
+ ASSERT (pid >= rel->packet_id);
+
+ e->opcode = opcode;
+ e->next_try = 0;
+ e->timeout = 0;
+ dmsg (D_REL_DEBUG, "ACK mark active incoming ID " packet_id_format, (packet_id_print_type)e->packet_id);
+ return;
+ }
+ }
+ ASSERT (0); /* buf not found in rel */
+}
+
+/*
+ * Enable an outgoing buffer previously returned by a get function as active.
+ */
+
+void
+reliable_mark_active_outgoing (struct reliable *rel, struct buffer *buf, int opcode)
+{
+ int i;
+ for (i = 0; i < rel->size; ++i)
+ {
+ struct reliable_entry *e = &rel->array[i];
+ if (buf == &e->buf)
+ {
+ /* Write mode, increment packet_id (i.e. sequence number)
+ linearly and prepend id to packet */
+ packet_id_type net_pid;
+ e->packet_id = rel->packet_id++;
+ net_pid = htonpid (e->packet_id);
+ ASSERT (buf_write_prepend (buf, &net_pid, sizeof (net_pid)));
+ e->active = true;
+ e->opcode = opcode;
+ e->next_try = 0;
+ e->timeout = rel->initial_timeout;
+ dmsg (D_REL_DEBUG, "ACK mark active outgoing ID " packet_id_format, (packet_id_print_type)e->packet_id);
+ return;
+ }
+ }
+ ASSERT (0); /* buf not found in rel */
+}
+
+/* delete a buffer previously activated by reliable_mark_active() */
+void
+reliable_mark_deleted (struct reliable *rel, struct buffer *buf, bool inc_pid)
+{
+ int i;
+ for (i = 0; i < rel->size; ++i)
+ {
+ struct reliable_entry *e = &rel->array[i];
+ if (buf == &e->buf)
+ {
+ e->active = false;
+ if (inc_pid)
+ rel->packet_id = e->packet_id + 1;
+ return;
+ }
+ }
+ ASSERT (0);
+}
+
+#if 0
+
+void
+reliable_ack_debug_print (const struct reliable_ack *ack, char *desc)
+{
+ int i;
+
+ printf ("********* struct reliable_ack %s\n", desc);
+ for (i = 0; i < ack->len; ++i)
+ {
+ printf (" %d: " packet_id_format "\n", i, (packet_id_print_type) ack->packet_id[i]);
+ }
+}
+
+void
+reliable_debug_print (const struct reliable *rel, char *desc)
+{
+ int i;
+ update_time ();
+
+ printf ("********* struct reliable %s\n", desc);
+ printf (" initial_timeout=%d\n", (int)rel->initial_timeout);
+ printf (" packet_id=" packet_id_format "\n", rel->packet_id);
+ printf (" now=" time_format "\n", now);
+ for (i = 0; i < rel->size; ++i)
+ {
+ const struct reliable_entry *e = &rel->array[i];
+ if (e->active)
+ {
+ printf (" %d: packet_id=" packet_id_format " len=%d", i, e->packet_id, e->buf.len);
+ printf (" next_try=" time_format, e->next_try);
+ printf ("\n");
+ }
+ }
+}
+
+#endif
+
+#else
+static void dummy(void) {}
+#endif /* USE_CRYPTO && USE_SSL*/