.I p-replay
probability (default 1 in 20) of being left in the queue.
.TP
+.BI drop\fR[\fP: p-drop\fR]
+Randomly drop messages. Each message has a 1 in
+.I p-drop
+probability (default 1 in 5) of being discarded.
+.TP
.BI corrupt\fR[\fP: p-corrupt\fR]
Randomly corrupt messages. Each message has a 1 in
.I p-corrupt
{
corrupt *c;
if (ac > 1)
- die(1, "syntax: filt:corrupt[:PCORRUPT]");
+ die(1, "syntax: filt:corrupt[:P-CORRUPT]");
c = CREATE(corrupt);
if (ac > 0)
c->p_corrupt = atoi(av[0]);
f->func = docorrupt;
}
+/*----- Drop filter -------------------------------------------------------*/
+
+typedef struct drop {
+ unsigned p_drop;
+} drop;
+
+static void dodrop(filter *f, const octet *buf, size_t sz)
+{
+ drop *d = f->state;
+
+ if (!RND(d->p_drop))
+ puts("drop packet");
+ else
+ PASS(f->next, buf, sz);
+}
+
+static void adddrop(filter *f, unsigned ac, char **av)
+{
+ drop *d;
+ if (ac > 1)
+ die(1, "syntax: filt:drop[:P-DROP]");
+ d = CREATE(drop);
+ if (ac > 0)
+ d->p_drop = atoi(av[0]);
+ else
+ d->p_drop = 5;
+ f->state = d;
+ f->func = dodrop;
+}
+
/*----- Delay filter ------------------------------------------------------*/
typedef struct delaynode {
unsigned i;
if (ac < 1 || ac > 3)
- die(1, "syntax: filt:delay:QLEN[:MILLIS:PREPLAY]");
+ die(1, "syntax: filt:delay:QLEN[:MILLIS:P-REPLAY]");
d = CREATE(delay);
d->max = atoi(av[0]);
if (ac > 1)
{ "send", addsend },
{ "fork", addfork },
{ "delay", adddelay },
+ { "drop", adddrop },
{ "corrupt", addcorrupt },
{ 0, 0 }
};
send\n\
fork:TAG\n\
delay:QLEN[:MILLIS:P-REPLAY]\n\
+ drop[:P-DROP]\n\
corrupt[:P-CORRUPT]\n",
fp);
}
* Switch received. Committed; send data; move to @KXS_SWITCH@.
*/
-/*----- Tunable parameters ------------------------------------------------*/
-
-#define T_VALID SEC(20) /* Challenge validity period */
-#define T_RETRY SEC(10) /* Challenge retransmit interval */
-
-#define VALIDP(kx, now) ((now) < (kx)->t_valid)
-
/*----- Static tables -----------------------------------------------------*/
static const char *const pkname[] = {
/*----- Various utilities -------------------------------------------------*/
+/* --- @VALIDP@ --- *
+ *
+ * Arguments: @const keyexch *kx@ = key exchange state
+ * @time_t now@ = current time in seconds
+ *
+ * Returns: Whether the challenge in the key-exchange state is still
+ * valid or should be regenerated.
+ */
+
+#define VALIDP(kx, now) ((now) < (kx)->t_valid)
+
/* --- @hashge@ --- *
*
* Arguments: @ghash *h@ = pointer to hash context
/* --- @settimer@ --- *
*
* Arguments: @keyexch *kx@ = pointer to key exchange context
- * @time_t t@ = when to set the timer for
+ * @struct timeval *tv@ = when to set the timer for
*
* Returns: ---
*
* Use: Sets the timer for the next key exchange attempt.
*/
-static void settimer(keyexch *kx, time_t t)
+static void settimer(keyexch *kx, struct timeval *tv)
{
- struct timeval tv;
- if (kx->f & KXF_TIMER)
- sel_rmtimer(&kx->t);
- tv.tv_sec = t;
- tv.tv_usec = 0;
- sel_addtimer(&sel, &kx->t, &tv, timer, kx);
+ if (kx->f & KXF_TIMER) sel_rmtimer(&kx->t);
+ sel_addtimer(&sel, &kx->t, tv, timer, kx);
kx->f |= KXF_TIMER;
}
+/* --- @f2tv@ --- *
+ *
+ * Arguments: @struct timeval *tv@ = where to write the timeval
+ * @double t@ = a time as a floating point number
+ *
+ * Returns: ---
+ *
+ * Use: Converts a floating-point time into a timeval.
+ */
+
+static void f2tv(struct timeval *tv, double t)
+{
+ tv->tv_sec = t;
+ tv->tv_usec = (t - tv->tv_sec)*MILLION;
+}
+
+/* --- @wobble@ --- *
+ *
+ * Arguments: @double t@ = a time interval
+ *
+ * Returns: The same time interval, with a random error applied.
+ */
+
+static double wobble(double t)
+{
+ uint32 r = rand_global.ops->word(&rand_global);
+ double w = (r/F_2P32) - 0.5;
+ return (t + t*w*T_WOBBLE);
+}
+
+/* --- @rs_time@ --- *
+ *
+ * Arguments: @retry *rs@ = current retry state
+ * @struct timeval *tv@ = where to write the result
+ * @const struct timeval *now@ = current time, or null
+ *
+ * Returns: ---
+ *
+ * Use: Computes a time at which to retry sending a key-exchange
+ * packet. This algorithm is subject to change, but it's
+ * currently a capped exponential backoff, slightly randomized
+ * to try to keep clients from hammering a server that's only
+ * just woken up.
+ *
+ * If @now@ is null then the function works out the time for
+ * itself.
+ */
+
+static void rs_time(retry *rs, struct timeval *tv, const struct timeval *now)
+{
+ double t;
+ struct timeval rtv;
+
+ if (!rs->t)
+ t = SEC(2);
+ else {
+ t = (rs->t * 5)/4;
+ if (t > MIN(5)) t = MIN(5);
+ }
+ rs->t = t;
+
+ if (!now) {
+ now = tv;
+ gettimeofday(tv, 0);
+ }
+ f2tv(&rtv, wobble(t));
+ TV_ADD(tv, now, &rtv);
+}
+
+/* --- @retry_reset@ --- *
+ *
+ * Arguments: @retry *rs@ = retry state
+ *
+ * Returns: --
+ *
+ * Use: Resets a retry state to indicate that progress has been
+ * made. Also useful for initializing the state in the first
+ * place.
+ */
+
+static void rs_reset(retry *rs) { rs->t = 0; }
+
/*----- Challenge management ----------------------------------------------*/
/* --- Notes on challenge management --- *
kxc->kx = kx;
kxc->f = 0;
kx->r[i] = kxc;
+ rs_reset(&kxc->rs);
return (kxc);
}
if (kxc->f & KXF_TIMER)
sel_rmtimer(&kxc->t);
gettimeofday(&tv, 0);
- tv.tv_sec += T_RETRY;
+ rs_time(&kxc->rs, &tv, &tv);
sel_addtimer(&sel, &kxc->t, &tv, kxc_timer, kxc);
kxc->f |= KXF_TIMER;
}
kxchal *kxc;
buf bb;
stats *st = p_stats(kx->p);
+ struct timeval tv;
buf *b;
switch (kx->s) {
p_txend(kx->p);
}
- if (kx->s < KXS_SWITCH)
- settimer(kx, time(0) + T_RETRY);
+ if (kx->s < KXS_SWITCH) {
+ rs_time(&kx->rs, &tv, 0);
+ settimer(kx, &tv);
+ }
}
/* --- @decryptrest@ --- *
static void kxfinish(keyexch *kx)
{
kxchal *kxc = kx->r[0];
+ struct timeval now, tv;
+
ks_activate(kxc->ks);
- settimer(kx, ks_tregen(kxc->ks));
+ gettimeofday(&now, 0);
+ f2tv(&tv, wobble(T_REGEN));
+ TV_ADD(&tv, &now, &tv);
+ settimer(kx, &tv);
kx->s = KXS_SWITCH;
a_notify("KXDONE", "?PEER", kx->p, A_END);
p_stats(kx->p)->t_kx = time(0);
void kx_message(keyexch *kx, unsigned msg, buf *b)
{
- time_t now = time(0);
+ struct timeval now, tv;
stats *st = p_stats(kx->p);
size_t sz = BSZ(b);
int rc;
+ gettimeofday(&now, 0);
+ rs_reset(&kx->rs);
if (kx->f & KXF_CORK) {
- start(kx, now);
- settimer(kx, now + T_RETRY);
+ start(kx, now.tv_sec);
+ rs_time(&kx->rs, &tv, &now);
+ settimer(kx, &tv);
a_notify("KXSTART", A_END);
}
if (checkpub(kx))
return;
- if (!VALIDP(kx, now)) {
+ if (!VALIDP(kx, now.tv_sec)) {
stop(kx);
- start(kx, now);
+ start(kx, now.tv_sec);
}
T( trace(T_KEYEXCH, "keyexch: processing %s packet from `%s'",
msg < KX_NMSG ? pkname[msg] : "unknown", p_name(kx->p)); )
return (-1);
}
kx->f = KXF_DEAD | KXF_PUBKEY | f;
+ rs_reset(&kx->rs);
if (!(kx->f & KXF_CORK)) {
start(kx, time(0));
resend(kx);
#include "tripe.h"
-/*----- Tunable parameters ------------------------------------------------*/
-
-#define T_EXP MIN(60) /* Expiry time for a key */
-#define T_REGEN MIN(45) /* Regeneration time for a key */
-
/*----- Handy macros ------------------------------------------------------*/
#define KEYOK(ks, now) ((ks)->sz_exp > 0 && (ks)->t_exp > now)
return (ks);
}
-/* --- @ks_tregen@ --- *
- *
- * Arguments: @keyset *ks@ = pointer to a keyset
- *
- * Returns: The time at which moves ought to be made to replace this key.
- */
-
-time_t ks_tregen(keyset *ks) { return (ks->t_exp - T_EXP + T_REGEN); }
-
/* --- @ks_activate@ --- *
*
* Arguments: @keyset *ks@ = pointer to a keyset
m4_define([USLIP], [$abs_top_builddir/uslip/tripe-uslip])
m4_define([PKSTREAM],
[$abs_top_builddir/pkstream/pkstream -b127.0.0.1 -p127.0.0.1])
+m4_define([MITM], [$abs_top_builddir/proxy/tripe-mitm])
## Sequences. (These are used for testing the replay protection machinery.)
m4_define([R32], [ 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 dnl
[WITH_TRIPEX([$3], [$4 $7],
[$8])])])])
-## COMMS_EPING(adir, aname, bdir, bname)
+## RETRY(n, body)
+m4_define([RETRY], [
+ n=0 rc=1
+ while test $n -lt $1; do
+ if $2
+ then rc=0; break
+ fi
+ n=$(( $n + 1 ))
+ done
+ exit $rc
+])
+
+## COMMS_EPING(adir, aname, bdir, bname, [n])
m4_define([COMMS_EPING], [
- AT_CHECK([TRIPECTL -d$1 EPING $4],, [ignore])
- AT_CHECK([TRIPECTL -d$3 EPING $2],, [ignore])
+ AT_CHECK([RETRY([m4_default([$5], [1])],
+ [TRIPECTL -d$1 EPING $4])],, [ignore])
+ AT_CHECK([RETRY([m4_default([$5], [1])],
+ [TRIPECTL -d$3 EPING $2])],, [ignore])
])
## COMMS_SLIP(adir, aname, bdir, bname)
AT_CLEANUP
+###--------------------------------------------------------------------------
+### Adverse communication.
+
+AT_SETUP([server retry])
+AT_KEYWORDS([backoff])
+export TRIPE_SLIPIF=USLIP
+
+for i in alice bob; do (mkdir $i; cd $i; SETUPDIR([beta])); done
+
+WITH_2TRIPES([alice], [bob], [-nslip], [-talice], [-tbob], [
+
+ ## Set up the evil proxy.
+ alicemitm=24516 bobmitm=14016
+ MITM -kalice/keyring.pub >mitm.out 2>mitm.err \
+ peer:alice:$alicemitm:127.0.0.1:$(cat alice/port) \
+ peer:bob:$bobmitm:127.0.0.1:$(cat bob/port) \
+ filt:drop:5 filt:send& mitmpid=$!
+ strace -omitm.trace -p$mitmpid& mitmtrace=$!
+ trap 'kill $mitmpid $mitmtrace; exit 127' EXIT INT QUIT TERM HUP
+
+ ## Try to establish keys anyway.
+ AWAIT_KXDONE([alice], [alice], [bob], [bob], [
+ AT_CHECK([TRIPECTL -dalice ADD -cork bob INET 127.0.0.1 $alicemitm])
+ AT_CHECK([TRIPECTL -dbob ADD alice INET 127.0.0.1 $bobmitm])
+ ])
+
+ ## Check pinging.
+ COMMS_EPING([alice], [alice], [bob], [bob], [10])
+ COMMS_EPING([bob], [bob], [alice], [alice], [10])
+
+ ## Tear down the MITM proxy.
+ kill $mitmpid
+ wait $mitmpid
+ wait $mitmtrace
+])
+
+AT_CLEANUP
+
###--------------------------------------------------------------------------
### Services.
#define SEC(n) (n##u)
#define MIN(n) (n##u * 60u)
+#define F_2P32 (65536.0*65536.0)
#define MEG(n) (n##ul * 1024ul * 1024ul)
+/* --- Timing parameters --- */
+
+#define T_EXP MIN(60) /* Expiry time for a key */
+#define T_REGEN MIN(40) /* Regeneration time for a key */
+
+#define T_VALID SEC(20) /* Challenge validity period */
+#define T_RETRYMIN SEC(2) /* Minimum retry interval */
+#define T_RETRYMAX MIN(5) /* Maximum retry interval */
+#define T_RETRYGROW (5.0/4.0) /* Retry interval growth factor */
+
+#define T_WOBBLE (1.0/3.0) /* Relative timer randomness */
+
/* --- Other things --- */
#define PKBUFSZ 65536
* Clive Jones.
*/
+typedef struct retry {
+ double t; /* Current retry time */
+} retry;
+
#define KX_NCHAL 16u
typedef struct kxchal {
keyset *ks; /* Pointer to temporary keyset */
unsigned f; /* Various useful flags */
sel_timer t; /* Response timer for challenge */
+ retry rs; /* Retry state */
octet hc[MAXHASHSZ]; /* Hash of his challenge */
octet ck[MAXHASHSZ]; /* His magical check value */
octet hswrq_in[MAXHASHSZ]; /* Inbound switch request message */
unsigned f; /* Various useful flags */
unsigned s; /* Current state in exchange */
sel_timer t; /* Timer for next exchange */
+ retry rs; /* Retry state */
ge *kpub; /* Peer's public key */
time_t texp_kpub; /* Expiry time for public key */
mp *alpha; /* My temporary secret */
size_t /*x*/, size_t /*y*/, size_t /*z*/,
peer */*p*/);
-/* --- @ks_tregen@ --- *
- *
- * Arguments: @keyset *ks@ = pointer to a keyset
- *
- * Returns: The time at which moves ought to be made to replace this key.
- */
-
-extern time_t ks_tregen(keyset */*ks*/);
-
/* --- @ks_activate@ --- *
*
* Arguments: @keyset *ks@ = pointer to a keyset
~mdw / tripe / commitdiff