X-Git-Url: https://git.distorted.org.uk/~mdw/tripe/blobdiff_plain/e04c2d50fd96f3f31bc96851c55c6efecc10469c..9cda68ab3974b1f2c08a5896929890bf4a973e9a:/server/keyexch.c?ds=sidebyside

diff --git a/server/keyexch.c b/server/keyexch.c
index 396ecaed..b1f23d73 100644
--- a/server/keyexch.c
+++ b/server/keyexch.c
@@ -1,7 +1,5 @@
 /* -*-c-*-
  *
- * $Id$
- *
  * Key exchange protocol
  *
  * (c) 2001 Straylight/Edgeware
@@ -77,22 +75,25 @@
  *	Switch received.  Committed; send data; move to @KXS_SWITCH@.
  */
 
-/*----- Tunable parameters ------------------------------------------------*/
-
-#define T_VALID MIN(2)			/* 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[] = {
-  "pre-challenge", "cookie", "challenge",
-  "reply", "switch-rq", "switch-ok"
+  "pre-challenge", "challenge", "reply", "switch-rq", "switch-ok"
 };
 
 /*----- 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
@@ -264,24 +265,102 @@ static void timer(struct timeval *tv, void *v)
 /* --- @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 --- *
@@ -366,6 +445,7 @@ static kxchal *kxc_new(keyexch *kx)
   kxc->kx = kx;
   kxc->f = 0;
   kx->r[i] = kxc;
+  rs_reset(&kxc->rs);
   return (kxc);
 }
 
@@ -460,7 +540,7 @@ static void kxc_answer(keyexch *kx, kxchal *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;
 }
@@ -606,7 +686,7 @@ static kxchal *respond(keyexch *kx, unsigned msg, buf *b)
     h = GH_INIT(algs.h);
     HASH_STRING(h, "tripe-check-hash");
     GH_HASH(h, ck, indexsz);
-    GH_DONE(h, kxc->hc);
+    GH_DONE(h, kxc->ck);
     GH_DESTROY(h);
 
     h = GH_INIT(algs.h);
@@ -727,6 +807,7 @@ static void resend(keyexch *kx)
   kxchal *kxc;
   buf bb;
   stats *st = p_stats(kx->p);
+  struct timeval tv;
   buf *b;
 
   switch (kx->s) {
@@ -769,8 +850,10 @@ static void resend(keyexch *kx)
     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@ --- *
@@ -795,6 +878,7 @@ static int decryptrest(keyexch *kx, kxchal *kxc, unsigned msg, buf *b)
     a_warn("KX", "?PEER", kx->p, "decrypt-failed", "%s", pkname[msg], A_END);
     return (-1);
   }
+  if (!BOK(&bb)) return (-1);
   buf_init(b, BBASE(&bb), BLEN(&bb));
   return (0);
 }
@@ -910,8 +994,13 @@ bad:
 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);
@@ -1067,7 +1156,7 @@ static void start(keyexch *kx, time_t now)
 
   assert(kx->f & KXF_DEAD);
 
-  kx->f &= ~KXF_DEAD;
+  kx->f &= ~(KXF_DEAD | KXF_CORK);
   kx->nr = 0;
   kx->alpha = mprand_range(MP_NEW, gg->r, &rand_global, 0);
   kx->c = G_CREATE(gg); G_EXP(gg, kx->c, gg->g, kx->alpha);
@@ -1158,19 +1247,27 @@ void kx_start(keyexch *kx, int forcep)
 
 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.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)); )
 
@@ -1233,7 +1330,7 @@ void kx_free(keyexch *kx)
 
 void kx_newkeys(keyexch *kx)
 {
-  if (km_getpubkey(p_name(kx->p), kx->kpub, &kx->texp_kpub))
+  if (km_getpubkey(p_tag(kx->p), kx->kpub, &kx->texp_kpub))
     return;
   kx->f |= KXF_PUBKEY;
   if ((kx->f & KXF_DEAD) || kx->s != KXS_SWITCH) {
@@ -1250,6 +1347,7 @@ void kx_newkeys(keyexch *kx)
  * Arguments:	@keyexch *kx@ = pointer to key exchange context
  *		@peer *p@ = pointer to peer context
  *		@keyset **ks@ = pointer to keyset list
+ *		@unsigned f@ = various useful flags
  *
  * Returns:	Zero if OK, nonzero if it failed.
  *
@@ -1258,19 +1356,22 @@ void kx_newkeys(keyexch *kx)
  *		exchange.
  */
 
-int kx_init(keyexch *kx, peer *p, keyset **ks)
+int kx_init(keyexch *kx, peer *p, keyset **ks, unsigned f)
 {
   kx->ks = ks;
   kx->p = p;
   kx->kpub = G_CREATE(gg);
-  if (km_getpubkey(p_name(p), kx->kpub, &kx->texp_kpub)) {
+  if (km_getpubkey(p_tag(p), kx->kpub, &kx->texp_kpub)) {
     G_DESTROY(gg, kx->kpub);
     return (-1);
   }
-  kx->f = KXF_DEAD | KXF_PUBKEY;
-  start(kx, time(0));
-  resend(kx);
-  /* Don't notify here: the ADD message hasn't gone out yet. */
+  kx->f = KXF_DEAD | KXF_PUBKEY | f;
+  rs_reset(&kx->rs);
+  if (!(kx->f & KXF_CORK)) {
+    start(kx, time(0));
+    resend(kx);
+    /* Don't notify here: the ADD message hasn't gone out yet. */
+  }
   return (0);
 }