server/keyexch.c: Randomized exponential retransmit backoff.

[tripe] / server / tripe.h

diff --git a/server/tripe.h b/server/tripe.h
index d447326ec39837087f2fbcdaf47be63ddc168fee..ad20daa72255dce993051e05f121541e1f0e95df 100644 (file)
--- a/server/tripe.h
+++ b/server/tripe.h
@@ -134,6 +134,7 @@
 
 #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 --- */
@@ -142,7 +143,11 @@
 #define T_REGEN MIN(40)                        /* Regeneration time for a key */
 
 #define T_VALID SEC(20)                        /* Challenge validity period */
-#define T_RETRY SEC(10)                        /* Challenge retransmit interval */
+#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 --- */
 
@@ -246,6 +251,10 @@ typedef struct keyset {
  * Clive Jones.
  */
 
+typedef struct retry {
+  double t;                            /* Current retry time */
+} retry;
+
 #define KX_NCHAL 16u
 
 typedef struct kxchal {
@@ -255,6 +264,7 @@ 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 */
@@ -269,6 +279,7 @@ typedef struct keyexch {
   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 */