gnunet

commit a0fd1312543aea6391b5a391153ce3672f1bbd6a
parent 4642b0748c466736c5fddb72133ab698b5f4fbd0
Author: Martin Schanzenbach <schanzen@gnunet.org>
Date:   Thu,  6 Aug 2026 18:16:25 +0200

dht: never route with a zero network size estimate

Diffstat:
M
src/service/dht/gnunet-service-dht.c
 | 
8
++++----
M
src/service/dht/gnunet-service-dht.h
 | 
9
+++++++++
M
src/service/dht/gnunet-service-dht_neighbours.c
 | 
11
++++++++---

3 files changed, 21 insertions(+), 7 deletions(-)
diff --git a/src/service/dht/gnunet-service-dht.c b/src/service/dht/gnunet-service-dht.c
@@ -176,7 +176,7 @@ static struct MyAddress *a_tail;
  * log of the current network size estimate, used as the point where
  * we switch between random and deterministic routing.
  */
-static double log_of_network_size_estimate;
+static double log_of_network_size_estimate = MINIMUM_LOG_NSE;
 
 /**
  * Are we already serving clients?  We suspend the service until PILS
@@ -207,14 +207,14 @@ update_network_size_estimate (void *cls,
                             "# Network size estimates received",
                             1,
                             GNUNET_NO);
-  /* do not allow estimates < 0.5 */
+  /* do not allow estimates < #MINIMUM_LOG_NSE */
   u->network_size_estimate = pow (2.0,
-                                  GNUNET_MAX (0.5,
+                                  GNUNET_MAX (MINIMUM_LOG_NSE,
                                               logestimate));
   for (struct GDS_Underlay *p = u_head; NULL != p; p = p->next)
     sum += p->network_size_estimate;
   if (sum <= 2.0)
-    log_of_network_size_estimate = 0.5;
+    log_of_network_size_estimate = MINIMUM_LOG_NSE;
   else
     log_of_network_size_estimate = log2 (sum);
 }
diff --git a/src/service/dht/gnunet-service-dht.h b/src/service/dht/gnunet-service-dht.h
@@ -193,6 +193,15 @@ GDS_CLIENTS_process_put (const struct GNUNET_DATACACHE_Block *bd,
                          uint32_t desired_replication_level);
 
 /**
+ * Floor for the log of the network size estimate, and the value we use
+ * before the NSE service has told us anything.  Routing divides by the
+ * estimate and drops requests whose hop count exceeds a multiple of it,
+ * so zero is not a usable "unknown".
+ */
+#define MINIMUM_LOG_NSE 0.5
+
+
+/**
  * Our routing table gained a peer.  Reset the retry back-off of all
  * pending client GET requests and re-transmit them now: a request that
  * found no route earlier has been backing off for up to 15 minutes
diff --git a/src/service/dht/gnunet-service-dht_neighbours.c b/src/service/dht/gnunet-service-dht_neighbours.c
@@ -824,8 +824,13 @@ get_forward_count (uint16_t hop_count,
   uint32_t forward_count;
   float target_value;
   double rm1;
+  double nse = GDS_NSE_get ();
 
-  if (hop_count > GDS_NSE_get () * 4.0)
+  /* Guard the divisor below: an NSE of zero would make target_value
+     infinite (or NaN), and the conversion to uint32_t undefined. */
+  if (! (nse >= MINIMUM_LOG_NSE))
+    nse = MINIMUM_LOG_NSE;
+  if (hop_count > nse * 4.0)
   {
     /* forcefully terminate */
     GNUNET_STATISTICS_update (GDS_stats,
@@ -834,7 +839,7 @@ get_forward_count (uint16_t hop_count,
                               GNUNET_NO);
     return 0;
   }
-  if (hop_count > GDS_NSE_get () * 2.0)
+  if (hop_count > nse * 2.0)
   {
     /* Once we have reached our ideal number of hops, only forward to 1 peer */
     return 1;
@@ -847,7 +852,7 @@ get_forward_count (uint16_t hop_count,
                 target_replication);
   rm1 = target_replication - 1.0;
   target_value =
-    1 + (rm1) / (GDS_NSE_get () + (rm1 * hop_count));
+    1 + (rm1) / (nse + (rm1 * hop_count));
 
   /* Set forward count to floor of target_value */
   forward_count = (uint32_t) target_value;