Merge branch 'zesterer/exploit-patching' into 'master'

Prevented double-spawning of chunks

See merge request veloren/veloren!2908

server/src/lib.rs

@@ -96,7 +96,7 @@ use prometheus_hyper::Server as PrometheusServer;
 use specs::{join::Join, Builder, Entity as EcsEntity, Entity, SystemData, WorldExt};
 use std::{
     i32,
-    ops::{Deref, DerefMut, Range},
+    ops::{Deref, DerefMut},
     sync::Arc,
     time::{Duration, Instant},
 };
@@ -137,7 +137,7 @@ impl Default for SpawnPoint {
 // server-side. This is independent of the client's view distance and exists to
 // avoid exploits such as small view distance chunk reloading and also to keep
 // various mechanics working fluidly (i.e: not unloading nearby entities).
-pub const MIN_VD: Range<u32> = 5..6;
+pub const MIN_VD: u32 = 6;
 
 // Tick count used for throttling network updates
 // Note this doesn't account for dt (so update rate changes with tick rate)

server/src/sys/msg/terrain.rs

@@ -114,7 +114,7 @@ impl<'a> System<'a> for Sys {
                         .0
                         .xy()
                         .map2(TerrainChunkSize::RECT_SIZE, |e, sz| e as i32 / sz as i32);
-                    for rpos in Spiral2d::new().take((crate::MIN_VD.start as usize + 1).pow(2)) {
+                    for rpos in Spiral2d::new().take((crate::MIN_VD as usize + 1).pow(2)) {
                         let key = player_chunk + rpos;
                         if terrain.get_key(key).is_none() {
                             events.push(ServerEvent::ChunkRequest(entity, key));

server/src/sys/terrain.rs

@@ -495,13 +495,17 @@ pub fn chunk_in_vd(
     terrain: &TerrainGrid,
     vd: u32,
 ) -> bool {
+    // This fuzzy threshold prevents chunks rapidly unloading and reloading when
+    // players move over a chunk border.
+    const UNLOAD_THRESHOLD: u32 = 2;
+
     let player_chunk_pos = terrain.pos_key(player_pos.map(|e| e as i32));
 
     let adjusted_dist_sqr = (player_chunk_pos - chunk_pos)
-        .map(|e: i32| (e.abs() as u32).saturating_sub(2))
+        .map(|e: i32| e.abs() as u32)
         .magnitude_squared();
 
-    adjusted_dist_sqr <= vd.max(crate::MIN_VD.end).pow(2)
+    adjusted_dist_sqr <= (vd.max(crate::MIN_VD) + UNLOAD_THRESHOLD).pow(2)
 }
 
 fn is_spawn_chunk(chunk_pos: Vec2<i32>, spawn_pos: SpawnPoint, terrain: &TerrainGrid) -> bool {