Refine movement anticheat again (#7004)

* Account for walking speed in vertical dir
* Avoid undefined behaviour due to division-by-zero

diff --git a/src/content_sao.cpp b/src/content_sao.cpp
index b5e43bf1b5a1e33dd36f22bbfbe9b9482bf4dd8c..1234e3915246d1e22e4e52cf3b2f92cd39d121b8 100644 (file)
--- a/src/content_sao.cpp
+++ b/src/content_sao.cpp
@@ -1414,6 +1414,12 @@ bool PlayerSAO::checkMovementCheat()
        //        until this can be verified correctly, tolerate higher jumping speeds
        player_max_jump *= 2.0;
 
+       // Don't divide by zero!
+       if (player_max_walk < 0.0001f)
+               player_max_walk = 0.0001f;
+       if (player_max_jump < 0.0001f)
+               player_max_jump = 0.0001f;
+
        v3f diff = (m_base_position - m_last_good_position);
        float d_vert = diff.Y;
        diff.Y = 0;
@@ -1422,8 +1428,11 @@ bool PlayerSAO::checkMovementCheat()
 
        // FIXME: Checking downwards movement is not easily possible currently,
        //        the server could calculate speed differences to examine the gravity
-       if (d_vert > 0)
-               required_time = MYMAX(required_time, d_vert / player_max_jump);
+       if (d_vert > 0) {
+               // In certain cases (water, ladders) walking speed is applied vertically
+               float s = MYMAX(player_max_jump, player_max_walk);
+               required_time = MYMAX(required_time, d_vert / s);
+       }
 
        if (m_move_pool.grab(required_time)) {
                m_last_good_position = m_base_position;