fix rare issues when converting encodings

add readme for AC

Plugins/Stats/Cheat/README.md

@@ -0,0 +1,79 @@
+# IW4MAdmin Anticheat
+**Initial document draft | 8.30.19**
+
+**IW4MAdmin** anticheat for IW4x uses data from in-game logs to track player locations, hit locations, and view angles
+to validate against a known set of play styles.
+Every hit event ocurring in the game (Damage or Kill from a gun) is captured by IW4MAdmin and analyzed.
+**Session analysis** occurs against all hit events since the player connected to the server.
+**Lifetime analysis** occurs against all hit events ever occuring for a given player.
+## Detection Types
+### Bone
+Compares the number of times a particular bone is hit against the number of hits on all other bones.
+Many rudimentary aimbots lock onto a particular player bone position such as _Head_, or _Upper Torso_.
+This detection method has the highest chance of a false positive, as non-cheaters can play abnormally 
+(e.g. going for headshots, or using a weapon that unconciously changes their playstyle)
+
+#### Hit Location Reference
+| Number | Hit Location    |
+|--------|-----------------|
+| 2      | Head            |
+| 3      | Neck            |
+| 4      | Upper Torso     |
+| 5      | Lower Torso     |
+| 6      | Upper Right Arm |
+| 7      | Upper Left Arm  |
+| 8      | Lower Right Arm |
+| 9      | Lower Left Arm  |
+| 10     | Right Hand      |
+| 11     | Left Hand       |
+| 12     | Upper Right Leg |
+| 13     | Upper Left Leg  |
+| 14     | Lower Right Leg |
+| 15     | Right Foot      |
+| 16     | Left Foot       |
+### Chest
+Identical to *Bone* detection, except it specifically compares the ratio of Upper Torso / Lower Torso hit counts.
+It can be thought of as a focused bone detection type, as most aimbots don't aim to unusual bones such as a foot.
+As with *Bone* detection, this is prone to false positives.
+### Offset
+Compares the player angles from three snapshots. The first snapshot being the snapshot immediately before the server registered the hit for a player.
+The second snapshot is the "frame" the server registered the kill. The final snapshot is the snapshot immediately after the server registers the hit.
+The algorithm is:
+```
+let a = first snapshot angles
+let b = second snapshot angles
+let c = third snapshot angles
+offset = ((a - b) + (c - b)) - (a-c)
+```
+This detection method is very effective at detecting silent aimbots. 
+Silent aimbots "fake" a shot by changing a player's view angles for a single snapshot. From a spectator's position, the single snapshot view angle altering is not visible. 
+The larger "FOV" (field of view) from a silent aimbot, the more absolute difference between the three snapshots. 
+Over time if the average distance between these two viewangles is higher than expected, a detection is triggered.
+False positives are very rare with this detection. However, extreme client lag can trigger a false positive in special situations.
+### Strain
+Analyzes the frequency, viewangle distance, and player distance between hits.
+The algorithm is:
+```
+let v = view angle distance between two hits  
+let t = delta time (time between hits)  
+let d = distance between the attacker and victim
+let s = decay over time
+strain = ((v / t) * d)^s
+```
+A high value indicates fast target switching at large distance intervals, which if done naturally, requires an extreme level of mechanical effort.
+"Rage" aimbots commonly switch to targets as fast as possible in any direction.
+### Recoil
+Compares the average of the last few snapshots of player angles to 0. Client sided no recoil prevents the view angle "Z" axis from changing.
+If the average view angle "Z" axis value remains 0, the detection is triggered. 
+As of 8.30.19, there are no known false positives for this detection.
+Several weapons which do not have any recoil from the game are excluded in this detection.
+### Format
+Detection penalty reasons are as follow:
+<_detectionType_>-<_location/value_>@<_hitCount_>
+Example:
+- detectionType = Strain
+- value = 1.39
+- hitCount = 136
+
+Result: **Strain-1.39@136**
+This reason is only visible to logged in privileged users.

SharedLibraryCore/RCon/Connection.cs

@@ -86,6 +86,8 @@ namespace SharedLibraryCore.RCon
                 return defaultEncoding.GetString(convertedBytes);
             }
 
+            try
+            {
                 string convertedRConPassword = convertEncoding(RConPassword);
                 string convertedParameters = convertEncoding(parameters);
 
@@ -114,6 +116,15 @@ namespace SharedLibraryCore.RCon
                         payload = string.Format(Config.CommandPrefixes.RConCommand, convertedRConPassword, "status\0").Select(Convert.ToByte).ToArray();
                         break;
                 }
+            }
+
+            // this happens when someone tries to send something that can't be converted into a 7 bit character set
+            // e.g: emoji -> windows-1252
+            catch (OverflowException)
+            {
+                connectionState.OnComplete.Release(1);
+                throw new NetworkException($"Invalid character expected when converting encodings - {parameters}");
+            }
 
             byte[] response = null;