Handle invalid packet size more gracefully

flake.lock

@@ -0,0 +1,61 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1738136902,
+        "narHash": "sha256-pUvLijVGARw4u793APze3j6mU1Zwdtz7hGkGGkD87qw=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "9a5db3142ce450045840cc8d832b13b8a2018e0c",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,40 @@
+# This is an example flake.nix for a Switch project based on devkitA64.
+# It will work on any devkitPro example with a Makefile out of the box.
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = {
+    self,
+    nixpkgs,
+    flake-utils,
+    ...
+  }:
+    flake-utils.lib.eachDefaultSystem (system: let
+      pkgs = import nixpkgs {
+        inherit system;
+      };
+    in {
+      devShells.default = pkgs.mkShell {
+        name = "smov2-server-dev";
+        buildInputs = with pkgs; [
+          curlftpfs
+          rustPlatform.bindgenHook
+          rustc
+          cargo
+          rustfmt
+          gcc
+          rust-analyzer
+          cmake
+          clippy
+        ];
+
+        # Each package provides a shell hook that sets all necessary
+        # environmental variables. This part is necessary, otherwise your build
+        # system won't know where to find devkitPro. By setting these
+        # variables we allow devkitPro's example Makefiles to work out of the box.
+      };
+    });
+}

src/net/packet.rs

@@ -302,7 +302,9 @@ where
             },
         };
 
-        let excess_padding = p_size as usize - data.get_size();
+        let excess_padding = (p_size as usize).checked_sub(data.get_size());
+        let excess_padding = excess_padding.ok_or(EncodingError::InvalidSize)?;
+
         if excess_padding > 0 {
             buf.advance(excess_padding);
         }

src/types/errors.rs

@@ -74,6 +74,8 @@ pub enum ChannelError {
 
 #[derive(Error, Debug)]
 pub enum EncodingError {
+    #[error("Invalid Packet Size")]
+    InvalidSize,
     #[error("Not enough data")]
     NotEnoughData,
     #[error("Invalid string data")]
@@ -109,6 +111,7 @@ impl SMOError {
         match self {
             Self::Encoding(EncodingError::ConnectionClose)
             | Self::Encoding(EncodingError::ConnectionReset)
+            | Self::Encoding(EncodingError::InvalidSize)
             | Self::Channel(_) => ErrorSeverity::ClientFatal,
             _ => ErrorSeverity::NonCritical,
         }