From 8e46d4cde35aa5d52d01e5481f789ab05d3cfa50 Mon Sep 17 00:00:00 2001
From: Lyn <lynatic@noreply.git.shibe.pro>
Date: Thu, 14 Nov 2024 01:48:38 +0100
Subject: [PATCH] open wireguard port; keep mtu low

---
 meta/hextools.nix               | 87 +++++++++++++++++++++++++++++++++
 meta/math.nix                   | 45 +++++++++++++++++
 modules/services/wgautomesh.nix |  6 ++-
 3 files changed, 137 insertions(+), 1 deletion(-)
 create mode 100644 meta/hextools.nix
 create mode 100644 meta/math.nix

diff --git a/meta/hextools.nix b/meta/hextools.nix
new file mode 100644
index 0000000..a33cb86
--- /dev/null
+++ b/meta/hextools.nix
@@ -0,0 +1,87 @@
+# Credits to https://github.com/Misterio77/nix-colors/blob/b92df8f5eb1fa20d8e09810c03c9dc0d94ef2820/lib/core/conversions.nix#L87
+{
+  lib,
+  math ? import ./math.nix {inherit lib;},
+}: let
+  hexToDecMap = {
+    "0" = 0;
+    "1" = 1;
+    "2" = 2;
+    "3" = 3;
+    "4" = 4;
+    "5" = 5;
+    "6" = 6;
+    "7" = 7;
+    "8" = 8;
+    "9" = 9;
+    "a" = 10;
+    "b" = 11;
+    "c" = 12;
+    "d" = 13;
+    "e" = 14;
+    "f" = 15;
+  };
+  base16To10 = exponent: scalar: scalar * math.pow 16 exponent;
+  /*
+    Converts a hexadecimal character to decimal.
+  Only takes a string of length 1.
+
+  Type: hexCharToDec :: string -> int
+
+  Args:
+    hex: A hexadecimal character.
+
+  Example:
+    hexCharToDec "5"
+    => 5
+    hexCharToDec "e"
+    => 14
+    hexCharToDec "A"
+    => 10
+  */
+  hexCharToDec = hex: let
+    inherit (lib) toLower;
+    lowerHex = toLower hex;
+  in
+    if builtins.stringLength hex != 1
+    then throw "Function only accepts a single character."
+    else if hexToDecMap ? ${lowerHex}
+    then hexToDecMap."${lowerHex}"
+    else throw "Character ${hex} is not a hexadecimal value.";
+in rec {
+  /*
+    Converts from hexadecimal to decimal.
+
+  Type: hexToDec :: string -> int
+
+  Args:
+    hex: A hexadecimal string.
+
+  Example:
+    hexadecimal "12"
+    => 18
+    hexadecimal "FF"
+    => 255
+    hexadecimal "abcdef"
+    => 11259375
+  */
+  hexToDec = hex: let
+    inherit (lib) stringToCharacters reverseList imap0 foldl;
+    decimals = builtins.map hexCharToDec (stringToCharacters hex);
+    decimalsAscending = reverseList decimals;
+    decimalsPowered = imap0 base16To10 decimalsAscending;
+  in
+    foldl builtins.add 0 decimalsPowered;
+
+  hexToIP = inputString: let
+    len = builtins.stringLength inputString;
+    oct1 = builtins.substring (len - 4) 2 inputString;
+    oct2 = builtins.substring (len - 2) 2 inputString;
+    oct1_dec = builtins.toString (hexToDec oct1);
+    oct2_dec = builtins.toString (hexToDec oct2);
+  in "${oct1_dec}.${oct2_dec}";
+  hostnameToIP = inputString: let
+    sha256Hash = builtins.hashString "sha256" inputString;
+  in
+    hexToIP sha256Hash;
+}
diff --git a/meta/math.nix b/meta/math.nix
new file mode 100644
index 0000000..cb7a181
--- /dev/null
+++ b/meta/math.nix
@@ -0,0 +1,45 @@
+{lib}: rec {
+  /*
+  Base raised to the power of the exponent.
+
+  Type: pow :: int or float -> int -> int
+
+  Args:
+    base: The base.
+    exponent: The exponent.
+
+  Example:
+    pow 0 1000
+    => 0
+    pow 1000 0
+    => 1
+    pow 2 30
+    => 1073741824
+    pow 3 3
+    => 27
+    pow (-5) 3
+    => -125
+  */
+  pow = base: exponent: let
+    inherit (lib) mod;
+  in
+    if exponent > 1
+    then let
+      x = pow base (exponent / 2);
+      odd_exp = mod exponent 2 == 1;
+    in
+      x
+      * x
+      * (
+        if odd_exp
+        then base
+        else 1
+      )
+    else if exponent == 1
+    then base
+    else if exponent == 0 && base == 0
+    then throw "undefined"
+    else if exponent == 0
+    then 1
+    else throw "undefined";
+}
diff --git a/modules/services/wgautomesh.nix b/modules/services/wgautomesh.nix
index e1dfd97..e42c6b8 100644
--- a/modules/services/wgautomesh.nix
+++ b/modules/services/wgautomesh.nix
@@ -40,6 +40,10 @@ in {
     default = true;
   };
   config = {
+    networking.firewall.allowedUDPPorts = [
+      wireguardPort
+    ];
+
     networking.wireguard.interfaces.wg0 = {
       ips =
         if cfg.useIPv6
@@ -47,7 +51,7 @@ in {
         else ["${meshnetwork.wg_subnets.IPv4}"];
       listenPort = wireguardPort;
       privateKeyFile = "/var/lib/wireguard-keys/private";
-      mtu = 1420;
+      mtu = 1200;
     };
 
     services.wgautomesh = {