From 33bcefc45b4a8881310f77a2bbda466a8b0f466a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Karel=20Ko=C4=8D=C3=AD?= <cynerd@email.cz>
Date: Wed, 18 Jan 2023 11:45:18 +0100
Subject: lib: add my own library functions

---
 lib/default.nix | 30 ++++++++++++++++++++++++++++++
 lib/ipv4.nix    | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)
 create mode 100644 lib/default.nix
 create mode 100644 lib/ipv4.nix

(limited to 'lib')

diff --git a/lib/default.nix b/lib/default.nix
new file mode 100644
index 0000000..036af97
--- /dev/null
+++ b/lib/default.nix
@@ -0,0 +1,30 @@
+nixpkgslib: let
+  lib = nixpkgslib // nlib;
+
+  nlib = with builtins;
+  with lib; {
+    # Generic power of number
+    pow = base: e:
+      if e == 0
+      then 1
+      else foldl (a: b: a * base) 1 (genList id (e - 1));
+    # Power of 2
+    pow2 = pow 2;
+
+    # Convert integer to list of bits
+    int2bits = len: e: reverseList (genList (x: bitAnd e (pow2 (x + 1)) > 0) len);
+    # Reverse operation for int2bits
+    bits2int = l: let
+      len = length l;
+      zf = a: b:
+        if a
+        then pow2 b
+        else 0;
+    in
+      foldl add 0 (zipListsWith zf l (genList (i: len - i) len));
+
+    # IPv4 utilities
+    ipv4 = import ./ipv4.nix lib;
+  };
+in
+  nlib
diff --git a/lib/ipv4.nix b/lib/ipv4.nix
new file mode 100644
index 0000000..c843cb6
--- /dev/null
+++ b/lib/ipv4.nix
@@ -0,0 +1,38 @@
+lib:
+with builtins;
+with lib; rec {
+  # Converts string representation of IPv4 address to 32 bits
+  ip2bits = ip: let
+    perBits = map (x: int2bits 8 (toInt x)) (splitString "." ip);
+  in
+    flatten perBits;
+  # Converts 32 bits to IPv4
+  bits2ip = bits: let
+    bts = i: toString (bits2int (sublist (i * 8) 8 bits));
+  in "${bts 0}.${bts 1}.${bts 2}.${bts 3}";
+
+  # Convert IPv4 to number
+  ip2int = ip: bits2int (ip2bits ip);
+  # Convert number to IPv4
+  int2ip = ip: bits2ip (int2bits 32 ip);
+
+  # Generate bits for netmas of gitven prefix length
+  netmaskBits = prefixLength: genList (x: x < prefixLength) 32;
+  # Convert IP network prefix length to network mask
+  prefix2netmask = prefixLength: bits2ip (netmaskBits prefixLength);
+  # Mask IP by network mask specified by given network prefix length
+  prefix2ip = ip: prefixLength: let
+    a = netmaskBits prefixLength;
+    b = ip2bits ip;
+  in
+    bits2ip (zipListsWith (a: b: a && b) a b);
+  # Last address in the range
+  prefix2broadcast = ip: prefixLength: let
+    a = netmaskBits prefixLength;
+    b = ip2bits ip;
+  in
+    bits2ip (zipListsWith (a: b: !a || b) a b);
+
+  # Offset address in network
+  ipAdd = ip: prefixLength: off: int2ip ((ip2int (prefix2ip ip prefixLength)) + off);
+}
-- 
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