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oddlama_nixos-extra-modules/lib/net.nix

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inputs: _final: prev:
let
inherit (prev.lib)
all
any
assertMsg
elem
filter
flip
foldl'
hasInfix
head
min
partition
range
recursiveUpdate
reverseList
splitString
substring
unique
warnIf
;
# From misc.nix
inherit (prev.lib)
hexToDec
;
# IP address math library
# https://gist.github.com/duairc/5c9bb3c922e5d501a1edb9e7b3b845ba
# Plus some extensions by us
libNet =
(import ./netu.nix {
inherit (inputs.nixpkgs) lib;
}).lib;
in
{
lib = recursiveUpdate prev.lib {
inherit (libNet)
arithmetic
typechecks
bit
implementations
parsers
;
net = recursiveUpdate (removeAttrs libNet.net [ "types" ]) {
cidr = rec {
# host :: (ip | mac | integer) -> cidr -> ip
#
# Wrapper that extends the original host function to
# check whether the argument `n` is in-range for the given cidr.
#
# Examples:
#
# > net.cidr.host 255 "192.168.1.0/24"
# "192.168.1.255"
# > net.cidr.host (256) "192.168.1.0/24"
# <fails with an error message>
# > net.cidr.host (-1) "192.168.1.0/24"
# "192.168.1.255"
# > net.cidr.host (-256) "192.168.1.0/24"
# "192.168.1.0"
# > net.cidr.host (-257) "192.168.1.0/24"
# <fails with an error message>
host =
i: n:
let
cap = libNet.net.cidr.capacity n;
intCheck = builtins.isInt i -> (i >= (-cap) && i < cap);
ipCheck = libNet.net.types.ip.check i -> ((libNet.net.types.ip-in n).check result);
result = libNet.net.cidr.host i n;
in
assert assertMsg (ipCheck && intCheck) "The host ${toString i} lies outside of ${n}";
result;
# hostCidr :: (ip | mac | integer) -> cidr -> cidr
#
# Returns the nth host in the given cidr range (like cidr.host)
# but as a cidr that retains the original prefix length.
#
# Examples:
#
# > net.cidr.hostCidr 2 "192.168.1.0/24"
# "192.168.1.2/24"
hostCidr = n: x: "${libNet.net.cidr.host n x}/${toString (libNet.net.cidr.length x)}";
# ip :: (cidr | ip) -> ip
#
# Returns just the ip part of the cidr.
#
# Examples:
#
# > net.cidr.ip "192.168.1.100/24"
# "192.168.1.100"
# > net.cidr.ip "192.168.1.100"
# "192.168.1.100"
ip = x: head (splitString "/" x);
# canonicalize :: cidr -> cidr
#
# Replaces the ip of the cidr with the canonical network address
# (first contained address in range)
#
# Examples:
#
# > net.cidr.canonicalize "192.168.1.100/24"
# "192.168.1.0/24"
canonicalize = x: libNet.net.cidr.make (libNet.net.cidr.length x) (ip x);
# mergev4 :: [cidrv4 | ipv4] -> (cidrv4 | null)
#
# Returns the smallest cidr network that includes all given networks.
# If no cidr mask is given, /32 is assumed.
#
# Examples:
#
# > net.cidr.mergev4 ["192.168.1.1/24" "192.168.6.1/32"]
# "192.168.0.0/21"
mergev4 =
addrs_:
let
# Append /32 if necessary
addrs = map (x: if hasInfix "/" x then x else "${x}/32") addrs_;
# The smallest occurring length is the first we need to start checking, since
# any greater cidr length represents a smaller address range which
# wouldn't contain all of the original addresses.
startLength = foldl' min 32 (map libNet.net.cidr.length addrs);
possibleLengths = reverseList (range 0 startLength);
# The first ip address will be "expanded" in cidr length until it covers all other
# used addresses.
firstIp = ip (head addrs);
# Return the first (i.e. greatest length -> smallest prefix) cidr length
# in the list that covers all used addresses
bestLength = head (
filter
# All given addresses must be contained by the generated address.
(len: all (x: libNet.net.cidr.contains (ip x) (libNet.net.cidr.make len firstIp)) addrs)
possibleLengths
);
in
assert assertMsg (!any (hasInfix ":") addrs) "mergev4 cannot operate on ipv6 addresses";
if addrs == [ ] then null else libNet.net.cidr.make bestLength firstIp;
# mergev6 :: [cidrv6 | ipv6] -> (cidrv6 | null)
#
# Returns the smallest cidr network that includes all given networks.
# If no cidr mask is given, /128 is assumed.
#
# Examples:
#
# > net.cidr.mergev6 ["fd00:dead:cafe::/64" "fd00:fd12:3456:7890::/56"]
# "fd00:c000::/18"
mergev6 =
addrs_:
let
# Append /128 if necessary
addrs = map (x: if hasInfix "/" x then x else "${x}/128") addrs_;
# The smallest occurring length is the first we need to start checking, since
# any greater cidr length represents a smaller address range which
# wouldn't contain all of the original addresses.
startLength = foldl' min 128 (map libNet.net.cidr.length addrs);
possibleLengths = reverseList (range 0 startLength);
# The first ip address will be "expanded" in cidr length until it covers all other
# used addresses.
firstIp = ip (head addrs);
# Return the first (i.e. greatest length -> smallest prefix) cidr length
# in the list that covers all used addresses
bestLength = head (
filter
# All given addresses must be contained by the generated address.
(len: all (x: libNet.net.cidr.contains (ip x) (libNet.net.cidr.make len firstIp)) addrs)
possibleLengths
);
in
assert assertMsg (all (hasInfix ":") addrs) "mergev6 cannot operate on ipv4 addresses";
if addrs == [ ] then null else libNet.net.cidr.make bestLength firstIp;
# merge :: [cidr] -> { cidrv4 = (cidrv4 | null); cidrv6 = (cidrv4 | null); }
#
# Returns the smallest cidr network that includes all given networks,
# but yields two separate result for all given ipv4 and ipv6 addresses.
# Equivalent to calling mergev4 and mergev6 on a partition individually.
merge =
addrs:
let
v4_and_v6 = partition (hasInfix ":") addrs;
in
{
cidrv4 = mergev4 v4_and_v6.wrong;
cidrv6 = mergev6 v4_and_v6.right;
};
# assignIps :: cidr -> [int | ip] -> [string] -> [ip]
#
# Assigns a semi-stable ip address from the given cidr network to each hostname.
# The algorithm is based on hashing (abusing sha256) with linear probing.
# The order of hosts doesn't matter. No ip (or offset) from the reserved list
# will be assigned. The network address and broadcast address will always be reserved
# automatically.
#
# Examples:
#
# > net.cidr.assignIps "192.168.100.1/24" [] ["a" "b" "c"]
# { a = "192.168.100.202"; b = "192.168.100.74"; c = "192.168.100.226"; }
#
# > net.cidr.assignIps "192.168.100.1/24" [] ["a" "b" "c" "a-new-elem"]
# { a = "192.168.100.202"; a-new-elem = "192.168.100.88"; b = "192.168.100.74"; c = "192.168.100.226"; }
#
# > net.cidr.assignIps "192.168.100.1/24" [202 "192.168.100.74"] ["a" "b" "c"]
# { a = "192.168.100.203"; b = "192.168.100.75"; c = "192.168.100.226"; }
assignIps =
net: reserved: hosts:
let
cidrSize = libNet.net.cidr.size net;
capacity = libNet.net.cidr.capacity net;
# The base address of the network. Used to convert ip-based reservations to offsets
baseAddr = host 0 net;
# Reserve some values for the network, host and broadcast address.
# The network and broadcast address should never be used, and we
# want to reserve the host address for the host. We also convert
# any ips to offsets here.
init = unique (
[
0
(capacity - 1)
]
++ flip map reserved (x: if builtins.typeOf x == "int" then x else -(libNet.net.ip.diff baseAddr x))
);
nHosts = builtins.length hosts;
nInit = builtins.length init;
# Pre-sort all hosts, to ensure ordering invariance
sortedHosts =
warnIf ((nInit + nHosts) > 0.3 * capacity)
"assignIps: hash stability may be degraded since utilization is >30%"
(builtins.sort builtins.lessThan hosts);
# Generates a hash (i.e. offset value) for a given hostname
hashElem =
x:
builtins.bitAnd (capacity - 1) (
hexToDec (builtins.substring 0 16 (builtins.hashString "sha256" x))
);
# Do linear probing. Returns the first unused value at or after the given value.
probe =
avoid: value:
if
elem value avoid
# TODO lib.mod
# Poor man's modulo, because nix has no modulo. Luckily we operate on a residue
# class of x modulo 2^n, so we can use bitAnd instead.
then
probe avoid (builtins.bitAnd (capacity - 1) (value + 1))
else
value;
# Hash a new element and avoid assigning any existing values.
assignOne =
{
assigned,
used,
}:
x:
let
value = probe used (hashElem x);
in
{
assigned = assigned // {
${x} = host value net;
};
used = [ value ] ++ used;
};
in
assert assertMsg (
cidrSize >= 2 && cidrSize <= 62
) "assignIps: cidrSize=${toString cidrSize} is not in [2, 62].";
assert assertMsg (nHosts <= capacity - nInit)
"assignIps: number of hosts (${toString nHosts}) must be <= capacity (${toString capacity}) - reserved (${toString nInit})";
# Assign an ip in the subnet to each element, in order
(foldl' assignOne {
assigned = { };
used = init;
} sortedHosts).assigned;
};
ip = rec {
# Checks whether the given address (with or without cidr notation) is an ipv4 address.
isv4 = x: !isv6 x;
# Checks whether the given address (with or without cidr notation) is an ipv6 address.
isv6 = hasInfix ":";
};
mac = {
# Adds offset to the given base address and ensures the result is in
# a locally administered range by replacing the second nibble with a 2.
addPrivate =
base: offset:
let
added = libNet.net.mac.add base offset;
pre = substring 0 1 added;
suf = substring 2 (-1) added;
in
"${pre}2${suf}";
# assignMacs :: mac (base) -> int (size) -> [int | mac] (reserved) -> [string] (hosts) -> [mac]
#
# Assigns a semi-stable MAC address starting in [base, base + 2^size) to each hostname.
# The algorithm is based on hashing (abusing sha256) with linear probing.
# The order of hosts doesn't matter. No mac (or offset) from the reserved list
# will be assigned.
#
# Examples:
#
# > net.mac.assignMacs "11:22:33:00:00:00" 24 [] ["a" "b" "c"]
# { a = "11:22:33:1b:bd:ca"; b = "11:22:33:39:59:4a"; c = "11:22:33:50:7a:e2"; }
#
# > net.mac.assignMacs "11:22:33:00:00:00" 24 [] ["a" "b" "c" "a-new-elem"]
# { a = "11:22:33:1b:bd:ca"; a-new-elem = "11:22:33:d6:5d:58"; b = "11:22:33:39:59:4a"; c = "11:22:33:50:7a:e2"; }
#
# > net.mac.assignMacs "11:22:33:00:00:00" 24 ["11:22:33:1b:bd:ca"] ["a" "b" "c"]
# { a = "11:22:33:1b:bd:cb"; b = "11:22:33:39:59:4a"; c = "11:22:33:50:7a:e2"; }
assignMacs =
base: size: reserved: hosts:
let
capacity = libNet.bit.left 1 size;
baseAsInt = libNet.net.mac.diff base "00:00:00:00:00:00";
init = unique (
flip map reserved (x: if builtins.typeOf x == "int" then x else libNet.net.mac.diff x base)
);
nHosts = builtins.length hosts;
nInit = builtins.length init;
# Pre-sort all hosts, to ensure ordering invariance
sortedHosts =
warnIf ((nInit + nHosts) > 0.3 * capacity)
"assignMacs: hash stability may be degraded since utilization is >30%"
(builtins.sort builtins.lessThan hosts);
# Generates a hash (i.e. offset value) for a given hostname
hashElem =
x: builtins.bitAnd (capacity - 1) (hexToDec (substring 0 16 (builtins.hashString "sha256" x)));
# Do linear probing. Returns the first unused value at or after the given value.
probe =
avoid: value:
if
elem value avoid
# TODO lib.mod
# Poor man's modulo, because nix has no modulo. Luckily we operate on a residue
# class of x modulo 2^n, so we can use bitAnd instead.
then
probe avoid (builtins.bitAnd (capacity - 1) (value + 1))
else
value;
# Hash a new element and avoid assigning any existing values.
assignOne =
{
assigned,
used,
}:
x:
let
value = probe used (hashElem x);
in
{
assigned = assigned // {
${x} = libNet.net.mac.add value base;
};
used = [ value ] ++ used;
};
in
assert assertMsg (size >= 2 && size <= 62) "assignMacs: size=${toString size} is not in [2, 62].";
assert assertMsg (
builtins.bitAnd (capacity - 1) baseAsInt == 0
) "assignMacs: the size=${toString size} least significant bits of the base mac address must be 0.";
assert assertMsg (nHosts <= capacity - nInit)
"assignMacs: number of hosts (${toString nHosts}) must be <= capacity (${toString capacity}) - reserved (${toString nInit})";
# Assign an ip in the subnet to each element, in order
(foldl' assignOne {
assigned = { };
used = init;
} sortedHosts).assigned;
};
};
types.net = libNet.net.types;
};
}
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