lib.network: ipv6 parser from string
Add a library function to parse and validate an IPv6 address from a string. It can parse the first two versions of an IPv6 address according to https://datatracker.ietf.org/doc/html/rfc4291#section-2.2. The third form "x❌x❌x:x.d.d.d.d" is not yet implemented. Optionally parser can accept prefix length (128 is default). Add shell script network.sh to test IPv6 parser functionality.
This commit is contained in:
woojiq
parent
52cc703bba
commit
d559eed93a
@ -64,6 +64,9 @@ let
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# linux kernel configuration
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kernel = callLibs ./kernel.nix;
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# network
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network = callLibs ./network;
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# TODO: For consistency, all builtins should also be available from a sub-library;
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# these are the only ones that are currently not
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inherit (builtins) addErrorContext isPath trace;
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49
lib/network/default.nix
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49
lib/network/default.nix
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@ -0,0 +1,49 @@
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{ lib }:
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let
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inherit (import ./internal.nix { inherit lib; }) _ipv6;
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in
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{
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ipv6 = {
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/**
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Creates an `IPv6Address` object from an IPv6 address as a string. If
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the prefix length is omitted, it defaults to 64. The parser is limited
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to the first two versions of IPv6 addresses addressed in RFC 4291.
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The form "x:x:x:x:x:x:d.d.d.d" is not yet implemented. Addresses are
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NOT compressed, so they are not always the same as the canonical text
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representation of IPv6 addresses defined in RFC 5952.
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# Type
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```
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fromString :: String -> IPv6Address
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```
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# Examples
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```nix
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fromString "2001:DB8::ffff/32"
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=> {
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address = "2001:db8:0:0:0:0:0:ffff";
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prefixLength = 32;
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}
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```
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# Arguments
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- [addr] An IPv6 address with optional prefix length.
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*/
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fromString =
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addr:
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let
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splittedAddr = _ipv6.split addr;
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addrInternal = splittedAddr.address;
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prefixLength = splittedAddr.prefixLength;
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address = _ipv6.toStringFromExpandedIp addrInternal;
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in
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{
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inherit address prefixLength;
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};
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};
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}
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209
lib/network/internal.nix
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209
lib/network/internal.nix
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@ -0,0 +1,209 @@
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{
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lib ? import ../.,
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}:
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let
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inherit (builtins)
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map
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match
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genList
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length
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concatMap
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head
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toString
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;
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inherit (lib) lists strings trivial;
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inherit (lib.lists) last;
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/*
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IPv6 addresses are 128-bit identifiers. The preferred form is 'x:x:x:x:x:x:x:x',
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where the 'x's are one to four hexadecimal digits of the eight 16-bit pieces of
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the address. See RFC 4291.
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*/
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ipv6Bits = 128;
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ipv6Pieces = 8; # 'x:x:x:x:x:x:x:x'
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ipv6PieceBits = 16; # One piece in range from 0 to 0xffff.
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ipv6PieceMaxValue = 65535; # 2^16 - 1
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in
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let
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/**
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Expand an IPv6 address by removing the "::" compression and padding them
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with the necessary number of zeros. Converts an address from the string to
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the list of strings which then can be parsed using `_parseExpanded`.
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Throws an error when the address is malformed.
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# Type: String -> [ String ]
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# Example:
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```nix
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expandIpv6 "2001:DB8::ffff"
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=> ["2001" "DB8" "0" "0" "0" "0" "0" "ffff"]
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```
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*/
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expandIpv6 =
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addr:
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if match "^[0-9A-Fa-f:]+$" addr == null then
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throw "${addr} contains malformed characters for IPv6 address"
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else
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let
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pieces = strings.splitString ":" addr;
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piecesNoEmpty = lists.remove "" pieces;
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piecesNoEmptyLen = length piecesNoEmpty;
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zeros = genList (_: "0") (ipv6Pieces - piecesNoEmptyLen);
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hasPrefix = strings.hasPrefix "::" addr;
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hasSuffix = strings.hasSuffix "::" addr;
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hasInfix = strings.hasInfix "::" addr;
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in
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if addr == "::" then
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zeros
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else if
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let
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emptyCount = length pieces - piecesNoEmptyLen;
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emptyExpected =
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# splitString produces two empty pieces when "::" in the beginning
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# or in the end, and only one when in the middle of an address.
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if hasPrefix || hasSuffix then
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2
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else if hasInfix then
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1
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else
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0;
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in
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emptyCount != emptyExpected
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|| (hasInfix && piecesNoEmptyLen >= ipv6Pieces) # "::" compresses at least one group of zeros.
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|| (!hasInfix && piecesNoEmptyLen != ipv6Pieces)
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then
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throw "${addr} is not a valid IPv6 address"
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# Create a list of 8 elements, filling some of them with zeros depending
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# on where the "::" was found.
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else if hasPrefix then
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zeros ++ piecesNoEmpty
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else if hasSuffix then
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piecesNoEmpty ++ zeros
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else if hasInfix then
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concatMap (piece: if piece == "" then zeros else [ piece ]) pieces
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else
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pieces;
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/**
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Parses an expanded IPv6 address (see `expandIpv6`), converting each part
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from a string to an u16 integer. Returns an internal representation of IPv6
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address (list of integers) that can be easily processed by other helper
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functions.
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Throws an error some element is not an u16 integer.
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# Type: [ String ] -> IPv6
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# Example:
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```nix
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parseExpandedIpv6 ["2001" "DB8" "0" "0" "0" "0" "0" "ffff"]
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=> [8193 3512 0 0 0 0 0 65535]
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```
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*/
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parseExpandedIpv6 =
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addr:
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assert lib.assertMsg (
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length addr == ipv6Pieces
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) "parseExpandedIpv6: expected list of integers with ${ipv6Pieces} elements";
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let
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u16FromHexStr =
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hex:
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let
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parsed = trivial.fromHexString hex;
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in
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if 0 <= parsed && parsed <= ipv6PieceMaxValue then
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parsed
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else
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throw "0x${hex} is not a valid u16 integer";
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in
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map (piece: u16FromHexStr piece) addr;
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in
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let
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/**
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Parses an IPv6 address from a string to the internal representation (list
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of integers).
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# Type: String -> IPv6
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# Example:
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```nix
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parseIpv6FromString "2001:DB8::ffff"
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=> [8193 3512 0 0 0 0 0 65535]
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```
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*/
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parseIpv6FromString = addr: parseExpandedIpv6 (expandIpv6 addr);
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in
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{
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/*
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Internally, an IPv6 address is stored as a list of 16-bit integers with 8
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elements. Wherever you see `IPv6` in internal functions docs, it means that
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it is a list of integers produced by one of the internal parsers, such as
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`parseIpv6FromString`
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*/
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_ipv6 = {
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/**
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Converts an internal representation of an IPv6 address (i.e, a list
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of integers) to a string. The returned string is not a canonical
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representation as defined in RFC 5952, i.e zeros are not compressed.
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# Type: IPv6 -> String
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# Example:
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```nix
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parseIpv6FromString [8193 3512 0 0 0 0 0 65535]
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=> "2001:db8:0:0:0:0:0:ffff"
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```
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*/
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toStringFromExpandedIp =
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pieces: strings.concatMapStringsSep ":" (piece: strings.toLower (trivial.toHexString piece)) pieces;
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/**
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Extract an address and subnet prefix length from a string. The subnet
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prefix length is optional and defaults to 128. The resulting address and
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prefix length are validated and converted to an internal representation
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that can be used by other functions.
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# Type: String -> [ {address :: IPv6, prefixLength :: Int} ]
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# Example:
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```nix
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split "2001:DB8::ffff/32"
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=> {
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address = [8193 3512 0 0 0 0 0 65535];
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prefixLength = 32;
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}
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```
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*/
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split =
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addr:
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let
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splitted = strings.splitString "/" addr;
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splittedLength = length splitted;
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in
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if splittedLength == 1 then # [ ip ]
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{
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address = parseIpv6FromString addr;
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prefixLength = ipv6Bits;
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}
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else if splittedLength == 2 then # [ ip subnet ]
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{
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address = parseIpv6FromString (head splitted);
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prefixLength =
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let
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n = strings.toInt (last splitted);
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in
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if 1 <= n && n <= ipv6Bits then
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n
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else
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throw "${addr} IPv6 subnet should be in range [1;${toString ipv6Bits}], got ${toString n}";
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}
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else
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throw "${addr} is not a valid IPv6 address in CIDR notation";
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};
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}
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117
lib/tests/network.sh
Executable file
117
lib/tests/network.sh
Executable file
@ -0,0 +1,117 @@
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#!/usr/bin/env bash
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# Tests lib/network.nix
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# Run:
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# [nixpkgs]$ lib/tests/network.sh
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# or:
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# [nixpkgs]$ nix-build lib/tests/release.nix
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set -euo pipefail
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shopt -s inherit_errexit
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if [[ -n "${TEST_LIB:-}" ]]; then
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NIX_PATH=nixpkgs="$(dirname "$TEST_LIB")"
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else
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NIX_PATH=nixpkgs="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.."; pwd)"
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fi
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export NIX_PATH
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die() {
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echo >&2 "test case failed: " "$@"
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exit 1
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}
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tmp="$(mktemp -d)"
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clean_up() {
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rm -rf "$tmp"
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}
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trap clean_up EXIT SIGINT SIGTERM
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work="$tmp/work"
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mkdir "$work"
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cd "$work"
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prefixExpression='
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let
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lib = import <nixpkgs/lib>;
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internal = import <nixpkgs/lib/network/internal.nix> {
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inherit lib;
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};
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in
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with lib;
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with lib.network;
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'
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expectSuccess() {
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local expr=$1
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local expectedResult=$2
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if ! result=$(nix-instantiate --eval --strict --json --show-trace \
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--expr "$prefixExpression ($expr)"); then
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die "$expr failed to evaluate, but it was expected to succeed"
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fi
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if [[ ! "$result" == "$expectedResult" ]]; then
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die "$expr == $result, but $expectedResult was expected"
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fi
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}
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expectSuccessRegex() {
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local expr=$1
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local expectedResultRegex=$2
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if ! result=$(nix-instantiate --eval --strict --json --show-trace \
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--expr "$prefixExpression ($expr)"); then
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die "$expr failed to evaluate, but it was expected to succeed"
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fi
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if [[ ! "$result" =~ $expectedResultRegex ]]; then
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die "$expr == $result, but $expectedResultRegex was expected"
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fi
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}
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expectFailure() {
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local expr=$1
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local expectedErrorRegex=$2
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if result=$(nix-instantiate --eval --strict --json --show-trace 2>"$work/stderr" \
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--expr "$prefixExpression ($expr)"); then
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die "$expr evaluated successfully to $result, but it was expected to fail"
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fi
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if [[ ! "$(<"$work/stderr")" =~ $expectedErrorRegex ]]; then
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die "Error was $(<"$work/stderr"), but $expectedErrorRegex was expected"
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fi
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}
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# Internal functions
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expectSuccess '(internal._ipv6.split "0:0:0:0:0:0:0:0").address' '[0,0,0,0,0,0,0,0]'
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expectSuccess '(internal._ipv6.split "000a:000b:000c:000d:000e:000f:ffff:aaaa").address' '[10,11,12,13,14,15,65535,43690]'
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expectSuccess '(internal._ipv6.split "::").address' '[0,0,0,0,0,0,0,0]'
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expectSuccess '(internal._ipv6.split "::0000").address' '[0,0,0,0,0,0,0,0]'
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expectSuccess '(internal._ipv6.split "::1").address' '[0,0,0,0,0,0,0,1]'
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expectSuccess '(internal._ipv6.split "::ffff").address' '[0,0,0,0,0,0,0,65535]'
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expectSuccess '(internal._ipv6.split "::000f").address' '[0,0,0,0,0,0,0,15]'
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expectSuccess '(internal._ipv6.split "::1:1:1:1:1:1:1").address' '[0,1,1,1,1,1,1,1]'
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expectSuccess '(internal._ipv6.split "1::").address' '[1,0,0,0,0,0,0,0]'
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expectSuccess '(internal._ipv6.split "1:1:1:1:1:1:1::").address' '[1,1,1,1,1,1,1,0]'
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expectSuccess '(internal._ipv6.split "1:1:1:1::1:1:1").address' '[1,1,1,1,0,1,1,1]'
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expectSuccess '(internal._ipv6.split "1::1").address' '[1,0,0,0,0,0,0,1]'
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expectFailure 'internal._ipv6.split "0:0:0:0:0:0:0:-1"' "contains malformed characters for IPv6 address"
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expectFailure 'internal._ipv6.split "::0:"' "is not a valid IPv6 address"
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expectFailure 'internal._ipv6.split ":0::"' "is not a valid IPv6 address"
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expectFailure 'internal._ipv6.split "0::0:"' "is not a valid IPv6 address"
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expectFailure 'internal._ipv6.split "0:0:"' "is not a valid IPv6 address"
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expectFailure 'internal._ipv6.split "0:0:0:0:0:0:0:0:0"' "is not a valid IPv6 address"
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expectFailure 'internal._ipv6.split "0:0:0:0:0:0:0:0:"' "is not a valid IPv6 address"
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expectFailure 'internal._ipv6.split "::0:0:0:0:0:0:0:0"' "is not a valid IPv6 address"
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expectFailure 'internal._ipv6.split "0::0:0:0:0:0:0:0"' "is not a valid IPv6 address"
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expectFailure 'internal._ipv6.split "::10000"' "0x10000 is not a valid u16 integer"
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expectSuccess '(internal._ipv6.split "::").prefixLength' '128'
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expectSuccess '(internal._ipv6.split "::/1").prefixLength' '1'
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expectSuccess '(internal._ipv6.split "::/128").prefixLength' '128'
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expectFailure '(internal._ipv6.split "::/0").prefixLength' "IPv6 subnet should be in range \[1;128\], got 0"
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expectFailure '(internal._ipv6.split "::/129").prefixLength' "IPv6 subnet should be in range \[1;128\], got 129"
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expectFailure '(internal._ipv6.split "/::/").prefixLength' "is not a valid IPv6 address in CIDR notation"
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# Library API
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expectSuccess 'lib.network.ipv6.fromString "2001:DB8::ffff/64"' '{"address":"2001:db8:0:0:0:0:0:ffff","prefixLength":64}'
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expectSuccess 'lib.network.ipv6.fromString "1234:5678:90ab:cdef:fedc:ba09:8765:4321/44"' '{"address":"1234:5678:90ab:cdef:fedc:ba09:8765:4321","prefixLength":44}'
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echo >&2 tests ok
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@ -65,6 +65,9 @@ pkgs.runCommand "nixpkgs-lib-tests-nix-${nix.version}" {
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echo "Running lib/tests/sources.sh"
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TEST_LIB=$PWD/lib bash lib/tests/sources.sh
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echo "Running lib/tests/network.sh"
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TEST_LIB=$PWD/lib bash lib/tests/network.sh
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echo "Running lib/fileset/tests.sh"
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TEST_LIB=$PWD/lib bash lib/fileset/tests.sh
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