ipaddr

README

Forked IP address parsing functions

This directory contains a subset of code from the Go project's net package as of Go 1.16, used under the Go project license which we've included here in LICENSE and PATENTS, which are also copied from the Go project.

Terraform has its own fork of these functions because Go 1.17 included a breaking change to reject IPv4 address octets written with leading zeros.

The Go project rationale for that change was that Go historically interpreted leading-zero octets inconsistently with many other implementations, trimming off the zeros and still treating the rest as decimal rather than treating the octet as octal.

The Go team made the reasonable observation that having a function that interprets a non-normalized form in a manner inconsistent with other implementations may cause naive validation or policy checks to produce incorrect results, and thus it's a potential security concern. For more information, see Go issue #30999.

After careful consideration, the Terraform team has concluded that Terraform's use of these functions as part of the implementation of the cidrhost, cidrsubnet, cidrsubnets, and cidrnetmask functions has a more limited impact than the general availability of these functions in the Go standard library, and so we can't justify a similar exception to our Terraform 1.0 compatibility promises as the Go team made to their Go 1.0 compatibility promises.

If you're considering using this package for new functionality other than the built-in functions mentioned above, please do so only if consistency with the behavior of those functions is important. Otherwise, new features are not burdened by the same compatibility constraints and so should typically prefer to use the stricter interpretation of the upstream parsing functions.

Documentation

Overview

Package ipaddr is a fork of a subset of the Go standard "net" package which retains parsing behaviors from Go 1.16 or earlier.

Don't use this for any new code without careful consideration. See the README.md in the package directory for more information.

Index

• Constants
• Variables
• func ParseCIDR(s string) (IP, *IPNet, error)
• type IP
  • func ParseIP(s string) IP
• type IPNet
• type ParseError

Constants

const IPv4len = stdnet.IPv4len

const IPv6len = stdnet.IPv6len

Variables

var CIDRMask = stdnet.CIDRMask

var IPv4 = stdnet.IPv4

Functions

func ParseCIDR

func ParseCIDR(s string) (IP, *IPNet, error)

ParseCIDR parses s as a CIDR notation IP address and prefix length, like "192.0.2.0/24" or "2001:db8::/32", as defined in RFC 4632 and RFC 4291.

It returns the IP address and the network implied by the IP and prefix length. For example, ParseCIDR("192.0.2.1/24") returns the IP address 192.0.2.1 and the network 192.0.2.0/24.

Types

type IP

type IP = stdnet.IP

func ParseIP

func ParseIP(s string) IP

ParseIP parses s as an IP address, returning the result. The string s can be in IPv4 dotted decimal ("192.0.2.1"), IPv6 ("2001:db8::68"), or IPv4-mapped IPv6 ("::ffff:192.0.2.1") form. If s is not a valid textual representation of an IP address, ParseIP returns nil.

type IPNet

type IPNet = stdnet.IPNet

type ParseError

type ParseError = stdnet.ParseError