package netip

import "net/netip"

Package netip defines an IP address type that's a small value type. Building on that Addr type, the package also defines AddrPort (an IP address and a port) and Prefix (an IP address and a bit length prefix).

Compared to the net.IP type, Addr type takes less memory, is immutable, and is comparable (supports == and being a map key).

Index

Types

type Addr

type Addr struct {
	// contains filtered or unexported fields
}

Addr represents an IPv4 or IPv6 address (with or without a scoped addressing zone), similar to net.IP or net.IPAddr.

Unlike net.IP or net.IPAddr, Addr is a comparable value type (it supports == and can be a map key) and is immutable.

The zero Addr is not a valid IP address. Addr{} is distinct from both 0.0.0.0 and ::.

func AddrFrom16

func AddrFrom16(addr [16]byte) Addr

AddrFrom16 returns the IPv6 address given by the bytes in addr. An IPv4-mapped IPv6 address is left as an IPv6 address. (Use Unmap to convert them if needed.)

func AddrFrom4

func AddrFrom4(addr [4]byte) Addr

AddrFrom4 returns the address of the IPv4 address given by the bytes in addr.

func AddrFromSlice

func AddrFromSlice(slice []byte) (ip Addr, ok bool)

AddrFromSlice parses the 4- or 16-byte byte slice as an IPv4 or IPv6 address. Note that a net.IP can be passed directly as the []byte argument. If slice's length is not 4 or 16, AddrFromSlice returns Addr{}, false.

func IPv4Unspecified

func IPv4Unspecified() Addr

IPv4Unspecified returns the IPv4 unspecified address "0.0.0.0".

func IPv6LinkLocalAllNodes

func IPv6LinkLocalAllNodes() Addr

IPv6LinkLocalAllNodes returns the IPv6 link-local all nodes multicast address ff02::1.

func IPv6LinkLocalAllRouters

func IPv6LinkLocalAllRouters() Addr

IPv6LinkLocalAllRouters returns the IPv6 link-local all routers multicast address ff02::2.

func IPv6Loopback

func IPv6Loopback() Addr

IPv6Loopback returns the IPv6 loopback address ::1.

func IPv6Unspecified

func IPv6Unspecified() Addr

IPv6Unspecified returns the IPv6 unspecified address "::".

func MustParseAddr

func MustParseAddr(s string) Addr

MustParseAddr calls ParseAddr(s) and panics on error. It is intended for use in tests with hard-coded strings.

func ParseAddr

func ParseAddr(s string) (Addr, error)

ParseAddr parses s as an IP address, returning the result. The string s can be in dotted decimal ("192.0.2.1"), IPv6 ("2001:db8::68"), or IPv6 with a scoped addressing zone ("fe80::1cc0:3e8c:119f:c2e1%ens18").

func (Addr) AppendTo

func (ip Addr) AppendTo(b []byte) []byte

AppendTo appends a text encoding of ip, as generated by Addr.MarshalText, to b and returns the extended buffer.

func (Addr) As16

func (ip Addr) As16() (a16 [16]byte)

As16 returns the IP address in its 16-byte representation. IPv4 addresses are returned as IPv4-mapped IPv6 addresses. IPv6 addresses with zones are returned without their zone (use the Addr.Zone method to get it). The ip zero value returns all zeroes.

func (Addr) As4

func (ip Addr) As4() (a4 [4]byte)

As4 returns an IPv4 or IPv4-in-IPv6 address in its 4-byte representation. If ip is the zero Addr or an IPv6 address, As4 panics. Note that 0.0.0.0 is not the zero Addr.

func (Addr) AsSlice

func (ip Addr) AsSlice() []byte

AsSlice returns an IPv4 or IPv6 address in its respective 4-byte or 16-byte representation.

func (Addr) BitLen

func (ip Addr) BitLen() int

BitLen returns the number of bits in the IP address: 128 for IPv6, 32 for IPv4, and 0 for the zero Addr.

Note that IPv4-mapped IPv6 addresses are considered IPv6 addresses and therefore have bit length 128.

func (Addr) Compare

func (ip Addr) Compare(ip2 Addr) int

Compare returns an integer comparing two IPs. The result will be 0 if ip == ip2, -1 if ip < ip2, and +1 if ip > ip2. The definition of "less than" is the same as the Addr.Less method.

func (Addr) Is4

func (ip Addr) Is4() bool

Is4 reports whether ip is an IPv4 address.

It returns false for IPv4-mapped IPv6 addresses. See Addr.Unmap.

func (Addr) Is4In6

func (ip Addr) Is4In6() bool

Is4In6 reports whether ip is an IPv4-mapped IPv6 address.

func (Addr) Is6

func (ip Addr) Is6() bool

Is6 reports whether ip is an IPv6 address, including IPv4-mapped IPv6 addresses.

func (Addr) IsGlobalUnicast

func (ip Addr) IsGlobalUnicast() bool

IsGlobalUnicast reports whether ip is a global unicast address.

It returns true for IPv6 addresses which fall outside of the current IANA-allocated 2000::/3 global unicast space, with the exception of the link-local address space. It also returns true even if ip is in the IPv4 private address space or IPv6 unique local address space. It returns false for the zero Addr.

For reference, see RFC 1122, RFC 4291, and RFC 4632.

func (Addr) IsInterfaceLocalMulticast

func (ip Addr) IsInterfaceLocalMulticast() bool

IsInterfaceLocalMulticast reports whether ip is an IPv6 interface-local multicast address.

func (Addr) IsLinkLocalMulticast

func (ip Addr) IsLinkLocalMulticast() bool

IsLinkLocalMulticast reports whether ip is a link-local multicast address.

func (Addr) IsLinkLocalUnicast

func (ip Addr) IsLinkLocalUnicast() bool

IsLinkLocalUnicast reports whether ip is a link-local unicast address.

func (Addr) IsLoopback

func (ip Addr) IsLoopback() bool

IsLoopback reports whether ip is a loopback address.

func (Addr) IsMulticast

func (ip Addr) IsMulticast() bool

IsMulticast reports whether ip is a multicast address.

func (Addr) IsPrivate

func (ip Addr) IsPrivate() bool

IsPrivate reports whether ip is a private address, according to RFC 1918 (IPv4 addresses) and RFC 4193 (IPv6 addresses). That is, it reports whether ip is in 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, or fc00::/7. This is the same as net.IP.IsPrivate.

func (Addr) IsUnspecified

func (ip Addr) IsUnspecified() bool

IsUnspecified reports whether ip is an unspecified address, either the IPv4 address "0.0.0.0" or the IPv6 address "::".

Note that the zero Addr is not an unspecified address.

func (Addr) IsValid

func (ip Addr) IsValid() bool

IsValid reports whether the Addr is an initialized address (not the zero Addr).

Note that "0.0.0.0" and "::" are both valid values.

func (Addr) Less

func (ip Addr) Less(ip2 Addr) bool

Less reports whether ip sorts before ip2. IP addresses sort first by length, then their address. IPv6 addresses with zones sort just after the same address without a zone.

func (Addr) MarshalBinary

func (ip Addr) MarshalBinary() ([]byte, error)

MarshalBinary implements the encoding.BinaryMarshaler interface. It returns a zero-length slice for the zero Addr, the 4-byte form for an IPv4 address, and the 16-byte form with zone appended for an IPv6 address.

func (Addr) MarshalText

func (ip Addr) MarshalText() ([]byte, error)

MarshalText implements the encoding.TextMarshaler interface, The encoding is the same as returned by Addr.String, with one exception: If ip is the zero Addr, the encoding is the empty string.

func (Addr) Next

func (ip Addr) Next() Addr

Next returns the address following ip. If there is none, it returns the zero Addr.

func (Addr) Prefix

func (ip Addr) Prefix(b int) (Prefix, error)

Prefix keeps only the top b bits of IP, producing a Prefix of the specified length. If ip is a zero Addr, Prefix always returns a zero Prefix and a nil error. Otherwise, if bits is less than zero or greater than ip.BitLen(), Prefix returns an error.

func (Addr) Prev

func (ip Addr) Prev() Addr

Prev returns the IP before ip. If there is none, it returns the IP zero value.

func (Addr) String

func (ip Addr) String() string

String returns the string form of the IP address ip. It returns one of 5 forms:

Note that unlike package net's IP.String method, IPv4-mapped IPv6 addresses format with a "::ffff:" prefix before the dotted quad.

func (Addr) StringExpanded

func (ip Addr) StringExpanded() string

StringExpanded is like Addr.String but IPv6 addresses are expanded with leading zeroes and no "::" compression. For example, "2001:db8::1" becomes "2001:0db8:0000:0000:0000:0000:0000:0001".

func (Addr) Unmap

func (ip Addr) Unmap() Addr

Unmap returns ip with any IPv4-mapped IPv6 address prefix removed.

That is, if ip is an IPv6 address wrapping an IPv4 address, it returns the wrapped IPv4 address. Otherwise it returns ip unmodified.

func (*Addr) UnmarshalBinary

func (ip *Addr) UnmarshalBinary(b []byte) error

UnmarshalBinary implements the encoding.BinaryUnmarshaler interface. It expects data in the form generated by MarshalBinary.

func (*Addr) UnmarshalText

func (ip *Addr) UnmarshalText(text []byte) error

UnmarshalText implements the encoding.TextUnmarshaler interface. The IP address is expected in a form accepted by ParseAddr.

If text is empty, UnmarshalText sets *ip to the zero Addr and returns no error.

func (Addr) WithZone

func (ip Addr) WithZone(zone string) Addr

WithZone returns an IP that's the same as ip but with the provided zone. If zone is empty, the zone is removed. If ip is an IPv4 address, WithZone is a no-op and returns ip unchanged.

func (Addr) Zone

func (ip Addr) Zone() string

Zone returns ip's IPv6 scoped addressing zone, if any.

type AddrPort

type AddrPort struct {
	// contains filtered or unexported fields
}

AddrPort is an IP and a port number.

func AddrPortFrom

func AddrPortFrom(ip Addr, port uint16) AddrPort

AddrPortFrom returns an AddrPort with the provided IP and port. It does not allocate.

func MustParseAddrPort

func MustParseAddrPort(s string) AddrPort

MustParseAddrPort calls ParseAddrPort(s) and panics on error. It is intended for use in tests with hard-coded strings.

func ParseAddrPort

func ParseAddrPort(s string) (AddrPort, error)

ParseAddrPort parses s as an AddrPort.

It doesn't do any name resolution: both the address and the port must be numeric.

func (AddrPort) Addr

func (p AddrPort) Addr() Addr

Addr returns p's IP address.

func (AddrPort) AppendTo

func (p AddrPort) AppendTo(b []byte) []byte

AppendTo appends a text encoding of p, as generated by AddrPort.MarshalText, to b and returns the extended buffer.

func (AddrPort) Compare

func (p AddrPort) Compare(p2 AddrPort) int

Compare returns an integer comparing two AddrPorts. The result will be 0 if p == p2, -1 if p < p2, and +1 if p > p2. AddrPorts sort first by IP address, then port.

func (AddrPort) IsValid

func (p AddrPort) IsValid() bool

IsValid reports whether p.Addr() is valid. All ports are valid, including zero.

func (AddrPort) MarshalBinary

func (p AddrPort) MarshalBinary() ([]byte, error)

MarshalBinary implements the encoding.BinaryMarshaler interface. It returns Addr.MarshalBinary with an additional two bytes appended containing the port in little-endian.

func (AddrPort) MarshalText

func (p AddrPort) MarshalText() ([]byte, error)

MarshalText implements the encoding.TextMarshaler interface. The encoding is the same as returned by AddrPort.String, with one exception: if p.Addr() is the zero Addr, the encoding is the empty string.

func (AddrPort) Port

func (p AddrPort) Port() uint16

Port returns p's port.

func (AddrPort) String

func (p AddrPort) String() string

func (*AddrPort) UnmarshalBinary

func (p *AddrPort) UnmarshalBinary(b []byte) error

UnmarshalBinary implements the encoding.BinaryUnmarshaler interface. It expects data in the form generated by AddrPort.MarshalBinary.

func (*AddrPort) UnmarshalText

func (p *AddrPort) UnmarshalText(text []byte) error

UnmarshalText implements the encoding.TextUnmarshaler interface. The AddrPort is expected in a form generated by AddrPort.MarshalText or accepted by ParseAddrPort.

type Prefix

type Prefix struct {
	// contains filtered or unexported fields
}

Prefix is an IP address prefix (CIDR) representing an IP network.

The first Prefix.Bits() of Addr() are specified. The remaining bits match any address. The range of Bits() is [0,32] for IPv4 or [0,128] for IPv6.

func MustParsePrefix

func MustParsePrefix(s string) Prefix

MustParsePrefix calls ParsePrefix(s) and panics on error. It is intended for use in tests with hard-coded strings.

func ParsePrefix

func ParsePrefix(s string) (Prefix, error)

ParsePrefix parses s as an IP address prefix. The string can be in the form "192.168.1.0/24" or "2001:db8::/32", the CIDR notation defined in RFC 4632 and RFC 4291. IPv6 zones are not permitted in prefixes, and an error will be returned if a zone is present.

Note that masked address bits are not zeroed. Use Masked for that.

func PrefixFrom

func PrefixFrom(ip Addr, bits int) Prefix

PrefixFrom returns a Prefix with the provided IP address and bit prefix length.

It does not allocate. Unlike Addr.Prefix, PrefixFrom does not mask off the host bits of ip.

If bits is less than zero or greater than ip.BitLen, Prefix.Bits will return an invalid value -1.

func (Prefix) Addr

func (p Prefix) Addr() Addr

Addr returns p's IP address.

func (Prefix) AppendTo

func (p Prefix) AppendTo(b []byte) []byte

AppendTo appends a text encoding of p, as generated by Prefix.MarshalText, to b and returns the extended buffer.

func (Prefix) Bits

func (p Prefix) Bits() int

Bits returns p's prefix length.

It reports -1 if invalid.

func (Prefix) Contains

func (p Prefix) Contains(ip Addr) bool

Contains reports whether the network p includes ip.

An IPv4 address will not match an IPv6 prefix. An IPv4-mapped IPv6 address will not match an IPv4 prefix. A zero-value IP will not match any prefix. If ip has an IPv6 zone, Contains returns false, because Prefixes strip zones.

func (Prefix) IsSingleIP

func (p Prefix) IsSingleIP() bool

IsSingleIP reports whether p contains exactly one IP.

func (Prefix) IsValid

func (p Prefix) IsValid() bool

IsValid reports whether p.Bits() has a valid range for p.Addr(). If p.Addr() is the zero Addr, IsValid returns false. Note that if p is the zero Prefix, then p.IsValid() == false.

func (Prefix) MarshalBinary

func (p Prefix) MarshalBinary() ([]byte, error)

MarshalBinary implements the encoding.BinaryMarshaler interface. It returns Addr.MarshalBinary with an additional byte appended containing the prefix bits.

func (Prefix) MarshalText

func (p Prefix) MarshalText() ([]byte, error)

MarshalText implements the encoding.TextMarshaler interface, The encoding is the same as returned by Prefix.String, with one exception: If p is the zero value, the encoding is the empty string.

func (Prefix) Masked

func (p Prefix) Masked() Prefix

Masked returns p in its canonical form, with all but the high p.Bits() bits of p.Addr() masked off.

If p is zero or otherwise invalid, Masked returns the zero Prefix.

func (Prefix) Overlaps

func (p Prefix) Overlaps(o Prefix) bool

Overlaps reports whether p and o contain any IP addresses in common.

If p and o are of different address families or either have a zero IP, it reports false. Like the Contains method, a prefix with an IPv4-mapped IPv6 address is still treated as an IPv6 mask.

func (Prefix) String

func (p Prefix) String() string

String returns the CIDR notation of p: "<ip>/<bits>".

func (*Prefix) UnmarshalBinary

func (p *Prefix) UnmarshalBinary(b []byte) error

UnmarshalBinary implements the encoding.BinaryUnmarshaler interface. It expects data in the form generated by Prefix.MarshalBinary.

func (*Prefix) UnmarshalText

func (p *Prefix) UnmarshalText(text []byte) error

UnmarshalText implements the encoding.TextUnmarshaler interface. The IP address is expected in a form accepted by ParsePrefix or generated by Prefix.MarshalText.