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Published: Jun 30, 2021 License: BSD-3-Clause Imports: 4 Imported by: 0




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const (
	IPv4len = 4
	IPv6len = 16

IP address lengths (bytes).


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var (
	IPv4bcast     = IPv4(255, 255, 255, 255) // limited broadcast
	IPv4allsys    = IPv4(224, 0, 0, 1)       // all systems
	IPv4allrouter = IPv4(224, 0, 0, 2)       // all routers
	IPv4zero      = IPv4(0, 0, 0, 0)         // all zeros

Well-known IPv4 addresses

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var (
	IPv6zero                   = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
	IPv6unspecified            = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
	IPv6loopback               = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}
	IPv6interfacelocalallnodes = IP{0xff, 0x01, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01}
	IPv6linklocalallnodes      = IP{0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01}
	IPv6linklocalallrouters    = IP{0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x02}

Well-known IPv6 addresses

View Source
var ErrClosed = errClosed

ErrClosed is the error returned by an I/O call on a network connection that has already been closed, or that is closed by another goroutine before the I/O is completed. This may be wrapped in another error, and should normally be tested using errors.Is(err, net.ErrClosed).

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var (
	ErrNotImplemented = errors.New("operation not implemented")


func JoinHostPort

func JoinHostPort(host, port string) string

JoinHostPort combines host and port into a network address of the form "host:port". If host contains a colon, as found in literal IPv6 addresses, then JoinHostPort returns "[host]:port".

See func Dial for a description of the host and port parameters.

func ParseCIDR

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

ParseCIDR parses s as a CIDR notation IP address and prefix length, like "" 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("") returns the IP address and the network

func SplitHostPort

func SplitHostPort(hostport string) (host, port string, err error)

SplitHostPort splits a network address of the form "host:port", "host%zone:port", "[host]:port" or "[host%zone]:port" into host or host%zone and port.

A literal IPv6 address in hostport must be enclosed in square brackets, as in "[::1]:80", "[::1%lo0]:80".

See func Dial for a description of the hostport parameter, and host and port results.


type Addr

type Addr interface {
	Network() string // name of the network (for example, "tcp", "udp")
	String() string  // string form of address (for example, "", "[2001:db8::1]:80")

Addr represents a network end point address.

The two methods Network and String conventionally return strings that can be passed as the arguments to Dial, but the exact form and meaning of the strings is up to the implementation.

type AddrError

type AddrError struct {
	Err  string
	Addr string

func (*AddrError) Error

func (e *AddrError) Error() string

func (*AddrError) Temporary

func (e *AddrError) Temporary() bool

func (*AddrError) Timeout

func (e *AddrError) Timeout() bool

type Conn

type Conn interface {
	// Read reads data from the connection.
	// Read can be made to time out and return an error after a fixed
	// time limit; see SetDeadline and SetReadDeadline.
	Read(b []byte) (n int, err error)

	// Write writes data to the connection.
	// Write can be made to time out and return an error after a fixed
	// time limit; see SetDeadline and SetWriteDeadline.
	Write(b []byte) (n int, err error)

	// Close closes the connection.
	// Any blocked Read or Write operations will be unblocked and return errors.
	Close() error

	// LocalAddr returns the local network address.
	LocalAddr() Addr

	// RemoteAddr returns the remote network address.
	RemoteAddr() Addr

	// SetDeadline sets the read and write deadlines associated
	// with the connection. It is equivalent to calling both
	// SetReadDeadline and SetWriteDeadline.
	// A deadline is an absolute time after which I/O operations
	// fail instead of blocking. The deadline applies to all future
	// and pending I/O, not just the immediately following call to
	// Read or Write. After a deadline has been exceeded, the
	// connection can be refreshed by setting a deadline in the future.
	// If the deadline is exceeded a call to Read or Write or to other
	// I/O methods will return an error that wraps os.ErrDeadlineExceeded.
	// This can be tested using errors.Is(err, os.ErrDeadlineExceeded).
	// The error's Timeout method will return true, but note that there
	// are other possible errors for which the Timeout method will
	// return true even if the deadline has not been exceeded.
	// An idle timeout can be implemented by repeatedly extending
	// the deadline after successful Read or Write calls.
	// A zero value for t means I/O operations will not time out.
	SetDeadline(t time.Time) error

	// SetReadDeadline sets the deadline for future Read calls
	// and any currently-blocked Read call.
	// A zero value for t means Read will not time out.
	SetReadDeadline(t time.Time) error

	// SetWriteDeadline sets the deadline for future Write calls
	// and any currently-blocked Write call.
	// Even if write times out, it may return n > 0, indicating that
	// some of the data was successfully written.
	// A zero value for t means Write will not time out.
	SetWriteDeadline(t time.Time) error

Conn is a generic stream-oriented network connection.

Multiple goroutines may invoke methods on a Conn simultaneously.

func Dial

func Dial(network, address string) (Conn, error)

type Dialer

type Dialer struct {
	Timeout   time.Duration
	Deadline  time.Time
	DualStack bool
	KeepAlive time.Duration

func (*Dialer) DialContext

func (d *Dialer) DialContext(ctx context.Context, network, address string) (Conn, error)

type Error

type Error interface {
	Timeout() bool   // Is the error a timeout?
	Temporary() bool // Is the error temporary?

An Error represents a network error.

type IP

type IP []byte

An IP is a single IP address, a slice of bytes. Functions in this package accept either 4-byte (IPv4) or 16-byte (IPv6) slices as input.

Note that in this documentation, referring to an IP address as an IPv4 address or an IPv6 address is a semantic property of the address, not just the length of the byte slice: a 16-byte slice can still be an IPv4 address.

func IPv4

func IPv4(a, b, c, d byte) IP

IPv4 returns the IP address (in 16-byte form) of the IPv4 address a.b.c.d.

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 (""), IPv6 ("2001:db8::68"), or IPv4-mapped IPv6 ("::ffff:") form. If s is not a valid textual representation of an IP address, ParseIP returns nil.

func (IP) DefaultMask

func (ip IP) DefaultMask() IPMask

DefaultMask returns the default IP mask for the IP address ip. Only IPv4 addresses have default masks; DefaultMask returns nil if ip is not a valid IPv4 address.

func (IP) Equal

func (ip IP) Equal(x IP) bool

Equal reports whether ip and x are the same IP address. An IPv4 address and that same address in IPv6 form are considered to be equal.

func (IP) IsGlobalUnicast

func (ip IP) IsGlobalUnicast() bool

IsGlobalUnicast reports whether ip is a global unicast address.

The identification of global unicast addresses uses address type identification as defined in RFC 1122, RFC 4632 and RFC 4291 with the exception of IPv4 directed broadcast addresses. It returns true even if ip is in IPv4 private address space or local IPv6 unicast address space.

func (IP) IsInterfaceLocalMulticast

func (ip IP) IsInterfaceLocalMulticast() bool

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

func (IP) IsLinkLocalMulticast

func (ip IP) IsLinkLocalMulticast() bool

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

func (IP) IsLinkLocalUnicast

func (ip IP) IsLinkLocalUnicast() bool

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

func (IP) IsLoopback

func (ip IP) IsLoopback() bool

IsLoopback reports whether ip is a loopback address.

func (IP) IsMulticast

func (ip IP) IsMulticast() bool

IsMulticast reports whether ip is a multicast address.

func (IP) IsUnspecified

func (ip IP) IsUnspecified() bool

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

func (IP) MarshalText

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

MarshalText implements the encoding.TextMarshaler interface. The encoding is the same as returned by String, with one exception: When len(ip) is zero, it returns an empty slice.

func (IP) Mask

func (ip IP) Mask(mask IPMask) IP

Mask returns the result of masking the IP address ip with mask.

func (IP) String

func (ip IP) String() string

String returns the string form of the IP address ip. It returns one of 4 forms:

- "<nil>", if ip has length 0
- dotted decimal (""), if ip is an IPv4 or IP4-mapped IPv6 address
- IPv6 ("2001:db8::1"), if ip is a valid IPv6 address
- the hexadecimal form of ip, without punctuation, if no other cases apply

func (IP) To16

func (ip IP) To16() IP

To16 converts the IP address ip to a 16-byte representation. If ip is not an IP address (it is the wrong length), To16 returns nil.

func (IP) To4

func (ip IP) To4() IP

To4 converts the IPv4 address ip to a 4-byte representation. If ip is not an IPv4 address, To4 returns nil.

func (*IP) UnmarshalText

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

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

type IPAddr

type IPAddr struct {
	IP   IP
	Zone string // IPv6 scoped addressing zone

IPAddr represents the address of an IP end point.

type IPMask

type IPMask []byte

An IPMask is a bitmask that can be used to manipulate IP addresses for IP addressing and routing.

See type IPNet and func ParseCIDR for details.

func CIDRMask

func CIDRMask(ones, bits int) IPMask

CIDRMask returns an IPMask consisting of 'ones' 1 bits followed by 0s up to a total length of 'bits' bits. For a mask of this form, CIDRMask is the inverse of IPMask.Size.

func IPv4Mask

func IPv4Mask(a, b, c, d byte) IPMask

IPv4Mask returns the IP mask (in 4-byte form) of the IPv4 mask a.b.c.d.

func (IPMask) Size

func (m IPMask) Size() (ones, bits int)

Size returns the number of leading ones and total bits in the mask. If the mask is not in the canonical form--ones followed by zeros--then Size returns 0, 0.

func (IPMask) String

func (m IPMask) String() string

String returns the hexadecimal form of m, with no punctuation.

type IPNet

type IPNet struct {
	IP   IP     // network number
	Mask IPMask // network mask

An IPNet represents an IP network.

func (*IPNet) Contains

func (n *IPNet) Contains(ip IP) bool

Contains reports whether the network includes ip.

func (*IPNet) Network

func (n *IPNet) Network() string

Network returns the address's network name, "ip+net".

func (*IPNet) String

func (n *IPNet) String() string

String returns the CIDR notation of n like "" or "2001:db8::/48" as defined in RFC 4632 and RFC 4291. If the mask is not in the canonical form, it returns the string which consists of an IP address, followed by a slash character and a mask expressed as hexadecimal form with no punctuation like "".

type Listener

type Listener interface {
	// Accept waits for and returns the next connection to the listener.
	Accept() (Conn, error)

	// Close closes the listener.
	// Any blocked Accept operations will be unblocked and return errors.
	Close() error

	// Addr returns the listener's network address.
	Addr() Addr

A Listener is a generic network listener for stream-oriented protocols.

Multiple goroutines may invoke methods on a Listener simultaneously.

func Listen

func Listen(network, address string) (Listener, error)

type OpError

type OpError struct {
	// Op is the operation which caused the error, such as
	// "read" or "write".
	Op string

	// Net is the network type on which this error occurred,
	// such as "tcp" or "udp6".
	Net string

	// For operations involving a remote network connection, like
	// Dial, Read, or Write, Source is the corresponding local
	// network address.
	Source Addr

	// Addr is the network address for which this error occurred.
	// For local operations, like Listen or SetDeadline, Addr is
	// the address of the local endpoint being manipulated.
	// For operations involving a remote network connection, like
	// Dial, Read, or Write, Addr is the remote address of that
	// connection.
	Addr Addr

	// Err is the error that occurred during the operation.
	// The Error method panics if the error is nil.
	Err error

OpError is the error type usually returned by functions in the net package. It describes the operation, network type, and address of an error.

func (*OpError) Error

func (e *OpError) Error() string

func (*OpError) Unwrap

func (e *OpError) Unwrap() error

type ParseError

type ParseError struct {
	// Type is the type of string that was expected, such as
	// "IP address", "CIDR address".
	Type string

	// Text is the malformed text string.
	Text string

A ParseError is the error type of literal network address parsers.

func (*ParseError) Error

func (e *ParseError) Error() string

type TCPConn

type TCPConn struct {
	// contains filtered or unexported fields

TCPConn is an implementation of the Conn interface for TCP network connections.

func (*TCPConn) CloseWrite

func (c *TCPConn) CloseWrite() error

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