version: 1.10

package net

import "net"

Overview

Package net provides a portable interface for network I/O, including TCP/IP,
UDP, domain name resolution, and Unix domain sockets.

Although the package provides access to low-level networking primitives, most
clients will need only the basic interface provided by the Dial, Listen, and
Accept functions and the associated Conn and Listener interfaces. The crypto/tls
package uses the same interfaces and similar Dial and Listen functions.

The Dial function connects to a server:

  1. conn, err := net.Dial("tcp", "golang.org:80")
  2. if err != nil {
  3.     // handle error
  4. }
  5. fmt.Fprintf(conn, "GET / HTTP/1.0\r\n\r\n")
  6. status, err := bufio.NewReader(conn).ReadString('\n')
  7. // ...

The Listen function creates servers:

  1. ln, err := net.Listen("tcp", ":8080")
  2. if err != nil {
  3.     // handle error
  4. }
  5. for {
  6.     conn, err := ln.Accept()
  7.     if err != nil {
  8.         // handle error
  9.     }
  10.     go handleConnection(conn)
  11. }

Name Resolution

The method for resolving domain names, whether indirectly with functions like
Dial or directly with functions like LookupHost and LookupAddr, varies by
operating system.

On Unix systems, the resolver has two options for resolving names. It can use a
pure Go resolver that sends DNS requests directly to the servers listed in
/etc/resolv.conf, or it can use a cgo-based resolver that calls C library
routines such as getaddrinfo and getnameinfo.

By default the pure Go resolver is used, because a blocked DNS request consumes
only a goroutine, while a blocked C call consumes an operating system thread.
When cgo is available, the cgo-based resolver is used instead under a variety of
conditions: on systems that do not let programs make direct DNS requests (OS X),
when the LOCALDOMAIN environment variable is present (even if empty), when the
RES_OPTIONS or HOSTALIASES environment variable is non-empty, when the
ASR_CONFIG environment variable is non-empty (OpenBSD only), when
/etc/resolv.conf or /etc/nsswitch.conf specify the use of features that the Go
resolver does not implement, and when the name being looked up ends in .local or
is an mDNS name.

The resolver decision can be overridden by setting the netdns value of the
GODEBUG environment variable (see package runtime) to go or cgo, as in:

  1. export GODEBUG=netdns=go    # force pure Go resolver
  2. export GODEBUG=netdns=cgo   # force cgo resolver

The decision can also be forced while building the Go source tree by setting the
netgo or netcgo build tag.

A numeric netdns setting, as in GODEBUG=netdns=1, causes the resolver to print
debugging information about its decisions. To force a particular resolver while
also printing debugging information, join the two settings by a plus sign, as in
GODEBUG=netdns=go+1.

On Plan 9, the resolver always accesses /net/cs and /net/dns.

On Windows, the resolver always uses C library functions, such as GetAddrInfo
and DnsQuery.

Index

Examples

Package files

addrselect.go cgo_linux.go cgo_resnew.go cgo_socknew.go cgo_unix.go conf.go dial.go dnsclient.go dnsclient_unix.go dnsconfig_unix.go dnsmsg.go error_posix.go fd_unix.go file.go file_unix.go hook.go hook_unix.go hosts.go interface.go interface_linux.go ip.go iprawsock.go iprawsock_posix.go ipsock.go ipsock_posix.go lookup.go lookup_unix.go mac.go net.go nss.go parse.go pipe.go port.go port_unix.go rawconn.go sendfile_linux.go sock_cloexec.go sock_linux.go sock_posix.go sockopt_linux.go sockopt_posix.go sockoptip_linux.go sockoptip_posix.go tcpsock.go tcpsock_posix.go tcpsockopt_posix.go tcpsockopt_unix.go udpsock.go udpsock_posix.go unixsock.go unixsock_posix.go writev_unix.go

Constants

  1. const (
  2.     IPv4len = 4
  3.     IPv6len = 16
  4. )

IP address lengths (bytes).

Variables

  1. var (
  2.     IPv4bcast     = IPv4(255, 255, 255, 255) // limited broadcast
  3.     IPv4allsys    = IPv4(224, 0, 0, 1)       // all systems
  4.     IPv4allrouter = IPv4(224, 0, 0, 2)       // all routers
  5.     IPv4zero      = IPv4(0, 0, 0, 0)         // all zeros
  6. )

Well-known IPv4 addresses

  1. var (
  2.     IPv6zero                   = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
  3.     IPv6unspecified            = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
  4.     IPv6loopback               = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}
  5.     IPv6interfacelocalallnodes = IP{0xff, 0x01, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01}
  6.     IPv6linklocalallnodes      = IP{0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01}
  7.     IPv6linklocalallrouters    = IP{0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x02}
  8. )

Well-known IPv6 addresses

  1. var DefaultResolver = &Resolver{}

DefaultResolver is the resolver used by the package-level Lookup functions and
by Dialers without a specified Resolver.

  1. var (
  2.     ErrWriteToConnected = errors.New("use of WriteTo with pre-connected connection")
  3. )

Various errors contained in OpError.

func InterfaceAddrs


  1. func InterfaceAddrs() ([]Addr, error)


InterfaceAddrs returns a list of the system’s unicast interface addresses.

The returned list does not identify the associated interface; use Interfaces and
Interface.Addrs for more detail.

func Interfaces


  1. func Interfaces() ([]Interface, error)


Interfaces returns a list of the system’s network interfaces.

func JoinHostPort


  1. 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 LookupAddr


  1. func LookupAddr(addr string) (names []string, err error)


LookupAddr performs a reverse lookup for the given address, returning a list of
names mapping to that address.

When using the host C library resolver, at most one result will be returned. To
bypass the host resolver, use a custom Resolver.

func LookupCNAME


  1. func LookupCNAME(host string) (cname string, err error)


LookupCNAME returns the canonical name for the given host. Callers that do not
care about the canonical name can call LookupHost or LookupIP directly; both
take care of resolving the canonical name as part of the lookup.

A canonical name is the final name after following zero or more CNAME records.
LookupCNAME does not return an error if host does not contain DNS “CNAME”
records, as long as host resolves to address records.

func LookupHost


  1. func LookupHost(host string) (addrs []string, err error)


LookupHost looks up the given host using the local resolver. It returns a slice
of that host’s addresses.

func LookupIP


  1. func LookupIP(host string) ([]IP, error)


LookupIP looks up host using the local resolver. It returns a slice of that
host’s IPv4 and IPv6 addresses.

func LookupMX


  1. func LookupMX(name string) ([]MX, error)


LookupMX returns the DNS MX records for the given domain name sorted by
preference.

func LookupNS


  1. func LookupNS(name string) ([]NS, error)


LookupNS returns the DNS NS records for the given domain name.

func LookupPort


  1. func LookupPort(network, service string) (port int, err error)


LookupPort looks up the port for the given network and service.

func LookupSRV


  1. func LookupSRV(service, proto, name string) (cname string, addrs []SRV, err error)


LookupSRV tries to resolve an SRV query of the given service, protocol, and
domain name. The proto is “tcp” or “udp”. The returned records are sorted by
priority and randomized by weight within a priority.

LookupSRV constructs the DNS name to look up following RFC 2782. That is, it
looks up _service._proto.name. To accommodate services publishing SRV records
under non-standard names, if both service and proto are empty strings, LookupSRV
looks up name directly.

func LookupTXT


  1. func LookupTXT(name string) ([]string, error)


LookupTXT returns the DNS TXT records for the given domain name.

func SplitHostPort


  1. 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


  1. type Addr interface {
        Network() string // name of the network (for example, "tcp", "udp")
        String() string  // string form of address (for example, "192.0.2.1:25", "[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


  1. type AddrError struct {
        Err  string
        Addr string
    }



func (AddrError) Error


  1. func (e AddrError) Error() string



func (AddrError) Temporary


  1. func (e AddrError) Temporary() bool



func (AddrError) Timeout


  1. func (e AddrError) Timeout() bool



type Buffers


  1. type Buffers [][]byte


Buffers contains zero or more runs of bytes to write.

On certain machines, for certain types of connections, this is optimized into an
OS-specific batch write operation (such as “writev”).

func (Buffers) Read


  1. func (v Buffers) Read(p []byte) (n int, err error)



func (Buffers) WriteTo


  1. func (v Buffers) WriteTo(w io.Writer) (n int64, err error)



type Conn


  1. type Conn interface {
        // Read reads data from the connection.
        // Read can be made to time out and return an Error with Timeout() == true
        // 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 with Timeout() == true
        // 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 with a timeout (see type Error) 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.
        //
        // 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


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


Dial connects to the address on the named network.

Known networks are “tcp”, “tcp4” (IPv4-only), “tcp6” (IPv6-only), “udp”, “udp4”
(IPv4-only), “udp6” (IPv6-only), “ip”, “ip4” (IPv4-only), “ip6” (IPv6-only),
“unix”, “unixgram” and “unixpacket”.

For TCP and UDP networks, the address has the form “host:port”. The host must be
a literal IP address, or a host name that can be resolved to IP addresses. The
port must be a literal port number or a service name. If the host is a literal
IPv6 address it must be enclosed in square brackets, as in “[2001:db8::1]:80” or
“[fe80::1%zone]:80”. The zone specifies the scope of the literal IPv6 address as
defined in RFC 4007. The functions JoinHostPort and SplitHostPort manipulate a
pair of host and port in this form. When using TCP, and the host resolves to
multiple IP addresses, Dial will try each IP address in order until one
succeeds.

Examples:

Dial(“tcp”, “golang.org:http”)
Dial(“tcp”, “192.0.2.1:http”)
Dial(“tcp”, “198.51.100.1:80”)
Dial(“udp”, “[2001:db8::1]:domain”)
Dial(“udp”, “[fe80::1%lo0]:53”)
Dial(“tcp”, “:80”)

For IP networks, the network must be “ip”, “ip4” or “ip6” followed by a colon
and a literal protocol number or a protocol name, and the address has the form
“host”. The host must be a literal IP address or a literal IPv6 address with
zone. It depends on each operating system how the operating system behaves with
a non-well known protocol number such as “0” or “255”.

Examples:

Dial(“ip4:1”, “192.0.2.1”)
Dial(“ip6:ipv6-icmp”, “2001:db8::1”)
Dial(“ip6:58”, “fe80::1%lo0”)

For TCP, UDP and IP networks, if the host is empty or a literal unspecified IP
address, as in “:80”, “0.0.0.0:80” or “[::]:80” for TCP and UDP, “”, “0.0.0.0”
or “::” for IP, the local system is assumed.

For Unix networks, the address must be a file system path.

func DialTimeout


  1. func DialTimeout(network, address string, timeout time.Duration) (Conn, error)


DialTimeout acts like Dial but takes a timeout.

The timeout includes name resolution, if required. When using TCP, and the host
in the address parameter resolves to multiple IP addresses, the timeout is
spread over each consecutive dial, such that each is given an appropriate
fraction of the time to connect.

See func Dial for a description of the network and address parameters.

func FileConn


  1. func FileConn(f os.File) (c Conn, err error)


FileConn returns a copy of the network connection corresponding to the open file
f. It is the caller’s responsibility to close f when finished. Closing c does
not affect f, and closing f does not affect c.

func Pipe


  1. func Pipe() (Conn, Conn)


Pipe creates a synchronous, in-memory, full duplex network connection; both ends
implement the Conn interface. Reads on one end are matched with writes on the
other, copying data directly between the two; there is no internal buffering.

type DNSConfigError


  1. type DNSConfigError struct {
        Err error
    }


DNSConfigError represents an error reading the machine’s DNS configuration. (No
longer used; kept for compatibility.)

func (DNSConfigError) Error


  1. func (e DNSConfigError) Error() string



func (DNSConfigError) Temporary


  1. func (e DNSConfigError) Temporary() bool



func (DNSConfigError) Timeout


  1. func (e DNSConfigError) Timeout() bool



type DNSError


  1. type DNSError struct {
        Err         string // description of the error
        Name        string // name looked for
        Server      string // server used
        IsTimeout   bool   // if true, timed out; not all timeouts set this
        IsTemporary bool   // if true, error is temporary; not all errors set this
    }


DNSError represents a DNS lookup error.

func (DNSError) Error


  1. func (e DNSError) Error() string



func (DNSError) Temporary


  1. func (e DNSError) Temporary() bool


Temporary reports whether the DNS error is known to be temporary. This is not
always known; a DNS lookup may fail due to a temporary error and return a
DNSError for which Temporary returns false.

func (DNSError) Timeout


  1. func (e DNSError) Timeout() bool


Timeout reports whether the DNS lookup is known to have timed out. This is not
always known; a DNS lookup may fail due to a timeout and return a DNSError for
which Timeout returns false.

type Dialer


  1. type Dialer struct {
        // Timeout is the maximum amount of time a dial will wait for
        // a connect to complete. If Deadline is also set, it may fail
        // earlier.
        //
        // The default is no timeout.
        //
        // When using TCP and dialing a host name with multiple IP
        // addresses, the timeout may be divided between them.
        //
        // With or without a timeout, the operating system may impose
        // its own earlier timeout. For instance, TCP timeouts are
        // often around 3 minutes.
        Timeout time.Duration

        // Deadline is the absolute point in time after which dials
        // will fail. If Timeout is set, it may fail earlier.
        // Zero means no deadline, or dependent on the operating system
        // as with the Timeout option.
        Deadline time.Time

        // LocalAddr is the local address to use when dialing an
        // address. The address must be of a compatible type for the
        // network being dialed.
        // If nil, a local address is automatically chosen.
        LocalAddr Addr

        // DualStack enables RFC 6555-compliant "Happy Eyeballs"
        // dialing when the network is "tcp" and the host in the
        // address parameter resolves to both IPv4 and IPv6 addresses.
        // This allows a client to tolerate networks where one address
        // family is silently broken.
        DualStack bool

        // FallbackDelay specifies the length of time to wait before
        // spawning a fallback connection, when DualStack is enabled.
        // If zero, a default delay of 300ms is used.
        FallbackDelay time.Duration

        // KeepAlive specifies the keep-alive period for an active
        // network connection.
        // If zero, keep-alives are not enabled. Network protocols
        // that do not support keep-alives ignore this field.
        KeepAlive time.Duration

        // Resolver optionally specifies an alternate resolver to use.
        Resolver Resolver

        // Cancel is an optional channel whose closure indicates that
        // the dial should be canceled. Not all types of dials support
        // cancelation.
        //
        // Deprecated: Use DialContext instead.
        Cancel <-chan struct{}
    }


A Dialer contains options for connecting to an address.

The zero value for each field is equivalent to dialing without that option.
Dialing with the zero value of Dialer is therefore equivalent to just calling
the Dial function.

func (Dialer) Dial


  1. func (d Dialer) Dial(network, address string) (Conn, error)


Dial connects to the address on the named network.

See func Dial for a description of the network and address parameters.

func (Dialer) DialContext


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


DialContext connects to the address on the named network using the provided
context.

The provided Context must be non-nil. If the context expires before the
connection is complete, an error is returned. Once successfully connected, any
expiration of the context will not affect the connection.

When using TCP, and the host in the address parameter resolves to multiple
network addresses, any dial timeout (from d.Timeout or ctx) is spread over each
consecutive dial, such that each is given an appropriate fraction of the time to
connect. For example, if a host has 4 IP addresses and the timeout is 1 minute,
the connect to each single address will be given 15 seconds to complete before
trying the next one.

See func Dial for a description of the network and address parameters.

type Error


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


An Error represents a network error.

type Flags


  1. type Flags uint



  1. const (
        FlagUp           Flags = 1 << iota // interface is up
        FlagBroadcast                      // interface supports broadcast access capability
        FlagLoopback                       // interface is a loopback interface
        FlagPointToPoint                   // interface belongs to a point-to-point link
        FlagMulticast                      // interface supports multicast access capability
    )



func (Flags) String


  1. func (f Flags) String() string



type HardwareAddr


  1. type HardwareAddr []byte


A HardwareAddr represents a physical hardware address.

func ParseMAC


  1. func ParseMAC(s string) (hw HardwareAddr, err error)


ParseMAC parses s as an IEEE 802 MAC-48, EUI-48, EUI-64, or a 20-octet IP over
InfiniBand link-layer address using one of the following formats:

01:23:45:67:89:ab
01:23:45:67:89:ab:cd:ef
01:23:45:67:89:ab:cd:ef:00:00:01:23:45:67:89:ab:cd:ef:00:00
01-23-45-67-89-ab
01-23-45-67-89-ab-cd-ef
01-23-45-67-89-ab-cd-ef-00-00-01-23-45-67-89-ab-cd-ef-00-00
0123.4567.89ab
0123.4567.89ab.cdef
0123.4567.89ab.cdef.0000.0123.4567.89ab.cdef.0000

func (HardwareAddr) String


  1. func (a HardwareAddr) String() string



type IP


  1. 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


  1. 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.


Example:

fmt.Println(net.IPv4(8, 8, 8, 8))

// Output:
// 8.8.8.8

func ParseCIDR


  1. 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.


Example:

ipv4Addr, ipv4Net, err := net.ParseCIDR(“192.0.2.1/24”)
if err != nil {
log.Fatal(err)
}
fmt.Println(ipv4Addr)
fmt.Println(ipv4Net)

ipv6Addr, ipv6Net, err := net.ParseCIDR(“2001:db8:a0b:12f0::1/32”)
if err != nil {
log.Fatal(err)
}
fmt.Println(ipv6Addr)
fmt.Println(ipv6Net)

// Output:
// 192.0.2.1
// 192.0.2.0/24
// 2001:db8:a0b:12f0::1
// 2001:db8::/32

func ParseIP


  1. func ParseIP(s string) IP


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


Example:

fmt.Println(net.ParseIP(“192.0.2.1”))
fmt.Println(net.ParseIP(“2001:db8::68”))
fmt.Println(net.ParseIP(“192.0.2”))

// Output:
// 192.0.2.1
// 2001:db8::68
//

func (IP) DefaultMask


  1. 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.


Example:

ip := net.ParseIP(“192.0.2.1”)
fmt.Println(ip.DefaultMask())

// Output:
// ffffff00

func (IP) Equal


  1. 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


  1. 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


  1. func (ip IP) IsInterfaceLocalMulticast() bool


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

func (IP) IsLinkLocalMulticast


  1. func (ip IP) IsLinkLocalMulticast() bool


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

func (IP) IsLinkLocalUnicast


  1. func (ip IP) IsLinkLocalUnicast() bool


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

func (IP) IsLoopback


  1. func (ip IP) IsLoopback() bool


IsLoopback reports whether ip is a loopback address.

func (IP) IsMulticast


  1. func (ip IP) IsMulticast() bool


IsMulticast reports whether ip is a multicast address.

func (IP) IsUnspecified


  1. func (ip IP) IsUnspecified() bool


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

func (IP) MarshalText


  1. 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


  1. func (ip IP) Mask(mask IPMask) IP


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


Example:

ipv4Addr := net.ParseIP(“192.0.2.1”)
// This mask corresponds to a /24 subnet for IPv4.
ipv4Mask := net.CIDRMask(24, 32)
fmt.Println(ipv4Addr.Mask(ipv4Mask))

ipv6Addr := net.ParseIP(“2001:db8:a0b:12f0::1”)
// This mask corresponds to a /32 subnet for IPv6.
ipv6Mask := net.CIDRMask(32, 128)
fmt.Println(ipv6Addr.Mask(ipv6Mask))

// Output:
// 192.0.2.0
// 2001:db8::

func (IP) String


  1. func (ip IP) String() string


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

- ““, if ip has length 0
- dotted decimal (“192.0.2.1”), 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


  1. 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


  1. 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


  1. 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


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


IPAddr represents the address of an IP end point.

func ResolveIPAddr


  1. func ResolveIPAddr(network, address string) (IPAddr, error)


ResolveIPAddr returns an address of IP end point.

The network must be an IP network name.

If the host in the address parameter is not a literal IP address, ResolveIPAddr
resolves the address to an address of IP end point. Otherwise, it parses the
address as a literal IP address. The address parameter can use a host name, but
this is not recommended, because it will return at most one of the host name’s
IP addresses.

See func Dial for a description of the network and address parameters.

func (IPAddr) Network


  1. func (a IPAddr) Network() string


Network returns the address’s network name, “ip”.

func (IPAddr) String


  1. func (a IPAddr) String() string



type IPConn


  1. type IPConn struct {
        // contains filtered or unexported fields
    }


IPConn is the implementation of the Conn and PacketConn interfaces for IP
network connections.

func DialIP


  1. func DialIP(network string, laddr, raddr IPAddr) (IPConn, error)


DialIP acts like Dial for IP networks.

The network must be an IP network name; see func Dial for details.

If laddr is nil, a local address is automatically chosen. If the IP field of
raddr is nil or an unspecified IP address, the local system is assumed.

func ListenIP


  1. func ListenIP(network string, laddr IPAddr) (IPConn, error)


ListenIP acts like ListenPacket for IP networks.

The network must be an IP network name; see func Dial for details.

If the IP field of laddr is nil or an unspecified IP address, ListenIP listens
on all available IP addresses of the local system except multicast IP addresses.

func (IPConn) Close


  1. func (c IPConn) Close() error


Close closes the connection.

func (IPConn) File


  1. func (c IPConn) File() (f os.File, err error)


File sets the underlying os.File to blocking mode and returns a copy. It is the
caller’s responsibility to close f when finished. Closing c does not affect f,
and closing f does not affect c.

The returned os.File’s file descriptor is different from the connection’s.
Attempting to change properties of the original using this duplicate may or may
not have the desired effect.

On Unix systems this will cause the SetDeadline methods to stop working.

func (IPConn) LocalAddr


  1. func (c IPConn) LocalAddr() Addr


LocalAddr returns the local network address. The Addr returned is shared by all
invocations of LocalAddr, so do not modify it.

func (IPConn) Read


  1. func (c IPConn) Read(b []byte) (int, error)


Read implements the Conn Read method.

func (IPConn) ReadFrom


  1. func (c IPConn) ReadFrom(b []byte) (int, Addr, error)


ReadFrom implements the PacketConn ReadFrom method.

func (IPConn) ReadFromIP


  1. func (c IPConn) ReadFromIP(b []byte) (int, IPAddr, error)


ReadFromIP acts like ReadFrom but returns an IPAddr.

func (IPConn) ReadMsgIP


  1. func (c IPConn) ReadMsgIP(b, oob []byte) (n, oobn, flags int, addr IPAddr, err error)


ReadMsgIP reads a message from c, copying the payload into b and the associated
out-of-band data into oob. It returns the number of bytes copied into b, the
number of bytes copied into oob, the flags that were set on the message and the
source address of the message.

The packages golang.org/x/net/ipv4 and golang.org/x/net/ipv6 can be used to
manipulate IP-level socket options in oob.

func (IPConn) RemoteAddr


  1. func (c IPConn) RemoteAddr() Addr


RemoteAddr returns the remote network address. The Addr returned is shared by
all invocations of RemoteAddr, so do not modify it.

func (IPConn) SetDeadline


  1. func (c IPConn) SetDeadline(t time.Time) error


SetDeadline implements the Conn SetDeadline method.

func (IPConn) SetReadBuffer


  1. func (c IPConn) SetReadBuffer(bytes int) error


SetReadBuffer sets the size of the operating system’s receive buffer associated
with the connection.

func (IPConn) SetReadDeadline


  1. func (c IPConn) SetReadDeadline(t time.Time) error


SetReadDeadline implements the Conn SetReadDeadline method.

func (IPConn) SetWriteBuffer


  1. func (c IPConn) SetWriteBuffer(bytes int) error


SetWriteBuffer sets the size of the operating system’s transmit buffer
associated with the connection.

func (IPConn) SetWriteDeadline


  1. func (c IPConn) SetWriteDeadline(t time.Time) error


SetWriteDeadline implements the Conn SetWriteDeadline method.

func (IPConn) SyscallConn


  1. func (c IPConn) SyscallConn() (syscall.RawConn, error)


SyscallConn returns a raw network connection. This implements the syscall.Conn
interface.

func (IPConn) Write


  1. func (c IPConn) Write(b []byte) (int, error)


Write implements the Conn Write method.

func (IPConn) WriteMsgIP


  1. func (c IPConn) WriteMsgIP(b, oob []byte, addr IPAddr) (n, oobn int, err error)


WriteMsgIP writes a message to addr via c, copying the payload from b and the
associated out-of-band data from oob. It returns the number of payload and
out-of-band bytes written.

The packages golang.org/x/net/ipv4 and golang.org/x/net/ipv6 can be used to
manipulate IP-level socket options in oob.

func (IPConn) WriteTo


  1. func (c IPConn) WriteTo(b []byte, addr Addr) (int, error)


WriteTo implements the PacketConn WriteTo method.

func (IPConn) WriteToIP


  1. func (c IPConn) WriteToIP(b []byte, addr IPAddr) (int, error)


WriteToIP acts like WriteTo but takes an IPAddr.

type IPMask


  1. type IPMask []byte


An IP mask is an IP address.

func CIDRMask


  1. func CIDRMask(ones, bits int) IPMask


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


Example:

// This mask corresponds to a /31 subnet for IPv4.
fmt.Println(net.CIDRMask(31, 32))

// This mask corresponds to a /64 subnet for IPv6.
fmt.Println(net.CIDRMask(64, 128))

// Output:
// fffffffe
// ffffffffffffffff0000000000000000

func IPv4Mask


  1. 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.


Example:

fmt.Println(net.IPv4Mask(255, 255, 255, 0))

// Output:
// ffffff00

func (IPMask) Size


  1. 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


  1. func (m IPMask) String() string


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

type IPNet


  1. type IPNet struct {
        IP   IP     // network number
        Mask IPMask // network mask
    }


An IPNet represents an IP network.

func (IPNet) Contains


  1. func (n IPNet) Contains(ip IP) bool


Contains reports whether the network includes ip.

func (IPNet) Network


  1. func (n IPNet) Network() string


Network returns the address’s network name, “ip+net”.

func (IPNet) String


  1. func (n IPNet) String() string


String returns the CIDR notation of n like “192.0.2.1/24” 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
“198.51.100.1/c000ff00”.

type Interface


  1. type Interface struct {
        Index        int          // positive integer that starts at one, zero is never used
        MTU          int          // maximum transmission unit
        Name         string       // e.g., "en0", "lo0", "eth0.100"
        HardwareAddr HardwareAddr // IEEE MAC-48, EUI-48 and EUI-64 form
        Flags        Flags        // e.g., FlagUp, FlagLoopback, FlagMulticast
    }


Interface represents a mapping between network interface name and index. It also
represents network interface facility information.

func InterfaceByIndex


  1. func InterfaceByIndex(index int) (Interface, error)


InterfaceByIndex returns the interface specified by index.

On Solaris, it returns one of the logical network interfaces sharing the logical
data link; for more precision use InterfaceByName.

func InterfaceByName


  1. func InterfaceByName(name string) (Interface, error)


InterfaceByName returns the interface specified by name.

func (Interface) Addrs


  1. func (ifi Interface) Addrs() ([]Addr, error)


Addrs returns a list of unicast interface addresses for a specific interface.

func (Interface) MulticastAddrs


  1. func (ifi Interface) MulticastAddrs() ([]Addr, error)


MulticastAddrs returns a list of multicast, joined group addresses for a
specific interface.

type InvalidAddrError


  1. type InvalidAddrError string



func (InvalidAddrError) Error


  1. func (e InvalidAddrError) Error() string



func (InvalidAddrError) Temporary


  1. func (e InvalidAddrError) Temporary() bool



func (InvalidAddrError) Timeout


  1. func (e InvalidAddrError) Timeout() bool



type Listener


  1. 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.


Example:

// Listen on TCP port 2000 on all available unicast and
// anycast IP addresses of the local system.
l, err := net.Listen(“tcp”, “:2000”)
if err != nil {
log.Fatal(err)
}
defer l.Close()
for {
// Wait for a connection.
conn, err := l.Accept()
if err != nil {
log.Fatal(err)
}
// Handle the connection in a new goroutine.
// The loop then returns to accepting, so that
// multiple connections may be served concurrently.
go func(c net.Conn) {
// Echo all incoming data.
io.Copy(c, c)
// Shut down the connection.
c.Close()
}(conn)
}

func FileListener


  1. func FileListener(f os.File) (ln Listener, err error)


FileListener returns a copy of the network listener corresponding to the open
file f. It is the caller’s responsibility to close ln when finished. Closing ln
does not affect f, and closing f does not affect ln.

func Listen


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


Listen announces on the local network address.

The network must be “tcp”, “tcp4”, “tcp6”, “unix” or “unixpacket”.

For TCP networks, if the host in the address parameter is empty or a literal
unspecified IP address, Listen listens on all available unicast and anycast IP
addresses of the local system. To only use IPv4, use network “tcp4”. The address
can use a host name, but this is not recommended, because it will create a
listener for at most one of the host’s IP addresses. If the port in the address
parameter is empty or “0”, as in “127.0.0.1:” or “[::1]:0”, a port number is
automatically chosen. The Addr method of Listener can be used to discover the
chosen port.

See func Dial for a description of the network and address parameters.

type MX


  1. type MX struct {
        Host string
        Pref uint16
    }


An MX represents a single DNS MX record.

type NS


  1. type NS struct {
        Host string
    }


An NS represents a single DNS NS record.

type OpError


  1. 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.
        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


  1. func (e OpError) Error() string



func (OpError) Temporary


  1. func (e OpError) Temporary() bool



func (OpError) Timeout


  1. func (e OpError) Timeout() bool



type PacketConn


  1. type PacketConn interface {
        // ReadFrom reads a packet from the connection,
        // copying the payload into b. It returns the number of
        // bytes copied into b and the return address that
        // was on the packet.
        // ReadFrom can be made to time out and return
        // an Error with Timeout() == true after a fixed time limit;
        // see SetDeadline and SetReadDeadline.
        ReadFrom(b []byte) (n int, addr Addr, err error)

        // WriteTo writes a packet with payload b to addr.
        // WriteTo can be made to time out and return
        // an Error with Timeout() == true after a fixed time limit;
        // see SetDeadline and SetWriteDeadline.
        // On packet-oriented connections, write timeouts are rare.
        WriteTo(b []byte, addr Addr) (n int, err error)

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

        // LocalAddr returns the local network address.
        LocalAddr() 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 with a timeout (see type Error) instead of
        // blocking. The deadline applies to all future and pending
        // I/O, not just the immediately following call to ReadFrom or
        // WriteTo. After a deadline has been exceeded, the connection
        // can be refreshed by setting a deadline in the future.
        //
        // An idle timeout can be implemented by repeatedly extending
        // the deadline after successful ReadFrom or WriteTo 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 ReadFrom calls
        // and any currently-blocked ReadFrom call.
        // A zero value for t means ReadFrom will not time out.
        SetReadDeadline(t time.Time) error

        // SetWriteDeadline sets the deadline for future WriteTo calls
        // and any currently-blocked WriteTo 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 WriteTo will not time out.
        SetWriteDeadline(t time.Time) error
    }


PacketConn is a generic packet-oriented network connection.

Multiple goroutines may invoke methods on a PacketConn simultaneously.

func FilePacketConn


  1. func FilePacketConn(f os.File) (c PacketConn, err error)


FilePacketConn returns a copy of the packet network connection corresponding to
the open file f. It is the caller’s responsibility to close f when finished.
Closing c does not affect f, and closing f does not affect c.

func ListenPacket


  1. func ListenPacket(network, address string) (PacketConn, error)


ListenPacket announces on the local network address.

The network must be “udp”, “udp4”, “udp6”, “unixgram”, or an IP transport. The
IP transports are “ip”, “ip4”, or “ip6” followed by a colon and a literal
protocol number or a protocol name, as in “ip:1” or “ip:icmp”.

For UDP and IP networks, if the host in the address parameter is empty or a
literal unspecified IP address, ListenPacket listens on all available IP
addresses of the local system except multicast IP addresses. To only use IPv4,
use network “udp4” or “ip4:proto”. The address can use a host name, but this is
not recommended, because it will create a listener for at most one of the host’s
IP addresses. If the port in the address parameter is empty or “0”, as in
“127.0.0.1:” or “[::1]:0”, a port number is automatically chosen. The LocalAddr
method of PacketConn can be used to discover the chosen port.

See func Dial for a description of the network and address parameters.

type ParseError


  1. 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


  1. func (e ParseError) Error() string



type Resolver


  1. type Resolver struct {
        // PreferGo controls whether Go's built-in DNS resolver is preferred
        // on platforms where it's available. It is equivalent to setting
        // GODEBUG=netdns=go, but scoped to just this resolver.
        PreferGo bool

        // StrictErrors controls the behavior of temporary errors
        // (including timeout, socket errors, and SERVFAIL) when using
        // Go's built-in resolver. For a query composed of multiple
        // sub-queries (such as an A+AAAA address lookup, or walking the
        // DNS search list), this option causes such errors to abort the
        // whole query instead of returning a partial result. This is
        // not enabled by default because it may affect compatibility
        // with resolvers that process AAAA queries incorrectly.
        StrictErrors bool

        // Dial optionally specifies an alternate dialer for use by
        // Go's built-in DNS resolver to make TCP and UDP connections
        // to DNS services. The host in the address parameter will
        // always be a literal IP address and not a host name, and the
        // port in the address parameter will be a literal port number
        // and not a service name.
        // If the Conn returned is also a PacketConn, sent and received DNS
        // messages must adhere to RFC 1035 section 4.2.1, "UDP usage".
        // Otherwise, DNS messages transmitted over Conn must adhere
        // to RFC 7766 section 5, "Transport Protocol Selection".
        // If nil, the default dialer is used.
        Dial func(ctx context.Context, network, address string) (Conn, error)
    }


A Resolver looks up names and numbers.

A nil Resolver is equivalent to a zero Resolver.

func (Resolver) LookupAddr


  1. func (r Resolver) LookupAddr(ctx context.Context, addr string) (names []string, err error)


LookupAddr performs a reverse lookup for the given address, returning a list of
names mapping to that address.

func (Resolver) LookupCNAME


  1. func (r Resolver) LookupCNAME(ctx context.Context, host string) (cname string, err error)


LookupCNAME returns the canonical name for the given host. Callers that do not
care about the canonical name can call LookupHost or LookupIP directly; both
take care of resolving the canonical name as part of the lookup.

A canonical name is the final name after following zero or more CNAME records.
LookupCNAME does not return an error if host does not contain DNS “CNAME”
records, as long as host resolves to address records.

func (Resolver) LookupHost


  1. func (r Resolver) LookupHost(ctx context.Context, host string) (addrs []string, err error)


LookupHost looks up the given host using the local resolver. It returns a slice
of that host’s addresses.

func (Resolver) LookupIPAddr


  1. func (r Resolver) LookupIPAddr(ctx context.Context, host string) ([]IPAddr, error)


LookupIPAddr looks up host using the local resolver. It returns a slice of that
host’s IPv4 and IPv6 addresses.

func (Resolver) LookupMX


  1. func (r Resolver) LookupMX(ctx context.Context, name string) ([]MX, error)


LookupMX returns the DNS MX records for the given domain name sorted by
preference.

func (Resolver) LookupNS


  1. func (r Resolver) LookupNS(ctx context.Context, name string) ([]NS, error)


LookupNS returns the DNS NS records for the given domain name.

func (Resolver) LookupPort


  1. func (r Resolver) LookupPort(ctx context.Context, network, service string) (port int, err error)


LookupPort looks up the port for the given network and service.

func (Resolver) LookupSRV


  1. func (r Resolver) LookupSRV(ctx context.Context, service, proto, name string) (cname string, addrs []SRV, err error)


LookupSRV tries to resolve an SRV query of the given service, protocol, and
domain name. The proto is “tcp” or “udp”. The returned records are sorted by
priority and randomized by weight within a priority.

LookupSRV constructs the DNS name to look up following RFC 2782. That is, it
looks up _service._proto.name. To accommodate services publishing SRV records
under non-standard names, if both service and proto are empty strings, LookupSRV
looks up name directly.

func (Resolver) LookupTXT


  1. func (r Resolver) LookupTXT(ctx context.Context, name string) ([]string, error)


LookupTXT returns the DNS TXT records for the given domain name.

type SRV


  1. type SRV struct {
        Target   string
        Port     uint16
        Priority uint16
        Weight   uint16
    }


An SRV represents a single DNS SRV record.

type TCPAddr


  1. type TCPAddr struct {
        IP   IP
        Port int
        Zone string // IPv6 scoped addressing zone
    }


TCPAddr represents the address of a TCP end point.

func ResolveTCPAddr


  1. func ResolveTCPAddr(network, address string) (TCPAddr, error)


ResolveTCPAddr returns an address of TCP end point.

The network must be a TCP network name.

If the host in the address parameter is not a literal IP address or the port is
not a literal port number, ResolveTCPAddr resolves the address to an address of
TCP end point. Otherwise, it parses the address as a pair of literal IP address
and port number. The address parameter can use a host name, but this is not
recommended, because it will return at most one of the host name’s IP addresses.

See func Dial for a description of the network and address parameters.

func (TCPAddr) Network


  1. func (a TCPAddr) Network() string


Network returns the address’s network name, “tcp”.

func (TCPAddr) String


  1. func (a TCPAddr) String() string



type TCPConn


  1. type TCPConn struct {
        // contains filtered or unexported fields
    }


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

func DialTCP


  1. func DialTCP(network string, laddr, raddr TCPAddr) (TCPConn, error)


DialTCP acts like Dial for TCP networks.

The network must be a TCP network name; see func Dial for details.

If laddr is nil, a local address is automatically chosen. If the IP field of
raddr is nil or an unspecified IP address, the local system is assumed.

func (TCPConn) Close


  1. func (c TCPConn) Close() error


Close closes the connection.

func (TCPConn) CloseRead


  1. func (c TCPConn) CloseRead() error


CloseRead shuts down the reading side of the TCP connection. Most callers should
just use Close.

func (TCPConn) CloseWrite


  1. func (c TCPConn) CloseWrite() error


CloseWrite shuts down the writing side of the TCP connection. Most callers
should just use Close.

func (TCPConn) File


  1. func (c TCPConn) File() (f os.File, err error)


File sets the underlying os.File to blocking mode and returns a copy. It is the
caller’s responsibility to close f when finished. Closing c does not affect f,
and closing f does not affect c.

The returned os.File’s file descriptor is different from the connection’s.
Attempting to change properties of the original using this duplicate may or may
not have the desired effect.

On Unix systems this will cause the SetDeadline methods to stop working.

func (TCPConn) LocalAddr


  1. func (c TCPConn) LocalAddr() Addr


LocalAddr returns the local network address. The Addr returned is shared by all
invocations of LocalAddr, so do not modify it.

func (TCPConn) Read


  1. func (c TCPConn) Read(b []byte) (int, error)


Read implements the Conn Read method.

func (TCPConn) ReadFrom


  1. func (c TCPConn) ReadFrom(r io.Reader) (int64, error)


ReadFrom implements the io.ReaderFrom ReadFrom method.

func (TCPConn) RemoteAddr


  1. func (c TCPConn) RemoteAddr() Addr


RemoteAddr returns the remote network address. The Addr returned is shared by
all invocations of RemoteAddr, so do not modify it.

func (TCPConn) SetDeadline


  1. func (c TCPConn) SetDeadline(t time.Time) error


SetDeadline implements the Conn SetDeadline method.

func (TCPConn) SetKeepAlive


  1. func (c TCPConn) SetKeepAlive(keepalive bool) error


SetKeepAlive sets whether the operating system should send keepalive messages on
the connection.

func (TCPConn) SetKeepAlivePeriod


  1. func (c TCPConn) SetKeepAlivePeriod(d time.Duration) error


SetKeepAlivePeriod sets period between keep alives.

func (TCPConn) SetLinger


  1. func (c TCPConn) SetLinger(sec int) error


SetLinger sets the behavior of Close on a connection which still has data
waiting to be sent or to be acknowledged.

If sec < 0 (the default), the operating system finishes sending the data in the
background.

If sec == 0, the operating system discards any unsent or unacknowledged data.

If sec > 0, the data is sent in the background as with sec < 0. On some
operating systems after sec seconds have elapsed any remaining unsent data may
be discarded.

func (TCPConn) SetNoDelay


  1. func (c TCPConn) SetNoDelay(noDelay bool) error


SetNoDelay controls whether the operating system should delay packet
transmission in hopes of sending fewer packets (Nagle’s algorithm). The default
is true (no delay), meaning that data is sent as soon as possible after a Write.

func (TCPConn) SetReadBuffer


  1. func (c TCPConn) SetReadBuffer(bytes int) error


SetReadBuffer sets the size of the operating system’s receive buffer associated
with the connection.

func (TCPConn) SetReadDeadline


  1. func (c TCPConn) SetReadDeadline(t time.Time) error


SetReadDeadline implements the Conn SetReadDeadline method.

func (TCPConn) SetWriteBuffer


  1. func (c TCPConn) SetWriteBuffer(bytes int) error


SetWriteBuffer sets the size of the operating system’s transmit buffer
associated with the connection.

func (TCPConn) SetWriteDeadline


  1. func (c TCPConn) SetWriteDeadline(t time.Time) error


SetWriteDeadline implements the Conn SetWriteDeadline method.

func (TCPConn) SyscallConn


  1. func (c TCPConn) SyscallConn() (syscall.RawConn, error)


SyscallConn returns a raw network connection. This implements the syscall.Conn
interface.

func (TCPConn) Write


  1. func (c TCPConn) Write(b []byte) (int, error)


Write implements the Conn Write method.

type TCPListener


  1. type TCPListener struct {
        // contains filtered or unexported fields
    }


TCPListener is a TCP network listener. Clients should typically use variables of
type Listener instead of assuming TCP.

func ListenTCP


  1. func ListenTCP(network string, laddr TCPAddr) (TCPListener, error)


ListenTCP acts like Listen for TCP networks.

The network must be a TCP network name; see func Dial for details.

If the IP field of laddr is nil or an unspecified IP address, ListenTCP listens
on all available unicast and anycast IP addresses of the local system. If the
Port field of laddr is 0, a port number is automatically chosen.

func (TCPListener) Accept


  1. func (l TCPListener) Accept() (Conn, error)


Accept implements the Accept method in the Listener interface; it waits for the
next call and returns a generic Conn.

func (TCPListener) AcceptTCP


  1. func (l TCPListener) AcceptTCP() (TCPConn, error)


AcceptTCP accepts the next incoming call and returns the new connection.

func (TCPListener) Addr


  1. func (l TCPListener) Addr() Addr


Addr returns the listener’s network address, a TCPAddr. The Addr returned is
shared by all invocations of Addr, so do not modify it.

func (TCPListener) Close


  1. func (l TCPListener) Close() error


Close stops listening on the TCP address. Already Accepted connections are not
closed.

func (TCPListener) File


  1. func (l TCPListener) File() (f os.File, err error)


File returns a copy of the underlying os.File, set to blocking mode. It is the
caller’s responsibility to close f when finished. Closing l does not affect f,
and closing f does not affect l.

The returned os.File’s file descriptor is different from the connection’s.
Attempting to change properties of the original using this duplicate may or may
not have the desired effect.

func (TCPListener) SetDeadline


  1. func (l TCPListener) SetDeadline(t time.Time) error


SetDeadline sets the deadline associated with the listener. A zero time value
disables the deadline.

func (TCPListener) SyscallConn


  1. func (l TCPListener) SyscallConn() (syscall.RawConn, error)


SyscallConn returns a raw network connection. This implements the syscall.Conn
interface.

The returned RawConn only supports calling Control. Read and Write return an
error.

type UDPAddr


  1. type UDPAddr struct {
        IP   IP
        Port int
        Zone string // IPv6 scoped addressing zone
    }


UDPAddr represents the address of a UDP end point.

func ResolveUDPAddr


  1. func ResolveUDPAddr(network, address string) (UDPAddr, error)


ResolveUDPAddr returns an address of UDP end point.

The network must be a UDP network name.

If the host in the address parameter is not a literal IP address or the port is
not a literal port number, ResolveUDPAddr resolves the address to an address of
UDP end point. Otherwise, it parses the address as a pair of literal IP address
and port number. The address parameter can use a host name, but this is not
recommended, because it will return at most one of the host name’s IP addresses.

See func Dial for a description of the network and address parameters.

func (UDPAddr) Network


  1. func (a UDPAddr) Network() string


Network returns the address’s network name, “udp”.

func (UDPAddr) String


  1. func (a UDPAddr) String() string



type UDPConn


  1. type UDPConn struct {
        // contains filtered or unexported fields
    }


UDPConn is the implementation of the Conn and PacketConn interfaces for UDP
network connections.

func DialUDP


  1. func DialUDP(network string, laddr, raddr UDPAddr) (UDPConn, error)


DialUDP acts like Dial for UDP networks.

The network must be a UDP network name; see func Dial for details.

If laddr is nil, a local address is automatically chosen. If the IP field of
raddr is nil or an unspecified IP address, the local system is assumed.

func ListenMulticastUDP


  1. func ListenMulticastUDP(network string, ifi Interface, gaddr UDPAddr) (UDPConn, error)


ListenMulticastUDP acts like ListenPacket for UDP networks but takes a group
address on a specific network interface.

The network must be a UDP network name; see func Dial for details.

ListenMulticastUDP listens on all available IP addresses of the local system
including the group, multicast IP address. If ifi is nil, ListenMulticastUDP
uses the system-assigned multicast interface, although this is not recommended
because the assignment depends on platforms and sometimes it might require
routing configuration. If the Port field of gaddr is 0, a port number is
automatically chosen.

ListenMulticastUDP is just for convenience of simple, small applications. There
are golang.org/x/net/ipv4 and golang.org/x/net/ipv6 packages for general purpose
uses.

func ListenUDP


  1. func ListenUDP(network string, laddr UDPAddr) (UDPConn, error)


ListenUDP acts like ListenPacket for UDP networks.

The network must be a UDP network name; see func Dial for details.

If the IP field of laddr is nil or an unspecified IP address, ListenUDP listens
on all available IP addresses of the local system except multicast IP addresses.
If the Port field of laddr is 0, a port number is automatically chosen.

func (UDPConn) Close


  1. func (c UDPConn) Close() error


Close closes the connection.

func (UDPConn) File


  1. func (c UDPConn) File() (f os.File, err error)


File sets the underlying os.File to blocking mode and returns a copy. It is the
caller’s responsibility to close f when finished. Closing c does not affect f,
and closing f does not affect c.

The returned os.File’s file descriptor is different from the connection’s.
Attempting to change properties of the original using this duplicate may or may
not have the desired effect.

On Unix systems this will cause the SetDeadline methods to stop working.

func (UDPConn) LocalAddr


  1. func (c UDPConn) LocalAddr() Addr


LocalAddr returns the local network address. The Addr returned is shared by all
invocations of LocalAddr, so do not modify it.

func (UDPConn) Read


  1. func (c UDPConn) Read(b []byte) (int, error)


Read implements the Conn Read method.

func (UDPConn) ReadFrom


  1. func (c UDPConn) ReadFrom(b []byte) (int, Addr, error)


ReadFrom implements the PacketConn ReadFrom method.

func (UDPConn) ReadFromUDP


  1. func (c UDPConn) ReadFromUDP(b []byte) (int, UDPAddr, error)


ReadFromUDP acts like ReadFrom but returns a UDPAddr.

func (UDPConn) ReadMsgUDP


  1. func (c UDPConn) ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr UDPAddr, err error)


ReadMsgUDP reads a message from c, copying the payload into b and the associated
out-of-band data into oob. It returns the number of bytes copied into b, the
number of bytes copied into oob, the flags that were set on the message and the
source address of the message.

The packages golang.org/x/net/ipv4 and golang.org/x/net/ipv6 can be used to
manipulate IP-level socket options in oob.

func (UDPConn) RemoteAddr


  1. func (c UDPConn) RemoteAddr() Addr


RemoteAddr returns the remote network address. The Addr returned is shared by
all invocations of RemoteAddr, so do not modify it.

func (UDPConn) SetDeadline


  1. func (c UDPConn) SetDeadline(t time.Time) error


SetDeadline implements the Conn SetDeadline method.

func (UDPConn) SetReadBuffer


  1. func (c UDPConn) SetReadBuffer(bytes int) error


SetReadBuffer sets the size of the operating system’s receive buffer associated
with the connection.

func (UDPConn) SetReadDeadline


  1. func (c UDPConn) SetReadDeadline(t time.Time) error


SetReadDeadline implements the Conn SetReadDeadline method.

func (UDPConn) SetWriteBuffer


  1. func (c UDPConn) SetWriteBuffer(bytes int) error


SetWriteBuffer sets the size of the operating system’s transmit buffer
associated with the connection.

func (UDPConn) SetWriteDeadline


  1. func (c UDPConn) SetWriteDeadline(t time.Time) error


SetWriteDeadline implements the Conn SetWriteDeadline method.

func (UDPConn) SyscallConn


  1. func (c UDPConn) SyscallConn() (syscall.RawConn, error)


SyscallConn returns a raw network connection. This implements the syscall.Conn
interface.

func (UDPConn) Write


  1. func (c UDPConn) Write(b []byte) (int, error)


Write implements the Conn Write method.

func (UDPConn) WriteMsgUDP


  1. func (c UDPConn) WriteMsgUDP(b, oob []byte, addr UDPAddr) (n, oobn int, err error)


WriteMsgUDP writes a message to addr via c if c isn’t connected, or to c’s
remote address if c is connected (in which case addr must be nil). The payload
is copied from b and the associated out-of-band data is copied from oob. It
returns the number of payload and out-of-band bytes written.

The packages golang.org/x/net/ipv4 and golang.org/x/net/ipv6 can be used to
manipulate IP-level socket options in oob.

func (UDPConn) WriteTo


  1. func (c UDPConn) WriteTo(b []byte, addr Addr) (int, error)


WriteTo implements the PacketConn WriteTo method.

func (UDPConn) WriteToUDP


  1. func (c UDPConn) WriteToUDP(b []byte, addr UDPAddr) (int, error)


WriteToUDP acts like WriteTo but takes a UDPAddr.

type UnixAddr


  1. type UnixAddr struct {
        Name string
        Net  string
    }


UnixAddr represents the address of a Unix domain socket end point.

func ResolveUnixAddr


  1. func ResolveUnixAddr(network, address string) (UnixAddr, error)


ResolveUnixAddr returns an address of Unix domain socket end point.

The network must be a Unix network name.

See func Dial for a description of the network and address parameters.

func (UnixAddr) Network


  1. func (a UnixAddr) Network() string


Network returns the address’s network name, “unix”, “unixgram” or “unixpacket”.

func (UnixAddr) String


  1. func (a UnixAddr) String() string



type UnixConn


  1. type UnixConn struct {
        // contains filtered or unexported fields
    }


UnixConn is an implementation of the Conn interface for connections to Unix
domain sockets.

func DialUnix


  1. func DialUnix(network string, laddr, raddr UnixAddr) (UnixConn, error)


DialUnix acts like Dial for Unix networks.

The network must be a Unix network name; see func Dial for details.

If laddr is non-nil, it is used as the local address for the connection.

func ListenUnixgram


  1. func ListenUnixgram(network string, laddr UnixAddr) (UnixConn, error)


ListenUnixgram acts like ListenPacket for Unix networks.

The network must be “unixgram”.

func (UnixConn) Close


  1. func (c UnixConn) Close() error


Close closes the connection.

func (UnixConn) CloseRead


  1. func (c UnixConn) CloseRead() error


CloseRead shuts down the reading side of the Unix domain connection. Most
callers should just use Close.

func (UnixConn) CloseWrite


  1. func (c UnixConn) CloseWrite() error


CloseWrite shuts down the writing side of the Unix domain connection. Most
callers should just use Close.

func (UnixConn) File


  1. func (c UnixConn) File() (f os.File, err error)


File sets the underlying os.File to blocking mode and returns a copy. It is the
caller’s responsibility to close f when finished. Closing c does not affect f,
and closing f does not affect c.

The returned os.File’s file descriptor is different from the connection’s.
Attempting to change properties of the original using this duplicate may or may
not have the desired effect.

On Unix systems this will cause the SetDeadline methods to stop working.

func (UnixConn) LocalAddr


  1. func (c UnixConn) LocalAddr() Addr


LocalAddr returns the local network address. The Addr returned is shared by all
invocations of LocalAddr, so do not modify it.

func (UnixConn) Read


  1. func (c UnixConn) Read(b []byte) (int, error)


Read implements the Conn Read method.

func (UnixConn) ReadFrom


  1. func (c UnixConn) ReadFrom(b []byte) (int, Addr, error)


ReadFrom implements the PacketConn ReadFrom method.

func (UnixConn) ReadFromUnix


  1. func (c UnixConn) ReadFromUnix(b []byte) (int, UnixAddr, error)


ReadFromUnix acts like ReadFrom but returns a UnixAddr.

func (UnixConn) ReadMsgUnix


  1. func (c UnixConn) ReadMsgUnix(b, oob []byte) (n, oobn, flags int, addr UnixAddr, err error)


ReadMsgUnix reads a message from c, copying the payload into b and the
associated out-of-band data into oob. It returns the number of bytes copied into
b, the number of bytes copied into oob, the flags that were set on the message
and the source address of the message.

Note that if len(b) == 0 and len(oob) > 0, this function will still read (and
discard) 1 byte from the connection.

func (UnixConn) RemoteAddr


  1. func (c UnixConn) RemoteAddr() Addr


RemoteAddr returns the remote network address. The Addr returned is shared by
all invocations of RemoteAddr, so do not modify it.

func (UnixConn) SetDeadline


  1. func (c UnixConn) SetDeadline(t time.Time) error


SetDeadline implements the Conn SetDeadline method.

func (UnixConn) SetReadBuffer


  1. func (c UnixConn) SetReadBuffer(bytes int) error


SetReadBuffer sets the size of the operating system’s receive buffer associated
with the connection.

func (UnixConn) SetReadDeadline


  1. func (c UnixConn) SetReadDeadline(t time.Time) error


SetReadDeadline implements the Conn SetReadDeadline method.

func (UnixConn) SetWriteBuffer


  1. func (c UnixConn) SetWriteBuffer(bytes int) error


SetWriteBuffer sets the size of the operating system’s transmit buffer
associated with the connection.

func (UnixConn) SetWriteDeadline


  1. func (c UnixConn) SetWriteDeadline(t time.Time) error


SetWriteDeadline implements the Conn SetWriteDeadline method.

func (UnixConn) SyscallConn


  1. func (c UnixConn) SyscallConn() (syscall.RawConn, error)


SyscallConn returns a raw network connection. This implements the syscall.Conn
interface.

func (UnixConn) Write


  1. func (c UnixConn) Write(b []byte) (int, error)


Write implements the Conn Write method.

func (UnixConn) WriteMsgUnix


  1. func (c UnixConn) WriteMsgUnix(b, oob []byte, addr UnixAddr) (n, oobn int, err error)


WriteMsgUnix writes a message to addr via c, copying the payload from b and the
associated out-of-band data from oob. It returns the number of payload and
out-of-band bytes written.

Note that if len(b) == 0 and len(oob) > 0, this function will still write 1 byte
to the connection.

func (UnixConn) WriteTo


  1. func (c UnixConn) WriteTo(b []byte, addr Addr) (int, error)


WriteTo implements the PacketConn WriteTo method.

func (UnixConn) WriteToUnix


  1. func (c UnixConn) WriteToUnix(b []byte, addr UnixAddr) (int, error)


WriteToUnix acts like WriteTo but takes a UnixAddr.

type UnixListener


  1. type UnixListener struct {
        // contains filtered or unexported fields
    }


UnixListener is a Unix domain socket listener. Clients should typically use
variables of type Listener instead of assuming Unix domain sockets.

func ListenUnix


  1. func ListenUnix(network string, laddr UnixAddr) (UnixListener, error)


ListenUnix acts like Listen for Unix networks.

The network must be “unix” or “unixpacket”.

func (UnixListener) Accept


  1. func (l UnixListener) Accept() (Conn, error)


Accept implements the Accept method in the Listener interface. Returned
connections will be of type UnixConn.

func (UnixListener) AcceptUnix


  1. func (l UnixListener) AcceptUnix() (UnixConn, error)


AcceptUnix accepts the next incoming call and returns the new connection.

func (UnixListener) Addr


  1. func (l UnixListener) Addr() Addr


Addr returns the listener’s network address. The Addr returned is shared by all
invocations of Addr, so do not modify it.

func (UnixListener) Close


  1. func (l UnixListener) Close() error


Close stops listening on the Unix address. Already accepted connections are not
closed.

func (UnixListener) File


  1. func (l UnixListener) File() (f os.File, err error)


File returns a copy of the underlying os.File, set to blocking mode. It is the
caller’s responsibility to close f when finished. Closing l does not affect f,
and closing f does not affect l.

The returned os.File’s file descriptor is different from the connection’s.
Attempting to change properties of the original using this duplicate may or may
not have the desired effect.

func (UnixListener) SetDeadline


  1. func (l UnixListener) SetDeadline(t time.Time) error


SetDeadline sets the deadline associated with the listener. A zero time value
disables the deadline.

func (UnixListener) SetUnlinkOnClose


  1. func (l UnixListener) SetUnlinkOnClose(unlink bool)


SetUnlinkOnClose sets whether the underlying socket file should be removed from
the file system when the listener is closed.

The default behavior is to unlink the socket file only when package net created
it. That is, when the listener and the underlying socket file were created by a
call to Listen or ListenUnix, then by default closing the listener will remove
the socket file. but if the listener was created by a call to FileListener to
use an already existing socket file, then by default closing the listener will
not remove the socket file.

func (UnixListener) SyscallConn


  1. func (l *UnixListener) SyscallConn() (syscall.RawConn, error)


SyscallConn returns a raw network connection. This implements the syscall.Conn
interface.

The returned RawConn only supports calling Control. Read and Write return an
error.

type UnknownNetworkError


  1. type UnknownNetworkError string



func (UnknownNetworkError) Error


  1. func (e UnknownNetworkError) Error() string



func (UnknownNetworkError) Temporary


  1. func (e UnknownNetworkError) Temporary() bool



func (UnknownNetworkError) Timeout


  1. func (e UnknownNetworkError) Timeout() bool



Bugs

  • ☞ On NaCl and Windows, the FileConn, FileListener and FilePacketConn functions
    are not implemented.
  • ☞ On NaCl, methods and functions related to Interface are not implemented.
  • ☞ On DragonFly BSD, NetBSD, OpenBSD, Plan 9 and Solaris, the MulticastAddrs
    method of Interface is not implemented.

  • ☞ On every POSIX platform, reads from the “ip4” network using the ReadFrom or
    ReadFromIP method might not return a complete IPv4 packet, including its
    header, even if there is space available. This can occur even in cases where
    Read or ReadMsgIP could return a complete packet. For this reason, it is
    recommended that you do not use these methods if it is important to receive
    a full packet.

    The Go 1 compatibility guidelines make it impossible for us to change the
    behavior of these methods; use Read or ReadMsgIP instead.

  • ☞ On NaCl and Plan 9, the ReadMsgIP and WriteMsgIP methods of IPConn are not
    implemented.
  • ☞ On Windows, the File method of IPConn is not implemented.
  • ☞ On DragonFly BSD and OpenBSD, listening on the “tcp” and “udp” networks does
    not listen for both IPv4 and IPv6 connections. This is due to the fact that
    IPv4 traffic will not be routed to an IPv6 socket - two separate sockets are
    required if both address families are to be supported. See inet6(4) for
    details.
  • ☞ On Windows, the Read and Write methods of syscall.RawConn are not
    implemented.
  • ☞ On NaCl and Plan 9, the Control, Read and Write methods of syscall.RawConn
    are not implemented.
  • ☞ On Windows, the File method of TCPListener is not implemented.
  • ☞ On NaCl and Plan 9, the ReadMsgUDP and WriteMsgUDP methods of UDPConn are
    not implemented.
  • ☞ On Windows, the File method of UDPConn is not implemented.
  • ☞ On NaCl, the ListenMulticastUDP function is not implemented.

Subdirectories