net/net.go

// TINYGO: The following is copied and modified from Go 1.21.4 official implementation.

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package net

import (
	"time"
)

// 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 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")
}

// Conn is a generic stream-oriented network connection.
//
// Multiple goroutines may invoke methods on a Conn simultaneously.
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, if known.
	LocalAddr() Addr

	// RemoteAddr returns the remote network address, if known.
	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
}

// A Listener is a generic network listener for stream-oriented protocols.
//
// Multiple goroutines may invoke methods on a Listener simultaneously.
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
}

// An Error represents a network error.
type Error interface {
	error
	Timeout() bool // Is the error a timeout?

	// Deprecated: Temporary errors are not well-defined.
	// Most "temporary" errors are timeouts, and the few exceptions are surprising.
	// Do not use this method.
	Temporary() bool
}

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

func (e *OpError) Unwrap() error { return e.Err }

func (e *OpError) Error() string {
	if e == nil {
		return "<nil>"
	}
	s := e.Op
	if e.Net != "" {
		s += " " + e.Net
	}
	if e.Source != nil {
		s += " " + e.Source.String()
	}
	if e.Addr != nil {
		if e.Source != nil {
			s += "->"
		} else {
			s += " "
		}
		s += e.Addr.String()
	}
	s += ": " + e.Err.Error()
	return s
}

type timeout interface {
	Timeout() bool
}

func (e *OpError) Timeout() bool {
	t, ok := e.Err.(timeout)
	return ok && t.Timeout()
}

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

func (e *ParseError) Error() string { return "invalid " + e.Type + ": " + e.Text }

type AddrError struct {
	Err  string
	Addr string
}

func (e *AddrError) Error() string {
	if e == nil {
		return "<nil>"
	}
	s := e.Err
	if e.Addr != "" {
		s = "address " + e.Addr + ": " + s
	}
	return s
}

// errNetClosing is the type of the variable ErrNetClosing.
// This is used to implement the net.Error interface.
type errNetClosing struct{}

// Error returns the error message for ErrNetClosing.
// Keep this string consistent because of issue #4373:
// since historically programs have not been able to detect
// this error, they look for the string.
func (e errNetClosing) Error() string { return "use of closed network connection" }

func (e errNetClosing) Timeout() bool   { return false }
func (e errNetClosing) Temporary() bool { return false }

// errClosed exists just so that the docs for ErrClosed don't mention
// the internal package poll.
var errClosed = errNetClosing{}

// 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).
var ErrClosed error = errClosed