detour

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Overview

Package detour provides a net.Conn interface to dial another dialer if a site fails to connect directly. It maintains three states of a connection: initial, direct and detoured along with a temporary whitelist across connections. It also add a blocked site to permanent whitelist.

The action taken and state transistion in each phase is as follows: +-------------------------+-----------+-------------+-------------+-------------+-------------+ | | no error | timeout* | conn reset/ | content | other error | | | | | dns hijack | hijack | | +-------------------------+-----------+-------------+-------------+-------------+-------------+ | dial (intial) | noop | detour | detour | n/a | noop | | first read (intial) | direct | detour(buf) | detour(buf) | detour(buf) | noop | | | | add to tl | add to tl | add to tl | | | follow-up read (direct) | direct | add to tl | add to tl | add to tl | noop | | follow-up read (detour) | noop | rm from tl | rm from tl | rm from tl | rm from tl | | close (direct) | noop | n/a | n/a | n/a | n/a | | close (detour) | add to wl | n/a | n/a | n/a | n/a | +-------------------------+-----------+-------------+-------------+-------------+-------------+ | next dial/read(in tl)***| noop | rm from tl | rm from tl | rm from tl | rm from tl | | next close(in tl) | add to wl | n/a | n/a | n/a | n/a | +-------------------------+-----------+-------------+-------------+-------------+-------------+ (buf) = resend buffer tl = temporary whitelist wl = permanent whitelist

• The timeout for first read is firstReadTimeoutToDetour, otherwise it's based on system default or caller supplied deadline.

** DNS hijacking is only checked at dial time. *** Connection is always detoured if the site is in tl or wl.

Index

• func AddToWl(addr string, permanent bool)
• func Dialer(directDialer dialFunc, detourDialer dialFunc) dialFunc
• func DumpWhitelist() (wl []string)
• func ForceWhitelist(addr string)
• func RemoveFromWl(addr string)
• func SetCountry(country string)
• type Conn
  • func (dc *Conn) Close() error
  • func (dc *Conn) LocalAddr() net.Addr
  • func (dc *Conn) Read(b []byte) (n int, err error)
  • func (dc *Conn) RemoteAddr() net.Addr
  • func (dc *Conn) SetDeadline(t time.Time) error
  • func (dc *Conn) SetReadDeadline(t time.Time) error
  • func (dc *Conn) SetWriteDeadline(t time.Time) error
  • func (dc *Conn) Wrapped() net.Conn
  • func (dc *Conn) Write(b []byte) (n int, err error)
• type Detector

Functions

func AddToWl

func AddToWl(addr string, permanent bool)

AddToWl adds a domain to whitelist, all subdomains of this domain are also considered to be in the whitelist.

func Dialer

func Dialer(directDialer dialFunc, detourDialer dialFunc) dialFunc

Dialer returns a function with same signature of net.Dialer.DialContext().

func DumpWhitelist

func DumpWhitelist() (wl []string)

func ForceWhitelist

func ForceWhitelist(addr string)

func RemoveFromWl

func RemoveFromWl(addr string)

func SetCountry

func SetCountry(country string)

SetCountry sets the ISO 3166-1 alpha-2 country code to load country specific detection rules

Types

type Conn

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

func (*Conn) Close

func (dc *Conn) Close() error

Close implements the function from net.Conn

func (*Conn) LocalAddr

func (dc *Conn) LocalAddr() net.Addr

LocalAddr implements the function from net.Conn

func (*Conn) Read

func (dc *Conn) Read(b []byte) (n int, err error)

Read() implements the function from net.Conn

func (*Conn) RemoteAddr

func (dc *Conn) RemoteAddr() net.Addr

RemoteAddr implements the function from net.Conn

func (*Conn) SetDeadline

func (dc *Conn) SetDeadline(t time.Time) error

SetDeadline implements the function from net.Conn

func (*Conn) SetReadDeadline

func (dc *Conn) SetReadDeadline(t time.Time) error

SetReadDeadline implements the function from net.Conn

func (*Conn) SetWriteDeadline

func (dc *Conn) SetWriteDeadline(t time.Time) error

SetWriteDeadline implements the function from net.Conn

func (*Conn) Wrapped

func (dc *Conn) Wrapped() net.Conn

Wrapped exposes the underlying connection.

func (*Conn) Write

func (dc *Conn) Write(b []byte) (n int, err error)

Write implements the function from net.Conn

type Detector

type Detector struct {
	DNSPoisoned        func(net.Conn) bool
	TamperingSuspected func(error) bool
	FakeResponse       func([]byte) bool
}

Detector is just a set of rules to check if a site is potentially blocked or not