syncthing/lib/dialer/internal.go

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// Copyright (C) 2015 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.
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package dialer
import (
"net"
"net/http"
"net/url"
"os"
"strings"
"time"
"golang.org/x/net/proxy"
"github.com/syncthing/syncthing/lib/logger"
)
var (
l = logger.DefaultLogger.NewFacility("dialer", "Dialing connections")
proxyDialer proxy.Dialer
usingProxy bool
noFallback = os.Getenv("ALL_PROXY_NO_FALLBACK") != ""
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)
type dialFunc func(network, addr string) (net.Conn, error)
func init() {
l.SetDebug("dialer", strings.Contains(os.Getenv("STTRACE"), "dialer") || os.Getenv("STTRACE") == "all")
proxy.RegisterDialerType("socks", socksDialerFunction)
proxyDialer = getDialer(proxy.Direct)
usingProxy = proxyDialer != proxy.Direct
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if usingProxy {
http.DefaultTransport = &http.Transport{
Dial: Dial,
Proxy: http.ProxyFromEnvironment,
TLSHandshakeTimeout: 10 * time.Second,
}
// Defer this, so that logging gets setup.
go func() {
time.Sleep(500 * time.Millisecond)
l.Infoln("Proxy settings detected")
if noFallback {
l.Infoln("Proxy fallback disabled")
}
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}()
} else {
go func() {
time.Sleep(500 * time.Millisecond)
l.Debugln("Dialer logging disabled, as no proxy was detected")
}()
}
}
func dialWithFallback(proxyDialFunc dialFunc, fallbackDialFunc dialFunc, network, addr string) (net.Conn, error) {
conn, err := proxyDialFunc(network, addr)
if err == nil {
l.Debugf("Dialing %s address %s via proxy - success, %s -> %s", network, addr, conn.LocalAddr(), conn.RemoteAddr())
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SetTCPOptions(conn)
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return dialerConn{
conn, newDialerAddr(network, addr),
}, nil
}
l.Debugf("Dialing %s address %s via proxy - error %s", network, addr, err)
if noFallback {
return conn, err
}
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conn, err = fallbackDialFunc(network, addr)
if err == nil {
l.Debugf("Dialing %s address %s via fallback - success, %s -> %s", network, addr, conn.LocalAddr(), conn.RemoteAddr())
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SetTCPOptions(conn)
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} else {
l.Debugf("Dialing %s address %s via fallback - error %s", network, addr, err)
}
return conn, err
}
// This is a rip off of proxy.FromURL for "socks" URL scheme
func socksDialerFunction(u *url.URL, forward proxy.Dialer) (proxy.Dialer, error) {
var auth *proxy.Auth
if u.User != nil {
auth = new(proxy.Auth)
auth.User = u.User.Username()
if p, ok := u.User.Password(); ok {
auth.Password = p
}
}
return proxy.SOCKS5("tcp", u.Host, auth, forward)
}
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// This is a rip off of proxy.FromEnvironment with a custom forward dialer
func getDialer(forward proxy.Dialer) proxy.Dialer {
allProxy := os.Getenv("all_proxy")
if len(allProxy) == 0 {
return forward
}
proxyURL, err := url.Parse(allProxy)
if err != nil {
return forward
}
prxy, err := proxy.FromURL(proxyURL, forward)
if err != nil {
return forward
}
noProxy := os.Getenv("no_proxy")
if len(noProxy) == 0 {
return prxy
}
perHost := proxy.NewPerHost(prxy, forward)
perHost.AddFromString(noProxy)
return perHost
}
type timeoutDirectDialer struct {
timeout time.Duration
}
func (d *timeoutDirectDialer) Dial(network, addr string) (net.Conn, error) {
return net.DialTimeout(network, addr, d.timeout)
}
type dialerConn struct {
net.Conn
addr net.Addr
}
func (c dialerConn) RemoteAddr() net.Addr {
return c.addr
}
func newDialerAddr(network, addr string) net.Addr {
netaddr, err := net.ResolveIPAddr(network, addr)
if err == nil {
return netaddr
}
return fallbackAddr{network, addr}
}
type fallbackAddr struct {
network string
addr string
}
func (a fallbackAddr) Network() string {
return a.network
}
func (a fallbackAddr) String() string {
return a.addr
}