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jeremybenn |
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package proxy
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import (
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"net"
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"strings"
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)
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// A PerHost directs connections to a default Dailer unless the hostname
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// requested matches one of a number of exceptions.
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type PerHost struct {
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def, bypass Dialer
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bypassNetworks []*net.IPNet
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bypassIPs []net.IP
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bypassZones []string
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bypassHosts []string
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}
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// NewPerHost returns a PerHost Dialer that directs connections to either
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// defaultDialer or bypass, depending on whether the connection matches one of
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// the configured rules.
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func NewPerHost(defaultDialer, bypass Dialer) *PerHost {
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return &PerHost{
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def: defaultDialer,
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bypass: bypass,
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}
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}
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// Dial connects to the address addr on the network net through either
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// defaultDialer or bypass.
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func (p *PerHost) Dial(network, addr string) (c net.Conn, err error) {
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host, _, err := net.SplitHostPort(addr)
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if err != nil {
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return nil, err
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}
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return p.dialerForRequest(host).Dial(network, addr)
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}
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func (p *PerHost) dialerForRequest(host string) Dialer {
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if ip := net.ParseIP(host); ip != nil {
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for _, net := range p.bypassNetworks {
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if net.Contains(ip) {
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return p.bypass
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}
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}
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for _, bypassIP := range p.bypassIPs {
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if bypassIP.Equal(ip) {
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return p.bypass
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}
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}
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return p.def
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}
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for _, zone := range p.bypassZones {
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if strings.HasSuffix(host, zone) {
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return p.bypass
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}
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if host == zone[1:] {
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// For a zone "example.com", we match "example.com"
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// too.
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return p.bypass
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}
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}
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for _, bypassHost := range p.bypassHosts {
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if bypassHost == host {
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return p.bypass
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}
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}
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return p.def
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}
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// AddFromString parses a string that contains comma-separated values
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// specifing hosts that should use the bypass proxy. Each value is either an
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// IP address, a CIDR range, a zone (*.example.com) or a hostname
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// (localhost). A best effort is made to parse the string and errors are
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// ignored.
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func (p *PerHost) AddFromString(s string) {
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hosts := strings.Split(s, ",")
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for _, host := range hosts {
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host = strings.TrimSpace(host)
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if len(host) == 0 {
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continue
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}
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if strings.Contains(host, "/") {
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// We assume that it's a CIDR address like 127.0.0.0/8
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if _, net, err := net.ParseCIDR(host); err == nil {
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p.AddNetwork(net)
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}
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continue
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}
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if ip := net.ParseIP(host); ip != nil {
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p.AddIP(ip)
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continue
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}
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if strings.HasPrefix(host, "*.") {
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p.AddZone(host[1:])
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continue
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}
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p.AddHost(host)
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}
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}
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// AddIP specifies an IP address that will use the bypass proxy. Note that
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// this will only take effect if a literal IP address is dialed. A connection
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// to a named host will never match an IP.
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func (p *PerHost) AddIP(ip net.IP) {
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p.bypassIPs = append(p.bypassIPs, ip)
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}
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// AddIP specifies an IP range that will use the bypass proxy. Note that this
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// will only take effect if a literal IP address is dialed. A connection to a
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// named host will never match.
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func (p *PerHost) AddNetwork(net *net.IPNet) {
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p.bypassNetworks = append(p.bypassNetworks, net)
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}
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// AddZone specifies a DNS suffix that will use the bypass proxy. A zone of
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// "example.com" matches "example.com" and all of its subdomains.
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func (p *PerHost) AddZone(zone string) {
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if strings.HasSuffix(zone, ".") {
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zone = zone[:len(zone)-1]
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}
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if !strings.HasPrefix(zone, ".") {
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zone = "." + zone
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}
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p.bypassZones = append(p.bypassZones, zone)
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}
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// AddHost specifies a hostname that will use the bypass proxy.
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func (p *PerHost) AddHost(host string) {
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if strings.HasSuffix(host, ".") {
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host = host[:len(host)-1]
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}
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p.bypassHosts = append(p.bypassHosts, host)
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}
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