Dinesh Belwalkar | e63f7f9 | 2019-11-22 23:11:16 +0000 | [diff] [blame^] | 1 | // Copyright 2011 The Go Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package proxy |
| 6 | |
| 7 | import ( |
| 8 | "context" |
| 9 | "net" |
| 10 | "strings" |
| 11 | ) |
| 12 | |
| 13 | // A PerHost directs connections to a default Dialer unless the host name |
| 14 | // requested matches one of a number of exceptions. |
| 15 | type PerHost struct { |
| 16 | def, bypass Dialer |
| 17 | |
| 18 | bypassNetworks []*net.IPNet |
| 19 | bypassIPs []net.IP |
| 20 | bypassZones []string |
| 21 | bypassHosts []string |
| 22 | } |
| 23 | |
| 24 | // NewPerHost returns a PerHost Dialer that directs connections to either |
| 25 | // defaultDialer or bypass, depending on whether the connection matches one of |
| 26 | // the configured rules. |
| 27 | func NewPerHost(defaultDialer, bypass Dialer) *PerHost { |
| 28 | return &PerHost{ |
| 29 | def: defaultDialer, |
| 30 | bypass: bypass, |
| 31 | } |
| 32 | } |
| 33 | |
| 34 | // Dial connects to the address addr on the given network through either |
| 35 | // defaultDialer or bypass. |
| 36 | func (p *PerHost) Dial(network, addr string) (c net.Conn, err error) { |
| 37 | host, _, err := net.SplitHostPort(addr) |
| 38 | if err != nil { |
| 39 | return nil, err |
| 40 | } |
| 41 | |
| 42 | return p.dialerForRequest(host).Dial(network, addr) |
| 43 | } |
| 44 | |
| 45 | // DialContext connects to the address addr on the given network through either |
| 46 | // defaultDialer or bypass. |
| 47 | func (p *PerHost) DialContext(ctx context.Context, network, addr string) (c net.Conn, err error) { |
| 48 | host, _, err := net.SplitHostPort(addr) |
| 49 | if err != nil { |
| 50 | return nil, err |
| 51 | } |
| 52 | d := p.dialerForRequest(host) |
| 53 | if x, ok := d.(ContextDialer); ok { |
| 54 | return x.DialContext(ctx, network, addr) |
| 55 | } |
| 56 | return dialContext(ctx, d, network, addr) |
| 57 | } |
| 58 | |
| 59 | func (p *PerHost) dialerForRequest(host string) Dialer { |
| 60 | if ip := net.ParseIP(host); ip != nil { |
| 61 | for _, net := range p.bypassNetworks { |
| 62 | if net.Contains(ip) { |
| 63 | return p.bypass |
| 64 | } |
| 65 | } |
| 66 | for _, bypassIP := range p.bypassIPs { |
| 67 | if bypassIP.Equal(ip) { |
| 68 | return p.bypass |
| 69 | } |
| 70 | } |
| 71 | return p.def |
| 72 | } |
| 73 | |
| 74 | for _, zone := range p.bypassZones { |
| 75 | if strings.HasSuffix(host, zone) { |
| 76 | return p.bypass |
| 77 | } |
| 78 | if host == zone[1:] { |
| 79 | // For a zone ".example.com", we match "example.com" |
| 80 | // too. |
| 81 | return p.bypass |
| 82 | } |
| 83 | } |
| 84 | for _, bypassHost := range p.bypassHosts { |
| 85 | if bypassHost == host { |
| 86 | return p.bypass |
| 87 | } |
| 88 | } |
| 89 | return p.def |
| 90 | } |
| 91 | |
| 92 | // AddFromString parses a string that contains comma-separated values |
| 93 | // specifying hosts that should use the bypass proxy. Each value is either an |
| 94 | // IP address, a CIDR range, a zone (*.example.com) or a host name |
| 95 | // (localhost). A best effort is made to parse the string and errors are |
| 96 | // ignored. |
| 97 | func (p *PerHost) AddFromString(s string) { |
| 98 | hosts := strings.Split(s, ",") |
| 99 | for _, host := range hosts { |
| 100 | host = strings.TrimSpace(host) |
| 101 | if len(host) == 0 { |
| 102 | continue |
| 103 | } |
| 104 | if strings.Contains(host, "/") { |
| 105 | // We assume that it's a CIDR address like 127.0.0.0/8 |
| 106 | if _, net, err := net.ParseCIDR(host); err == nil { |
| 107 | p.AddNetwork(net) |
| 108 | } |
| 109 | continue |
| 110 | } |
| 111 | if ip := net.ParseIP(host); ip != nil { |
| 112 | p.AddIP(ip) |
| 113 | continue |
| 114 | } |
| 115 | if strings.HasPrefix(host, "*.") { |
| 116 | p.AddZone(host[1:]) |
| 117 | continue |
| 118 | } |
| 119 | p.AddHost(host) |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | // AddIP specifies an IP address that will use the bypass proxy. Note that |
| 124 | // this will only take effect if a literal IP address is dialed. A connection |
| 125 | // to a named host will never match an IP. |
| 126 | func (p *PerHost) AddIP(ip net.IP) { |
| 127 | p.bypassIPs = append(p.bypassIPs, ip) |
| 128 | } |
| 129 | |
| 130 | // AddNetwork specifies an IP range that will use the bypass proxy. Note that |
| 131 | // this will only take effect if a literal IP address is dialed. A connection |
| 132 | // to a named host will never match. |
| 133 | func (p *PerHost) AddNetwork(net *net.IPNet) { |
| 134 | p.bypassNetworks = append(p.bypassNetworks, net) |
| 135 | } |
| 136 | |
| 137 | // AddZone specifies a DNS suffix that will use the bypass proxy. A zone of |
| 138 | // "example.com" matches "example.com" and all of its subdomains. |
| 139 | func (p *PerHost) AddZone(zone string) { |
| 140 | if strings.HasSuffix(zone, ".") { |
| 141 | zone = zone[:len(zone)-1] |
| 142 | } |
| 143 | if !strings.HasPrefix(zone, ".") { |
| 144 | zone = "." + zone |
| 145 | } |
| 146 | p.bypassZones = append(p.bypassZones, zone) |
| 147 | } |
| 148 | |
| 149 | // AddHost specifies a host name that will use the bypass proxy. |
| 150 | func (p *PerHost) AddHost(host string) { |
| 151 | if strings.HasSuffix(host, ".") { |
| 152 | host = host[:len(host)-1] |
| 153 | } |
| 154 | p.bypassHosts = append(p.bypassHosts, host) |
| 155 | } |