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