per_host.go

Documentation: golang.org/x/net/proxy

     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  }
   156
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