github.com/psiphon-Labs/psiphon-tunnel-core@v2.0.28+incompatible/psiphon/upstreamproxy/upstreamproxy.go (about)

     1  /*
     2   * Copyright (c) 2015, Psiphon Inc.
     3   * All rights reserved.
     4   *
     5   * This program is free software: you can redistribute it and/or modify
     6   * it under the terms of the GNU General Public License as published by
     7   * the Free Software Foundation, either version 3 of the License, or
     8   * (at your option) any later version.
     9   *
    10   * This program is distributed in the hope that it will be useful,
    11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    13   * GNU General Public License for more details.
    14   *
    15   * You should have received a copy of the GNU General Public License
    16   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
    17   *
    18   */
    19  
    20  package upstreamproxy
    21  
    22  import (
    23  	"fmt"
    24  	"net"
    25  	"net/http"
    26  
    27  	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common"
    28  	"golang.org/x/net/proxy"
    29  )
    30  
    31  type DialFunc func(string, string) (net.Conn, error)
    32  
    33  type Error struct {
    34  	error
    35  }
    36  
    37  func proxyError(err error) error {
    38  	// Avoid multiple upstream.Error wrapping
    39  	if _, ok := err.(*Error); ok {
    40  		return err
    41  	}
    42  	return &Error{error: fmt.Errorf("upstreamproxy error: %s", err)}
    43  }
    44  
    45  type UpstreamProxyConfig struct {
    46  	ForwardDialFunc DialFunc
    47  	ProxyURIString  string
    48  	CustomHeaders   http.Header
    49  }
    50  
    51  // Dial implements the proxy.Dialer interface, allowing a UpstreamProxyConfig
    52  // to be passed to proxy.FromURL.
    53  func (u *UpstreamProxyConfig) Dial(network, addr string) (net.Conn, error) {
    54  	return u.ForwardDialFunc(network, addr)
    55  }
    56  
    57  func NewProxyDialFunc(config *UpstreamProxyConfig) DialFunc {
    58  	if config.ProxyURIString == "" {
    59  		return config.ForwardDialFunc
    60  	}
    61  	proxyURI, err := common.SafeParseURL(config.ProxyURIString)
    62  	if err != nil {
    63  		return func(network, addr string) (net.Conn, error) {
    64  			return nil, proxyError(fmt.Errorf("NewProxyDialFunc: SafeParseURL failed: %v", err))
    65  		}
    66  	}
    67  
    68  	dialer, err := proxy.FromURL(proxyURI, config)
    69  	if err != nil {
    70  		return func(network, addr string) (net.Conn, error) {
    71  			return nil, proxyError(fmt.Errorf("NewProxyDialFunc: proxy.FromURL: %v", err))
    72  		}
    73  	}
    74  	return dialer.Dial
    75  }