71 lines
2.2 KiB
Go
71 lines
2.2 KiB
Go
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package netxlite
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import (
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"context"
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"errors"
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"net"
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"net/url"
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"github.com/ooni/probe-cli/v3/internal/model"
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"golang.org/x/net/proxy"
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)
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// MaybeProxyDialer is a dialer that may use a proxy. If the ProxyURL is not configured,
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// this dialer is a passthrough for the next Dialer in chain. Otherwise, it will internally
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// create a SOCKS5 dialer that will connect to the proxy using the underlying Dialer.
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type MaybeProxyDialer struct {
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Dialer model.Dialer
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ProxyURL *url.URL
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}
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// NewMaybeProxyDialer creates a new NewMaybeProxyDialer.
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func NewMaybeProxyDialer(dialer model.Dialer, proxyURL *url.URL) *MaybeProxyDialer {
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return &MaybeProxyDialer{
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Dialer: dialer,
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ProxyURL: proxyURL,
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}
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}
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var _ model.Dialer = &MaybeProxyDialer{}
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// CloseIdleConnections implements Dialer.CloseIdleConnections.
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func (d *MaybeProxyDialer) CloseIdleConnections() {
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d.Dialer.CloseIdleConnections()
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}
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// ErrProxyUnsupportedScheme indicates we don't support a protocol scheme.
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var ErrProxyUnsupportedScheme = errors.New("proxy: unsupported scheme")
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// DialContext implements Dialer.DialContext.
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func (d *MaybeProxyDialer) DialContext(ctx context.Context, network, address string) (net.Conn, error) {
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url := d.ProxyURL
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if url == nil {
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return d.Dialer.DialContext(ctx, network, address)
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}
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if url.Scheme != "socks5" {
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return nil, ErrProxyUnsupportedScheme
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}
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// the code at proxy/socks5.go never fails; see https://git.io/JfJ4g
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child, _ := proxy.SOCKS5(network, url.Host, nil, &proxyDialerWrapper{d.Dialer})
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return d.dial(ctx, child, network, address)
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}
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func (d *MaybeProxyDialer) dial(
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ctx context.Context, child proxy.Dialer, network, address string) (net.Conn, error) {
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cd := child.(proxy.ContextDialer) // will work
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return cd.DialContext(ctx, network, address)
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}
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// proxyDialerWrapper is required because SOCKS5 expects a Dialer.Dial type but internally
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// it checks whether DialContext is available and prefers that. So, we need to use this
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// structure to cast our inner Dialer the way in which SOCKS5 likes it.
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//
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// See https://git.io/JfJ4g.
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type proxyDialerWrapper struct {
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model.Dialer
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}
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func (d *proxyDialerWrapper) Dial(network, address string) (net.Conn, error) {
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panic(errors.New("proxyDialerWrapper.Dial should not be called directly"))
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}
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