Merge pull request #157 from SenseUnit/force-resolve

Compound dialers

Author: Snawoot

README.md

@@ -412,6 +412,9 @@ Supported proxy schemes are:
 * `cached` - pseudo-dialer which caches construction of another dialer specified by URL passed in `url` parameter of query string. Useful for dialers which are constructed dynamically from JS router script and which load certificate files. Example: `cache://?url=https%3A%2F%2Fexample.org%3Fcert%3Dcert.pem%26key%3Dkey.pem&ttl=5m`. Query string parameters are:
    * `url` - actual proxy URL. Note that just like any query string parameter this one has to be URL-encoded to be passed as query string value.
    * `ttl` - time to live for cache record. Examples: `15s`, `2m`, `1h`.
+* `force-resolve` - pseudo-proxy forcing domain name resolve before it will be passed to the next proxy in the chain. Must wrap actual proxy dialer in the chain (i.e. be specified in last `-proxy` argument). Example: `force-resolve://`
+* `chain` - pseudo-proxy assembling a chain from other proxy specifications. Query string parameters are:
+  * `next` - specification of the next proxy in chain. This query string parameter can be specified more than once. Example: `chain://?next=http%3A%2F%2F127.0.0.1%3A57800&next=force-resolve%3A%2F%2F`.
 
 ## Configuration files
 

dialer/chain.go

@@ -0,0 +1,24 @@
+package dialer
+
+import (
+	"fmt"
+	"net/url"
+
+	xproxy "golang.org/x/net/proxy"
+)
+
+func ChainFromURL(u *url.URL, base xproxy.Dialer) (xproxy.Dialer, error) {
+	var d Dialer = MaybeWrapWithContextDialer(base)
+	params, err := url.ParseQuery(u.RawQuery)
+	if err != nil {
+		return nil, err
+	}
+	for i, proxySpec := range params["next"] {
+		newDialer, err := ProxyDialerFromURL(proxySpec, d)
+		if err != nil {
+			return nil, fmt.Errorf("unable to construct proxy chain: proxy spec #%d %q construction failed: %w", i+1, proxySpec, err)
+		}
+		d = newDialer
+	}
+	return d, nil
+}

dialer/dialer.go

@@ -24,6 +24,10 @@ func init() {
 	xproxy.RegisterDialerType("cached", GetCachedDialer)
 	xproxy.RegisterDialerType("socks5s", SOCKS5SDialerFromURL)
 	xproxy.RegisterDialerType("socks5hs", SOCKS5SDialerFromURL)
+	xproxy.RegisterDialerType("force-resolve", func(_ *url.URL, d xproxy.Dialer) (xproxy.Dialer, error) {
+		return NeverRequireHostname(MaybeWrapWithContextDialer(d)), nil
+	})
+	xproxy.RegisterDialerType("chain", ChainFromURL)
 }
 
 type LegacyDialer interface {

dialer/protect.go

@@ -10,12 +10,21 @@ type HostnameWanter interface {
 }
 
 type WrappedHostnameDialer struct {
-	Dialer Dialer
+	Dialer             Dialer
+	WantsHostnameValue bool
 }
 
 func AlwaysRequireHostname(d Dialer) Dialer {
 	return WrappedHostnameDialer{
-		Dialer: d,
+		Dialer:             d,
+		WantsHostnameValue: true,
+	}
+}
+
+func NeverRequireHostname(d Dialer) Dialer {
+	return WrappedHostnameDialer{
+		Dialer:             d,
+		WantsHostnameValue: false,
 	}
 }
 
@@ -28,7 +37,7 @@ func (w WrappedHostnameDialer) Dial(network, address string) (net.Conn, error) {
 }
 
 func (w WrappedHostnameDialer) WantsHostname(_ context.Context, _, _ string) bool {
-	return true
+	return w.WantsHostnameValue
 }
 
 var _ Dialer = WrappedHostnameDialer{}