Add c.Dialer(auth) which returns a net.proxy.

A bit more involved than David S' version, since it queries the control
port for an appropriate SOCKS listener.  This makes it easier to use.

dialer.go

@@ -0,0 +1,54 @@
+// dialer.go - Tor backed proxy.Dialer.
+//
+// To the extent possible under law, Yawning Angel waived all copyright
+// and related or neighboring rights to bulb, using the creative
+// commons "cc0" public domain dedication. See LICENSE or
+// <http://creativecommons.org/publicdomain/zero/1.0/> for full details.
+
+package bulb
+
+import (
+	"strconv"
+	"strings"
+
+	"golang.org/x/net/proxy"
+)
+
+// Dialer returns a proxy.Dialer for the given Tor instance.
+func (c *Conn) Dialer(auth *proxy.Auth) (proxy.Dialer, error) {
+	const (
+		cmdGetInfo     = "GETINFO"
+		socksListeners = "net/listeners/socks"
+		unixPrefix     = "unix:"
+	)
+
+	// Query for the SOCKS listeners via a GETINFO request.
+	resp, err := c.Request("%s %s", cmdGetInfo, socksListeners)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(resp.Data) != 1 {
+		return nil, newProtocolError("no SOCKS listeners configured")
+	}
+	splitResp := strings.Split(resp.Data[0], " ")
+	if len(splitResp) < 1 {
+		return nil, newProtocolError("no SOCKS listeners configured")
+	}
+
+	// The first listener will have a "net/listeners/socks=" prefix, and all
+	// entries are QuotedStrings.
+	laddrStr := strings.TrimPrefix(splitResp[0], socksListeners+"=")
+	if laddrStr == splitResp[0] {
+		return nil, newProtocolError("failed to parse SOCKS listener")
+	}
+	laddrStr, _ = strconv.Unquote(laddrStr)
+
+	// Construct the proxyDialer.
+	if strings.HasPrefix(laddrStr, unixPrefix) {
+		unixPath := strings.TrimPrefix(laddrStr, unixPrefix)
+		return proxy.SOCKS5("unix", unixPath, auth, proxy.Direct)
+	}
+
+	return proxy.SOCKS5("tcp", laddrStr, auth, proxy.Direct)
+}

examples/dialer/dialer.go

@@ -0,0 +1,55 @@
+// Dialer example.
+//
+// To the extent possible under law, Yawning Angel waived all copyright
+// and related or neighboring rights to bulb, using the creative
+// commons "cc0" public domain dedication. See LICENSE or
+// <http://creativecommons.org/publicdomain/zero/1.0/> for full details.
+
+package main
+
+import (
+	"io/ioutil"
+	"log"
+	"net/http"
+
+	"github.com/yawning/bulb"
+)
+
+func main() {
+	// Connect to a running tor instance.
+	//  * TCP: c, err := bulb.Dial("tcp4", "127.0.0.1:9051")
+	c, err := bulb.Dial("unix", "/var/run/tor/control")
+	if err != nil {
+		log.Fatalf("failed to connect to control port: %v", err)
+	}
+	defer c.Close()
+
+	// See what's really going on under the hood.
+	// Do not enable in production.
+	c.Debug(true)
+
+	// Authenticate with the control port.  The password argument
+	// here can be "" if no password is set (CookieAuth, no auth).
+	if err := c.Authenticate("ExamplePassword"); err != nil {
+		log.Fatalf("Authentication failed: %v", err)
+	}
+
+	// Get a proxy.Dialer that will use the given Tor instance for outgoing
+	// connections.
+	dialer, err := c.Dialer(nil)
+	if err != nil {
+		log.Fatalf("Failed to get Dialer: %v", err)
+	}
+
+	// Try using the Dialer for something...
+	orTransport := &http.Transport{Dial: dialer.Dial}
+	orHTTPClient := &http.Client{Transport: orTransport}
+	resp, err := orHTTPClient.Get("https://check.torproject.org/api/ip")
+	if err != nil {
+		log.Fatalf("Failed https GET: %v", err)
+	}
+	defer resp.Body.Close()
+	body, _ := ioutil.ReadAll(resp.Body)
+	log.Printf("HTTPS GET via Tor: %v", resp)
+	log.Printf(" Body: %s\n", body)
+}