feat: introduce ptx package for pluggable transports dialers (#373)

* feat: introduce ptx package for pluggable transports dialers Version 2 of the pluggable transports specification defines a function that's like `Dial() (net.Conn, error`). Because we use contexts as much as possible in `probe-cli`, we are wrapping such an interface into a `DialContext` func. The code for obfs4 is adapted from https://github.com/ooni/probe-cli/pull/341. The code for snowflake is significantly easier than it is in https://github.com/ooni/probe-cli/pull/341, because now Snowflake supports the PTv2 spec (thanks @cohosh!). The code for setting up a pluggable transport listener has also been adapted from https://github.com/ooni/probe-cli/pull/341. We cannot merge this code yet, because we need unit testing, yet the newly added code already seems suitable for these use cases: 1. testing by dialing and seeing whether we can dial (which is not very useful but still better than not doing it); 2. spawning tor+pluggable transports for circumvention (we need a little more hammering like we did in https://github.com/ooni/probe-cli/pull/341, which is basically https://github.com/ooni/probe/issues/1565, and then we will be able to do that, as demonstrated by the new, simple client which already allows us to use pluggable transports with tor); 3. testing by launching tor (when available) with a set of pluggable transports (which depends on https://github.com/ooni/probe-engine/issues/897 and has not been assigned an issue yet). * fix: tweaks after self code-review * feat: write quick tests for ptx/obfs4 (They run in 0.4s, so I think it's fine for them to always run.) * feat(ptx/snowflake): write unit and integration tests * feat: create a fake PTDialer The idea is that we'll use this simpler PTDialer for testing. * feat: finish writing tests for new package * Apply suggestions from code review * Update internal/ptx/dependencies_test.go Co-authored-by: Arturo Filastò <arturo@openobservatory.org> * Update internal/ptx/dependencies_test.go Co-authored-by: Arturo Filastò <arturo@openobservatory.org> * chore: use as testing bridge one that's used by tor browser The previous testing bridge used to be used by tor browser but it was subsequently removed here: https://gitlab.torproject.org/tpo/applications/tor-browser-build/-/commit/e26e91bef8bd8d04d79bdd69f087efd808bc925d See https://github.com/ooni/probe-cli/pull/373#discussion_r649820724 Co-authored-by: Arturo Filastò <arturo@openobservatory.org>
2021-06-14 10:20:54 +02:00
parent 06ee0e55a9
commit 85c71c09dc
16 changed files with 1657 additions and 4 deletions
@@ -0,0 +1,43 @@
+// Command ptxclient implements a pluggable transports CLI client. This command
+// is only meant for testing and is not production ready.
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"os/signal"
+
+	"github.com/apex/log"
+	"github.com/ooni/probe-cli/v3/internal/ptx"
+)
+
+func main() {
+	mode := flag.String("m", "snowflake", "one of snowflake and obfs4")
+	verbose := flag.Bool("v", false, "enable verbose mode")
+	flag.Parse()
+	if *verbose {
+		log.SetLevel(log.DebugLevel)
+	}
+	var dialer ptx.PTDialer
+	switch *mode {
+	case "snowflake":
+		dialer = &ptx.SnowflakeDialer{}
+	case "obfs4":
+		dialer = ptx.DefaultTestingOBFS4Bridge()
+	default:
+		fmt.Fprintf(os.Stderr, "unknown pluggable transport: %s\n", *mode)
+		os.Exit(1)
+	}
+	listener := &ptx.Listener{
+		PTDialer: dialer,
+		Logger:   log.Log,
+	}
+	if err := listener.Start(); err != nil {
+		log.WithError(err).Fatal("listener.Start failed")
+	}
+	sigch := make(chan os.Signal, 1)
+	signal.Notify(sigch, os.Interrupt)
+	<-sigch
+	listener.Stop()
+}