Bug 33931 - Patch TOPL for filtering bridges by type

From 9a2048f02d602cab7bd937c66a4d3f9c35fbfa9e Mon Sep 17 00:00:00 2001

From: Matthew Finkel <sysrqb@torproject.org>

Date: Thu, 30 Apr 2020 15:40:25 +0000

Subject: [PATCH] Bug 33931 - Filter bridges in stream by type

The InputStream contains a first-byte that indicates the format of the

following datastream. If the first-byte is 1, then the following stream

is a string of bridges that are separated by the '\n' byte. If the

first-byte is not 1, then the following data stream is default bridges

and that list should be filtered such that only the requested bridge

type is used.

---

 .../thali/toronionproxy/TorConfigBuilder.java | 35 ++++++++++++++++---

 1 file changed, 31 insertions(+), 4 deletions(-)

diff --git a/universal/src/main/java/com/msopentech/thali/toronionproxy/TorConfigBuilder.java b/universal/src/main/java/com/msopentech/thali/toronionproxy/TorConfigBuilder.java

index ab11948..2405097 100644

--- a/universal/src/main/java/com/msopentech/thali/toronionproxy/TorConfigBuilder.java

+++ b/universal/src/main/java/com/msopentech/thali/toronionproxy/TorConfigBuilder.java

@@ -535,9 +535,32 @@ public final class TorConfigBuilder {

     TorConfigBuilder addBridgesFromResources() throws IOException {

         if(settings.hasBridges()) {

             InputStream bridgesStream = context.getInstaller().openBridgesStream();

-            int formatType = bridgesStream.read();

-            if (formatType == 0) {

-                addBridges(bridgesStream);

+            // The first byte encodes the type of bridges contained within the

+            // following data stream. Currently, it may contain either default bridges

+            // or user-provided bridges.

+            int bridgesType = bridgesStream.read();

+

+            // When bridgesType is 0x01, then the following stream is

+            // user-provided (custom) bridges.

+            // When bridgesType is one of: 0x02 or 0x03, then the Stream

+            // consists of default PT bridges. That list must be filtered, after

+            // parsing each bridge line, such that only the requested bridge type

+            // is used.

+            if (bridgesType != 1) {

+                // Terrible hack. Must keep in sync with tas::CustomTorInstaller::openBridgesStream

+                // and transports defined by TorConfigBuilder::transportPlugin().

+                String reqBridgeType;

+                switch (bridgesType) {

+                    case 2:

+                        reqBridgeType = "obfs4";

+                        break;

+                    case 3:

+                        reqBridgeType = "meek_lite";

+                        break;

+                    default:

+                        throw new IOException("Requested unknown transport type: " + bridgesType);

+                }

+                addBridges(bridgesStream, reqBridgeType);

             } else {

                 addCustomBridges(bridgesStream);

             }

@@ -548,12 +571,16 @@ public final class TorConfigBuilder {

     /**

      * Add bridges from bridges.txt file.

      */

-    private void addBridges(InputStream input) {

+    private void addBridges(InputStream input, String bridgeType) {

         if (input == null) {

             return;

         }

         List<Bridge> bridges = readBridgesFromStream(input);

         for (Bridge b : bridges) {

+            if (!b.type.equals(bridgeType)) {

+                // This is not the transport we're looking for.

+                continue;

+            }

             bridge(b.type, b.config);

         }

     }

-- 

2.20.1

# build will pull down the correct android tool versions

patch -p1 < $rootdir/gradle.patch

patch -p1 < $rootdir/0001-Bug-33931-Filter-bridges-in-stream-by-type.patch

# Extract obfs4proxy from TorBrowser/Tor/PluggableTransports/obfs4proxy

tar --strip-components=4 -xf $rootdir/[% c('input_files_by_name/obfs4') %]

    name: gradle-dependencies

    exec: '[% INCLUDE "fetch-gradle-dependencies" %]'

  - filename: gradle.patch

  - filename: 0001-Bug-33931-Filter-bridges-in-stream-by-type.patch