Tor on Android
Kyle Williams
kyle.kwilliams at gmail.com
Mon Dec 29 00:36:09 UTC 2008
Thank you very much. :)I'll post some results when I have them.
- Kyle
On Sun, Dec 28, 2008 at 3:55 PM, Adam Langley <agl at imperialviolet.org>wrote:
> Looks like I should do a quick write up:
>
> One caveat, I'm running Android 1.1 PLAT-RC16, which is an unreleased
> testing version. However, I don't believe that anything pertinent has
> changed.
>
> 1) Setup your phone for debugging.
>
> Home -> Settings -> Applications -> Development. Check both "USB
> debugging" and "Stay Awake".
>
> 2) Setup udev
>
> See http://code.google.com/android/intro/develop-and-debug.html and
> search the page for "udev". This is to make sure that the USB device
> inodes get the correct permissions.
>
> 3) Download the SDK
>
> http://code.google.com/android/intro/installing.html
>
> Put the tools/ directory from the SDK in your $PATH. You'll need the
> adb utility from there.
>
> 4) Plug your phone into a USB port on your computer
>
> `adb devices` should list a single device.
>
> 5) Grab a full source release and build it
>
> Follow http://source.android.com/download. It's a lot of downloading,
> disk space and build time. If you aren't running an Intel x86 or
> x86-64 build platform you might have some issues. If you are running
> x86-64 you'll still have some issues. Many of them are covered on the
> above page but one which I had was that my distro (Ubuntu 8.10)
> doesn't seem to have 32-bit libreadline libraries.
>
> I built a 32-bit libreadline from source (this is from memory only):
> % export CC="gcc -m32"
> % ./configure
> % make
> % sudo cp libreadline.so.5.2 libhistory.so.5.2 /usr/lib32
> % sudo chmod a+rx /usr/lib32/libreadline.so.5.2
> /usr/lib32/libhistory.so.5.2
> % ldconfig (might setup the symlinks /usr/lib/libreadline.so for you,
> otherwise, do it manually)
>
> Hopefully you can do a successful `make` run with the android source.
>
> 6) Setup agcc
>
> Once you have a source build, you should have an ARM cross-compiler in
> mydroid/prebuilt/linux-x86/toolchain/arm-eabi-4.3.1/bin. The agcc[1]
> script will give all the correct arguments to it to build binaries
> with bionic etc. Put both agcc and ..../arm-eabi-4.3.1 in your $PATH.
>
> [1] http://plausible.org/andy/agcc
>
> 7) Build a test binary
>
> % cat > test.c <<EOF
> #include <stdio.h>
>
> int
> main() {
> printf("hello android\n");
> return 0;
> }
> EOF
>
> % agcc test.c
> % file ./a.out
>
> That should get you an ARM binary
>
> 8) Try running it
>
> % adb push a.out /sqlite_stmt_journals
> % adb shell
> $ cd /sqlite_stmt_journals
> $ ./a.out
>
> /sqlite_stmt_journals is just a tmpfs filesystem that's easy to get to.
>
> 9) Build libevent
>
> Download libevent
>
> % export CC="agcc"
> % ./configure --host=arm-eabi
>
> I had to manually disable select support in config.h and remove
> select.c (and everything else to do with select) from the Makefile
> because bionic seems to be missing fd_mask structures. I also didn't
> bother building anything in /test.
>
> Hopefully you end up with libevent.a (probably in .libs). Copy it to
> mydroid/out/target/product/generic/obj/lib.
>
> 10) Setup include paths
>
> I added these lines to the list of include paths in agcc:
>
> "-I$DROID/external/libevent-1.4.9-stable",
> "-I$DROID/external/openssl/include",
> "-I$DROID/external/zlib",
>
> The first is where I happened to build libevent. Your location may
> vary. The other two are path of the standard source distribution.
>
> 11) Build tor
>
> I used 0.2.0.32
>
> Firstly, Android doesn't include deprecated OpenSSL functions, so add
> a wrapper to src/common/crypto.c:
>
> +++ tor-0.2.0.32-agl/src/common/crypto.c 2008-12-28 12:24:25.000000000
> -0800
> @@ -387,6 +387,37 @@
> tor_free(env);
> }
>
> +RSA *RSA_generate_key(int bits, unsigned long e_value,
> + void (*callback)(int,int,void *), void *cb_arg)
> + {
> + BN_GENCB cb;
> + int i;
> + RSA *rsa = RSA_new();
> + BIGNUM *e = BN_new();
> +
> + if(!rsa || !e) goto err;
> +
> + /* The problem is when building with 8, 16, or 32 BN_ULONG,
> + * unsigned long can be larger */
> + for (i=0; i<(int)sizeof(unsigned long)*8; i++)
> + {
> + if (e_value & (1UL<<i))
> + if (BN_set_bit(e,i) == 0)
> + goto err;
> + }
> +
> + BN_GENCB_set_old(&cb, callback, cb_arg);
> +
> + if(RSA_generate_key_ex(rsa, bits, e, &cb)) {
> + BN_free(e);
> + return rsa;
> + }
> +err:
> + if(e) BN_free(e);
> + if(rsa) RSA_free(rsa);
> + return 0;
> +}
> +
>
> Then, the only other issues I had were with some odd namespace
> collision with log.h. I'll include the diffs, although I didn't bother
> pinning down the problem, I just worked around where it popped up:
>
> --- tor-0.2.0.32/src/common/log.h 2008-02-26 11:56:29.000000000 -0800
> +++ tor-0.2.0.32-agl/src/common/log.h 2008-12-28 12:02:17.000000000 -0800
> @@ -11,7 +11,7 @@
> * \brief Headers for log.c
> **/
>
> -#ifndef __LOG_H
> +#ifndef __TOR_LOG_H
> #define LOG_H_ID "$Id: log.h 13412 2008-02-07 05:31:47Z nickm $"
>
> #include "compat.h"
> @@ -180,6 +180,6 @@
>
> #endif /* !GNUC */
>
> -# define __LOG_H
> +# define __TOR_LOG_H
> #endif
> --- tor-0.2.0.32/src/or/buffers.c 2008-11-20 14:14:26.000000000 -0800
> +++ tor-0.2.0.32-agl/src/or/buffers.c 2008-12-28 12:03:08.000000000 -0800
> @@ -14,6 +14,7 @@
> * memory, file descriptors, or TLS connections.
> **/
> #define BUFFERS_PRIVATE
> +#include "src/common/log.h"
> #include "or.h"
>
> //#define PARANOIA
> diff -ur tor-0.2.0.32/src/or/circuitbuild.c
> tor-0.2.0.32-agl/src/or/circuitbuild.c
> --- tor-0.2.0.32/src/or/circuitbuild.c 2008-09-23 14:00:43.000000000 -0700
> +++ tor-0.2.0.32-agl/src/or/circuitbuild.c 2008-12-28 12:03:30.000000000
> -0800
> @@ -12,6 +12,7 @@
> * \brief The actual details of building circuits.
> **/
>
> +#include "src/common/log.h"
> #include "or.h"
>
> /********* START VARIABLES **********/
> Only in tor-0.2.0.32-agl/src/or: .deps
> diff -ur tor-0.2.0.32/src/or/eventdns.c tor-0.2.0.32-agl/src/or/eventdns.c
> --- tor-0.2.0.32/src/or/eventdns.c 2008-02-26 11:56:28.000000000 -0800
> +++ tor-0.2.0.32-agl/src/or/eventdns.c 2008-12-28 12:18:22.000000000 -0800
> @@ -121,6 +121,7 @@
> #endif
>
> /* for debugging possible memory leaks. */
> +#include "src/common/util.h"
> #define malloc(x) tor_malloc(x)
> #define realloc(x,y) tor_realloc((x),(y))
> #define free(x) tor_free(x)
> Only in tor-0.2.0.32-agl/src/or: Makefile
> diff -ur tor-0.2.0.32/src/or/or.h tor-0.2.0.32-agl/src/or/or.h
> --- tor-0.2.0.32/src/or/or.h 2008-11-20 14:14:26.000000000 -0800
> +++ tor-0.2.0.32-agl/src/or/or.h 2008-12-28 12:03:48.000000000 -0800
> @@ -75,7 +75,7 @@
>
> #include "crypto.h"
> #include "tortls.h"
> -#include "log.h"
> +#include "src/common/log.h"
> #include "compat.h"
> #include "container.h"
> #include "util.h"
>
> 12) Finish up
>
> I didn't bother building any of the Tor utilities once I had the Tor
> binary. You can copy it to the phone with adb push again and run it
> via the shell.
>
> First you should `export HOME=/sdcard` because the tmpfs is very small.
>
>
>
> That gets Tor running, however it's hardly very neat.
>
> The rest of Android is designed around Activies, as documented in the
> SDK documentation. I suspect that the way to go would be to build Tor
> as a .so, renaming the main function. You can use JNI[1] from a Java
> thread to start running Tor by calling the new alternative main. If
> you do this, you'll want to read [2] otherwise the system will
> randomly kill the process.
>
> I believe that there's a way to get Android to use an HTTP proxy.
> Certainly there's an http_proxy field in
> frameworks/base/core/java/android/provider/Settings.java. You might
> find details online about poking a value in a SQLite table. The
> sqlite3 binary that they reference isn't shipped on the phones, but
> you find it in mydroid/out/target/product/generic/system/xbin.
> However, I don't believe that the sqlite file lives in the same place
> anymore and I don't know where it moved to.
>
>
>
> AGL
>
> [1]
> http://davanum.wordpress.com/2007/12/09/android-invoke-jni-based-methods-bridging-cc-and-java/
> [2] http://code.google.com/android/reference/android/app/Service.html
>
> --
> Adam Langley agl at imperialviolet.org http://www.imperialviolet.org
>
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