Develop Reference

Compile libpcap using Android NDK

I've been doing a lot of attempts to get libpcap compiled for Android, and I don't see any pattern or any progress worth writing down.
I have a very simple sniffer (that works fine in a MIPS linux) that uses libpcap, so I thought to myself oh, ok... no biggie... I'll just compile libpcap for Android (in the end, Android is just a Linux)... and here's where the problems started. I have no idea on how to compile libpcap using ndk-build and the Android.mk and all that infrastructure.
I have the Android NDK in a directory. That NDK has the toolchains built (I have a lot of directories under ~/Documents/Projects/Android_NDK/toolchains/ ) but none of the toolchains has libpcap available.
I've tried with two different libpcap version or... branches:
The Android one, which is the one I'd like to use,
https://android.googlesource.com/platform/external/libpcap/
and the regular one:
http://www.tcpdump.org/release/libpcap-1.5.3.tar.gz
All tries I've done have been very unsuccessful. I've seen the question Android NDK: Link using a pre-compiled static library which is similar, but I'm still getting various errors.
I have downloaded those pcap libraries to their own directories. Maybe is that the problem? Do I need to put the Android libpcap in some directory within the NDK root directory and re-create the toolchains?
I'm using NDK-r9 on a MacOSX 10.9.2 64bit.

Finally!!
After getting annoyed by the non existing headers in and stuff like that, I found this question, that pointed to a SVN repo (http://sourceforge.net/p/prueba-android/code/HEAD/tree/trunk/jni/) with a libpcap that compiled!
If someone else wants additional details on how my Android.mk and directory structure looks like, please add a comment and I'll extend this answer.

Please read an excellent article at http://blog.umitproject.org/2011/05/libpcap-for-android.html. There are instructions that will help you link to libpcap, but the most important takeaway is that you cannot use libpcap on non-rooted Android. So maybe it's not worth your effort.
On a rooted device, you can simply install a free sniffer like Shark for Root.

If anyone else is having problems compiling libpcap for Android using the NDK, there is version 1.5.2 here with a built Android.mk file in it: https://android.googlesource.com/platform/external/libpcap.git and instructions for compiling this using the NDK are here: http://ducbh.blogspot.co.uk/2013/12/cross-compile-libpcap-for-android.html . I can confirm this works using the current NDK (r10b)...although you may have to add AndroidManifest.xml (blank) and and Application.mk that points to your Android.mk file.
I don't think it would be that difficult to modify the .mk file for the current libpcap version (1.6.2)

In case anyone ends up here in 2022+. You can now cross-compile for Android from the official source. Steps:
First, setup the NDK:
Download Android NDK (I used r21e) and extract to a directory of your choosing:
$ cd ~
$ mkdir Android
$ unzip android-ndk-r21e-linux-x86_64.zip
Prepare the environment variables for cross-compilation by placing the commands below (replace <YOUR_USER>) into a file named setup_env.sh (can be saved anywhere):
export NDK=/home/<YOUR_USER>/Android/android-ndk-r21e
export TOOLCHAIN=$NDK/toolchains/llvm/prebuilt/linux-x86_64
export TARGET=aarch64-linux-android
export API=21
export AR=$TOOLCHAIN/bin/$TARGET-ar
export AS=$TOOLCHAIN/bin/$TARGET-as
export CC=$TOOLCHAIN/bin/$TARGET$API-clang
export CXX=$TOOLCHAIN/bin/$TARGET$API-clang++
export LD=$TOOLCHAIN/bin/$TARGET-ld
export RANLIB=$TOOLCHAIN/bin/$TARGET-ranlib
export STRIP=$TOOLCHAIN/bin/$TARGET-strip
Now, build libpcap:
Download libpcap tar ball (e.g. https://www.tcpdump.org/release/libpcap-1.10.1.tar.gz)
Extract (in a directory of your choosing): tar xf libpcap-1.10.1.tar.gz
Prepare your env: source <path_to>/setup_env.sh
Change into the extract libpcap directory and configure: ./configure --host=aarch64-linux-android
I found the Makefile generated had the wrong linker set (line 48), so I had to change it to: LD = /home/<YOUR_USER>/Android/android-ndk-r21e/toolchains/llvm/prebuilt/linux-x86_64/x86_64-linux-android/bin/ld
Finally, build: make
This build worked for me with running tcpreplay on a rooted Android, hopefully it works for other purposes as well!

Fatal Error: openssl/evp.h No such file or directory

I successfully compiled openssl using android ndk build and .so files are built successfully.
I am trying to 'include' built .so files in an android project.
Getting an error in below line:
#include "openssl/evp.h"
fatal error: openssl/evp.h: No such file or directory
compilation terminated.
make: * [obj/local/armeabi/objs/iedemo/anotherdemo.o] Error 1
However, I am include stdio.h and string.h files.
I am explore /usr/include/openssl directory, I am able find all openssl related .h files here. And, stdio.h and string.h files are present in /usr/include directory.
I have installed libssl-dev package too. Command (sudo apt-get install libssl-dev)
Please help me!!

When encountering this problem on Debian or Ubuntu, it can be solved with the following command:
apt-get install libssl-dev

For people like me, that uses windows OS and they accidently came to this page and the above solutions did not solve their problem, can try the following solution:
I downloaded the OpenSSL executable from the official website, and selected the file with the description that contanins the following line (Recommended for software developers by the creators of OpenSSL).
At the time of writing this solution, the file version is (Win64 OpenSSL v3.0.0), and it can be directly downloaded from the following link.
Here is an Image for more declaration:
After that, I did the following steps:
Install the OpenSSL form the .exe file.
Copy the bin folder directory path (in my case it was C:\Program Files\OpenSSL-Win64\bin) and add it to the system enviroment variables.
Copy the include folder directory path (in my case it was C:\Program Files\OpenSSL-Win64\include) and add it to the system enviroment variables.
Then compile the source code that used the openssl library and header files, they should be compiled with no errors.

Your Android.mk should specify the openssl include directory (not /usr/include/openssl, but the one that goes with the files that you built for Android using NDK. Something similar to
LOCAL_C_INCLUDES += /home/Charan/openssl/include
But you will also need to specify the path for .so files that you have built, and make sure they are correctly deployed with your app. The things can go messy, but luckily there is a working example: openSSL using Android's NDK problems.

I ran into this when building a PHP package using PECL and was able to install the header file as part of openssl-devel
On CentOS/RHEL: yum install openssl-devel
On Ubuntu/Debian: apt-get install openssl-devel

Android, build openssl-fips-2.0

Trying to build openssl-fips-2.0 with NDK, before I was lucky found this link and did it easily.
https://github.com/guardianproject/openssl-android
Now trying to do the same thing against thew latest openssl-fips-2.0, got source from here:
http://opensslfoundation.com/testing/validation-2.0/
Do I have to follow the document about cross-compilation to make a build? And easier approach?
Thanks in advance

How to build OpenSSL FIPS 2.0 on Mac OS X 10.7 with android-ndk-r8
Install JDK, android-sdk, android-ndk
Install GCC on Mac
Xcode\Preferences\Components\Command Line Tools\install.
Setup environment for build:
$ANDROID_NDK_HOME is my android-ndk folder
export ANDROID_NDK=$ANDROID_NDK_HOME
export FIPS_SIG=$PWD/util/incore
export PATH="$ANDROID_NDK/toolchains/arm-linux-androideabi-4.4.3/prebuilt/linux-x86/bin":$PATH
export MACHINE=armv7l
export RELEASE=2.6.32.GMU
export SYSTEM=android
export ARCH=arm
export CROSS_COMPILE="arm-linux-androideabi-"
export ANDROID_DEV="$ANDROID_NDK/platforms/android-14/arch-arm/usr"
export HOSTCC=gcc
build fips openssl module:
gunzip -c openssl-fips-2.0.tar.gz | tar xf -
cd openssl-fips-2.0/
./config
make
make install # copy files to /usr/local/ssl/
build fips capable openssl library (.a)
gunzip -c openssl-1.0.1c.tar.gz | tar xf -
cd openssl-1.0.1c/
./config fips --with-fipslibdir=/usr/local/ssl/fips-2.0/lib/
make depend
make
There you go.

Why? If you have to modify the build scripts, the resulting module won't be FIPS compliant, and you most certainly need to modify to build on Android.

Thank you Nikolay and brewphone . It would have been great If I found your post earlier. I have managed to build fips-openssl for my phone.I had to add a little awk snippet in the fipsld script to get it working.(openssl-fips-1.2.3)
brewphone, I have the libcrypto.a and libssl.a from the build and I statically link them to create a library for my application. Is that the best way to do it?
Thanks!

f anyone else runs into the same problem I did, the key to getting this to work as described above by brewphone (thanks btw for your insight) is to package the un-stripped libs as content and then copy them to the apps data folder after which the System.load("/data/data/myapp/files/libcrypto.so.1.0.0") and System.load("/data/data/myapp/files/libssl.so.1.0.0") did the trick.
Interestingly, just changing the makefiles to put the version number before the .so extension caused the fingerprint to fail even though the fips stuff was not touched.
brewphone, if you managed to do this another way, please let me know :)

Android.mk rules to make a file.o from many files.txt then link it with other files.o produced from files.cpp

I'm porting a modem connection manager written in C++ from linux to gingerbread. This does not end up being an "app" with a "gui" that I would use a java wrapper with the NDK but a service that is called at boot from "init.rc". I found some not up to date docs related to android build system under build/core/. There you find some html files explaining the basics of Android build system and several "file.mk" which are some templates for common situation like creating a c++ executable, static libraries, shared library etc.
I place my tree with all the sources under external/myservice and it's meant to be compiled at the same time as Android itself. (I've already ported the kernel to my platform and it works, just the modem left to go)
In a subfolder in an Android.mk file, I have a bunch of ".cpp" files listed with the variable LOCAL_SRC_FILES := cppfile1.cpp cppfile2.cpp .... That will generate cppfile1.o cppfile2.o ...
I need to link those cppfile*.o with objfile.o to form a libfile.so. I found the rules on how to generate a libfile.so from a bunch of files.o.
Where things get complicated, is to port the "linux makefile" command to create objfile.o. Here is how it looks like
$(LD) $(LDFLAGS) -r -b binary -o QMIDB.o \
QMI/Entity.txt \
QMI/EnumEntry.txt \
QMI/Enum.txt \
QMI/Field.txt \
QMI/Struct.txt
Which means it is a linker job to merge a bunch of text file to make that objfile.o. That file is just a bunch of initialized data structure, there is no code to execute in it but it's pretty ugly to look at all files.txt with a text editor.
I have no clue how to integrate that in the Android.mk file. How can it be done? I'd even appreciate just a hint on where I can find more information. It is easy to find information on building Android applications but it's another story to find anything closer to Android/Kernel itself.

From the mk. file file you can easily get so file....
You need to use android Ndk setup and cygwin setup if you are using windows platform to genreate so file from your native code.
Firstly install and place ndk to a location...
Then install cygwin setup not default one check all features in the installation process (it a sort of linux terminal) as ndk-build command is recognized from linux terminal.
Now from your cygwin terminal get access to your project folder jni file.. or where mk is placed...
http://developer.android.com/sdk/ndk/index.html
Use the following referal how to run ndk-build command from cygwin terminal..
Now providing complete path of ndk we use the ndk-build command...
After that the complied code generates the .so file for our project...
Now what we are using System.loadlibrary command to use the so file i.e our native code can now be used.
Note to get so file form mk we need to complie using ndk setup.We can't directly copy paste so file to make our native code run.Also we we are using windows platfrom we will need to use cygwin setup to do that

Android build .jar from command line fails

I would like to generate some .jar for tools to include in an Android project.
So I use command tool "javac" which works great.
But when I try to use Android SDK, it fails:
C:\Dev\Tools.java:123: package android.util does not exist
android.util.Log.d("MYTAG", "hello !");
To compile, I use this command:
"C:\Program Files (x86)\Java\jdk1.6.0_23\bin\javac.exe" -g -d C:\Gen C:\Dev\Tools.java
Any help?

"javac" is the Java compiler, not the tool used to create JAR files, so just compiling a class does not generate a jar file
To be able to compile a class, you must also tell the compiler where it can find the required libraries. This is automatically done for system libraries, but you'll have to pass the path to the Android libraries. This can be done by specifying the folders/jar files using the -classpath parameter on the command line, or by adding it to the respective CLASSPATH environment variable.