Including OpenSSL in Ardupilot source code

ArduRover Rover 4.0
1

I am having trouble integrating the OpenSSL libraries into my ardupilot source code to be used in the Rover folder under the GCS_Mavlink.cpp file.

So far I have done:

  1. In the root wscript file, under def configure() added:
    cfg.env.INCLUDES_OPENSSL = [‘C:/Users/smt5965/Documents/OpenSSL/include’]
    cfg.env.LIB_OPENSSL = [‘crypto’, ‘ssl’]
    cfg.env.LIBPATH_OPENSSL = [‘C:/Users/smt5965/Documents/OpenSSL’]

  2. Then, specifically in the wscript file in the Rover folder, added:
    ‘OPENSSL’ in
    bld.ap_program(
    program_name=‘ardurover’,
    program_groups=[‘bin’, ‘rover’],
    use=vehicle + ‘_libs OPENSSL’,
    )

  3. I added this as I saw in stack over flow under configure() but I am not sure if this is the correct way to implement:
    cfg.check_cfg(
    package= ‘openssl’,
    args=[‘–cflags’, ‘–libs’],
    uselib_store=‘OPENSSL’,
    mandatory=TRUE
    )

Now I have tried to ./waf rover and build the firmware, however, I always get a file not found error at the beginning of my GCS_Mavlink.cpp in Rover folder, at the line #include <openssl/pem.h>.
This means that the waf system is properly pointing to the correct headers even though it is explicitly stated under the INCLUDES. One other reason is that I have not set a proper build dependency in the build part of the wscript inside the Rover folder itself. I think its a simple fix but I just need to figure out how I can link this external OpenSSL library to my ardupilot source code.

2

What board are you building for?

3

You can see how I added CMSIS to chibios in this PR: In-flight dynamic FFT analysis by andyp1per · Pull Request #11886 · ArduPilot/ardupilot · GitHub

4

I am building for Pixhawk1.

5

Yeah so a lot of this stuff needs to go in the chibios waf stuff so my PR above is a good starting point

6

Gotcha, I will try this out in the next couple days. Thank you for the lead I’ll let you know how it goes.

7

I am now getting this error:
In file included from …/…/…/OpenSSL/include/openssl/pem.h:20,
from …/…/Rover/GCS_Mavlink.cpp:6:
…/…/…/OpenSSL/include/openssl/bio.h:707:17: error: ‘FILE’ was not declared in this scope
707 | BIO *BIO_new_fp(FILE *stream, int close_flag);
| ^~~~
compilation terminated due to -Wfatal-errors.

This means that my OpenSSL library is being correctly found, but I am missing FILE not declared.
I added #include <stdio.h> into my GCS_Mavlink.cpp file, however, I am still getting the same error in Cygwin. Do you know why this is?

8

the posix implementation in ChibiOS is incomplete

9

Within the boards.py, under the class ChibiOS, I added:
env.INLUDES += ‘path/to/openssl/include’
env.LIB += ‘path/to/openssl/lib’

This found the OpenSSL libraries but resulted in the BIO_new_fp error FILE not found error.

Where can I look at the posix implementation within ChibiOS? I tried looking at the PR but am confused as to where to proceed.

10
11

All of this seems to be the same on my source code in terms of the posix_compat.h file. I also added #include <stdio.h> into the GCS_Mavlink.cpp file where I am implementing the OpenSSL library, but still get the same FILE error. I am wondering if this is because Stdio.h might be looking on the Windows side meanwhile I am trying to build on Cygwin and cygwin is looking at a potential stdio.h file inside Cygwin?

12

Maybe, you’ll have to nut it out

13

Seems like OpenSSL will not work since it is such a big system to compile into Pixhawk1. Tried a different library, Tinycrypt, and that worked without errors.