Compilation issues in external SRTP using third party library wolfssl support

[MahipalChalla]

Hello everyone,
I am working on a small task to generate session keys in external SRTP using the third-party library WolfSSL. As a starting step, I downloaded external SRTP from GitHub and the WolfSSL version wolfssl-5.7.4-gplv3-fips-ready. Initially, I enabled SRTP-related macros (WOLFSSL_SRTP) in the WolfSSL build, compiled it using CMake, and generated static and dynamic libraries

support KDF: Added below definations in CMakeLists.txt:

add_definitions(-DWC_SRTP_KDF)
add_definitions(-DHAVE_AES_ECB)
add_definitions(-DWOLFSSL_AES_COUNTER)

On the external SRTP build side, I enabled WolfSSL-related macros (ENABLE_WOLFSSL, WOLFSSL_KDF and WOLFSSL) and made the following changes in the CMakeLists.txt file:

Specify the path to the WolfSSL include directory and library

set(WOLFSSL_INCLUDE_DIR "/usr/local/include")
set(WOLFSSL_LIBRARY "/usr/local/lib/libwolfssl.a")

However, when attempting to compile in the Linux environment, I observed the following issues. I have checked the respective function headers and definitions available in /usr/local/include and /usr/local/lib.

/home/mahi/CTS/libsrtp-main/srtp/srtp.c:799:27: error: ‘WC_SRTP_MAX_SALT’ undeclared here (not in a function)
799 | #define MAX_SRTP_SALT_LEN WC_SRTP_MAX_SALT
| ^~~~~~~~~~~~~~~~
/home/mahi/CTS/libsrtp-main/srtp/srtp.c:808:25: note: in expansion of macro ‘MAX_SRTP_SALT_LEN’
808 | uint8_t master_salt[MAX_SRTP_SALT_LEN];
| ^~~~~~~~~~~~~~~~~
/home/mahi/CTS/libsrtp-main/srtp/srtp.c: In function ‘srtp_kdf_generate’:
/home/mahi/CTS/libsrtp-main/srtp/srtp.c:858:11: error: implicit declaration of function ‘wc_SRTP_KDF_label’ [-Werror=implicit-function-declaration]
858 | err = wc_SRTP_KDF_label(kdf->master_key, kdf->master_key_len,
| ^~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make[2]: *** [CMakeFiles/srtp3.dir/build.make:79: CMakeFiles/srtp3.dir/srtp/srtp.c.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:114: CMakeFiles/srtp3.dir/all] Error 2
make: *** [Makefile:146: all] Error 2

[pabuhler]

Hi,

I have no problem to build if I download the latest wolfssl code. I use the cmake file in #735 to point to a local install of wolfssl and builds fine, including the KDF function.

Perhaps it is because you have the fips version?

If you look at https://github.com/cisco/libsrtp/actions/runs/12264388268/job/34218114347?pr=735#step:2:5 you can see how we build wolfssl for CI testing, and the resulting features at https://github.com/cisco/libsrtp/actions/runs/12264388268/job/34218114347?pr=735#step:2:255 maybe you can compare to your build or try to reproduce with these steps.