unit testing udp crypto protocol application

We have designed and developed a tiny protocol similar to SSL. A lightweight protocol for low-end embedded devices (developed using C). Currently, the development is apart the server part is developed and client part is being developed by another team. To verify the the server part, I have taken the module to visual studio c++ project and tested using sample packets using PacketSender Tool. However, when using RSA encryption where even for hard-coded AES key, it is generating different cipher each time as it uses padding scheme PKCS#1 v1.5. So, hardcoded packet cannot be used to test my server application.

Each context are already verified using SelfTest. Where we could we verify the various contexts such as rsa-operation, aes-operation, hash based verification individually.

Each context has Init() Context Operations such as hash, encipher, decipher, verify, etc. Free() SelfTest()

I tried GoogleTest, it looks similar to SelfTest that I have already made for. I require to verify the whole process in protocol. I mean, I have written ssl_handshake(), to be done unit/system test. I do not like to develop complete simulation or part to test/verify code that I developed.

Right now, the application is running on UDP Server, Is there any framework to make my task simple. Even i thought of creating a new thread that send sample packet to server and create custom UDP's recvfrom and sendto functions with signals b/w thread to handle data. But it is going like writing the entire client-side application.