Simple Smart Contract on Unikraft

This is a simple smart contract-like program running on Unikraft. It starts a server on port 12345 and waits for a integer (4 bytes) to be received. It then replies with the incremented value of the integer.

Currently the C and C++ builds are available working.

For the C build you need to clone:

• Unikraft
• lwip

For the C++ build you need to clone:

• Unikraft
• lwip
• lib-libunwind
• lib-libcxx
• lib-libcxxabi
• lib-compiler-rt
• lib-newlib

Make sure that every repository is on the staging branch.

All libraries must be cloned in the same folder. In each programming language subfolder (c/, cpp/) edit the Makefile file and update the variables to point to the correct location:

• Update the UK_ROOT variable to point to the location of the Unikraft clone.
• Update the UK_LIBS variable to point to the folder storing the library clones.

If you get a Cannot find library error at one of the following steps, you may need to add the lib- prefix to the libraries listed in the LIBS variable. For instance, $(UK_LIBS)/lwip becomes $(UK_LIBS)/lib-lwip

In each programming language folder, configure the builds by running:

make menuconfig

You don't need to do anything else here. The configuration is loaded from the Config.uk file. Just save the configuration. As a result of this, a .config file is created.

Build the unikernel image by running:

make

The resulting image is in the build/ subfolder, named c_kvm-x86_64 or cpp_kvm-x86_64.

The resulting image is to be loaded as part of a KVM virtual machine with a software bridge allowing outside network access to the server application. Start the image by using the run_net_static script (you require sudo privileges):

razvan@yggdrasil:~/.../unikraft-my/apps/app-smart-contract-simple$ ./run_net_static
Usage: ./run_net_static <kvm_image>

razvan@yggdrasil:~/.../unikraft-my/apps/app-smart-contract-simple$ ./run_net_static c/build/c_kvm-x86_64
[...]
0: Set IPv4 address 172.44.0.2 mask 255.255.255.0 gw 172.44.0.1
en0: Added
en0: Interface is up
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Listening on port 12345...
[...]

The server applications waits for connection on IP address 172.44.0.2, on TCP port 12345. Test it by running (on another terminal):

$ netcat 172.44.0.2 12345
a
b

Send a to the server and the server replies with an increment (b). The server prints out information messages:

Received connection from 172.44.0.1:43464
Received: 2657
Sent: 2658

When done, close the server / KVM machine using Ctrl+c.