My project is as follows:

There is a source and there is a sink. In between the source and sink there may be n no. of computers connected in a network. Let these intermediate computers be called nodes. The source sends out some information. This information reaches to all the intermediate nodes. Each of the node reads that information, if necessary modifies/adds to the information and then forwards it to all the nodes it is connected to. This way finally the information reaches the sink.

The sink then gives a reply and this reply traverses the same path of intermediate nodes and reaches the source.

Is there any sample project in C which will help me to implement the above
situation?

first fix your protocols and then the rest should be easy

Try this: http://beej.us/guide/bgnet/