Unable to find Valid MAC address

Each Ethernet card needs to have a unique MAC address on a network. The user needs to provide that unique address to the Interniche stack through the get_mac_addr() function. This function usually reads this address from a flash memory, so the actual way this is done depends on the board the software is running onto. If the flash memory is corrupt or has been erased, then this function isn't able to give a unique MAC address anymore.

You should either try to put back a valid mac address in the flash (the board documentation should say how to do it) or modify the get_mac_addr() to return a MAC address defined by you (do only that for testing!)

You are right about the DHCP part, but you should try to solve the MAC address problem first, and then look into Dhcp. Using an Ethernet packet sniffer such as Wireshark can help debug Dhcp problems.