get_route_info()

The goal of get_route_info() is to read routing table entries from the file routeinfo.txt, and update each node’s routing table, which is stored as a linked list of destinations. Each line in the file follows this format:

source;destination;nextHop;cost

For example:

nodeA;nodeC;nodeB;8
nodeB;nodeD;nodeC;7
nodeC;nodeA;nodeB;8

Each line tells us: From source, to reach destination, send the packet first to nextHop with the given cost.

How do we do this?

To build the routing tables, you need to:

1. File I/O:

   • Open the file using fopen().

2. Input Parsing:

   • Use fgets() to read each line.

   • Use sscanf() to extract the source, destination, next hop, and cost.

3. Find the Source Node:

   • Use find_node() to find the source node in the main node list.

   • If the node is not found, ignore that entry.

4. Insert the Destination:

   • Create a new destination node (dest_node_t).

   • Fill in its values: destination name, next hop, cost.

   • Set packets_sent and bytes_sent to 0.

   • Use insert_dest_front() to add it to the source node’s destination list.

5. Return:

   • Return 0 on success.

   • Return 1 if the file could not be opened.