1. To do While (1) Receive hello Search for more neighbors?
Process neighbor states (sort of like what we did)
Search for more neighbors?
Check and if so, search
Update neighbor set
If some neighbors have timed out, remove them
Send hello messages to neighbors
Send every 10 sec

2. Provided Classes Packet ptr: holds the data as a char buffer
totalSize:
When data is being written to the pkt, totalSize is the size of the buffer, which is Packet::bufferLength, which is 2000
When data is being read from pkt, total size is the total amount to data available for rading
offset: where in the buffer data should be read or written from. This is an internal variable. There is no need to adjust this or use its value
Before writing to pkt
pkt.getReadyForWriting();
Other methods will be demonstrated in the next slides

3. Of type HostId, which is discussed next
Provided Classes
UdpSocket
E.g., bind socket to port 10000
UdpSocket udpSocket;
udpSocket.bindToPort(10000);
Get packet if ready
Packet pkt;
If (udpSocket.checkForNewPacket(pkt, 2)>0)
// process data
else
// data is not ready
Send data
// fill the packet …
udpSocket.sendTo(pkt, destinationHostId)
Of type HostId, which is discussed next

4. Provided Classes HostId char _address[ADDRESS_LENGTH];
Boost::uint16_t _port;
E.g., set address and port
HostId host(address, port);
E.g., get HostId from packet
Packet pkt;
HostId host;
If (udpSocket.checkForNewPacket(pkt, 2)>0)
host.getFromPacket(pkt);
E.g., put HostId onto packet
HostId thisHost;
// thisHost is the the ip and port of this instance of the program. So messages send from this instance of the program are sent from the source thisHost. Code is included on creating thisHost
thisHost.addToPacket(pkt);
udpSocket.sendTo(pkt, hostId);
E.g., check if thisHost is the same as hostId
If (thisHost == hostId) {
// yes, they are the same }
E.g., send pkt with thisHost to all host in allHost list
for(HostId &hosted : allHost)

5. Provided Classes NeighborInfo HostId hostId; // the id of neighbor
time_t timeWhenLastHelloArrived;
Functions
addToPacket
getFromPacket
updateTimeToCurrentTime() ==
Only checks hostId’s match, ignores timeWhenLastHelloArrived
E.g.,
Packet pkt;
for( NeighborInfo &neighbor : allNeighbors)
Neighbor.addToPkt(pkt);

6. Provided Classes HelloMessage Functions
uint8_t type // not important for this project
HostId source;
uint16_t numberOfNeighbors;
list<HostId> neighbors;
Functions
Show
E.g., during development, include the following to see the contents of the message and verify that the data is sensiable: helloMessage.show()
addToPacket
getFromPacket
addToNeighborList
E.g., add neighbors to helloMessage
HelloMessage helloMessage;
helloMessage.type = HELLO_MESSAGE_TYPE;
helloMessage.source = thisHost;
for(NeighborInfo &neighborInfo : bidirectionalNeighbors)
helloMessage.addToNeighborList(neighborInfo.hostId);
// helloMessage.show(); // for debugging and testing olny
Packet pkt;
pkt.getPktReadyForWriting….
helloMessage.addToPacket(pkt);
udpSocket.sentTo(pkt, someDestinationHostId);

7. Classes, Class Methods, and Examples unneeded methods are not listed
class UdpSocket: used to send a receive a packet
UdpSocket udpSocket; // declares a socket object
udpSocket.bindToPort(portNum); // binds the socket to port portNum
udpSocket.checkForNewPacket(pkt, timeout); //
Checks for a new packet. Returns a positive value if a packet has arrive and returns 0 or less than 0 if no packet arrived
pkt is a Packet object
timeout is the maximum time (in seconds) to wait for a packet. If no packet arrives within this time, then the function returns with value 0
udpSocket.sendTo(pkt, hostId); // sends packet pkt to destination hostId
class Packet: holds raw data for sending or receiving via a UdpSocket object
Packet pkt; // declare a packet object
pkt.getReadyForWriting(); // gets the packet object ready for writing

8. Classes, Class Methods, and Examples unneeded methods are not listed
class HostId: holds data about a host (specifically, the IP address and port the host is using)
HostId hostId; // declares a host object
hostId.show(); // prints the IP address and port
hostIdA == hostIdB ; // compares two hostId and returns true if both hosts have the same IP address and port
class NeighborInfo: holds data about a neighbor (specifically, the neighbor’s HostId and the last time when a hello was received from the neighbor)
NeighborInfo neighbor; // declares the neighborInfo object
neighborA == neighbor; // compares two neighbors and returns true if the neighbors have the same IP address and port. Does to compare the last time a hello was received
neighbor.updateTimeToCurrentTime(); // sets the timeWhenLastHelloArrived
Neighbor.hostId // the hostId of the neighbor object
class HelloMesssage: holds a hello message for sending or that has been received
HelloMessage helloMessage; // declares a HelloMessage object
helloMessage.getFromPacket(pkt); // reads the hello message from the pkt and puts it into a HelloMessage object
helloMessage.addToPacket(pkt); // puts data from a HelloMessage objective into a pkt object
helloMessage.source // the HostId of the sender of the HelloMessage
helloMessage.source == hostIdA // is true if the source of the helloMessage is hostIdA
for (NeighborInfo & neighbor : bidirectionalNeighbors) {
if neighbor.hostId == helloMessage.source
printf(“is bidirectional\n”);
} // prints message if the source of the hello message is in the bidirectionalNeighbors list
helloMessage.source = thisHost; // sets the source of the helloMessage to be this host
helloMessage.addToNeigbhorList(hostId); // adds a hostId to the list of recently heard neighbors in the helloMessage
helloMessage.addToNeighbors(neighbor.hostId);
} // adds the hosts in the bidirectionalNeighbors list to the helloMessage
for (HostId & hostId : helloMessage.neighbors) {
hostId.show();
} // prints the hostId of every host listed in the hello message’s list of recently heard neighbors
helloMessage.show(); // prints the contents of the helloMessage