notes.txt

network stuff 

the tcp protocol is statfull protocol because it maintain a session between the client and the server (require handshake)
the udp is statless don't maintain a session (just send a data)

in the case of the tcp the os maintain a connection table for the connections using these info
(Source IP, Source Port, Destination IP, Destination Port, State)
and therefor it handles the reliability (ordering and retrans)

in the case of udp the os only manage delivering the backet to the correct process based on the port number 





--->wildcard ip address (0.0.0.0) listen for all the interfaces in the system if there ip address for wifi and another for ethernet and
another for loopback it dosn't matter the source (multihomed host)



--->the UDB based applications must take care of the ip fragementation becaue in the UDB there is not way to know the MTU of the path 
and to make the ip datagrame less than the  (minimum reassembly buffer)




---------- the kernel deals with the network ---------------------------------------------------------------------------------------------

the server open a socket with specific ip and specific port to listen for connections in this socket and when it accept a connection 
it becomes a specific thing between the client socket and the server socket 


for each socket the kernel makes a 2 queues (this is analogy not the exact data structure that used)
and we can control the size of these queues by the backlog parameter 


1--syn queue (handles clients that didn't completed the 3 way hand shake yet)

2--accept queue (when the request complete the handshake it move from the syn q to this q  ) and not yet accepted from the application 


when the application make sys call accept() it accept from the completed connections in the accept queue and make another 2 queues dedicated
for this connection 
and this connection now contain all info about the client (ip and port) and the server socket (ip and port)
(and the connection bind to a file descriptor that in the PCB for this process )


1--send queue (when the process sends data to this connection it go to this queue)

2--recieve queue (when the process read data from this connection it recv it from this queue)