Computer network learning notes 7-tcp programming process and interview questions

As a client, you need to meet the conditions
1、 know “ The server ” Of ip、port
2、Connect Active connection “ The server ”
3、 The functions you need to use
socket— establish “ Take the initiative TCP Socket ”
connect— Connect “ The server ”
send— Send data to “ The server ”
recv— Accept “ The server ” Response
close— Close the connection

As TCP The conditions that the server needs to meet
1、 Have a known address bind
2、 Let the operating system know that it is a server , Not the client listen
3、 Waiting for the connection accpet
For connection oriented TCP Agreement for , The establishment of the connection really means the beginning of data communication .




tcp The programming flow of the client
1) Create a TCP Socket
2)bind binding （ Optional ）
3）connect Link server
4） Send data to the server send
5） Receive server data recv
6） Close socket

tcp Programming process of server
1） Create a tcp Listening socket
2） Use bind function Give listening socket Binding fixed ip And the port
3） Use listen Create a connection queue Active to passive
4） Use accpet Function from the connection queue Extract completed connections Get connected socket
5） Get the client's request as well as Respond to clients
6） Close the connected socket
7） Close listening socket

1、listen The role of ？
Change socket from active to passive .
Causes the operating system to set up a connection queue for the socket , Used to record all connections connected to the socket

2、listen The link queue created is divided into several parts ？
Two parts Complete the connection Incomplete connection Switch after three handshakes

3、 tcp Socket Listening socket and The difference between connected sockets ？
The listening socket is used to accept connection requests from clients .
The socket is connected to communicate with the client .

4、tcp Why can't the application layer receive 0 Length packet ？
0 The length data is used as the other socket application layer to close