Address Structure - Advanced Unix Programming - Lecture Slides, Slides of Computer Programming

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Week 7 Topics

• Basic TCP sockets

– Socket address structure

– Byte ordering and manipulation functions

– socket, connect, bind, listen, accept

• Client-Server design

• Concurrent server

Basic TCP sockets

• Socket address structure

• Byte ordering and manipulation functions

• socket, connect, bind, listen, accept

connect

• #include <sys/socket.h>

int connect(int sockfd, const struct sockaddr

*servaddr, socklen_t addrlen);

• servaddr : socket address structure (IP address and port)
• connect actively starts the TCP connection

establishment phase

• Possible errors
  • ECONNREFUSED
  • EHOSTUNREACH
  • ETIMEDOUT
  • Etc
• Close the socket after error

bind

• #include <sys/socket.h>

int bind(int sockfd, const struct sockaddr &myaddr,

socklen_t addlen);

• myaddr contains its own address

Address port result

INADDR_ANY 0 system selects addr and port

INADDR_ANY !=0 system selects addr, user selects

port

Local IP address 0 user selects addr, system selects

port

Local IP address !=0 user selects both addr and port

• Client does not have to bind , system assigns a port
• See example2.c

accept

• Blocking by default

#include <sys/socket.h> int accept (int sockfd, struct sockaddr *cliaddr, socklen_t *addrlen);

• Creates a new socket and returns a file descriptor

associated with that socket

• Gives client’s address in cliaddr
• See example2.c