Socket is an end point communication between two systems on a network. Socket is a combination of IP address an port on one system.
socket(int domain, int type, int protocol) => creates an unnamed socket inside the kernel and returns an integer known as socket descriptor.
1st arg. – takes domain/family for internet family of IPv4 addresses. we use AF_INET.
2nd arg. – they are of two types -
SOCK_STREAM
SOCK_DGRAM
3rd arg. – generally left ’0′. to let the kernel decides the default protocol to use for this connection.
Various system calls used in socket() are :
bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
listen(int sockfd, int backlog);
connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
accept(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
bind(), connect() and accept() are same but there is a difference i.e. :
bind() and connect() have server sockfd and server address
accept() have server sockfd and client address
