Berkeley Sockets - Socket API Functions

Socket API Functions

This list is a summary of functions or methods provided by the Berkeley sockets API library:

• socket creates a new socket of a certain socket type, identified by an integer number, and allocates system resources to it.
• bind is typically used on the server side, and associates a socket with a socket address structure, i.e. a specified local port number and IP address.
• listen is used on the server side, and causes a bound TCP socket to enter listening state.
• connect is used on the client side, and assigns a free local port number to a socket. In case of a TCP socket, it causes an attempt to establish a new TCP connection.
• accept is used on the server side. It accepts a received incoming attempt to create a new TCP connection from the remote client, and creates a new socket associated with the socket address pair of this connection.
• send and recv, or write and read, or sendto and recvfrom, are used for sending and receiving data to/from a remote socket.
• close causes the system to release resources allocated to a socket. In case of TCP, the connection is terminated.
• gethostbyname and gethostbyaddr are used to resolve host names and addresses. IPv4 only.
• select is used to pend, waiting for one or more of a provided list of sockets to be ready to read, ready to write, or that have errors.
• poll is used to check on the state of a socket in a set of sockets. The set can be tested to see if any socket can be written to, read from or if an error occurred.
• getsockopt is used to retrieve the current value of a particular socket option for the specified socket.
• setsockopt is used to set a particular socket option for the specified socket.

Further details are given below.