System Calls

• These are the system calls involving sockets:
  • socket, Creates a socket
  • close, Destroys a socket
  • connect, Creates a connection between two sockets
  • bind, Labels a server socket with an address
  • listen, Configures a socket to accept conditions
  • accept, Accepts a connection and creates a new socket for the connection
  Sockets are represented by file descriptors.
• Creating and Destroying Sockets
  • The socket and close functions create and destroy sockets, respectively.
  • When you create a socket, specify the three socket choices: namespace, communication style, and protocol.
    • PF_LOCAL or PF_UNIX specifies the local namespace, and PF_INET specifies Internet namespaces.
    • SOCK_STREAM for a connection-style socket, or use
      SOCK_DGRAM for a datagram-style socket.
    • Each protocol is valid for a particular namespace-style combination. Because there is usually one best protocol for each such pair, specifying 0 is usually the correct protocol.
  • If socket succeeds, it returns a file descriptor for the socket. You can read from or write to the socket using read, write, and so on, as with other file descriptors.
  • When you are finished with a socket, call close to remove it.