FBB::LocalServerSocket(3bobcat)

Unix Domain Server Socket
(libbobcat-dev_6.02.02)

2005-2022

NAME

SYNOPSIS

DESCRIPTION

NAMESPACE

INHERITS FROM

ENUMERATION

enum Socket
This enumeration holds two values:

• KEEP:
  When this value is specified at construction time, the file representing the Unix Domain Socket is not removed when the LocalServerSocket is destroyed.
• UNLINK:
  When this value is specified at construction time, the file representing the Unix Domain Socket is removed when the LocalServerSocket is destroyed. As a socket cannot be reused, this is the default value used with the LocalServerSocket constructor.

CONSTRUCTOR

• LocalServerSocket():
  This constructor creates an empty (non-functioning) FBB::LocalServerSocket object. Before it can be used, the open() member must be called (see below).
• LocalServerSocket(string const &name, Socket action = UNLINK) throw (Exception):
  This constructor initializes an FBB::LocalServerSocket object, which will listen for connection requests using the named Unix Domain socket. An FBB::Exception is thrown if the socket could not be constructed. If the constructor is given a second argument FBB::LocalServerSocket::KEEP, the constructed socket is not unlinked when the FBB::LocalServerSocket object is destroyed. The construction of the socket does not mean that the FBB::LocalServerSocket object is actually listening for connections. To start listening, the member listen() should be called.

Copy and move constructors (and assignment operators) are not available.

MEMBER FUNCTIONS

• size_t accept():
  The accept() member returns an size_t which is a file descriptor (socket) that may be used to communicate with the client requesting the connection. In more complex programs the returned file descriptor (socket) could be passed to a class derived from FBB::Fork, handling the communication with the child as a separate (child) process.

• void listen(size_t backlog = 5, bool blocking = true):
  The listen() member defines the way the FBB::LocalServerSocket will listen for clients requesting a connection. It can be used only once with a FBB::LocalServerSocket. An FBB::Exception object is thrown if listening fails.

  The listen() member's backlog parameter defines the size of the FBB::LocalServerSocket's internal queue in which connection requests may be stored waiting for their turn to be serviced. When backlog requests are waiting and another request arrives, then that request is lost.

  The member's second parameter, blocking, is used to control the blocking mode. By default, blocking is used, and listen() will wait until a connection is established. This is ok in situations where clients connect infrquently and for relatively short time intervals. Otherwise, in more complex programs, an FBB::Selector object can be used to sense input on the server socket and/or on various client sockets.

• void open(string const &name, Socket action = UNLINK):
  This member prepares a FBB::LocalServerSocket object for use. It should only be used in combination with the default constructor. Following open() the FBB:::LocalServerSocket object will be able to listen for connection requests using the named Unix Domain socket. An FBB::Exception is thrown if the socket could not be constructed. If the a second argument FBB::LocalServerSocket::KEEP, is provided the constructed socket is not unlinked when the FBB::LocalServerSocket object is destroyed. The construction of the socket does not mean that the FBB::LocalServerSocket object is actually listening for connections. To start listening, the member listen() should be called next.

EXAMPLE

    #include <iostream>
    #include <bobcat/localserversocket>
    #include <bobcat/ifdstream>
    #include <bobcat/ofdstream>

    using namespace std;
    using namespace FBB;

    int main(int argc, char **argv)
    try
    {
        if (argc == 1)
        {
            cerr << "Provide local filename, e.g., /tmp/uds\n";
            return 1;
        }

        LocalServerSocket server(argv[1]);

        cerr << "server using `" << argv[1] << "'" << endl;

        cout <<
            "The server terminates when it receives a single `q' on a line\n"
            "A connection is terminated when no input is received anymore.\n"
            "Then another connection is possible" << endl;

        server.listen();                // listen in blocking mode

        while (true)
        {
            int fd = server.accept();

            cerr << "Client FD = " << fd << ", " << endl;

            IFdStream in(fd);           // stream to read from client
            OFdStream out(fd);          // stream to write to client
            string cmd;

            while (getline(in, cmd))
            {
                cout << "Got: " << cmd << endl;
                out << "Got: " << cmd << "\r" << endl;

                if (cmd[0] == 'q')
                    return 0;
            }
            cout << "Ready for another connection\n";
        }
    }
    catch (Exception const &err)
    {
        cerr <<
            err.what() << endl <<
            "Server socket on port " << argv[1] <<
            " can't be opened" << endl;
        return -1;
    }
        

FILES

SEE ALSO

BUGS

BOBCAT PROJECT FILES

• https://fbb-git.gitlab.io/bobcat/: gitlab project page;
• bobcat_6.02.02-x.dsc: detached signature;
• bobcat_6.02.02-x.tar.gz: source archive;
• bobcat_6.02.02-x_i386.changes: change log;
• libbobcat1_6.02.02-x_*.deb: debian package containing the libraries;
• libbobcat1-dev_6.02.02-x_*.deb: debian package containing the libraries, headers and manual pages;

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