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A VU Handler for the URL Socket Scheme

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These functions provide VU namespace handlers for file-names that designate various kinds of sockets. By using these handlers, your programs can (almost) transparently handle filenames like:

     inet://myserver.host.com:10000

or

     unix:/tmp/.X11-unix/X0

Two kinds of sockets are available: server sockets and client sockets.

server sockets are created with socket(2) , bind(2) , and listen(2) . When vu_open is called, a call to listen(2) is made and the client connection (if any) is returned.

client sockets are created with socket(2) , bind(2) , and connect(2) .

Sockets may be named in either the unix or inet domains.

The syntax of these URLs is described in the documentation for url_socket_push_client_handler and url_socket_push_socket_handler .

Function url_socket_push_client_handler

void url_socket_push_client_handler (enum url_socket_domains domains,
                                     int default_port,
                                     int is_optional);

Push a VU namespace handler for client sockets.

     Domains:                        File Name:
     ------------------------------------------------------------------
     url_socket_unix                 unix:$PATH
     url_socket_inet                 inet://$HOST[:$PORT]
     url_socket_inet_or_unix         unix:$PATH or inet://$HOST[:$PORT]

Note that the $PATH of a unix domain socket is subject to ~ expansion using file_name_tilde_expand .

(See file_name_tilde_expand.)

default_port is used for internet-domain sockets.

If is_optional is 0 , the handler is immediately added to the VU namespace. If is_optional is not 0 , the handler is added to the list of optional handlers and may be enabled by vu_enable_optional_name_handler .

(See vu_enable_optional_name_handler.)

     Domains:                        Optional Handler Name:
     ------------------------------------------------------------------
     url_socket_unix                 client/unix
     url_socket_inet                 client/inet
     url_socket_inet_or_unix         client/any



Function url_socket_push_socket_handler

void url_socket_push_socket_handler 
     (enum url_socket_domains domains,
      int server_flags,
      int may_be_client,
      int only_server_url,
      int default_port,
      int backlog,
      url_socket_server_callback server_callback,
      url_socket_connect_callback connection_callback,
      url_socket_server_close_callback server_close_callback,
      void * closure,
      is_optional);

Push a VU namespace handler for server sockets. After this call, a call to vu_open with a suitable file name will work by creating a socket.

server_flags may be any bitwise combination of:

             O_NONBLOCK      # Don't block waiting for connections.

There are two kinds of file name patterns: those that can be used to name both clients and servers, and those that can only be used to name servers:

     server only:                    client or server:
     -------------------------------------------------
     unix-server:$PATH               unix:$PATH
     inet-server://$HOST[:$PORT]     inet://$HOST[:$PORT]

By default, both kinds of URL are accepted and interpreted as names of server sockets. Note that:

     `$PATH' of a unix domain socket is  subject to "~" expansion using 
     `file_name_tilde_expand'.

     `$HOST' of an internet-domain socket may be `INADDR_LOOPBACK'.
     If the URL is the name of a server, `$HOST' may also be
     `INADDR_ANY'.  (See `inet(4)'.)

     `$PORT' of an internet-domain server may be 0, meaning that the
     system should assign a port number which will be reported in 
     the server callback in the `server_addr' parameter (see below).

If may_be_client is not 0 , then accept both kinds of URLs, but interpret client or server URLs as naming client sockets (your process will open a connection to some other server).

If only_server_url is not 0 , then accept server only URLs, but not client or server URLs. In this case, may_be_client is ignored. This is especially useful in combination with url_socket_push_client_handler and other calls to vu_push_name_handler .

default_port is used when creating an internet-domain socket for which the port number was not specified in the file-name.

backlog is used for the call to listen(2) .

server_callback is called when a new server socket has been created successfully. It's arguments are explained below.

connect_callback is called when a new connection has been received. It's arguments are explained below.

server_close_callback is called when the server descriptor is closed. It's arguments are explained below.

closure is an opaque value passed to the callback functions.

If is_optional is 0 , the handler is immediately added to the VU namespace. If is_optional is non-0, the handler is added to the list of optional handlers and may be enabled by vu_enable_optional_name_handler .

  domain(s) only_server_url may_be_client         Optional Handler Name
  --------------------------------------------------------------------
  unix            0               0               server/unix
  inet            0               0               server/inet
  inet_or_unix    0               0               server/any
  unix            0               1               socket/unix
  inet            0               1               socket/inet
  inet_or_unix    0               1               socket/any
  unix            1               *               socket/unix-server
  inet            1               *               socket/inet-server
  inet_or_unix    1               *               socket/any-server

Calling Conventions for Callbacks

 typedef void (*url_socket_server_callback) (char * path,
                                             int server_flags,
                                             int flags,
                                             int mode,
                                             int server_fd,
                                             struct sockaddr * server_addr,
                                             int server_addr_len,
                                             void * closure);

     `path' is the file name that caused the server socket to
     be created.

     `server_flags' is 0 or a bit-wise combination of `O_NONBLOCK'.

     `flags' is the `flags' parameter passed to `vu_open', if this
     server socket was created by a call to `vu_open', 0 otherwise.

     `mode' is the `mode' parameter passed to `vu_open', if this
     server socket was created by a call to `vu_open', 0 otherwise.

     `server_fd' is the descriptor number of the server socket.

     `server_addr' and `server_addr_len' is the address passed to
     `bind'.

     `closure' is the `closure' argument passed to
     `url_socket_push_socket_handler'.

 typedef void (*url_socket_connect_callback) 
             (char * path,
              int flags,
              int mode,
              int server_fd,
              int connection_fd,
              struct sockaddr * client_addr,
              int client_addr_len,
              void * closure);

     `path' is the file name that caused the client connection to this
     server to be created.

     `flags' is the `flags' parameter passed to `vu_open'.

     `mode' is the `mode' parameter passed to `vu_open'.

     `server_fd' is the descriptor number of the server socket.

     `connection_fd' is the descriptor number of the client connection.

     `client_addr' and `client_addr_len' is the address from `accept'.

     `closure' is the `closure' argument passed to
     `url_socket_push_socket_handler'.

 typedef void (*url_socket_server_close_callback) 
             (int server_fd,
              struct sockaddr * server_addr,
              int server_addr_len,
              void * closure);

     `server_fd' is the descriptor number of the server socket.

     `server_addr' and `server_addr_len' is the address passed to
     `bind'.

     `closure' is the `closure' argument passed to
     `url_socket_push_socket_handler'.



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