//
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// Copyright 2021 Staysail Systems, Inc. <info@staysail.tech>
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// Copyright 2018 Capitar IT Group BV <info@capitar.com>
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// Copyright 2018 Devolutions <info@devolutions.net>
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//
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// This software is supplied under the terms of the MIT License, a
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// copy of which should be located in the distribution where this
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// file was obtained (LICENSE.txt). A copy of the license may also be
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// found online at https://opensource.org/licenses/MIT.
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//
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#ifndef PROTOCOL_SP_TRANSPORT_H
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#define PROTOCOL_SP_TRANSPORT_H
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#include "core/options.h"
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// Endpoint operations are called by the socket in a
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// protocol-independent fashion. The socket makes individual calls,
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// which are expected to block if appropriate (except for destroy), or
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// run asynchronously if an aio is provided. Endpoints are unable to
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// call back into the socket, to prevent recusive entry and deadlock.
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//
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// For a given endpoint, the framework holds a lock so that each entry
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// point is run exclusively of the others. (Transports must still guard
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// against any asynchronous operations they manage themselves, though.)
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struct nni_sp_dialer_ops {
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// d_init creates a vanilla dialer. The value created is
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// used for the first argument for all other dialer functions.
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int (*d_init)(void **, nni_url *, nni_dialer *);
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// d_fini frees the resources associated with the dialer.
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// The dialer will already have been closed.
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void (*d_fini)(void *);
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// d_connect establishes a connection. It can return errors
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// NNG_EACCESS, NNG_ECONNREFUSED, NNG_EBADADDR,
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// NNG_ECONNFAILED, NNG_ETIMEDOUT, and NNG_EPROTO.
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void (*d_connect)(void *, nni_aio *);
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// d_close stops the dialer from operating altogether. It
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// does not affect pipes that have already been created. It is
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// nonblocking.
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void (*d_close)(void *);
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// d_getopt is used to obtain an option.
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int (*d_getopt)(void *, const char *, void *, size_t *, nni_type);
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// d_setopt is used to set or change an option.
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int (*d_setopt)(void *, const char *, const void *, size_t, nni_type);
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// d_options is an array of dialer options. The final
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// element must have a NULL name. If this member is NULL, then
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// no dialer specific options are available.
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nni_option *d_options;
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};
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struct nni_sp_listener_ops {
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// l_init creates a vanilla listener. The value created is
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// used for the first argument for all other listener functions.
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int (*l_init)(void **, nni_url *, nni_listener *);
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// l_fini frees the resources associated with the listener.
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// The listener will already have been closed.
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void (*l_fini)(void *);
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// l_bind just does the bind() and listen() work,
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// reserving the address but not creating any connections.
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// It should return NNG_EADDRINUSE if the address is already
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// taken. It can also return NNG_EBADADDR for an unsuitable
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// address, or NNG_EACCESS for permission problems.
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int (*l_bind)(void *);
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// l_accept accepts an inbound connection.
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void (*l_accept)(void *, nni_aio *);
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// l_close stops the listener from operating altogether. It
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// does not affect pipes that have already been created. It is
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// nonblocking.
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void (*l_close)(void *);
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// l_getopt is used to obtain an option.
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int (*l_getopt)(void *, const char *, void *, size_t *, nni_type);
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// l_setopt is used to set or change an option.
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int (*l_setopt)(void *, const char *, const void *, size_t, nni_type);
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// l_options is an array of listener options. The final
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// element must have a NULL name. If this member is NULL, then
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// no dialer specific options are available.
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nni_option *l_options;
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};
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// Pipe operations are entry points called by the socket. These may be
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// called with socket locks held, so it is forbidden for the transport
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// to call back into the socket at this point. (Which is one reason
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// pointers back to socket or even enclosing pipe state, are not
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// provided.)
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struct nni_sp_pipe_ops {
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// p_init initializes the pipe data structures. The main
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// purpose of this is so that the pipe will see the upper
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// layer nni_pipe and get a chance to register stats and such.
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int (*p_init)(void *, nni_pipe *);
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// p_fini destroys the pipe. This should clean up all local
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// resources, including closing files and freeing memory, used
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// by the pipe. After this call returns, the system will not
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// make further calls on the same pipe.
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void (*p_fini)(void *);
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// p_stop stops the pipe, waiting for any callbacks that are
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// outstanding to complete. This is done before tearing down
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// resources with p_fini.
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void (*p_stop)(void *);
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// p_aio_send queues the message for transmit. If this fails,
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// then the caller may try again with the same message (or free
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// it). If the call succeeds, then the transport has taken
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// ownership of the message, and the caller may not use it
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// again. The transport will have the responsibility to free
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// the message (nng_msg_free()) when it is finished with it.
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void (*p_send)(void *, nni_aio *);
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// p_recv schedules a message receive. This will be performed
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// even for cases where no data is expected, to allow detection
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// of a remote disconnect.
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void (*p_recv)(void *, nni_aio *);
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// p_close closes the pipe. Further recv or send operations
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// should return back NNG_ECLOSED.
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void (*p_close)(void *);
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// p_peer returns the peer protocol. This may arrive in
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// whatever transport specific manner is appropriate.
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uint16_t (*p_peer)(void *);
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// p_getopt is used to obtain an option. Pipes don't implement
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// option setting.
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int (*p_getopt)(void *, const char *, void *, size_t *, nni_type);
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};
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// Transport implementation details. Transports must implement the
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// interfaces in this file.
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struct nni_sp_tran {
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// tran_link is for framework use only - it must initialized
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// to zero before registration.
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nni_list_node tran_link;
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// tran_scheme is the transport scheme, such as "tcp" or "inproc".
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const char *tran_scheme;
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// tran_dialer links our dialer-specific operations.
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const nni_sp_dialer_ops *tran_dialer;
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// tran_listener links our listener-specific operations.
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const nni_sp_listener_ops *tran_listener;
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// tran_pipe links our pipe-specific operations.
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const nni_sp_pipe_ops *tran_pipe;
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// tran_init is called once during library initialization.
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void (*tran_init)(void);
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// tran_fini is called during library shutdown.
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// It should release any global resources.
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void (*tran_fini)(void);
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};
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// These APIs are used by the framework internally, and not for use by
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// transport implementations.
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extern nni_sp_tran *nni_sp_tran_find(nni_url *);
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extern int nni_sp_tran_sys_init(void);
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extern void nni_sp_tran_sys_fini(void);
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extern void nni_sp_tran_register(nni_sp_tran *);
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#endif // PROTOCOL_SP_TRANSPORT_H
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