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/*
* Copyright 2016 Garrett D'Amore <garrett@damore.org>
*
* This software is supplied under the terms of the MIT License, a
* copy of which should be located in the distribution where this
* file was obtained (LICENSE.txt). A copy of the license may also be
* found online at https://opensource.org/licenses/MIT.
*/
#ifndef CORE_PROTOCOL_H
#define CORE_PROTOCOL_H
/*
* Protocol implementation details. Protocols must implement the
* interfaces in this file. Note that implementing new protocols is
* not necessarily intended to be a trivial task. The protocol developer
* must understand the nature of nng, as they are responsible for handling
* most of the logic. The protocol generally does most of the work for
* locking, and calls into the transport's pipe functions to do actual
* work, and the pipe functions generally assume no locking is needed.
* As a consequence, most of the concurrency in nng exists in the protocol
* implementations.
*
* Pipe operations may block, or even reenter the protoccol entry points
* (for example nni_pipe_close() causes the protocols proto_remove_pipe
* entry point to be called), so it is very important that protocols do
* not hold any locks across calls to pipe functions.
*/
struct nni_protocol {
/*
* Protocol information.
*/
uint16_t proto_self; /* our 16-bit protocol ID */
uint16_t proto_peer; /* who we peer with (protocol ID) */
const char * proto_name; /* string version of our name */
/*
* Create protocol instance data, which will be stored on the socket.
*/
int (*proto_create)(void **, nni_socket_t);
/*
* Destroy the protocol instance.
*/
void (*proto_destroy)(void *);
/*
* Shutdown the protocol instance, including giving time to
* drain any outbound frames (linger). The protocol is not
* required to honor the linger.
*/
void (*proto_shutdown)(void *, uint64_t);
/*
* Add and remove pipes. These are called as connections are
* created or destroyed.
*/
int (*proto_add_pipe)(void *, nni_pipe_t);
int (*proto_remove_pipe)(void *, nni_pipe_t);
/*
* Option manipulation. These may be NULL.
*/
int (*proto_setopt)(void *, int, const void *, size_t);
int (*proto_getopt)(void *, int, void *, size_t *);
/*
* Receive filter. This may be NULL, but if it isn't, then
* messages coming into the system are routed here just before
* being delivered to the application. To drop the message,
* the protocol should return NULL, otherwise the message
* (possibly modified).
*/
nng_msg_t (*proto_recv_filter)(void *, nni_msg_t);
/*
* Send filter. This may be NULL, but if it isn't, then
* messages here are filtered just after they come from the
* application.
*/
nng_msg_t (*proto_send_filter)(void *, nni_msg_t);
};
/*
* These are socket methods that protocol operations can
* reasonably expect to call.
*/
/*
* nni_socket_sendq obtains the upper writeq. The protocol should
* recieve messages from this, and place them on the appropriate
* pipe.
*/
extern nni_msgqueue_t nni_socket_sendq(nni_socket_t);
/*
* nni_socket_recvq obtains the upper readq. The protocol should
* inject incoming messages from pipes to it.
*/
extern nni_msgqueue_t nni_socket_recvq(nni_socket_t);
/*
* nni_socket_recv_err sets an error code to be returned to clients
* rather than waiting for a message. Set it to 0 to resume normal
* receive operation.
*/
extern void nni_socket_recv_err(nni_socket_t, int);
/*
* nni_socket_send_err sets an error code to be returned to clients
* when they try to send, so that they don't have to timeout waiting
* for their message to be accepted for send. Set it to 0 to resume
* normal send operations.
*/
extern void nni_socket_send_err(nni_socket_t, int);
/*
* These functions are not used by protocols, but rather by the socket
* core implementation. The lookups can be used by transports as well.
*/
extern struct nni_protocol *nni_protocol_find(uint16_t);
extern const char *nni_protocol_name(uint16_t);
extern uint16_t nni_protocol_number(const char *);
#endif /* CORE_PROTOCOL_H */
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