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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.
struct nni_protocol {
uint16_t proto_self; // our 16-bit protocol ID
uint16_t proto_peer; // who we peer with (ID)
const char * proto_name; // string version of our name
size_t proto_pipe_size; // pipe private data size
//Create protocol instance, which will be stored on the socket.
int (*proto_create)(void **, nni_socket *);
// Destroy the protocol instance.
void (*proto_destroy)(void *);
// Add and remove pipes. These are called as connections are
// created or destroyed.
int (*proto_add_pipe)(void *, nni_pipe *, void *);
void (*proto_rem_pipe)(void *, void *);
// Thread functions for processing send & receive sides of
// protocol pipes. Send may be NULL, but recv should should not.
// (Recv needs to detect a closed pipe, if nothing else.)
void (*proto_pipe_send)(void *);
void (*proto_pipe_recv)(void *);
// 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 prtocol
// should return NULL, otherwise the message (possibly modified).
nni_msg * (*proto_recv_filter)(void *, nni_msg *);
// Send filter. This may be NULL, but if it isn't, then messages
// here are filtered just after they come from the application.
nni_msg * (*proto_send_filter)(void *, nni_msg *);
};
// These are socket methods that protocol operations can expect to call.
// Note that each of these should be called without any locks held, since
// the socket can reenter the protocol.
// nni_socket_sendq obtains the upper writeq. The protocol should
// recieve messages from this, and place them on the appropriate pipe.
extern nni_msgqueue *nni_socket_sendq(nni_socket *);
// nni_socket_recvq obtains the upper readq. The protocol should
// inject incoming messages from pipes to it.
extern nni_msgqueue *nni_socket_recvq(nni_socket *);
// 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 *, 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 *, 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 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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