//
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// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
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// Copyright 2018 Capitar IT Group BV <info@capitar.com>
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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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#include <string.h>
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#include "core/nng_impl.h"
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#include "nng/protocol/reqrep0/rep.h"
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// Response protocol in raw mode. The REP protocol is the "reply" side of a
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// request-reply pair. This is useful for building RPC servers, for
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// example.
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typedef struct xrep0_pipe xrep0_pipe;
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typedef struct xrep0_sock xrep0_sock;
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static void xrep0_sock_getq_cb(void *);
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static void xrep0_pipe_getq_cb(void *);
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static void xrep0_pipe_putq_cb(void *);
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static void xrep0_pipe_send_cb(void *);
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static void xrep0_pipe_recv_cb(void *);
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static void xrep0_pipe_fini(void *);
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// xrep0_sock is our per-socket protocol private structure.
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struct xrep0_sock {
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nni_msgq * uwq;
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nni_msgq * urq;
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nni_mtx lk;
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nni_atomic_int ttl;
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nni_id_map pipes;
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nni_aio aio_getq;
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};
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// xrep0_pipe is our per-pipe protocol private structure.
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struct xrep0_pipe {
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nni_pipe * pipe;
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xrep0_sock *rep;
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nni_msgq * sendq;
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nni_aio aio_getq;
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nni_aio aio_send;
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nni_aio aio_recv;
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nni_aio aio_putq;
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};
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static void
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xrep0_sock_fini(void *arg)
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{
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xrep0_sock *s = arg;
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nni_aio_fini(&s->aio_getq);
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nni_id_map_fini(&s->pipes);
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nni_mtx_fini(&s->lk);
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}
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static int
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xrep0_sock_init(void *arg, nni_sock *sock)
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{
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xrep0_sock *s = arg;
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nni_mtx_init(&s->lk);
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nni_aio_init(&s->aio_getq, xrep0_sock_getq_cb, s);
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nni_atomic_init(&s->ttl);
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nni_atomic_set(&s->ttl, 8); // Per RFC
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s->uwq = nni_sock_sendq(sock);
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s->urq = nni_sock_recvq(sock);
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nni_id_map_init(&s->pipes, 0, 0, false);
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return (0);
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}
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static void
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xrep0_sock_open(void *arg)
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{
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xrep0_sock *s = arg;
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// This starts us retrieving message from the upper write q.
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nni_msgq_aio_get(s->uwq, &s->aio_getq);
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}
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static void
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xrep0_sock_close(void *arg)
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{
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xrep0_sock *s = arg;
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nni_aio_close(&s->aio_getq);
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}
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static void
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xrep0_pipe_stop(void *arg)
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{
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xrep0_pipe *p = arg;
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nni_aio_stop(&p->aio_getq);
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nni_aio_stop(&p->aio_send);
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nni_aio_stop(&p->aio_recv);
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nni_aio_stop(&p->aio_putq);
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}
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static void
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xrep0_pipe_fini(void *arg)
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{
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xrep0_pipe *p = arg;
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nni_aio_fini(&p->aio_getq);
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nni_aio_fini(&p->aio_send);
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nni_aio_fini(&p->aio_recv);
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nni_aio_fini(&p->aio_putq);
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nni_msgq_fini(p->sendq);
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}
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static int
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xrep0_pipe_init(void *arg, nni_pipe *pipe, void *s)
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{
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xrep0_pipe *p = arg;
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int rv;
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nni_aio_init(&p->aio_getq, xrep0_pipe_getq_cb, p);
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nni_aio_init(&p->aio_send, xrep0_pipe_send_cb, p);
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nni_aio_init(&p->aio_recv, xrep0_pipe_recv_cb, p);
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nni_aio_init(&p->aio_putq, xrep0_pipe_putq_cb, p);
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p->pipe = pipe;
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p->rep = s;
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// We want a pretty deep send queue on pipes. The rationale here is
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// that the send rate will be mitigated by the receive rate.
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// If a slow pipe (req pipe not reading its own responses!?)
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// comes up, then we will start discarding its replies eventually,
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// but it takes some time. It would be poor form for a peer to
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// smash us with requests, but be unable to handle replies faster
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// than we can forward them. If they do that, their replies get
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// dropped. (From a DDoS perspective, it might be nice in the
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// future if we had a way to exert back pressure to the send side --
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// essentially don't let peers send requests faster than they are
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// willing to receive replies. Something to think about for the
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// future.)
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if ((rv = nni_msgq_init(&p->sendq, 64)) != 0) {
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xrep0_pipe_fini(p);
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return (rv);
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}
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return (0);
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}
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static int
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xrep0_pipe_start(void *arg)
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{
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xrep0_pipe *p = arg;
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xrep0_sock *s = p->rep;
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int rv;
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if (nni_pipe_peer(p->pipe) != NNG_REP0_PEER) {
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// Peer protocol mismatch.
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return (NNG_EPROTO);
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}
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nni_mtx_lock(&s->lk);
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rv = nni_id_set(&s->pipes, nni_pipe_id(p->pipe), p);
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nni_mtx_unlock(&s->lk);
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if (rv != 0) {
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return (rv);
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}
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nni_msgq_aio_get(p->sendq, &p->aio_getq);
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nni_pipe_recv(p->pipe, &p->aio_recv);
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return (0);
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}
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static void
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xrep0_pipe_close(void *arg)
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{
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xrep0_pipe *p = arg;
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xrep0_sock *s = p->rep;
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nni_aio_close(&p->aio_getq);
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nni_aio_close(&p->aio_send);
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nni_aio_close(&p->aio_recv);
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nni_aio_close(&p->aio_putq);
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nni_msgq_close(p->sendq);
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nni_mtx_lock(&s->lk);
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nni_id_remove(&s->pipes, nni_pipe_id(p->pipe));
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nni_mtx_unlock(&s->lk);
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}
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static void
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xrep0_sock_getq_cb(void *arg)
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{
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xrep0_sock *s = arg;
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nni_msgq * uwq = s->uwq;
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nni_msg * msg;
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uint32_t id;
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xrep0_pipe *p;
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// This watches for messages from the upper write queue,
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// extracts the destination pipe, and forwards it to the appropriate
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// destination pipe via a separate queue. This prevents a single bad
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// or slow pipe from gumming up the works for the entire socket.
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if (nni_aio_result(&s->aio_getq) != 0) {
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// Closed socket?
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return;
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}
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msg = nni_aio_get_msg(&s->aio_getq);
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nni_aio_set_msg(&s->aio_getq, NULL);
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// We yank the outgoing pipe id from the header
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if (nni_msg_header_len(msg) < 4) {
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nni_msg_free(msg);
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// Look for another message on the upper write queue.
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nni_msgq_aio_get(uwq, &s->aio_getq);
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return;
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}
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id = nni_msg_header_trim_u32(msg);
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// Look for the pipe, and attempt to put the message there
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// (non-blocking) if we can. If we can't for any reason, then we
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// free the message.
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nni_mtx_lock(&s->lk);
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if (((p = nni_id_get(&s->pipes, id)) == NULL) ||
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(nni_msgq_tryput(p->sendq, msg) != 0)) {
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nni_msg_free(msg);
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}
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nni_mtx_unlock(&s->lk);
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// Now look for another message on the upper write queue.
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nni_msgq_aio_get(uwq, &s->aio_getq);
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}
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static void
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xrep0_pipe_getq_cb(void *arg)
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{
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xrep0_pipe *p = arg;
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if (nni_aio_result(&p->aio_getq) != 0) {
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nni_pipe_close(p->pipe);
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return;
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}
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nni_aio_set_msg(&p->aio_send, nni_aio_get_msg(&p->aio_getq));
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nni_aio_set_msg(&p->aio_getq, NULL);
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nni_pipe_send(p->pipe, &p->aio_send);
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}
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static void
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xrep0_pipe_send_cb(void *arg)
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{
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xrep0_pipe *p = arg;
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if (nni_aio_result(&p->aio_send) != 0) {
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nni_msg_free(nni_aio_get_msg(&p->aio_send));
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nni_aio_set_msg(&p->aio_send, NULL);
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nni_pipe_close(p->pipe);
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return;
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}
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nni_msgq_aio_get(p->sendq, &p->aio_getq);
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}
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static void
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xrep0_pipe_recv_cb(void *arg)
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{
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xrep0_pipe *p = arg;
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xrep0_sock *s = p->rep;
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nni_msg * msg;
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int hops;
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int ttl;
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if (nni_aio_result(&p->aio_recv) != 0) {
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nni_pipe_close(p->pipe);
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return;
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}
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ttl = nni_atomic_get(&s->ttl);
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msg = nni_aio_get_msg(&p->aio_recv);
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nni_aio_set_msg(&p->aio_recv, NULL);
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nni_msg_set_pipe(msg, nni_pipe_id(p->pipe));
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// Store the pipe id in the header, first thing.
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nni_msg_header_append_u32(msg, nni_pipe_id(p->pipe));
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// Move backtrace from body to header
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hops = 1;
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for (;;) {
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bool end;
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uint8_t *body;
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if (hops > ttl) {
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// This isn't malformed, but it has gone through
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// too many hops. Do not disconnect, because we
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// can legitimately receive messages with too many
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// hops from devices, etc.
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goto drop;
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}
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hops++;
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if (nni_msg_len(msg) < 4) {
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// Peer is speaking garbage. Kick it.
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nni_msg_free(msg);
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nni_pipe_close(p->pipe);
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return;
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}
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body = nni_msg_body(msg);
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end = ((body[0] & 0x80u) != 0);
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if (nni_msg_header_append(msg, body, 4) != 0) {
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// Out of memory most likely, but keep going to
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// avoid breaking things.
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goto drop;
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}
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nni_msg_trim(msg, 4);
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if (end) {
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break;
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}
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}
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// Go ahead and send it up.
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nni_aio_set_msg(&p->aio_putq, msg);
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nni_msgq_aio_put(s->urq, &p->aio_putq);
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return;
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drop:
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nni_msg_free(msg);
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nni_pipe_recv(p->pipe, &p->aio_recv);
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}
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static void
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xrep0_pipe_putq_cb(void *arg)
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{
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xrep0_pipe *p = arg;
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if (nni_aio_result(&p->aio_putq) != 0) {
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nni_msg_free(nni_aio_get_msg(&p->aio_putq));
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nni_aio_set_msg(&p->aio_putq, NULL);
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nni_pipe_close(p->pipe);
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return;
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}
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nni_pipe_recv(p->pipe, &p->aio_recv);
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}
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static int
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xrep0_sock_set_maxttl(void *arg, const void *buf, size_t sz, nni_opt_type t)
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{
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xrep0_sock *s = arg;
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int ttl;
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int rv;
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if ((rv = nni_copyin_int(&ttl, buf, sz, 1, NNI_MAX_MAX_TTL, t)) == 0) {
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nni_atomic_set(&s->ttl, ttl);
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}
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return (rv);
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}
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static int
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xrep0_sock_get_maxttl(void *arg, void *buf, size_t *szp, nni_opt_type t)
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{
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xrep0_sock *s = arg;
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return (nni_copyout_int(nni_atomic_get(&s->ttl), buf, szp, t));
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}
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static void
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xrep0_sock_send(void *arg, nni_aio *aio)
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{
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xrep0_sock *s = arg;
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nni_msgq_aio_put(s->uwq, aio);
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}
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static void
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xrep0_sock_recv(void *arg, nni_aio *aio)
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{
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xrep0_sock *s = arg;
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nni_msgq_aio_get(s->urq, aio);
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}
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// This is the global protocol structure -- our linkage to the core.
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// This should be the only global non-static symbol in this file.
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static nni_proto_pipe_ops xrep0_pipe_ops = {
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.pipe_size = sizeof(xrep0_pipe),
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.pipe_init = xrep0_pipe_init,
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.pipe_fini = xrep0_pipe_fini,
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.pipe_start = xrep0_pipe_start,
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.pipe_close = xrep0_pipe_close,
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.pipe_stop = xrep0_pipe_stop,
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};
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static nni_option xrep0_sock_options[] = {
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{
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.o_name = NNG_OPT_MAXTTL,
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.o_get = xrep0_sock_get_maxttl,
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.o_set = xrep0_sock_set_maxttl,
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},
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// terminate list
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{
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.o_name = NULL,
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},
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};
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static nni_proto_sock_ops xrep0_sock_ops = {
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.sock_size = sizeof(xrep0_sock),
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.sock_init = xrep0_sock_init,
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.sock_fini = xrep0_sock_fini,
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.sock_open = xrep0_sock_open,
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.sock_close = xrep0_sock_close,
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.sock_options = xrep0_sock_options,
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.sock_send = xrep0_sock_send,
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.sock_recv = xrep0_sock_recv,
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};
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static nni_proto xrep0_proto = {
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.proto_version = NNI_PROTOCOL_VERSION,
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.proto_self = { NNG_REP0_SELF, NNG_REP0_SELF_NAME },
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.proto_peer = { NNG_REP0_PEER, NNG_REP0_PEER_NAME },
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.proto_flags = NNI_PROTO_FLAG_SNDRCV | NNI_PROTO_FLAG_RAW,
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.proto_sock_ops = &xrep0_sock_ops,
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.proto_pipe_ops = &xrep0_pipe_ops,
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};
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int
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nng_rep0_open_raw(nng_socket *sidp)
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{
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return (nni_proto_open(sidp, &xrep0_proto));
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}
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