1 files changed, 432 insertions, 0 deletions
diff --git a/src/sp/protocol/reqrep0/xrep.c b/src/sp/protocol/reqrep0/xrep.c
new file mode 100644
index 00000000..9737c600
--- /dev/null
+++ b/src/sp/protocol/reqrep0/xrep.c
@@ -0,0 +1,432 @@
+//
+// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// 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.
+//
+
+#include <string.h>
+
+#include "core/nng_impl.h"
+#include "nng/protocol/reqrep0/rep.h"
+
+// Response protocol in raw mode.  The REP protocol is the "reply" side of a
+// request-reply pair.  This is useful for building RPC servers, for
+// example.
+
+typedef struct xrep0_pipe xrep0_pipe;
+typedef struct xrep0_sock xrep0_sock;
+
+static void xrep0_sock_getq_cb(void *);
+static void xrep0_pipe_getq_cb(void *);
+static void xrep0_pipe_putq_cb(void *);
+static void xrep0_pipe_send_cb(void *);
+static void xrep0_pipe_recv_cb(void *);
+static void xrep0_pipe_fini(void *);
+
+// xrep0_sock is our per-socket protocol private structure.
+struct xrep0_sock {
+	nni_msgq *     uwq;
+	nni_msgq *     urq;
+	nni_mtx        lk;
+	nni_atomic_int ttl;
+	nni_id_map     pipes;
+	nni_aio        aio_getq;
+};
+
+// xrep0_pipe is our per-pipe protocol private structure.
+struct xrep0_pipe {
+	nni_pipe *  pipe;
+	xrep0_sock *rep;
+	nni_msgq *  sendq;
+	nni_aio     aio_getq;
+	nni_aio     aio_send;
+	nni_aio     aio_recv;
+	nni_aio     aio_putq;
+};
+
+static void
+xrep0_sock_fini(void *arg)
+{
+	xrep0_sock *s = arg;
+
+	nni_aio_fini(&s->aio_getq);
+	nni_id_map_fini(&s->pipes);
+	nni_mtx_fini(&s->lk);
+}
+
+static int
+xrep0_sock_init(void *arg, nni_sock *sock)
+{
+	xrep0_sock *s = arg;
+
+	nni_mtx_init(&s->lk);
+	nni_aio_init(&s->aio_getq, xrep0_sock_getq_cb, s);
+	nni_atomic_init(&s->ttl);
+	nni_atomic_set(&s->ttl, 8); // Per RFC
+	s->uwq = nni_sock_sendq(sock);
+	s->urq = nni_sock_recvq(sock);
+
+	nni_id_map_init(&s->pipes, 0, 0, false);
+	return (0);
+}
+
+static void
+xrep0_sock_open(void *arg)
+{
+	xrep0_sock *s = arg;
+
+	// This starts us retrieving message from the upper write q.
+	nni_msgq_aio_get(s->uwq, &s->aio_getq);
+}
+
+static void
+xrep0_sock_close(void *arg)
+{
+	xrep0_sock *s = arg;
+
+	nni_aio_close(&s->aio_getq);
+}
+
+static void
+xrep0_pipe_stop(void *arg)
+{
+	xrep0_pipe *p = arg;
+
+	nni_aio_stop(&p->aio_getq);
+	nni_aio_stop(&p->aio_send);
+	nni_aio_stop(&p->aio_recv);
+	nni_aio_stop(&p->aio_putq);
+}
+
+static void
+xrep0_pipe_fini(void *arg)
+{
+	xrep0_pipe *p = arg;
+
+	nni_aio_fini(&p->aio_getq);
+	nni_aio_fini(&p->aio_send);
+	nni_aio_fini(&p->aio_recv);
+	nni_aio_fini(&p->aio_putq);
+	nni_msgq_fini(p->sendq);
+}
+
+static int
+xrep0_pipe_init(void *arg, nni_pipe *pipe, void *s)
+{
+	xrep0_pipe *p = arg;
+	int         rv;
+
+	nni_aio_init(&p->aio_getq, xrep0_pipe_getq_cb, p);
+	nni_aio_init(&p->aio_send, xrep0_pipe_send_cb, p);
+	nni_aio_init(&p->aio_recv, xrep0_pipe_recv_cb, p);
+	nni_aio_init(&p->aio_putq, xrep0_pipe_putq_cb, p);
+
+	p->pipe = pipe;
+	p->rep  = s;
+
+	// We want a pretty deep send queue on pipes. The rationale here is
+	// that the send rate will be mitigated by the receive rate.
+	// If a slow pipe (req pipe not reading its own responses!?)
+	// comes up, then we will start discarding its replies eventually,
+	// but it takes some time.  It would be poor form for a peer to
+	// smash us with requests, but be unable to handle replies faster
+	// than we can forward them.  If they do that, their replies get
+	// dropped.  (From a DDoS perspective, it might be nice in the
+	// future if we had a way to exert back pressure to the send side --
+	// essentially don't let peers send requests faster than they are
+	// willing to receive replies.  Something to think about for the
+	// future.)
+	if ((rv = nni_msgq_init(&p->sendq, 64)) != 0) {
+		xrep0_pipe_fini(p);
+		return (rv);
+	}
+	return (0);
+}
+
+static int
+xrep0_pipe_start(void *arg)
+{
+	xrep0_pipe *p = arg;
+	xrep0_sock *s = p->rep;
+	int         rv;
+
+	if (nni_pipe_peer(p->pipe) != NNG_REP0_PEER) {
+		// Peer protocol mismatch.
+		return (NNG_EPROTO);
+	}
+
+	nni_mtx_lock(&s->lk);
+	rv = nni_id_set(&s->pipes, nni_pipe_id(p->pipe), p);
+	nni_mtx_unlock(&s->lk);
+	if (rv != 0) {
+		return (rv);
+	}
+
+	nni_msgq_aio_get(p->sendq, &p->aio_getq);
+	nni_pipe_recv(p->pipe, &p->aio_recv);
+	return (0);
+}
+
+static void
+xrep0_pipe_close(void *arg)
+{
+	xrep0_pipe *p = arg;
+	xrep0_sock *s = p->rep;
+
+	nni_aio_close(&p->aio_getq);
+	nni_aio_close(&p->aio_send);
+	nni_aio_close(&p->aio_recv);
+	nni_aio_close(&p->aio_putq);
+	nni_msgq_close(p->sendq);
+
+	nni_mtx_lock(&s->lk);
+	nni_id_remove(&s->pipes, nni_pipe_id(p->pipe));
+	nni_mtx_unlock(&s->lk);
+}
+
+static void
+xrep0_sock_getq_cb(void *arg)
+{
+	xrep0_sock *s   = arg;
+	nni_msgq *  uwq = s->uwq;
+	nni_msg *   msg;
+	uint32_t    id;
+	xrep0_pipe *p;
+
+	// This watches for messages from the upper write queue,
+	// extracts the destination pipe, and forwards it to the appropriate
+	// destination pipe via a separate queue.  This prevents a single bad
+	// or slow pipe from gumming up the works for the entire socket.
+
+	if (nni_aio_result(&s->aio_getq) != 0) {
+		// Closed socket?
+		return;
+	}
+
+	msg = nni_aio_get_msg(&s->aio_getq);
+	nni_aio_set_msg(&s->aio_getq, NULL);
+
+	// We yank the outgoing pipe id from the header
+	if (nni_msg_header_len(msg) < 4) {
+		nni_msg_free(msg);
+
+		// Look for another message on the upper write queue.
+		nni_msgq_aio_get(uwq, &s->aio_getq);
+		return;
+	}
+
+	id = nni_msg_header_trim_u32(msg);
+
+	// Look for the pipe, and attempt to put the message there
+	// (non-blocking) if we can.  If we can't for any reason, then we
+	// free the message.
+	nni_mtx_lock(&s->lk);
+	if (((p = nni_id_get(&s->pipes, id)) == NULL) ||
+	    (nni_msgq_tryput(p->sendq, msg) != 0)) {
+		nni_msg_free(msg);
+	}
+	nni_mtx_unlock(&s->lk);
+
+	// Now look for another message on the upper write queue.
+	nni_msgq_aio_get(uwq, &s->aio_getq);
+}
+
+static void
+xrep0_pipe_getq_cb(void *arg)
+{
+	xrep0_pipe *p = arg;
+
+	if (nni_aio_result(&p->aio_getq) != 0) {
+		nni_pipe_close(p->pipe);
+		return;
+	}
+
+	nni_aio_set_msg(&p->aio_send, nni_aio_get_msg(&p->aio_getq));
+	nni_aio_set_msg(&p->aio_getq, NULL);
+
+	nni_pipe_send(p->pipe, &p->aio_send);
+}
+
+static void
+xrep0_pipe_send_cb(void *arg)
+{
+	xrep0_pipe *p = arg;
+
+	if (nni_aio_result(&p->aio_send) != 0) {
+		nni_msg_free(nni_aio_get_msg(&p->aio_send));
+		nni_aio_set_msg(&p->aio_send, NULL);
+		nni_pipe_close(p->pipe);
+		return;
+	}
+
+	nni_msgq_aio_get(p->sendq, &p->aio_getq);
+}
+
+static void
+xrep0_pipe_recv_cb(void *arg)
+{
+	xrep0_pipe *p = arg;
+	xrep0_sock *s = p->rep;
+	nni_msg *   msg;
+	int         hops;
+	int         ttl;
+
+	if (nni_aio_result(&p->aio_recv) != 0) {
+		nni_pipe_close(p->pipe);
+		return;
+	}
+
+	ttl = nni_atomic_get(&s->ttl);
+
+	msg = nni_aio_get_msg(&p->aio_recv);
+	nni_aio_set_msg(&p->aio_recv, NULL);
+
+	nni_msg_set_pipe(msg, nni_pipe_id(p->pipe));
+
+	// Store the pipe id in the header, first thing.
+	nni_msg_header_append_u32(msg, nni_pipe_id(p->pipe));
+
+	// Move backtrace from body to header
+	hops = 1;
+	for (;;) {
+		bool     end;
+		uint8_t *body;
+		if (hops > ttl) {
+			// This isn't malformed, but it has gone through
+			// too many hops.  Do not disconnect, because we
+			// can legitimately receive messages with too many
+			// hops from devices, etc.
+			goto drop;
+		}
+		hops++;
+		if (nni_msg_len(msg) < 4) {
+			// Peer is speaking garbage. Kick it.
+			nni_msg_free(msg);
+			nni_pipe_close(p->pipe);
+			return;
+		}
+		body = nni_msg_body(msg);
+		end  = ((body[0] & 0x80u) != 0);
+		if (nni_msg_header_append(msg, body, 4) != 0) {
+			// Out of memory most likely, but keep going to
+			// avoid breaking things.
+			goto drop;
+		}
+		nni_msg_trim(msg, 4);
+		if (end) {
+			break;
+		}
+	}
+
+	// Go ahead and send it up.
+	nni_aio_set_msg(&p->aio_putq, msg);
+	nni_msgq_aio_put(s->urq, &p->aio_putq);
+	return;
+
+drop:
+	nni_msg_free(msg);
+	nni_pipe_recv(p->pipe, &p->aio_recv);
+}
+
+static void
+xrep0_pipe_putq_cb(void *arg)
+{
+	xrep0_pipe *p = arg;
+
+	if (nni_aio_result(&p->aio_putq) != 0) {
+		nni_msg_free(nni_aio_get_msg(&p->aio_putq));
+		nni_aio_set_msg(&p->aio_putq, NULL);
+		nni_pipe_close(p->pipe);
+		return;
+	}
+
+	nni_pipe_recv(p->pipe, &p->aio_recv);
+}
+
+static int
+xrep0_sock_set_maxttl(void *arg, const void *buf, size_t sz, nni_opt_type t)
+{
+	xrep0_sock *s = arg;
+	int         ttl;
+	int         rv;
+	if ((rv = nni_copyin_int(&ttl, buf, sz, 1, NNI_MAX_MAX_TTL, t)) == 0) {
+		nni_atomic_set(&s->ttl, ttl);
+	}
+	return (rv);
+}
+
+static int
+xrep0_sock_get_maxttl(void *arg, void *buf, size_t *szp, nni_opt_type t)
+{
+	xrep0_sock *s = arg;
+	return (nni_copyout_int(nni_atomic_get(&s->ttl), buf, szp, t));
+}
+
+static void
+xrep0_sock_send(void *arg, nni_aio *aio)
+{
+	xrep0_sock *s = arg;
+
+	nni_msgq_aio_put(s->uwq, aio);
+}
+
+static void
+xrep0_sock_recv(void *arg, nni_aio *aio)
+{
+	xrep0_sock *s = arg;
+
+	nni_msgq_aio_get(s->urq, aio);
+}
+
+// This is the global protocol structure -- our linkage to the core.
+// This should be the only global non-static symbol in this file.
+static nni_proto_pipe_ops xrep0_pipe_ops = {
+	.pipe_size  = sizeof(xrep0_pipe),
+	.pipe_init  = xrep0_pipe_init,
+	.pipe_fini  = xrep0_pipe_fini,
+	.pipe_start = xrep0_pipe_start,
+	.pipe_close = xrep0_pipe_close,
+	.pipe_stop  = xrep0_pipe_stop,
+};
+
+static nni_option xrep0_sock_options[] = {
+	{
+	    .o_name = NNG_OPT_MAXTTL,
+	    .o_get  = xrep0_sock_get_maxttl,
+	    .o_set  = xrep0_sock_set_maxttl,
+	},
+	// terminate list
+	{
+	    .o_name = NULL,
+	},
+};
+
+static nni_proto_sock_ops xrep0_sock_ops = {
+	.sock_size    = sizeof(xrep0_sock),
+	.sock_init    = xrep0_sock_init,
+	.sock_fini    = xrep0_sock_fini,
+	.sock_open    = xrep0_sock_open,
+	.sock_close   = xrep0_sock_close,
+	.sock_options = xrep0_sock_options,
+	.sock_send    = xrep0_sock_send,
+	.sock_recv    = xrep0_sock_recv,
+};
+
+static nni_proto xrep0_proto = {
+	.proto_version  = NNI_PROTOCOL_VERSION,
+	.proto_self     = { NNG_REP0_SELF, NNG_REP0_SELF_NAME },
+	.proto_peer     = { NNG_REP0_PEER, NNG_REP0_PEER_NAME },
+	.proto_flags    = NNI_PROTO_FLAG_SNDRCV | NNI_PROTO_FLAG_RAW,
+	.proto_sock_ops = &xrep0_sock_ops,
+	.proto_pipe_ops = &xrep0_pipe_ops,
+};
+
+int
+nng_rep0_open_raw(nng_socket *sidp)
+{
+	return (nni_proto_open(sidp, &xrep0_proto));
+}