Adding upstream version 9.1.upstream/9.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 928 insertions, 0 deletions

diff --git a/lib/mgmt_msg.c b/lib/mgmt_msg.c
new file mode 100644
index 0000000..1cd3240
--- /dev/null
+++ b/lib/mgmt_msg.c
@@ -0,0 +1,928 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * March 6 2023, Christian Hopps <chopps@labn.net>
+ *
+ * Copyright (C) 2021  Vmware, Inc.
+ *		       Pushpasis Sarkar <spushpasis@vmware.com>
+ * Copyright (c) 2023, LabN Consulting, L.L.C.
+ */
+#include <zebra.h>
+#include "debug.h"
+#include "network.h"
+#include "sockopt.h"
+#include "stream.h"
+#include "frrevent.h"
+#include "mgmt_msg.h"
+
+
+#define MGMT_MSG_DBG(dbgtag, fmt, ...)                                         \
+	do {                                                                   \
+		if (dbgtag)                                                    \
+			zlog_debug("%s: %s: " fmt, dbgtag, __func__,           \
+				   ##__VA_ARGS__);                             \
+	} while (0)
+
+#define MGMT_MSG_ERR(ms, fmt, ...)                                             \
+	zlog_err("%s: %s: " fmt, (ms)->idtag, __func__, ##__VA_ARGS__)
+
+DEFINE_MTYPE(LIB, MSG_CONN, "msg connection state");
+
+/**
+ * Read data from a socket into streams containing 1 or more full msgs headed by
+ * mgmt_msg_hdr which contain API messages (currently protobuf).
+ *
+ * Args:
+ *	ms: mgmt_msg_state for this process.
+ *	fd: socket/file to read data from.
+ *	debug: true to enable debug logging.
+ *
+ * Returns:
+ *	MPP_DISCONNECT - socket should be closed and connect retried.
+ *	MSV_SCHED_STREAM - this call should be rescheduled to run.
+ *	MPP_SCHED_BOTH - this call and the procmsg buf should be scheduled to
+ *run.
+ */
+enum mgmt_msg_rsched mgmt_msg_read(struct mgmt_msg_state *ms, int fd,
+				   bool debug)
+{
+	const char *dbgtag = debug ? ms->idtag : NULL;
+	size_t avail = STREAM_WRITEABLE(ms->ins);
+	struct mgmt_msg_hdr *mhdr = NULL;
+	size_t total = 0;
+	size_t mcount = 0;
+	ssize_t n, left;
+
+	assert(ms && fd != -1);
+
+	/*
+	 * Read as much as we can into the stream.
+	 */
+	while (avail > sizeof(struct mgmt_msg_hdr)) {
+		n = stream_read_try(ms->ins, fd, avail);
+
+		/* -2 is normal nothing read, and to retry */
+		if (n == -2) {
+			MGMT_MSG_DBG(dbgtag, "nothing more to read");
+			break;
+		}
+		if (n <= 0) {
+			if (n == 0)
+				MGMT_MSG_ERR(ms, "got EOF/disconnect");
+			else
+				MGMT_MSG_ERR(ms,
+					     "got error while reading: '%s'",
+					     safe_strerror(errno));
+			return MSR_DISCONNECT;
+		}
+		MGMT_MSG_DBG(dbgtag, "read %zd bytes", n);
+		ms->nrxb += n;
+		avail -= n;
+	}
+
+	/*
+	 * Check if we have read a complete messages or not.
+	 */
+	assert(stream_get_getp(ms->ins) == 0);
+	left = stream_get_endp(ms->ins);
+	while (left > (long)sizeof(struct mgmt_msg_hdr)) {
+		mhdr = (struct mgmt_msg_hdr *)(STREAM_DATA(ms->ins) + total);
+		if (!MGMT_MSG_IS_MARKER(mhdr->marker)) {
+			MGMT_MSG_DBG(dbgtag, "recv corrupt buffer, disconnect");
+			return MSR_DISCONNECT;
+		}
+		if ((ssize_t)mhdr->len > left)
+			break;
+
+		MGMT_MSG_DBG(dbgtag, "read full message len %u", mhdr->len);
+		total += mhdr->len;
+		left -= mhdr->len;
+		mcount++;
+	}
+
+	if (!mcount)
+		return MSR_SCHED_STREAM;
+
+	/*
+	 * We have read at least one message into the stream, queue it up.
+	 */
+	mhdr = (struct mgmt_msg_hdr *)(STREAM_DATA(ms->ins) + total);
+	stream_set_endp(ms->ins, total);
+	stream_fifo_push(&ms->inq, ms->ins);
+	ms->ins = stream_new(ms->max_msg_sz);
+	if (left) {
+		stream_put(ms->ins, mhdr, left);
+		stream_set_endp(ms->ins, left);
+	}
+
+	return MSR_SCHED_BOTH;
+}
+
+/**
+ * Process streams containing whole messages that have been pushed onto the
+ * FIFO. This should be called from an event/timer handler and should be
+ * reschedulable.
+ *
+ * Args:
+ *	ms: mgmt_msg_state for this process.
+ *	handle_mgs: function to call for each received message.
+ *	user: opaque value passed through to handle_msg.
+ *	debug: true to enable debug logging.
+ *
+ * Returns:
+ *	true if more to process (so reschedule) else false
+ */
+bool mgmt_msg_procbufs(struct mgmt_msg_state *ms,
+		       void (*handle_msg)(uint8_t version, uint8_t *msg,
+					  size_t msglen, void *user),
+		       void *user, bool debug)
+{
+	const char *dbgtag = debug ? ms->idtag : NULL;
+	struct mgmt_msg_hdr *mhdr;
+	struct stream *work;
+	uint8_t *data;
+	size_t left, nproc;
+
+	MGMT_MSG_DBG(dbgtag, "Have %zu streams to process", ms->inq.count);
+
+	nproc = 0;
+	while (nproc < ms->max_read_buf) {
+		work = stream_fifo_pop(&ms->inq);
+		if (!work)
+			break;
+
+		data = STREAM_DATA(work);
+		left = stream_get_endp(work);
+		MGMT_MSG_DBG(dbgtag, "Processing stream of len %zu", left);
+
+		for (; left > sizeof(struct mgmt_msg_hdr);
+		     left -= mhdr->len, data += mhdr->len) {
+			mhdr = (struct mgmt_msg_hdr *)data;
+
+			assert(MGMT_MSG_IS_MARKER(mhdr->marker));
+			assert(left >= mhdr->len);
+
+			handle_msg(MGMT_MSG_MARKER_VERSION(mhdr->marker),
+				   (uint8_t *)(mhdr + 1),
+				   mhdr->len - sizeof(struct mgmt_msg_hdr),
+				   user);
+			ms->nrxm++;
+			nproc++;
+		}
+
+		if (work != ms->ins)
+			stream_free(work); /* Free it up */
+		else
+			stream_reset(work); /* Reset stream for next read */
+	}
+
+	/* return true if should reschedule b/c more to process. */
+	return stream_fifo_head(&ms->inq) != NULL;
+}
+
+/**
+ * Write data from a onto the socket, using streams that have been queued for
+ * sending by mgmt_msg_send_msg. This function should be reschedulable.
+ *
+ * Args:
+ *	ms: mgmt_msg_state for this process.
+ *	fd: socket/file to read data from.
+ *	debug: true to enable debug logging.
+ *
+ * Returns:
+ *	MSW_SCHED_NONE - do not reschedule anything.
+ *	MSW_SCHED_STREAM - this call should be rescheduled to run again.
+ *	MSW_SCHED_WRITES_OFF - writes should be disabled with a timer to
+ *	    re-enable them a short time later
+ *	MSW_DISCONNECT - socket should be closed and reconnect retried.
+ *run.
+ */
+enum mgmt_msg_wsched mgmt_msg_write(struct mgmt_msg_state *ms, int fd,
+				    bool debug)
+{
+	const char *dbgtag = debug ? ms->idtag : NULL;
+	struct stream *s;
+	size_t nproc = 0;
+	ssize_t left;
+	ssize_t n;
+
+	if (ms->outs) {
+		MGMT_MSG_DBG(dbgtag,
+			     "found unqueued stream with %zu bytes, queueing",
+			     stream_get_endp(ms->outs));
+		stream_fifo_push(&ms->outq, ms->outs);
+		ms->outs = NULL;
+	}
+
+	for (s = stream_fifo_head(&ms->outq); s && nproc < ms->max_write_buf;
+	     s = stream_fifo_head(&ms->outq)) {
+		left = STREAM_READABLE(s);
+		assert(left);
+
+		n = stream_flush(s, fd);
+		if (n <= 0) {
+			if (n == 0)
+				MGMT_MSG_ERR(ms,
+					     "connection closed while writing");
+			else if (ERRNO_IO_RETRY(errno)) {
+				MGMT_MSG_DBG(
+					dbgtag,
+					"retry error while writing %zd bytes: %s (%d)",
+					left, safe_strerror(errno), errno);
+				return MSW_SCHED_STREAM;
+			} else
+				MGMT_MSG_ERR(
+					ms,
+					"error while writing %zd bytes: %s (%d)",
+					left, safe_strerror(errno), errno);
+
+			n = mgmt_msg_reset_writes(ms);
+			MGMT_MSG_DBG(dbgtag, "drop and freed %zd streams", n);
+
+			return MSW_DISCONNECT;
+		}
+
+		ms->ntxb += n;
+		if (n != left) {
+			MGMT_MSG_DBG(dbgtag, "short stream write %zd of %zd", n,
+				     left);
+			stream_forward_getp(s, n);
+			return MSW_SCHED_STREAM;
+		}
+
+		stream_free(stream_fifo_pop(&ms->outq));
+		MGMT_MSG_DBG(dbgtag, "wrote stream of %zd bytes", n);
+		nproc++;
+	}
+	if (s) {
+		MGMT_MSG_DBG(
+			dbgtag,
+			"reached %zu buffer writes, pausing with %zu streams left",
+			ms->max_write_buf, ms->outq.count);
+		return MSW_SCHED_STREAM;
+	}
+	MGMT_MSG_DBG(dbgtag, "flushed all streams from output q");
+	return MSW_SCHED_NONE;
+}
+
+
+/**
+ * Send a message by enqueueing it to be written over the socket by
+ * mgmt_msg_write.
+ *
+ * Args:
+ *	ms: mgmt_msg_state for this process.
+ *	version: version of this message, will be given to receiving side.
+ *	msg: the message to be sent.
+ *	len: the length of the message.
+ *	packf: a function to pack the message.
+ *	debug: true to enable debug logging.
+ *
+ * Returns:
+ *      0 on success, otherwise -1 on failure. The only failure mode is if a
+ *      the message exceeds the maximum message size configured on init.
+ */
+int mgmt_msg_send_msg(struct mgmt_msg_state *ms, uint8_t version, void *msg,
+		      size_t len, size_t (*packf)(void *msg, void *buf),
+		      bool debug)
+{
+	const char *dbgtag = debug ? ms->idtag : NULL;
+	struct mgmt_msg_hdr *mhdr;
+	struct stream *s;
+	uint8_t *dstbuf;
+	size_t endp, n;
+	size_t mlen = len + sizeof(*mhdr);
+
+	if (mlen > ms->max_msg_sz) {
+		MGMT_MSG_ERR(ms, "Message %zu > max size %zu, dropping", mlen,
+			     ms->max_msg_sz);
+		return -1;
+	}
+
+	if (!ms->outs) {
+		MGMT_MSG_DBG(dbgtag, "creating new stream for msg len %zu",
+			     len);
+		ms->outs = stream_new(ms->max_msg_sz);
+	} else if (STREAM_WRITEABLE(ms->outs) < mlen) {
+		MGMT_MSG_DBG(
+			dbgtag,
+			"enq existing stream len %zu and creating new stream for msg len %zu",
+			STREAM_WRITEABLE(ms->outs), mlen);
+		stream_fifo_push(&ms->outq, ms->outs);
+		ms->outs = stream_new(ms->max_msg_sz);
+	} else {
+		MGMT_MSG_DBG(
+			dbgtag,
+			"using existing stream with avail %zu for msg len %zu",
+			STREAM_WRITEABLE(ms->outs), mlen);
+	}
+	s = ms->outs;
+
+	/* We have a stream with space, pack the message into it. */
+	mhdr = (struct mgmt_msg_hdr *)(STREAM_DATA(s) + s->endp);
+	mhdr->marker = MGMT_MSG_MARKER(version);
+	mhdr->len = mlen;
+	stream_forward_endp(s, sizeof(*mhdr));
+	endp = stream_get_endp(s);
+	dstbuf = STREAM_DATA(s) + endp;
+	if (packf)
+		n = packf(msg, dstbuf);
+	else {
+		memcpy(dstbuf, msg, len);
+		n = len;
+	}
+	stream_set_endp(s, endp + n);
+	ms->ntxm++;
+
+	return 0;
+}
+
+/**
+ * Create and open a unix domain stream socket on the given path
+ * setting non-blocking and send and receive buffer sizes.
+ *
+ * Args:
+ *	path: path of unix domain socket to connect to.
+ *	sendbuf: size of socket send buffer.
+ *	recvbuf: size of socket receive buffer.
+ *	dbgtag: if non-NULL enable log debug, and use this tag.
+ *
+ * Returns:
+ *	socket fd or -1 on error.
+ */
+int mgmt_msg_connect(const char *path, size_t sendbuf, size_t recvbuf,
+		     const char *dbgtag)
+{
+	int ret, sock, len;
+	struct sockaddr_un addr;
+
+	MGMT_MSG_DBG(dbgtag, "connecting to server on %s", path);
+	sock = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (sock < 0) {
+		MGMT_MSG_DBG(dbgtag, "socket failed: %s", safe_strerror(errno));
+		return -1;
+	}
+
+	memset(&addr, 0, sizeof(struct sockaddr_un));
+	addr.sun_family = AF_UNIX;
+	strlcpy(addr.sun_path, path, sizeof(addr.sun_path));
+#ifdef HAVE_STRUCT_SOCKADDR_UN_SUN_LEN
+	len = addr.sun_len = SUN_LEN(&addr);
+#else
+	len = sizeof(addr.sun_family) + strlen(addr.sun_path);
+#endif /* HAVE_STRUCT_SOCKADDR_UN_SUN_LEN */
+	ret = connect(sock, (struct sockaddr *)&addr, len);
+	if (ret < 0) {
+		MGMT_MSG_DBG(dbgtag, "failed to connect on %s: %s", path,
+			     safe_strerror(errno));
+		close(sock);
+		return -1;
+	}
+
+	MGMT_MSG_DBG(dbgtag, "connected to server on %s", path);
+	set_nonblocking(sock);
+	setsockopt_so_sendbuf(sock, sendbuf);
+	setsockopt_so_recvbuf(sock, recvbuf);
+	return sock;
+}
+
+/**
+ * Reset the sending queue, by dequeueing all streams and freeing them. Return
+ * the number of streams freed.
+ *
+ * Args:
+ *	ms: mgmt_msg_state for this process.
+ *
+ * Returns:
+ *      Number of streams that were freed.
+ *
+ */
+size_t mgmt_msg_reset_writes(struct mgmt_msg_state *ms)
+{
+	struct stream *s;
+	size_t nproc = 0;
+
+	for (s = stream_fifo_pop(&ms->outq); s;
+	     s = stream_fifo_pop(&ms->outq), nproc++)
+		stream_free(s);
+
+	return nproc;
+}
+
+
+void mgmt_msg_init(struct mgmt_msg_state *ms, size_t max_read_buf,
+		   size_t max_write_buf, size_t max_msg_sz, const char *idtag)
+{
+	memset(ms, 0, sizeof(*ms));
+	ms->ins = stream_new(max_msg_sz);
+	stream_fifo_init(&ms->inq);
+	stream_fifo_init(&ms->outq);
+	ms->max_read_buf = max_write_buf;
+	ms->max_write_buf = max_read_buf;
+	ms->max_msg_sz = max_msg_sz;
+	ms->idtag = strdup(idtag);
+}
+
+void mgmt_msg_destroy(struct mgmt_msg_state *ms)
+{
+	mgmt_msg_reset_writes(ms);
+	if (ms->ins)
+		stream_free(ms->ins);
+	if (ms->outs)
+		stream_free(ms->outs);
+	free(ms->idtag);
+}
+
+/*
+ * Connections
+ */
+
+#define MSG_CONN_DEFAULT_CONN_RETRY_MSEC 250
+#define MSG_CONN_SEND_BUF_SIZE (1u << 16)
+#define MSG_CONN_RECV_BUF_SIZE (1u << 16)
+
+static void msg_client_sched_connect(struct msg_client *client,
+				     unsigned long msec);
+
+static void msg_conn_sched_proc_msgs(struct msg_conn *conn);
+static void msg_conn_sched_read(struct msg_conn *conn);
+static void msg_conn_sched_write(struct msg_conn *conn);
+
+static void msg_conn_write(struct event *thread)
+{
+	struct msg_conn *conn = EVENT_ARG(thread);
+	enum mgmt_msg_wsched rv;
+
+	rv = mgmt_msg_write(&conn->mstate, conn->fd, conn->debug);
+	if (rv == MSW_SCHED_STREAM)
+		msg_conn_sched_write(conn);
+	else if (rv == MSW_DISCONNECT)
+		msg_conn_disconnect(conn, conn->is_client);
+	else
+		assert(rv == MSW_SCHED_NONE);
+}
+
+static void msg_conn_read(struct event *thread)
+{
+	struct msg_conn *conn = EVENT_ARG(thread);
+	enum mgmt_msg_rsched rv;
+
+	rv = mgmt_msg_read(&conn->mstate, conn->fd, conn->debug);
+	if (rv == MSR_DISCONNECT) {
+		msg_conn_disconnect(conn, conn->is_client);
+		return;
+	}
+	if (rv == MSR_SCHED_BOTH)
+		msg_conn_sched_proc_msgs(conn);
+	msg_conn_sched_read(conn);
+}
+
+/* collapse this into mgmt_msg_procbufs */
+static void msg_conn_proc_msgs(struct event *thread)
+{
+	struct msg_conn *conn = EVENT_ARG(thread);
+
+	if (mgmt_msg_procbufs(&conn->mstate,
+			      (void (*)(uint8_t, uint8_t *, size_t,
+					void *))conn->handle_msg,
+			      conn, conn->debug))
+		/* there's more, schedule handling more */
+		msg_conn_sched_proc_msgs(conn);
+}
+
+static void msg_conn_sched_read(struct msg_conn *conn)
+{
+	event_add_read(conn->loop, msg_conn_read, conn, conn->fd,
+		       &conn->read_ev);
+}
+
+static void msg_conn_sched_write(struct msg_conn *conn)
+{
+	event_add_write(conn->loop, msg_conn_write, conn, conn->fd,
+			&conn->write_ev);
+}
+
+static void msg_conn_sched_proc_msgs(struct msg_conn *conn)
+{
+	event_add_event(conn->loop, msg_conn_proc_msgs, conn, 0,
+			&conn->proc_msg_ev);
+}
+
+
+void msg_conn_disconnect(struct msg_conn *conn, bool reconnect)
+{
+
+	/* disconnect short-circuit if present */
+	if (conn->remote_conn) {
+		conn->remote_conn->remote_conn = NULL;
+		conn->remote_conn = NULL;
+	}
+
+	if (conn->fd != -1) {
+		close(conn->fd);
+		conn->fd = -1;
+
+		/* Notify client through registered callback (if any) */
+		if (conn->notify_disconnect)
+			(void)(*conn->notify_disconnect)(conn);
+	}
+
+	if (reconnect) {
+		assert(conn->is_client);
+		msg_client_sched_connect(
+			container_of(conn, struct msg_client, conn),
+			MSG_CONN_DEFAULT_CONN_RETRY_MSEC);
+	}
+}
+
+int msg_conn_send_msg(struct msg_conn *conn, uint8_t version, void *msg,
+		      size_t mlen, size_t (*packf)(void *, void *),
+		      bool short_circuit_ok)
+{
+	const char *dbgtag = conn->debug ? conn->mstate.idtag : NULL;
+
+	if (conn->fd == -1) {
+		MGMT_MSG_ERR(&conn->mstate,
+			     "can't send message on closed connection");
+		return -1;
+	}
+
+	/* immediately handle the message if short-circuit is present */
+	if (conn->remote_conn && short_circuit_ok) {
+		uint8_t *buf = msg;
+		size_t n = mlen;
+		bool old;
+
+		if (packf) {
+			buf = XMALLOC(MTYPE_TMP, mlen);
+			n = packf(msg, buf);
+		}
+
+		++conn->short_circuit_depth;
+		MGMT_MSG_DBG(dbgtag, "SC send: depth %u msg: %p",
+			     conn->short_circuit_depth, msg);
+
+		old = conn->remote_conn->is_short_circuit;
+		conn->remote_conn->is_short_circuit = true;
+		conn->remote_conn->handle_msg(version, buf, n,
+					      conn->remote_conn);
+		conn->remote_conn->is_short_circuit = old;
+
+		--conn->short_circuit_depth;
+		MGMT_MSG_DBG(dbgtag, "SC return from depth: %u msg: %p",
+			     conn->short_circuit_depth, msg);
+
+		if (packf)
+			XFREE(MTYPE_TMP, buf);
+		return 0;
+	}
+
+	int rv = mgmt_msg_send_msg(&conn->mstate, version, msg, mlen, packf,
+				   conn->debug);
+
+	msg_conn_sched_write(conn);
+
+	return rv;
+}
+
+void msg_conn_cleanup(struct msg_conn *conn)
+{
+	struct mgmt_msg_state *ms = &conn->mstate;
+
+	/* disconnect short-circuit if present */
+	if (conn->remote_conn) {
+		conn->remote_conn->remote_conn = NULL;
+		conn->remote_conn = NULL;
+	}
+
+	if (conn->fd != -1) {
+		close(conn->fd);
+		conn->fd = -1;
+	}
+
+	EVENT_OFF(conn->read_ev);
+	EVENT_OFF(conn->write_ev);
+	EVENT_OFF(conn->proc_msg_ev);
+
+	mgmt_msg_destroy(ms);
+}
+
+/*
+ * Client Connections
+ */
+
+DECLARE_LIST(msg_server_list, struct msg_server, link);
+
+static struct msg_server_list_head msg_servers;
+
+static void msg_client_connect(struct msg_client *conn);
+
+static void msg_client_connect_timer(struct event *thread)
+{
+	msg_client_connect(EVENT_ARG(thread));
+}
+
+static void msg_client_sched_connect(struct msg_client *client,
+				     unsigned long msec)
+{
+	struct msg_conn *conn = &client->conn;
+	const char *dbgtag = conn->debug ? conn->mstate.idtag : NULL;
+
+	MGMT_MSG_DBG(dbgtag, "connection retry in %lu msec", msec);
+	if (msec)
+		event_add_timer_msec(conn->loop, msg_client_connect_timer,
+				     client, msec, &client->conn_retry_tmr);
+	else
+		event_add_event(conn->loop, msg_client_connect_timer, client, 0,
+				&client->conn_retry_tmr);
+}
+
+static bool msg_client_connect_short_circuit(struct msg_client *client)
+{
+	struct msg_conn *server_conn;
+	struct msg_server *server;
+	const char *dbgtag =
+		client->conn.debug ? client->conn.mstate.idtag : NULL;
+	union sockunion su = {0};
+	int sockets[2];
+
+	frr_each (msg_server_list, &msg_servers, server)
+		if (!strcmp(server->sopath, client->sopath))
+			break;
+	if (!server) {
+		MGMT_MSG_DBG(dbgtag,
+			     "no short-circuit connection available for %s",
+			     client->sopath);
+
+		return false;
+	}
+
+	if (socketpair(AF_UNIX, SOCK_STREAM, 0, sockets)) {
+		MGMT_MSG_ERR(
+			&client->conn.mstate,
+			"socketpair failed trying to short-circuit connection on %s: %s",
+			client->sopath, safe_strerror(errno));
+		return false;
+	}
+
+	/* client side */
+	client->conn.fd = sockets[0];
+	set_nonblocking(sockets[0]);
+	setsockopt_so_sendbuf(sockets[0], client->conn.mstate.max_write_buf);
+	setsockopt_so_recvbuf(sockets[0], client->conn.mstate.max_read_buf);
+
+	/* server side */
+	memset(&su, 0, sizeof(union sockunion));
+	server_conn = server->create(sockets[1], &su);
+
+	client->conn.remote_conn = server_conn;
+	server_conn->remote_conn = &client->conn;
+
+	MGMT_MSG_DBG(
+		dbgtag,
+		"short-circuit connection on %s server %s:%d to client %s:%d",
+		client->sopath, server_conn->mstate.idtag, server_conn->fd,
+		client->conn.mstate.idtag, client->conn.fd);
+
+	MGMT_MSG_DBG(
+		server_conn->debug ? server_conn->mstate.idtag : NULL,
+		"short-circuit connection on %s client %s:%d to server %s:%d",
+		client->sopath, client->conn.mstate.idtag, client->conn.fd,
+		server_conn->mstate.idtag, server_conn->fd);
+
+	return true;
+}
+
+
+/* Connect and start reading from the socket */
+static void msg_client_connect(struct msg_client *client)
+{
+	struct msg_conn *conn = &client->conn;
+	const char *dbgtag = conn->debug ? conn->mstate.idtag : NULL;
+
+	if (!client->short_circuit_ok ||
+	    !msg_client_connect_short_circuit(client))
+		conn->fd =
+			mgmt_msg_connect(client->sopath, MSG_CONN_SEND_BUF_SIZE,
+					 MSG_CONN_RECV_BUF_SIZE, dbgtag);
+
+	if (conn->fd == -1)
+		/* retry the connection */
+		msg_client_sched_connect(client,
+					 MSG_CONN_DEFAULT_CONN_RETRY_MSEC);
+	else if (client->notify_connect && client->notify_connect(client))
+		/* client connect notify failed */
+		msg_conn_disconnect(conn, true);
+	else
+		/* start reading */
+		msg_conn_sched_read(conn);
+}
+
+void msg_client_init(struct msg_client *client, struct event_loop *tm,
+		     const char *sopath,
+		     int (*notify_connect)(struct msg_client *client),
+		     int (*notify_disconnect)(struct msg_conn *client),
+		     void (*handle_msg)(uint8_t version, uint8_t *data,
+					size_t len, struct msg_conn *client),
+		     size_t max_read_buf, size_t max_write_buf,
+		     size_t max_msg_sz, bool short_circuit_ok,
+		     const char *idtag, bool debug)
+{
+	struct msg_conn *conn = &client->conn;
+	memset(client, 0, sizeof(*client));
+
+	conn->loop = tm;
+	conn->fd = -1;
+	conn->handle_msg = handle_msg;
+	conn->notify_disconnect = notify_disconnect;
+	conn->is_client = true;
+	conn->debug = debug;
+	client->short_circuit_ok = short_circuit_ok;
+	client->sopath = strdup(sopath);
+	client->notify_connect = notify_connect;
+
+	mgmt_msg_init(&conn->mstate, max_read_buf, max_write_buf, max_msg_sz,
+		      idtag);
+
+	/* XXX maybe just have client kick this off */
+	/* Start trying to connect to server */
+	msg_client_sched_connect(client, 0);
+}
+
+void msg_client_cleanup(struct msg_client *client)
+{
+	assert(client->conn.is_client);
+
+	EVENT_OFF(client->conn_retry_tmr);
+	free(client->sopath);
+
+	msg_conn_cleanup(&client->conn);
+}
+
+
+/*
+ * Server-side connections
+ */
+
+static void msg_server_accept(struct event *event)
+{
+	struct msg_server *server = EVENT_ARG(event);
+	int fd;
+	union sockunion su;
+
+	if (server->fd < 0)
+		return;
+
+	/* We continue hearing server listen socket. */
+	event_add_read(server->loop, msg_server_accept, server, server->fd,
+		       &server->listen_ev);
+
+	memset(&su, 0, sizeof(union sockunion));
+
+	/* We can handle IPv4 or IPv6 socket. */
+	fd = sockunion_accept(server->fd, &su);
+	if (fd < 0) {
+		zlog_err("Failed to accept %s client connection: %s",
+			 server->idtag, safe_strerror(errno));
+		return;
+	}
+	set_nonblocking(fd);
+	set_cloexec(fd);
+
+	DEBUGD(server->debug, "Accepted new %s connection", server->idtag);
+
+	server->create(fd, &su);
+}
+
+int msg_server_init(struct msg_server *server, const char *sopath,
+		    struct event_loop *loop,
+		    struct msg_conn *(*create)(int fd, union sockunion *su),
+		    const char *idtag, struct debug *debug)
+{
+	int ret;
+	int sock;
+	struct sockaddr_un addr;
+	mode_t old_mask;
+
+	memset(server, 0, sizeof(*server));
+	server->fd = -1;
+
+	sock = socket(AF_UNIX, SOCK_STREAM, PF_UNSPEC);
+	if (sock < 0) {
+		zlog_err("Failed to create %s server socket: %s", server->idtag,
+			 safe_strerror(errno));
+		goto fail;
+	}
+
+	addr.sun_family = AF_UNIX,
+	strlcpy(addr.sun_path, sopath, sizeof(addr.sun_path));
+	unlink(addr.sun_path);
+	old_mask = umask(0077);
+	ret = bind(sock, (struct sockaddr *)&addr, sizeof(addr));
+	if (ret < 0) {
+		zlog_err("Failed to bind %s server socket to '%s': %s",
+			 server->idtag, addr.sun_path, safe_strerror(errno));
+		umask(old_mask);
+		goto fail;
+	}
+	umask(old_mask);
+
+	ret = listen(sock, MGMTD_MAX_CONN);
+	if (ret < 0) {
+		zlog_err("Failed to listen on %s server socket: %s",
+			 server->idtag, safe_strerror(errno));
+		goto fail;
+	}
+
+	server->fd = sock;
+	server->loop = loop;
+	server->sopath = strdup(sopath);
+	server->idtag = strdup(idtag);
+	server->create = create;
+	server->debug = debug;
+
+	msg_server_list_add_head(&msg_servers, server);
+
+	event_add_read(server->loop, msg_server_accept, server, server->fd,
+		       &server->listen_ev);
+
+
+	DEBUGD(debug, "Started %s server, listening on %s", idtag, sopath);
+	return 0;
+
+fail:
+	if (sock >= 0)
+		close(sock);
+	server->fd = -1;
+	return -1;
+}
+
+void msg_server_cleanup(struct msg_server *server)
+{
+	DEBUGD(server->debug, "Closing %s server", server->idtag);
+
+	if (server->listen_ev)
+		EVENT_OFF(server->listen_ev);
+
+	msg_server_list_del(&msg_servers, server);
+
+	if (server->fd >= 0)
+		close(server->fd);
+	free((char *)server->sopath);
+	free((char *)server->idtag);
+
+	memset(server, 0, sizeof(*server));
+	server->fd = -1;
+}
+
+/*
+ * Initialize and start reading from the accepted socket
+ *
+ *     notify_connect - only called for disconnect i.e., connected == false
+ */
+void msg_conn_accept_init(struct msg_conn *conn, struct event_loop *tm, int fd,
+			  int (*notify_disconnect)(struct msg_conn *conn),
+			  void (*handle_msg)(uint8_t version, uint8_t *data,
+					     size_t len, struct msg_conn *conn),
+			  size_t max_read, size_t max_write, size_t max_size,
+			  const char *idtag)
+{
+	conn->loop = tm;
+	conn->fd = fd;
+	conn->notify_disconnect = notify_disconnect;
+	conn->handle_msg = handle_msg;
+	conn->is_client = false;
+
+	mgmt_msg_init(&conn->mstate, max_read, max_write, max_size, idtag);
+
+	/* start reading */
+	msg_conn_sched_read(conn);
+
+	/* Make socket non-blocking.  */
+	set_nonblocking(conn->fd);
+	setsockopt_so_sendbuf(conn->fd, MSG_CONN_SEND_BUF_SIZE);
+	setsockopt_so_recvbuf(conn->fd, MSG_CONN_RECV_BUF_SIZE);
+}
+
+struct msg_conn *
+msg_server_conn_create(struct event_loop *tm, int fd,
+		       int (*notify_disconnect)(struct msg_conn *conn),
+		       void (*handle_msg)(uint8_t version, uint8_t *data,
+					  size_t len, struct msg_conn *conn),
+		       size_t max_read, size_t max_write, size_t max_size,
+		       void *user, const char *idtag)
+{
+	struct msg_conn *conn = XMALLOC(MTYPE_MSG_CONN, sizeof(*conn));
+	memset(conn, 0, sizeof(*conn));
+	msg_conn_accept_init(conn, tm, fd, notify_disconnect, handle_msg,
+			     max_read, max_write, max_size, idtag);
+	conn->user = user;
+	return conn;
+}
+
+void msg_server_conn_delete(struct msg_conn *conn)
+{
+	if (!conn)
+		return;
+	msg_conn_cleanup(conn);
+	XFREE(MTYPE_MSG_CONN, conn);
+}