Merge pull request #13414 from LabNConsulting/chopps/no-mgmtd-nowrite-on-off

[mirror_frr.git] / lib / mgmt_msg.c

// 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);
                MGMT_MSG_DBG(dbgtag, "got %zd bytes", n);

                /* -2 is normal nothing read, and to retry */
                if (n == -2)
                        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;
                }
                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);
        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;

                if (packf) {
                        buf = XMALLOC(MTYPE_TMP, mlen);
                        n = packf(msg, buf);
                }

                MGMT_MSG_DBG(dbgtag, "SC send: depth %u msg: %p",
                             ++conn->short_circuit_depth, msg);

                conn->remote_conn->handle_msg(version, buf, n,
                                              conn->remote_conn);

                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);
        client->conn.is_short_circuit = true;

        /* server side */
        memset(&su, 0, sizeof(union sockunion));
        server_conn = server->create(sockets[1], &su);
        server_conn->is_short_circuit = true;

        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);
}