/*      $OpenBSD: control.c,v 1.11 2023/03/08 04:43:13 guenther Exp $ */

/*
 * Copyright (c) 2010 Claudio Jeker <claudio@openbsd.org>
 * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/queue.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <sys/un.h>
#include <errno.h>
#include <event.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "iscsid.h"
#include "log.h"

struct control {
        struct event            ev;
        struct pduq             channel;
        int                     fd;
};

struct control_state {
        struct event            ev;
        struct event            evt;
        int                     fd;
} *control_state;

#define CONTROL_BACKLOG 5

void    control_accept(int, short, void *);
void    control_close(struct control *);
void    control_dispatch(int, short, void *);
struct pdu *control_getpdu(char *, size_t);

int
control_init(char *path)
{
        struct sockaddr_un       sun;
        int                      fd;
        mode_t                   old_umask;

        if ((control_state = calloc(1, sizeof(*control_state))) == NULL) {
                log_warn("control_init: calloc");
                return -1;
        }

        if ((fd = socket(AF_UNIX, SOCK_SEQPACKET, 0)) == -1) {
                log_warn("control_init: socket");
                return -1;
        }

        bzero(&sun, sizeof(sun));
        sun.sun_family = AF_UNIX;
        if (strlcpy(sun.sun_path, path, sizeof(sun.sun_path)) >=
            sizeof(sun.sun_path)) {
                log_warnx("control_init: path %s too long", path);
                close(fd);
                return -1;
        }

        if (unlink(path) == -1)
                if (errno != ENOENT) {
                        log_warn("control_init: unlink %s", path);
                        close(fd);
                        return -1;
                }

        old_umask = umask(S_IXUSR|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH);
        if (bind(fd, (struct sockaddr *)&sun, sizeof(sun)) == -1) {
                log_warn("control_init: bind: %s", path);
                close(fd);
                umask(old_umask);
                return -1;
        }
        umask(old_umask);

        if (chmod(path, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP) == -1) {
                log_warn("control_init: chmod");
                close(fd);
                (void)unlink(path);
                return -1;
        }

        if (listen(fd, CONTROL_BACKLOG) == -1) {
                log_warn("control_init: listen");
                close(fd);
                (void)unlink(path);
                return -1;
        }

        socket_setblockmode(fd, 1);
        control_state->fd = fd;

        return 0;
}

void
control_cleanup(char *path)
{
        if (path)
                unlink(path);

        event_del(&control_state->ev);
        event_del(&control_state->evt);
        close(control_state->fd);
        free(control_state);
}

void
control_event_init(void)
{
        event_set(&control_state->ev, control_state->fd, EV_READ,
            control_accept, NULL);
        event_add(&control_state->ev, NULL);
        evtimer_set(&control_state->evt, control_accept, NULL);
}

void
control_accept(int listenfd, short event, void *bula)
{
        int                      connfd;
        socklen_t                len;
        struct sockaddr_un       sun;
        struct control          *c;

        event_add(&control_state->ev, NULL);
        if ((event & EV_TIMEOUT))
                return;

        len = sizeof(sun);
        if ((connfd = accept(listenfd,
            (struct sockaddr *)&sun, &len)) == -1) {
                /*
                 * Pause accept if we are out of file descriptors, or
                 * libevent will haunt us here too.
                 */
                if (errno == ENFILE || errno == EMFILE) {
                        struct timeval evtpause = { 1, 0 };

                        event_del(&control_state->ev);
                        evtimer_add(&control_state->evt, &evtpause);
                } else if (errno != EWOULDBLOCK && errno != EINTR &&
                    errno != ECONNABORTED)
                        log_warn("control_accept");
                return;
        }

        if ((c = malloc(sizeof(struct control))) == NULL) {
                log_warn("control_accept");
                close(connfd);
                return;
        }

        TAILQ_INIT(&c->channel);
        c->fd = connfd;
        event_set(&c->ev, connfd, EV_READ, control_dispatch, c);
        event_add(&c->ev, NULL);
}

void
control_close(struct control *c)
{
        event_del(&c->ev);
        close(c->fd);

        /* Some file descriptors are available again. */
        if (evtimer_pending(&control_state->evt, NULL)) {
                evtimer_del(&control_state->evt);
                event_add(&control_state->ev, NULL);
        }

        pdu_free_queue(&c->channel);
        free(c);
}

static char     cbuf[CONTROL_READ_SIZE];

void
control_dispatch(int fd, short event, void *bula)
{
        struct iovec iov[PDU_MAXIOV];
        struct msghdr msg;
        struct control *c = bula;
        struct pdu *pdu;
        ssize_t  n;
        unsigned int niov = 0;
        short flags = EV_READ;

        if (event & EV_TIMEOUT) {
                log_debug("control connection (fd %d) timed out.", fd);
                control_close(c);
                return;
        }
        if (event & EV_READ) {
                if ((n = recv(fd, cbuf, sizeof(cbuf), 0)) == -1 &&
                    !(errno == EAGAIN || errno == EINTR)) {
                        control_close(c);
                        return;
                }
                if (n == 0) {
                        control_close(c);
                        return;
                }
                pdu = control_getpdu(cbuf, n);
                if (!pdu) {
                        log_debug("control connection (fd %d) bad msg.", fd);
                        control_close(c);
                        return;
                }
                iscsid_ctrl_dispatch(c, pdu);
        }
        if (event & EV_WRITE) {
                if ((pdu = TAILQ_FIRST(&c->channel)) != NULL) {
                        for (niov = 0; niov < PDU_MAXIOV; niov++) {
                                iov[niov].iov_base = pdu->iov[niov].iov_base;
                                iov[niov].iov_len = pdu->iov[niov].iov_len;
                        }
                        bzero(&msg, sizeof(msg));
                        msg.msg_iov = iov;
                        msg.msg_iovlen = niov;
                        if (sendmsg(fd, &msg, 0) == -1) {
                                if (errno == EAGAIN || errno == ENOBUFS)
                                        goto requeue;
                                control_close(c);
                                return;
                        }
                        TAILQ_REMOVE(&c->channel, pdu, entry);
                }
        }
requeue:
        if (!TAILQ_EMPTY(&c->channel))
                flags |= EV_WRITE;

        event_del(&c->ev);
        event_set(&c->ev, fd, flags, control_dispatch, c);
        event_add(&c->ev, NULL);
}

struct pdu *
control_getpdu(char *buf, size_t len)
{
        struct pdu *p;
        struct ctrlmsghdr *cmh;
        void *data;
        size_t n;
        int i;

        if (len < sizeof(*cmh))
                return NULL;

        if (!(p = pdu_new()))
                return NULL;

        n = sizeof(*cmh);
        cmh = pdu_alloc(n);
        memcpy(cmh, buf, n);
        buf += n;
        len -= n;

        if (pdu_addbuf(p, cmh, n, 0)) {
                free(cmh);
fail:
                pdu_free(p);
                return NULL;
        }

        for (i = 0; i < 3; i++) {
                n = cmh->len[i];
                if (n == 0)
                        continue;
                if (PDU_LEN(n) > len)
                        goto fail;
                if (!(data = pdu_alloc(n)))
                        goto fail;
                memcpy(data, buf, n);
                if (pdu_addbuf(p, data, n, i + 1)) {
                        free(data);
                        goto fail;
                }
                buf += PDU_LEN(n);
                len -= PDU_LEN(n);
        }

        return p;
}

void
control_queue(void *ch, struct pdu *pdu)
{
        struct control *c = ch;

        TAILQ_INSERT_TAIL(&c->channel, pdu, entry);

        event_del(&c->ev);
        event_set(&c->ev, c->fd, EV_READ|EV_WRITE, control_dispatch, c);
        event_add(&c->ev, NULL);
}