/*      $OpenBSD: imsg.c,v 1.13 2015/12/09 11:54:12 tb Exp $    */

/*
 * 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/socket.h>
#include <sys/uio.h>

#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "imsg.h"

int      imsg_fd_overhead = 0;

int      imsg_get_fd(struct imsgbuf *);

void
imsg_init(struct imsgbuf *ibuf, int fd)
{
        msgbuf_init(&ibuf->w);
        memset(&ibuf->r, 0, sizeof(ibuf->r));
        ibuf->fd = fd;
        ibuf->w.fd = fd;
        ibuf->pid = getpid();
        TAILQ_INIT(&ibuf->fds);
}

ssize_t
imsg_read(struct imsgbuf *ibuf)
{
        struct msghdr            msg;
        struct cmsghdr          *cmsg;
        union {
                struct cmsghdr hdr;
                char    buf[CMSG_SPACE(sizeof(int) * 1)];
        } cmsgbuf;
        struct iovec             iov;
        ssize_t                  n = -1;
        int                      fd;
        struct imsg_fd          *ifd;

        memset(&msg, 0, sizeof(msg));
        memset(&cmsgbuf, 0, sizeof(cmsgbuf));

        iov.iov_base = ibuf->r.buf + ibuf->r.wpos;
        iov.iov_len = sizeof(ibuf->r.buf) - ibuf->r.wpos;
        msg.msg_iov = &iov;
        msg.msg_iovlen = 1;
        msg.msg_control = &cmsgbuf.buf;
        msg.msg_controllen = sizeof(cmsgbuf.buf);

        if ((ifd = calloc(1, sizeof(struct imsg_fd))) == NULL)
                return (-1);

again:
        if (getdtablecount() + imsg_fd_overhead +
            (int)((CMSG_SPACE(sizeof(int))-CMSG_SPACE(0))/sizeof(int))
            >= getdtablesize()) {
                errno = EAGAIN;
                free(ifd);
                return (-1);
        }

        if ((n = recvmsg(ibuf->fd, &msg, 0)) == -1) {
                if (errno == EINTR)
                        goto again;
                goto fail;
        }

        ibuf->r.wpos += n;

        for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
            cmsg = CMSG_NXTHDR(&msg, cmsg)) {
                if (cmsg->cmsg_level == SOL_SOCKET &&
                    cmsg->cmsg_type == SCM_RIGHTS) {
                        int i;
                        int j;

                        /*
                         * We only accept one file descriptor.  Due to C
                         * padding rules, our control buffer might contain
                         * more than one fd, and we must close them.
                         */
                        j = ((char *)cmsg + cmsg->cmsg_len -
                            (char *)CMSG_DATA(cmsg)) / sizeof(int);
                        for (i = 0; i < j; i++) {
                                fd = ((int *)CMSG_DATA(cmsg))[i];
                                if (ifd != NULL) {
                                        ifd->fd = fd;
                                        TAILQ_INSERT_TAIL(&ibuf->fds, ifd,
                                            entry);
                                        ifd = NULL;
                                } else
                                        close(fd);
                        }
                }
                /* we do not handle other ctl data level */
        }

fail:
        free(ifd);
        return (n);
}

ssize_t
imsg_get(struct imsgbuf *ibuf, struct imsg *imsg)
{
        size_t                   av, left, datalen;

        av = ibuf->r.wpos;

        if (IMSG_HEADER_SIZE > av)
                return (0);

        memcpy(&imsg->hdr, ibuf->r.buf, sizeof(imsg->hdr));
        if (imsg->hdr.len < IMSG_HEADER_SIZE ||
            imsg->hdr.len > MAX_IMSGSIZE) {
                errno = ERANGE;
                return (-1);
        }
        if (imsg->hdr.len > av)
                return (0);
        datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
        ibuf->r.rptr = ibuf->r.buf + IMSG_HEADER_SIZE;
        if (datalen == 0)
                imsg->data = NULL;
        else if ((imsg->data = malloc(datalen)) == NULL)
                return (-1);

        if (imsg->hdr.flags & IMSGF_HASFD)
                imsg->fd = imsg_get_fd(ibuf);
        else
                imsg->fd = -1;

        memcpy(imsg->data, ibuf->r.rptr, datalen);

        if (imsg->hdr.len < av) {
                left = av - imsg->hdr.len;
                memmove(&ibuf->r.buf, ibuf->r.buf + imsg->hdr.len, left);
                ibuf->r.wpos = left;
        } else
                ibuf->r.wpos = 0;

        return (datalen + IMSG_HEADER_SIZE);
}

int
imsg_compose(struct imsgbuf *ibuf, u_int32_t type, u_int32_t peerid,
    pid_t pid, int fd, const void *data, u_int16_t datalen)
{
        struct ibuf     *wbuf;

        if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
                return (-1);

        if (imsg_add(wbuf, data, datalen) == -1)
                return (-1);

        wbuf->fd = fd;

        imsg_close(ibuf, wbuf);

        return (1);
}

int
imsg_composev(struct imsgbuf *ibuf, u_int32_t type, u_int32_t peerid,
    pid_t pid, int fd, const struct iovec *iov, int iovcnt)
{
        struct ibuf     *wbuf;
        int              i, datalen = 0;

        for (i = 0; i < iovcnt; i++)
                datalen += iov[i].iov_len;

        if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
                return (-1);

        for (i = 0; i < iovcnt; i++)
                if (imsg_add(wbuf, iov[i].iov_base, iov[i].iov_len) == -1)
                        return (-1);

        wbuf->fd = fd;

        imsg_close(ibuf, wbuf);

        return (1);
}

/* ARGSUSED */
struct ibuf *
imsg_create(struct imsgbuf *ibuf, u_int32_t type, u_int32_t peerid,
    pid_t pid, u_int16_t datalen)
{
        struct ibuf     *wbuf;
        struct imsg_hdr  hdr;

        datalen += IMSG_HEADER_SIZE;
        if (datalen > MAX_IMSGSIZE) {
                errno = ERANGE;
                return (NULL);
        }

        hdr.type = type;
        hdr.flags = 0;
        hdr.peerid = peerid;
        if ((hdr.pid = pid) == 0)
                hdr.pid = ibuf->pid;
        if ((wbuf = ibuf_dynamic(datalen, MAX_IMSGSIZE)) == NULL) {
                return (NULL);
        }
        if (imsg_add(wbuf, &hdr, sizeof(hdr)) == -1)
                return (NULL);

        return (wbuf);
}

int
imsg_add(struct ibuf *msg, const void *data, u_int16_t datalen)
{
        if (datalen)
                if (ibuf_add(msg, data, datalen) == -1) {
                        ibuf_free(msg);
                        return (-1);
                }
        return (datalen);
}

void
imsg_close(struct imsgbuf *ibuf, struct ibuf *msg)
{
        struct imsg_hdr *hdr;

        hdr = (struct imsg_hdr *)msg->buf;

        hdr->flags &= ~IMSGF_HASFD;
        if (msg->fd != -1)
                hdr->flags |= IMSGF_HASFD;

        hdr->len = (u_int16_t)msg->wpos;

        ibuf_close(&ibuf->w, msg);
}

void
imsg_free(struct imsg *imsg)
{
        free(imsg->data);
}

int
imsg_get_fd(struct imsgbuf *ibuf)
{
        int              fd;
        struct imsg_fd  *ifd;

        if ((ifd = TAILQ_FIRST(&ibuf->fds)) == NULL)
                return (-1);

        fd = ifd->fd;
        TAILQ_REMOVE(&ibuf->fds, ifd, entry);
        free(ifd);

        return (fd);
}

int
imsg_flush(struct imsgbuf *ibuf)
{
        while (ibuf->w.queued)
                if (msgbuf_write(&ibuf->w) <= 0)
                        return (-1);
        return (0);
}

void
imsg_clear(struct imsgbuf *ibuf)
{
        int     fd;

        msgbuf_clear(&ibuf->w);
        while ((fd = imsg_get_fd(ibuf)) != -1)
                close(fd);
}