/*  $OpenBSD: imsg.c,v 1.19 2023/06/19 17:19:50 claudio 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 "openbsd-compat.h"

#include "imsg.h"

int  imsg_fd_overhead = 0;

static 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);

}

#ifdef _WIN32

ssize_t

imsg_read(struct imsgbuf *ibuf)

{

  ssize_t      n;

  uint8_t     *base;

  size_t       len;

  base = ibuf->r.buf + ibuf->r.wpos;

  len = sizeof(ibuf->r.buf) - ibuf->r.wpos;

  while ((n = recv(ibuf->fd, base, len, 0)) == -1) {

    if (errno != EINTR)

      return (-1);

  }

  ibuf->r.wpos += n;

  return (n);

}

#else

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);

}

#endif

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;

  if (datalen != 0)

    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, uint32_t type, uint32_t peerid, pid_t pid,

    int fd, const void *data, uint16_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);

  ibuf_fd_set(wbuf, fd);

  imsg_close(ibuf, wbuf);

  return (1);

}

int

imsg_composev(struct imsgbuf *ibuf, uint32_t type, uint32_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);

  ibuf_fd_set(wbuf, fd);

  imsg_close(ibuf, wbuf);

  return (1);

}

int

imsg_compose_ibuf(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid,

    pid_t pid, struct ibuf *buf)

{

  struct ibuf *wbuf = NULL;

  struct imsg_hdr  hdr;

  int save_errno;

  if (ibuf_size(buf) + IMSG_HEADER_SIZE > MAX_IMSGSIZE) {

    errno = ERANGE;

    goto fail;

  }

  hdr.type = type;

  hdr.len = ibuf_size(buf) + IMSG_HEADER_SIZE;

  hdr.flags = 0;

  hdr.peerid = peerid;

  if ((hdr.pid = pid) == 0)

    hdr.pid = ibuf->pid;

  if ((wbuf = ibuf_open(IMSG_HEADER_SIZE)) == NULL)

    goto fail;

  if (imsg_add(wbuf, &hdr, sizeof(hdr)) == -1)

    goto fail;

  ibuf_close(&ibuf->w, wbuf);

  ibuf_close(&ibuf->w, buf);

  return (1);

 fail:

  save_errno = errno;

  ibuf_free(buf);

  ibuf_free(wbuf);

  errno = save_errno;

  return (-1);

}

struct ibuf *

imsg_create(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid, pid_t pid,

    uint16_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, uint16_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 (ibuf_fd_avail(msg))

    hdr->flags |= IMSGF_HASFD;

  hdr->len = ibuf_size(msg);

  ibuf_close(&ibuf->w, msg);

}

void

imsg_free(struct imsg *imsg)

{

  freezero(imsg->data, imsg->hdr.len - IMSG_HEADER_SIZE);

}

static 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);

}