/* $OpenBSD: monitor_fdpass.c,v 1.23 2026/02/08 19:54:31 dtucker Exp $ */

/*

 * Copyright 2001 Niels Provos <provos@citi.umich.edu>

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include "includes.h"

#include <sys/types.h>

#include <sys/socket.h>

#include <sys/uio.h>

#include <sys/un.h>

#include <errno.h>

#include <poll.h>

#include <string.h>

#include <stdarg.h>

#include "log.h"

#include "monitor_fdpass.h"

int

mm_send_fd(int sock, int fd)

{

#if defined(HAVE_SENDMSG) && (defined(HAVE_ACCRIGHTS_IN_MSGHDR) || defined(HAVE_CONTROL_IN_MSGHDR))

  struct msghdr msg;

#ifndef HAVE_ACCRIGHTS_IN_MSGHDR

  union {

    struct cmsghdr hdr;

    char buf[CMSG_SPACE(sizeof(int))];

  } cmsgbuf;

  struct cmsghdr *cmsg;

#endif

  struct iovec vec;

  char ch = '\0';

  ssize_t n;

  struct pollfd pfd;

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

#ifdef HAVE_ACCRIGHTS_IN_MSGHDR

  msg.msg_accrights = (caddr_t)&fd;

  msg.msg_accrightslen = sizeof(fd);

#else

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

  msg.msg_control = (caddr_t)&cmsgbuf.buf;

  msg.msg_controllen = sizeof(cmsgbuf.buf);

  cmsg = CMSG_FIRSTHDR(&msg);

  cmsg->cmsg_len = CMSG_LEN(sizeof(int));

  cmsg->cmsg_level = SOL_SOCKET;

  cmsg->cmsg_type = SCM_RIGHTS;

  *(int *)CMSG_DATA(cmsg) = fd;

#endif

  vec.iov_base = &ch;

  vec.iov_len = 1;

  msg.msg_iov = &vec;

  msg.msg_iovlen = 1;

  pfd.fd = sock;

  pfd.events = POLLOUT;

  while ((n = sendmsg(sock, &msg, 0)) == -1 &&

      (errno == EAGAIN || errno == EINTR)) {

    debug3_f("sendmsg(%d): %s", fd, strerror(errno));

    (void)poll(&pfd, 1, -1);

  }

  if (n == -1) {

    error_f("sendmsg(%d): %s", fd, strerror(errno));

    return -1;

  }

  if (n != 1) {

    error_f("sendmsg: expected sent 1 got %zd", n);

    return -1;

  }

  return 0;

#else

  error_f("file descriptor passing not supported");

  return -1;

#endif

}

int

mm_receive_fd(int sock)

{

#if defined(HAVE_RECVMSG) && (defined(HAVE_ACCRIGHTS_IN_MSGHDR) || defined(HAVE_CONTROL_IN_MSGHDR))

  struct msghdr msg;

#ifndef HAVE_ACCRIGHTS_IN_MSGHDR

  union {

    struct cmsghdr hdr;

    char buf[CMSG_SPACE(sizeof(int))];

  } cmsgbuf;

  struct cmsghdr *cmsg;

#endif

  struct iovec vec;

  ssize_t n;

  char ch;

  int fd;

  struct pollfd pfd;

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

  vec.iov_base = &ch;

  vec.iov_len = 1;

  msg.msg_iov = &vec;

  msg.msg_iovlen = 1;

#ifdef HAVE_ACCRIGHTS_IN_MSGHDR

  msg.msg_accrights = (caddr_t)&fd;

  msg.msg_accrightslen = sizeof(fd);

#else

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

  msg.msg_control = &cmsgbuf.buf;

  msg.msg_controllen = sizeof(cmsgbuf.buf);

#endif

  pfd.fd = sock;

  pfd.events = POLLIN;

  while ((n = recvmsg(sock, &msg, 0)) == -1 &&

      (errno == EAGAIN || errno == EINTR)) {

    debug3_f("recvmsg: %s", strerror(errno));

    (void)poll(&pfd, 1, -1);

  }

  if (n == -1) {

    error_f("recvmsg: %s", strerror(errno));

    return -1;

  }

  if (n != 1) {

    error_f("recvmsg: expected received 1 got %zd", n);

    return -1;

  }

#ifdef HAVE_ACCRIGHTS_IN_MSGHDR

  if (msg.msg_accrightslen != sizeof(fd)) {

    error_f("no fd");

    return -1;

  }

#else

  cmsg = CMSG_FIRSTHDR(&msg);

  if (cmsg == NULL) {

    error_f("no message header");

    return -1;

  }

#ifndef BROKEN_CMSG_TYPE

  if (cmsg->cmsg_type != SCM_RIGHTS) {

    error_f("expected %d got %d", SCM_RIGHTS, cmsg->cmsg_type);

    return -1;

  }

#endif

  fd = (*(int *)CMSG_DATA(cmsg));

#endif

  return fd;

#else

  error_f("file descriptor passing not supported");

  return -1;

#endif

}