// SPDX-License-Identifier: ISC

/*  $OpenBSD$ */

/*

 * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>

 */

#include <zebra.h>

#include "memory.h"

#include "queue.h"

#include "imsg.h"

static int imsg_fd_overhead = 0;

static int imsg_get_fd(struct imsgbuf *);

#ifndef __OpenBSD__

/*

 * The original code calls getdtablecount() which is OpenBSD specific. Use

 * available_fds() from OpenSMTPD instead.

 */

static int available_fds(unsigned int n)

{

  unsigned int i;

  int ret, fds[256];

  if (n > (unsigned int)array_size(fds))

    return 1;

  ret = 0;

  for (i = 0; i < n; i++) {

    fds[i] = -1;

    if ((fds[i] = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {

      if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT)

        fds[i] = socket(AF_INET6, SOCK_DGRAM, 0);

      if (fds[i] < 0) {

        ret = 1;

        break;

      }

    }

  }

  for (i = 0; i < n && fds[i] >= 0; i++)

    close(fds[i]);

  return (ret);

}

#endif

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;

  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:

#ifdef __OpenBSD__

  if (getdtablecount() + imsg_fd_overhead

        + (int)((CMSG_SPACE(sizeof(int)) - CMSG_SPACE(0))

          / sizeof(int))

      >= getdtablesize()) {

#else

  if (available_fds(imsg_fd_overhead

        + (CMSG_SPACE(sizeof(int)) - CMSG_SPACE(0))

            / sizeof(int))) {

#endif

    errno = EAGAIN;

    free(ifd);

    return -1;

  }

  n = recvmsg(ibuf->fd, &msg, 0);

  if (n == -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;

  if (imsg->data)

    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;

  wbuf->fd = 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;

  wbuf->fd = fd;

  imsg_close(ibuf, wbuf);

  return 1;

}

/* ARGSUSED */

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;

  memset(&hdr, 0x00, IMSG_HEADER_SIZE);

  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 (msg->fd != -1)

    hdr->flags |= IMSGF_HASFD;

  hdr->len = (uint16_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_POP_FIRST(&ibuf->fds, entry)) == NULL)

    return -1;

  fd = ifd->fd;

  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);

}