/*  $OpenBSD: imsg-buffer.c,v 1.16 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 <limits.h>

#include <errno.h>

#include <endian.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include "openbsd-compat.h"

#include "imsg.h"

static int  ibuf_realloc(struct ibuf *, size_t);

static void ibuf_enqueue(struct msgbuf *, struct ibuf *);

static void ibuf_dequeue(struct msgbuf *, struct ibuf *);

static void msgbuf_drain(struct msgbuf *, size_t);

struct ibuf *

ibuf_open(size_t len)

{

  struct ibuf *buf;

  if (len == 0) {

    errno = EINVAL;

    return (NULL);

  }

  if ((buf = calloc(1, sizeof(struct ibuf))) == NULL)

    return (NULL);

  if ((buf->buf = calloc(len, 1)) == NULL) {

    free(buf);

    return (NULL);

  }

  buf->size = buf->max = len;

  buf->fd = -1;

  return (buf);

}

struct ibuf *

ibuf_dynamic(size_t len, size_t max)

{

  struct ibuf *buf;

  if (max < len) {

    errno = EINVAL;

    return (NULL);

  }

  if ((buf = calloc(1, sizeof(struct ibuf))) == NULL)

    return (NULL);

  if (len > 0) {

    if ((buf->buf = calloc(len, 1)) == NULL) {

      free(buf);

      return (NULL);

    }

  }

  buf->size = len;

  buf->max = max;

  buf->fd = -1;

  return (buf);

}

static int

ibuf_realloc(struct ibuf *buf, size_t len)

{

  unsigned char *b;

  /* on static buffers max is eq size and so the following fails */

  if (len > SIZE_MAX - buf->wpos || buf->wpos + len > buf->max) {

    errno = ERANGE;

    return (-1);

  }

  b = recallocarray(buf->buf, buf->size, buf->wpos + len, 1);

  if (b == NULL)

    return (-1);

  buf->buf = b;

  buf->size = buf->wpos + len;

  return (0);

}

void *

ibuf_reserve(struct ibuf *buf, size_t len)

{

  void  *b;

  if (len > SIZE_MAX - buf->wpos) {

    errno = ERANGE;

    return (NULL);

  }

  if (buf->wpos + len > buf->size)

    if (ibuf_realloc(buf, len) == -1)

      return (NULL);

  b = buf->buf + buf->wpos;

  buf->wpos += len;

  memset(b, 0, len);

  return (b);

}

int

ibuf_add(struct ibuf *buf, const void *data, size_t len)

{

  void *b;

  if ((b = ibuf_reserve(buf, len)) == NULL)

    return (-1);

  memcpy(b, data, len);

  return (0);

}

int

ibuf_add_buf(struct ibuf *buf, const struct ibuf *from)

{

  return ibuf_add(buf, from->buf, from->wpos);

}

int

ibuf_add_n8(struct ibuf *buf, uint64_t value)

{

  uint8_t v;

  if (value > UINT8_MAX) {

    errno = EINVAL;

    return (-1);

  }

  v = value;

  return ibuf_add(buf, &v, sizeof(v));

}

int

ibuf_add_n16(struct ibuf *buf, uint64_t value)

{

  uint16_t v;

  if (value > UINT16_MAX) {

    errno = EINVAL;

    return (-1);

  }

  v = htobe16(value);

  return ibuf_add(buf, &v, sizeof(v));

}

int

ibuf_add_n32(struct ibuf *buf, uint64_t value)

{

  uint32_t v;

  if (value > UINT32_MAX) {

    errno = EINVAL;

    return (-1);

  }

  v = htobe32(value);

  return ibuf_add(buf, &v, sizeof(v));

}

int

ibuf_add_n64(struct ibuf *buf, uint64_t value)

{

  value = htobe64(value);

  return ibuf_add(buf, &value, sizeof(value));

}

int

ibuf_add_zero(struct ibuf *buf, size_t len)

{

  void *b;

  if ((b = ibuf_reserve(buf, len)) == NULL)

    return (-1);

  return (0);

}

void *

ibuf_seek(struct ibuf *buf, size_t pos, size_t len)

{

  /* only allowed to seek in already written parts */

  if (len > SIZE_MAX - pos || pos + len > buf->wpos) {

    errno = ERANGE;

    return (NULL);

  }

  return (buf->buf + pos);

}

int

ibuf_set(struct ibuf *buf, size_t pos, const void *data, size_t len)

{

  void *b;

  if ((b = ibuf_seek(buf, pos, len)) == NULL)

    return (-1);

  memcpy(b, data, len);

  return (0);

}

int

ibuf_set_n8(struct ibuf *buf, size_t pos, uint64_t value)

{

  uint8_t v;

  if (value > UINT8_MAX) {

    errno = EINVAL;

    return (-1);

  }

  v = value;

  return (ibuf_set(buf, pos, &v, sizeof(v)));

}

int

ibuf_set_n16(struct ibuf *buf, size_t pos, uint64_t value)

{

  uint16_t v;

  if (value > UINT16_MAX) {

    errno = EINVAL;

    return (-1);

  }

  v = htobe16(value);

  return (ibuf_set(buf, pos, &v, sizeof(v)));

}

int

ibuf_set_n32(struct ibuf *buf, size_t pos, uint64_t value)

{

  uint32_t v;

  if (value > UINT32_MAX) {

    errno = EINVAL;

    return (-1);

  }

  v = htobe32(value);

  return (ibuf_set(buf, pos, &v, sizeof(v)));

}

int

ibuf_set_n64(struct ibuf *buf, size_t pos, uint64_t value)

{

  value = htobe64(value);

  return (ibuf_set(buf, pos, &value, sizeof(value)));

}

void *

ibuf_data(struct ibuf *buf)

{

  return (buf->buf);

}

size_t

ibuf_size(struct ibuf *buf)

{

  return (buf->wpos);

}

size_t

ibuf_left(struct ibuf *buf)

{

  return (buf->max - buf->wpos);

}

void

ibuf_close(struct msgbuf *msgbuf, struct ibuf *buf)

{

  ibuf_enqueue(msgbuf, buf);

}

void

ibuf_free(struct ibuf *buf)

{

  if (buf == NULL)

    return;

#ifdef NOTYET

  if (buf->fd != -1)

    close(buf->fd);

#endif

  freezero(buf->buf, buf->size);

  free(buf);

}

int

ibuf_fd_avail(struct ibuf *buf)

{

  return (buf->fd != -1);

}

int

ibuf_fd_get(struct ibuf *buf)

{

  int fd;

  fd = buf->fd;

#ifdef NOTYET

  buf->fd = -1;

#endif

  return (fd);

}

void

ibuf_fd_set(struct ibuf *buf, int fd)

{

  if (buf->fd != -1)

    close(buf->fd);

  buf->fd = fd;

}

#ifdef _WIN32

#define IBUF_WSABUF_WRITE_MAX 16

int

ibuf_write(struct msgbuf *msgbuf)

{

  DWORD    bytesSent;

  WSABUF     iov[IBUF_WSABUF_WRITE_MAX];

  struct ibuf *buf;

  unsigned int   i = 0;

  ssize_t n;

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

  TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {

    if (i >= IBUF_WSABUF_WRITE_MAX)

      break;

    iov[i].buf = buf->buf + buf->rpos;

    iov[i].len = buf->wpos - buf->rpos;

    i++;

  }

  if (WSASend(msgbuf->fd, iov, i, &bytesSent, 0, NULL, NULL))

    return (-1);

  n = bytesSent;

  if (n == 0) {     /* connection closed */

    errno = 0;

    return (0);

  }

  msgbuf_drain(msgbuf, n);

  return (1);

}

#else

int

ibuf_write(struct msgbuf *msgbuf)

{

  struct iovec   iov[IOV_MAX];

  struct ibuf *buf;

  unsigned int   i = 0;

  ssize_t n;

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

  TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {

    if (i >= IOV_MAX)

      break;

    iov[i].iov_base = buf->buf + buf->rpos;

    iov[i].iov_len = buf->wpos - buf->rpos;

    i++;

  }

again:

  if ((n = writev(msgbuf->fd, iov, i)) == -1) {

    if (errno == EINTR)

      goto again;

    if (errno == ENOBUFS)

      errno = EAGAIN;

    return (-1);

  }

  if (n == 0) {     /* connection closed */

    errno = 0;

    return (0);

  }

  msgbuf_drain(msgbuf, n);

  return (1);

}

#endif /* !_WIN32 */

void

msgbuf_init(struct msgbuf *msgbuf)

{

  msgbuf->queued = 0;

  msgbuf->fd = -1;

  TAILQ_INIT(&msgbuf->bufs);

}

static void

msgbuf_drain(struct msgbuf *msgbuf, size_t n)

{

  struct ibuf *buf, *next;

  for (buf = TAILQ_FIRST(&msgbuf->bufs); buf != NULL && n > 0;

      buf = next) {

    next = TAILQ_NEXT(buf, entry);

    if (n >= buf->wpos - buf->rpos) {

      n -= buf->wpos - buf->rpos;

      ibuf_dequeue(msgbuf, buf);

    } else {

      buf->rpos += n;

      n = 0;

    }

  }

}

void

msgbuf_clear(struct msgbuf *msgbuf)

{

  struct ibuf *buf;

  while ((buf = TAILQ_FIRST(&msgbuf->bufs)) != NULL)

    ibuf_dequeue(msgbuf, buf);

}

#ifdef _WIN32

int

msgbuf_write(struct msgbuf *msgbuf)

{

  struct ibuf *buf;

  TAILQ_FOREACH(buf, &msgbuf->bufs, entry)

    if (buf->fd != -1)

      return (-1);

  return ibuf_write(msgbuf);

}

#else

int

msgbuf_write(struct msgbuf *msgbuf)

{

  struct iovec   iov[IOV_MAX];

  struct ibuf *buf, *buf0 = NULL;

  unsigned int   i = 0;

  ssize_t    n;

  struct msghdr  msg;

  struct cmsghdr  *cmsg;

  union {

    struct cmsghdr  hdr;

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

  } cmsgbuf;

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

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

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

  TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {

    if (i >= IOV_MAX)

      break;

    if (i > 0 && buf->fd != -1)

      break;

    iov[i].iov_base = buf->buf + buf->rpos;

    iov[i].iov_len = buf->wpos - buf->rpos;

    i++;

    if (buf->fd != -1)

      buf0 = buf;

  }

  msg.msg_iov = iov;

  msg.msg_iovlen = i;

  if (buf0 != NULL) {

    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) = buf0->fd;

  }

again:

  if ((n = sendmsg(msgbuf->fd, &msg, 0)) == -1) {

    if (errno == EINTR)

      goto again;

    if (errno == ENOBUFS)

      errno = EAGAIN;

    return (-1);

  }

  if (n == 0) {     /* connection closed */

    errno = 0;

    return (0);

  }

  /*

   * assumption: fd got sent if sendmsg sent anything

   * this works because fds are passed one at a time

   */

  if (buf0 != NULL) {

    close(buf0->fd);

    buf0->fd = -1;

  }

  msgbuf_drain(msgbuf, n);

  return (1);

}

#endif /* !_WIN32 */

static void

ibuf_enqueue(struct msgbuf *msgbuf, struct ibuf *buf)

{

  TAILQ_INSERT_TAIL(&msgbuf->bufs, buf, entry);

  msgbuf->queued++;

}

static void

ibuf_dequeue(struct msgbuf *msgbuf, struct ibuf *buf)

{

  TAILQ_REMOVE(&msgbuf->bufs, buf, entry);

  if (buf->fd != -1) {

    close(buf->fd);

    buf->fd = -1;

  }

  msgbuf->queued--;

  ibuf_free(buf);

}