// SPDX-License-Identifier: ISC

/*  $OpenBSD$ */

/*

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

 */

#include <zebra.h>

#include "queue.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 *);

struct ibuf *ibuf_open(size_t len)

{

  struct ibuf *buf;

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

    return NULL;

  if ((buf->buf = malloc(len)) == 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)

    return NULL;

  if ((buf = ibuf_open(len)) == NULL)

    return NULL;

  if (max > 0)

    buf->max = max;

  return (buf);

}

static int ibuf_realloc(struct ibuf *buf, size_t len)

{

  uint8_t *b;

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

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

    errno = ERANGE;

    return -1;

  }

  b = realloc(buf->buf, buf->wpos + len);

  if (b == NULL)

    return -1;

  buf->buf = b;

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

  return 0;

}

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

{

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

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

      return -1;

  memcpy(buf->buf + buf->wpos, data, len);

  buf->wpos += len;

  return 0;

}

void *ibuf_reserve(struct ibuf *buf, size_t len)

{

  void *b;

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

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

      return NULL;

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

  buf->wpos += len;

  return (b);

}

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

{

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

  if (pos + len > buf->wpos)

    return NULL;

  return (buf->buf + pos);

}

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);

}

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;

}

void ibuf_free(struct ibuf *buf)

{

  if (buf == NULL)

    return;

  free(buf->buf);

  free(buf);

}

void msgbuf_init(struct msgbuf *msgbuf)

{

  msgbuf->queued = 0;

  msgbuf->fd = -1;

  TAILQ_INIT(&msgbuf->bufs);

}

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

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

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

      ibuf_dequeue(msgbuf, buf);

    } else {

      buf->rpos += n;

      n = 0;

    }

  }

}

void msgbuf_clear(struct msgbuf *msgbuf)

{

  struct ibuf *buf;

  while ((buf = TAILQ_POP_FIRST(&msgbuf->bufs, entry)) != NULL)

    ibuf_dequeue(msgbuf, buf);

}

int msgbuf_write(struct msgbuf *msgbuf)

{

  struct iovec iov[IOV_MAX];

  struct ibuf *buf;

  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;

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

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

    i++;

    if (buf->fd != -1)

      break;

  }

  msg.msg_iov = iov;

  msg.msg_iovlen = i;

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

    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;

    memcpy(CMSG_DATA(cmsg), &buf->fd, sizeof(int));

  }

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 (buf != NULL && buf->fd != -1) {

    close(buf->fd);

    buf->fd = -1;

  }

  msgbuf_drain(msgbuf, n);

  return 1;

}

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 done by caller */

  if (buf->fd != -1)

    close(buf->fd);

  msgbuf->queued--;

  ibuf_free(buf);

}