msg_parser.c

this is simple sip stack.

int msg_header_e(char b[], int bsiz, msg_header_t const *h, int flags)
{
  int n, m;

  assert(h); assert(h->sh_class);

  if (h == NULL || h->sh_class == NULL)
    return -1;

  n = msg_header_name_e(b, bsiz, h, flags);
  m = h->sh_class->hc_print(b + n, bsiz > n ? bsiz - n : 0, h, flags);
  if (h->sh_class->hc_name) {
    /* Ordinary header */
    if (bsiz > n + m + strlen(CRLF))
      strcpy(b + n + m, CRLF);
    return n + m + strlen(CRLF);
  }
  else
    return m;
}

/** Encode header name */
static inline
int
msg_header_name_e(char b[], int bsiz, msg_header_t const *h, int flags)
{
  int compact = MSG_IS_COMPACT(flags);
  char const *name;
  int n, n2;

  if (compact && h->sh_class->hc_short[0])
    name = h->sh_class->hc_short, n = 1;
  else
    name = h->sh_class->hc_name, n = h->sh_class->hc_len;

  if (!name || !name[0])
    return 0;

  n2 = compact ? n + 1 : n + 2;

  if (n2 < bsiz) {
    memcpy(b, name, n);
    b[n++] = ':';
    if (!compact)
      b[n++] = ' ';
    b[n++] = '\0';
  }

  return n2;
}

/* ====================================================================== */
/* Handling header chain */

static inline void serialize_first(msg_t *msg, msg_header_t *h);
static msg_header_t **serialize_one(msg_t *msg, msg_header_t *h,
				    msg_header_t **prev);

/** Return head of the fragment chain */
msg_header_t **msg_chain_head(msg_t const *msg)
{
  return msg ? (msg_header_t **)&msg->m_chain : NULL;
}

static inline msg_header_t **_msg_chain_head(msg_t const *msg)
{
  return msg ? (msg_header_t **)&msg->m_chain : NULL;
}

/** Return tail of the fragment chain */
static inline msg_header_t **msg_chain_tail(msg_t const *msg)
{
  return msg ? msg->m_tail : NULL;
}

/** Serialize headers into the fragment chain.
 *
 * The msg_serialize() collects the headers and other message components in
 * the fragment chain. It should be called before msg_prepare().
 *
 * @relates msg_s
 *
 * @param msg pointer to message object
 * @param pub public message structure
 *
 * @retval 0 when successful
 * @retval -1 upon an error
 */
int msg_serialize(msg_t *msg, msg_pub_t *pub)
{
  msg_header_t *h, **hh, **end;
  msg_header_t **separator;
  msg_header_t **payload;
  msg_header_t **multipart;
  msg_mclass_t const *mc = msg->m_class;
  msg_header_t **tail, ***ptail;

  if (!msg)
    return errno = EINVAL, -1;
  if (pub == NULL)
    pub = msg->m_object;

  /* There must be a first line */
  if (pub->msg_request)
    h = pub->msg_request;
  else if (pub->msg_status)
    h = pub->msg_status;
  else
    return errno = EINVAL, -1;

  serialize_first(msg, h);

  separator = (msg_header_t **)((char *)pub + mc->mc_separator->hr_offset);
  payload = (msg_header_t **)((char *)pub + mc->mc_payload->hr_offset);
  if (mc->mc_multipart->hr_class)
    multipart = (msg_header_t **)((char *)pub + mc->mc_multipart->hr_offset);
  else
    multipart = NULL;

  /* Find place to insert headers: before separator, payload and multipart */
  if (*separator && !msg_header_is_removed(*separator))
    ptail = &(*separator)->sh_prev;
  else if (*payload && !msg_header_is_removed(*payload))
    ptail = &(*payload)->sh_prev;
  else if (multipart && *multipart && !msg_header_is_removed(*multipart))
    ptail = &(*multipart)->sh_prev;
  else
    ptail = &msg->m_tail;

  tail = *ptail;

  end = (msg_header_t **)((char *)pub + pub->msg_size);

  for (hh = pub->msg_headers; hh < end; hh++) {
    if (!*hh)
      continue;
    if (hh == separator || hh == payload || hh == multipart)
      continue;
    tail = serialize_one(msg, *hh, tail);
  }

  /* Serialize separator, payload and multipart last */
  if (*separator)
    tail = serialize_one(msg, *separator, tail);

  *ptail = tail;

  /* Payload comes after separator but before multipart */
  if (ptail != &(*separator)->sh_prev)
    ;
  else if (*payload && !msg_header_is_removed(*payload))
    ptail = &(*payload)->sh_prev;
  else if (multipart && *multipart && !msg_header_is_removed(*multipart))
    ptail = &(*multipart)->sh_prev;
  else
    ptail = &msg->m_tail;

  tail = *ptail;

  if (*payload) {
    tail = serialize_one(msg, *payload, tail);
    *ptail = tail;
  }

  if (multipart && *multipart) {
    msg_header_t *last;

    last = msg_multipart_serialize(tail, (msg_multipart_t *)*multipart);

    msg->m_tail = &last->sh_succ;
  }

  assert(msg->m_chain && msg_chain_errors(msg->m_chain) == 0);

  return 0;
}

static inline
void serialize_first(msg_t *msg, msg_header_t *h)
{
  if (msg_header_is_removed(h)) {
    if ((h->sh_succ = msg->m_chain))
      h->sh_succ->sh_prev = &h->sh_succ;
    else
      msg->m_tail = &h->sh_succ;
    *(h->sh_prev = &msg->m_chain) = h;
  }
}

static
msg_header_t **serialize_one(msg_t *msg, msg_header_t *h, msg_header_t **prev)
{
  msg_header_t *last;
  msg_header_t *succ = *prev;

  if (msg_header_is_removed(h)) {
    /* Add the first header in the list to the chain */
    *prev = h; h->sh_prev = prev;
    for (last = h; last->sh_succ; last = last->sh_succ) {
      /* Ensure that chain is connected */
      assert(last->sh_next == last->sh_succ);
      assert(last->sh_succ->sh_prev = &last->sh_succ);
    }
    prev = &last->sh_succ;
  }

  if ((h = h->sh_next)) {
    assert(!msg_is_single(h));

    if (msg_is_single(h)) {
      for (; h; h = h->sh_next)
	if (!msg_header_is_removed(h))
	  msg_chain_remove(msg, h);
    }
    /* Add the rest of the headers in the list to the chain */
    else for (; h; h = h->sh_next) {
      if (msg_header_is_removed(h)) {
	*prev = h; h->sh_prev = prev;
	for (;h->sh_succ; h = h->sh_succ)
	  assert(h->sh_succ == h->sh_next);
	prev = &h->sh_succ;
      }
    }
  }

  *prev = succ;

  return prev;
}

/**Fill an I/O vector with message contents.
 *
 * The function msg_iovec() calculates number of entries in the I/O vector
 * required to send a message @a msg. It also fills in the I/O vector array,
 * if it is provided by the caller and it is large enough.
 *
 * @param msg
 * @param vec
 * @param veclen
 *
 * @return
 * The function msg_iovec() returns the number of entries in I/O
 * vector required by @a msg, or 0 upon an error.
 *
 * @note The caller should check that the I/O vector @a vec has enough
 * entries. If the @a vec is too short, it should allocate big enough
 * vector and re-invoke msg_iovec().
 */
int msg_iovec(msg_t *msg, msg_iovec_t vec[], int veclen)
{
  int len = 0, n = 0;
  char const *p = NULL;
  msg_header_t *h;

  unsigned total = 0;

  if (veclen <= 0)
    veclen = 0;

  for (h = msg->m_chain; h; h = h->sh_succ) {
    if (h->sh_data != p) {
      p = h->sh_data; len = h->sh_len;

      if (p == NULL)
	return 0;

      if (vec && n != veclen)
	/* new iovec entry */
	vec[n].mv_base = (void *)p, vec[n].mv_len  = len;
      else
	vec = NULL;

      p += len; n++;
    }
    else {
      /* extend old entry */
      len = h->sh_len;
      if (vec)
	vec[n-1].mv_len += len;
      p += len;
    }

    total += len;
  }

  msg->m_size = total;

  assert(n > 0);

  return n;
}

/** Insert a header to existing header chain.
 *
 * Headers are either inserted just before the payload, or after the first
 * line, depending on their type.
 *
 * @param msg  message object [IN]
 * @param pub  public message structure [IN/OUT]
 * @param prepend if true, add before same type of headers (instead after them)
 * @param head head of chain
 * @param h    header to insert
 *
 */
static
void msg_insert_chain(msg_t *msg,
		      msg_pub_t *pub,
		      int prepend,
		      msg_header_t **head,
		      msg_header_t *h)
{
  msg_mclass_t const *mc = msg->m_class;
  msg_header_t **hh;
  msg_header_t **separator;
  msg_header_t **payload;
  
  assert(msg && pub && head && h);

  separator = (msg_header_t **)((char *)pub + mc->mc_separator->hr_offset);
  payload = (msg_header_t **)((char *)pub + mc->mc_payload->hr_offset);

  if (msg_is_request(h)) {
    if (pub->msg_status)
      pub->msg_status = NULL;
    hh = head;
  }
  else if (msg_is_status(h)) {
    if (pub->msg_request)
      pub->msg_request = NULL;
    hh = head;
  }
  else if (msg_is_payload(h)) {
    /* Append */
    hh = msg_chain_tail(msg);
  }
  else if (prepend) {
    if (!msg_is_request(*head) && !msg_is_status(*head))
      hh = head;
    else
      hh = &((*head)->sh_succ);
  }
  /* Append headers before separator or payload */
  else if (*separator && (*separator)->sh_prev)
    hh = (*separator)->sh_prev;
  else if (*payload && (*payload)->sh_prev)
    hh = (*payload)->sh_prev;
  else
    hh = msg_chain_tail(msg);

  msg_insert_here_in_chain(msg, hh, h);
}

/** Insert one or more message header to the chain.
 *
 * The function msg_insert_here_in_chain() appends message header to the
 * chain of headers after the given header.
 *
 * @param msg  message
 * @param prev pointer to h_succ of previous fragment in the list
 * @param h    header to be inserted.
 *
 * @return The pointer to the last header inserted.
 */
static
void msg_insert_here_in_chain(msg_t *msg,
			      msg_header_t **prev,
			      msg_header_t *h)
{
  if (h) {
    msg_header_t *last, *next;
    assert(h->sh_prev == NULL);
    assert(prev);
    assert(!msg_chain_errors(h));

    for (last = h; last->sh_succ; last = last->sh_succ)
      ;

    last->sh_succ = next = *prev;
    *prev = h;
    h->sh_prev = prev;
    if (next)
      next->sh_prev = &last->sh_succ;
    else
      msg->m_tail = &last->sh_succ;

    assert(msg->m_chain && msg_chain_errors(msg->m_chain) == 0);
  }
}

/**
 * Remove a message from header chain.
 *
 * The function @c msg_chain_remove() removes a message header from the header
 * chain.
 *
 * @param msg  pointer to the message
 * @param h    pointer to the header in the list to be removed
 *
 * @return The pointer to the header just removed.
 */
static inline
msg_header_t *msg_chain_remove(msg_t *msg, msg_header_t *h)
{
  if (h) {
    if (h->sh_prev) {
      assert(*h->sh_prev == h);
      assert(h->sh_succ == NULL || h->sh_succ->sh_prev == &h->sh_succ);

      *h->sh_prev = h->sh_succ;
    }

    if (h->sh_succ)
      h->sh_succ->sh_prev = h->sh_prev;
    else if (msg && h->sh_prev)
      msg->m_tail = h->sh_prev;

    h->sh_succ = NULL; h->sh_prev = NULL;

    if (msg)
      assert(msg_chain_errors(msg->m_chain) == 0);
  }
  return h;
}

#ifndef NDEBUG
/**Check if header chain contains any loops.
 *
 * @return
 * Return 0 if no loop, -1 otherwise.
 */
static
int msg_chain_loop(msg_header_t const *h)
{
  msg_header_t const *h2;

  if (!h) return 0;

  for (h2 = h->sh_succ; h && h2 && h2->sh_succ; h = h->sh_succ) {
    if (h == h2 || h == h2->sh_succ)
      return 1;

    h2 = h2->sh_succ->sh_succ;

    if (h == h2)
      return 1;
  }

  return 0;
}

/** Check header chain consistency.
 *
 * @return
 * Return 0 if consistent, number of errors otherwise.
 */
static
int msg_chain_errors(msg_header_t const *h)
{
  if (msg_chain_loop(h))
    return -1;

  for (; h; h = h->sh_succ) {
    if (h->sh_succ && h->sh_succ->sh_prev != &h->sh_succ)
      return -1;
    if (h->sh_prev && h != (*h->sh_prev))
      return -1;
  }

  return 0;
}
#endif

/* ====================================================================== */
/* Handling message structure - allocating, adding and removing headers */

/** Allocate a header structure
 *
 * The msg_header_alloc() function allocates a generic MO header structure
 * and returns a pointer to it.
 *
 * @param home  memory home
 * @param hc    header class
 * @param extra amount of extra memory to be allocated after header structure
 *
 * @return
 * A pointer to the newly created header object, or @c NULL upon an error.
 */
msg_header_t *msg_header_alloc(su_home_t *home,
			       msg_hclass_t *hc,
			       int extra)
{
  int size = hc->hc_size;
  msg_header_t *h = su_alloc(home, size + extra);

  if (h) {
    memset(h, 0, size);
    h->sh_class = hc;
  }

  return h;
}

/**Add a (list of) header(s) to the header structure and fragment chain.
 *
 * The function @c msg_header_add() adds a header or list of headers into
 * the given place within the message structure. It also inserts the headers
 * into the the message fragment chain, if it exists.
 *
 * If the header is a prepend header, the new header is inserted before
 * existing headers of the same class. If the header is an append header,
 * the new header is inserted after existing headers of the same class. If
 * the header is a singleton, existing headers of the same class are
 * removed. If the header is a list header, the values in the new header are
 * added to the existing list.
 *
 * @param msg message owning the fragment chain
 * @param pub public message structure
 * @param hh  place in message structure to which header is added
 * @param h   list of header(s) to be added
 */
int msg_header_add(msg_t *msg,
		   msg_pub_t *pub,
		   msg_header_t **hh,
		   msg_header_t *h)
{
  msg_header_t **head, *old = NULL, *end;

  if (msg == NULL || h == NULL || h == MSG_HEADER_NONE || hh == NULL)
    return -1;
  if (pub == NULL)
    pub = msg->m_object;

  head = _msg_chain_head(msg);

  if (*head) {
    msg_header_t *sh, **prev;

    for (sh = h, prev = NULL; sh; sh = sh->sh_next) {
      sh->sh_succ = sh->sh_next;
      sh->sh_prev = prev;
      prev = &sh->sh_succ;
    }
  }

  switch (h->sh_class->hc_kind) {