/*
 * util.c - implementation of Telepathy-SofiaSIP utilities
 * Copyright (C) 2009, 2010 Nokia Corporation
 *   @author Mikhail Zabaluev <mikhail.zabaluev@nokia.com>
 *
 * This work is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This work is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this work; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include "util.h"

#include <string.h>


static const guchar escape_table[256] =
  { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1,
      /* Control characters except LF and CR.
       * NOTE: null character is intentionally flagged */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  /* 0x10 - 0x1f */
    0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  /* 0x22 == '"' */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0,  /* 0x5c == '\\' */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,  /* 0x7f */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, };

/**
 * tpsip_string_append_quoted:
 * @buf: a #GString to append the quoted text to
 * @text: text to append as a quoted string
 *
 * Appends to @buf the content of @text as a quoted string accordingly to SIP
 * or MIME syntax.
 */
void
tpsip_string_append_quoted (GString *buf, const gchar *text)
{
  const gchar *p;
  gchar quoted_pair[2] = { '\\', };

  g_string_append_c (buf, '"');

  p = text;
  while (*p)
    {
      const gchar *q;

      /* Get the following text span to append verbatim */
      for (q = p; !escape_table[(guchar) *q]; ++q)
        { /* do nothing */ }
      g_string_append_len (buf, p, q - p);

      if (*q == '\0')
        break;

      quoted_pair[1] = *q;
      g_string_append_len (buf, quoted_pair, 2);

      p = q + 1;
    }

  g_string_append_c (buf, '"');
}

/**
 * tpsip_quote_string:
 * @src: the source string
 *
 * Formats the content of @text as a quoted string accordingly to SIP
 * or MIME syntax.
 *
 * Returns: a newly allocated quoted string.
 * The string is to be freed with g_free().
 */
gchar *
tpsip_quote_string (const gchar *src)
{
  GString *buf;

  buf = g_string_sized_new (2);

  tpsip_string_append_quoted (buf, src);

  return g_string_free (buf, FALSE);
}

/**
 * tpsip_unquote_string:
 * @src: the quoted string, including the encompassing double quotes
 * @len: length of the string @src in bytes,
 *       or -1 if the string is null-terminated
 *
 * Extracts text out of a quoted string literal accordingly to SIP
 * or MIME syntax, unescaping characters preceded by backspaces.
 *
 * Returns: a newly allocated unquoted string.
 * The string is to be freed with g_free().
 */
gchar *
tpsip_unquote_string (const gchar *src, gssize len)
{
  gchar *res;
  gchar *p;
  gsize i;

  g_return_val_if_fail (src != NULL, NULL);

  if (len < 0)
    len = strlen (src);

  g_return_val_if_fail (len >= 2, NULL);
  g_return_val_if_fail (src[0] == '"' && src[len - 1] == '"', NULL);

  res = g_malloc (len - 2 + 1);

  p = res;

  for (i = 1; i < len - 1; ++i)
    {
      if (src[i] == '\\')
        {
          ++i;
          if (G_UNLIKELY (i == len - 1))
            {
              g_critical ("the quoted string is missing the termination quote, improperly escaped?");
              return NULL;
            }
        }
      *p++ = src[i];
    }
 
  *p = '\0';

  return res;
}