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/*
* Copyright © 2016 Kinvolk GmbH
* Copyright © 2017 Endless Mobile, Inc.
*
* SPDX-License-Identifier: LGPL-2.0+
*
* This library 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 of the License, or (at your option) any later version.
*
* This library 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 library. If not, see <https://www.gnu.org/licenses/>.
*
* Authors:
* - Krzesimir Nowak <krzesimir@kinvolk.io>
* - Philip Withnall <withnall@endlessm.com>
*/
#include "config.h"
#include <avahi-common/strlst.h>
#include <glib.h>
#include <glib-object.h>
#include <libglnx.h>
#include <string.h>
#include "ostree-autocleanups.h"
#include "ostree-repo-finder-avahi.h"
#include "ostree-repo-finder-avahi-private.h"
/* Reference: RFC 6763, §6. */
static gboolean
parse_txt_record (const guint8 *txt,
gsize txt_len,
const gchar **key,
gsize *key_len,
const guint8 **value,
gsize *value_len)
{
gsize i;
g_return_val_if_fail (key != NULL, FALSE);
g_return_val_if_fail (key_len != NULL, FALSE);
g_return_val_if_fail (value != NULL, FALSE);
g_return_val_if_fail (value_len != NULL, FALSE);
/* RFC 6763, §6.1. */
if (txt_len > 8900)
return FALSE;
*key = (const gchar *) txt;
*key_len = 0;
*value = NULL;
*value_len = 0;
for (i = 0; i < txt_len; i++)
{
if (txt[i] >= 0x20 && txt[i] <= 0x7e && txt[i] != '=')
{
/* Key character. */
*key_len = *key_len + 1;
continue;
}
else if (*key_len > 0 && txt[i] == '=')
{
/* Separator. */
*value = txt + (i + 1);
*value_len = txt_len - (i + 1);
return TRUE;
}
else
{
return FALSE;
}
}
/* The entire TXT record is the key; there is no ‘=’ or value. */
*value = NULL;
*value_len = 0;
return (*key_len > 0);
}
/* TODO: Docs. Return value is only valid as long as @txt is. Reference: RFC 6763, §6. */
GHashTable *
_ostree_txt_records_parse (AvahiStringList *txt_list)
{
AvahiStringList *l;
g_autoptr(GHashTable) out = NULL;
out = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, (GDestroyNotify) g_bytes_unref);
for (l = txt_list; l != NULL; l = avahi_string_list_get_next (l))
{
const guint8 *txt;
gsize txt_len;
const gchar *key;
const guint8 *value;
gsize key_len, value_len;
g_autofree gchar *key_allocated = NULL;
g_autoptr(GBytes) value_allocated = NULL;
txt = avahi_string_list_get_text (l);
txt_len = avahi_string_list_get_size (l);
if (!parse_txt_record (txt, txt_len, &key, &key_len, &value, &value_len))
{
g_debug ("Ignoring invalid TXT record of length %" G_GSIZE_FORMAT,
txt_len);
continue;
}
key_allocated = g_ascii_strdown (key, key_len);
if (g_hash_table_lookup_extended (out, key_allocated, NULL, NULL))
{
g_debug ("Ignoring duplicate TXT record ‘%s’", key_allocated);
continue;
}
/* Distinguish between the case where the entire record is the key
* (value == NULL) and the case where the record is the key + ‘=’ and the
* value is empty (value != NULL && value_len == 0). */
if (value != NULL)
value_allocated = g_bytes_new_static (value, value_len);
g_hash_table_insert (out, g_steal_pointer (&key_allocated), g_steal_pointer (&value_allocated));
}
return g_steal_pointer (&out);
}
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