140 lines
4.0 KiB
C
140 lines
4.0 KiB
C
/*
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* Copyright © 2016 Kinvolk GmbH
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* Copyright © 2017 Endless Mobile, Inc.
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*
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* SPDX-License-Identifier: LGPL-2.0+
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*
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* Authors:
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* - Krzesimir Nowak <krzesimir@kinvolk.io>
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* - Philip Withnall <withnall@endlessm.com>
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*/
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#include "config.h"
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#include <avahi-common/strlst.h>
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#include <glib.h>
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#include <glib-object.h>
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#include <libglnx.h>
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#include <string.h>
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#include "ostree-autocleanups.h"
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#include "ostree-repo-finder-avahi.h"
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#include "ostree-repo-finder-avahi-private.h"
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/* Reference: RFC 6763, §6. */
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static gboolean
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parse_txt_record (const guint8 *txt,
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gsize txt_len,
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const gchar **key,
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gsize *key_len,
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const guint8 **value,
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gsize *value_len)
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{
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gsize i;
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g_return_val_if_fail (key != NULL, FALSE);
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g_return_val_if_fail (key_len != NULL, FALSE);
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g_return_val_if_fail (value != NULL, FALSE);
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g_return_val_if_fail (value_len != NULL, FALSE);
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/* RFC 6763, §6.1. */
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if (txt_len > 8900)
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return FALSE;
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*key = (const gchar *) txt;
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*key_len = 0;
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*value = NULL;
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*value_len = 0;
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for (i = 0; i < txt_len; i++)
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{
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if (txt[i] >= 0x20 && txt[i] <= 0x7e && txt[i] != '=')
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{
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/* Key character. */
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*key_len = *key_len + 1;
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continue;
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}
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else if (*key_len > 0 && txt[i] == '=')
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{
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/* Separator. */
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*value = txt + (i + 1);
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*value_len = txt_len - (i + 1);
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return TRUE;
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}
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else
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{
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return FALSE;
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}
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}
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/* The entire TXT record is the key; there is no ‘=’ or value. */
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*value = NULL;
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*value_len = 0;
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return (*key_len > 0);
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}
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/* TODO: Docs. Return value is only valid as long as @txt is. Reference: RFC 6763, §6. */
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GHashTable *
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_ostree_txt_records_parse (AvahiStringList *txt_list)
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{
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AvahiStringList *l;
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g_autoptr(GHashTable) out = NULL;
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out = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, (GDestroyNotify) g_bytes_unref);
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for (l = txt_list; l != NULL; l = avahi_string_list_get_next (l))
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{
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const guint8 *txt;
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gsize txt_len;
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const gchar *key;
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const guint8 *value;
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gsize key_len, value_len;
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g_autofree gchar *key_allocated = NULL;
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g_autoptr(GBytes) value_allocated = NULL;
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txt = avahi_string_list_get_text (l);
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txt_len = avahi_string_list_get_size (l);
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if (!parse_txt_record (txt, txt_len, &key, &key_len, &value, &value_len))
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{
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g_debug ("Ignoring invalid TXT record of length %" G_GSIZE_FORMAT,
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txt_len);
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continue;
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}
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key_allocated = g_ascii_strdown (key, key_len);
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if (g_hash_table_lookup_extended (out, key_allocated, NULL, NULL))
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{
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g_debug ("Ignoring duplicate TXT record ‘%s’", key_allocated);
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continue;
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}
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/* Distinguish between the case where the entire record is the key
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* (value == NULL) and the case where the record is the key + ‘=’ and the
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* value is empty (value != NULL && value_len == 0). */
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if (value != NULL)
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value_allocated = g_bytes_new_static (value, value_len);
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g_hash_table_insert (out, g_steal_pointer (&key_allocated), g_steal_pointer (&value_allocated));
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}
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return g_steal_pointer (&out);
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}
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