128 lines
3.0 KiB
C
128 lines
3.0 KiB
C
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/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 2020, Sean Bright
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*
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* Sean Bright <sean.bright@gmail.com>
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*! \file
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* \brief DNS TXT Record Parsing API
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* \author Sean Bright <sean.bright@gmail.com>
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*/
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/*** MODULEINFO
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<support_level>core</support_level>
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***/
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#include "asterisk.h"
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#include <netinet/in.h>
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#include <resolv.h>
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#include "asterisk/dns_core.h"
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#include "asterisk/dns_txt.h"
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#include "asterisk/dns_internal.h"
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#include "asterisk/utils.h"
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struct ast_dns_record *dns_txt_alloc(struct ast_dns_query *query, const char *data, const size_t size)
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{
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struct ast_dns_txt_record *txt;
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const char *end_of_record = data + size;
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size_t count = 0;
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/* Because we can't allocate additional memory, the best we can do here is just
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* validate that this conforms to a TXT record. */
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while (data < end_of_record) {
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uint8_t byte_count = (uint8_t) *data;
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count++;
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data += byte_count + 1;
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}
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if (data != end_of_record) {
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/* This is not a valid TXT record, so we can bail out */
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return NULL;
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}
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txt = ast_calloc(1, sizeof(*txt) + size);
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if (!txt) {
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return NULL;
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}
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txt->count = count;
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txt->generic.data_ptr = txt->data;
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return (struct ast_dns_record *) txt;
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}
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size_t ast_dns_txt_get_count(const struct ast_dns_record *record)
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{
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struct ast_dns_txt_record *txt = (struct ast_dns_txt_record *) record;
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ast_assert(ast_dns_record_get_rr_type(record) == T_TXT);
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return txt->count;
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}
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struct ast_vector_string *ast_dns_txt_get_strings(const struct ast_dns_record *record)
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{
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struct ast_vector_string *strings;
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const size_t size = ast_dns_record_get_data_size(record);
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const char *data = ast_dns_record_get_data(record);
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const char *end_of_record = data + size;
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ast_assert(ast_dns_record_get_rr_type(record) == T_TXT);
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strings = ast_malloc(sizeof(struct ast_vector_const_string));
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if (!strings) {
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return NULL;
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}
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if (AST_VECTOR_INIT(strings, ast_dns_txt_get_count(record))) {
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ast_free(strings);
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return NULL;
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}
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while (data < end_of_record) {
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char *s;
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uint8_t bytes = (uint8_t) *data;
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s = ast_malloc(bytes + 1);
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if (!s) {
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ast_dns_txt_free_strings(strings);
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return NULL;
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}
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memcpy(s, &data[1], bytes);
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s[bytes] = 0;
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/* We know the size in advance so this can't fail */
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AST_VECTOR_APPEND(strings, s);
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data += bytes + 1;
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}
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/* Sanity check */
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if (data != end_of_record) {
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ast_dns_txt_free_strings(strings);
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return NULL;
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}
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return strings;
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}
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void ast_dns_txt_free_strings(struct ast_vector_string *strings)
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{
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AST_VECTOR_CALLBACK_VOID(strings, ast_free);
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AST_VECTOR_PTR_FREE(strings);
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}
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