dns_txt: Add TXT record parsing support
Change-Id: Ie0eca23b8e6f4c7d9846b6013d79099314d90ef5
This commit is contained in:
Sean Bright
George Joseph
parent
c40050d350
commit
479723f3cc
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@ -26,6 +26,9 @@
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#ifndef _ASTERISK_DNS_INTERNAL_H
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#define _ASTERISK_DNS_INTERNAL_H
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/*! \brief For AST_LIST */
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#include "asterisk/linkedlists.h"
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/*! \brief For AST_VECTOR */
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#include "asterisk/vector.h"
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@ -57,6 +60,16 @@ struct ast_dns_record {
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char data[0];
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};
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/*! \brief A TXT record */
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struct ast_dns_txt_record {
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/*! \brief Generic DNS record information */
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struct ast_dns_record generic;
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/*! \brief The number of character strings in the TXT record */
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size_t count;
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/*! \brief The raw DNS record */
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char data[0];
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};
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/*! \brief An SRV record */
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struct ast_dns_srv_record {
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/*! \brief Generic DNS record information */
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@ -199,6 +212,19 @@ struct ast_sched_context;
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*/
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struct ast_sched_context *ast_dns_get_sched(void);
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/*!
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* \brief Allocate and parse a DNS TXT record
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* \since 16.10.0, 17.4.0
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*
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* \param query The DNS query
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* \param data This specific TXT record
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* \param size The size of the TXT record
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*
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* \retval non-NULL success
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* \retval NULL failure
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*/
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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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* \brief Allocate and parse a DNS NAPTR record
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*
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@ -0,0 +1,64 @@
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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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#ifndef ASTERISK_DNS_TXT_H
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#define ASTERISK_DNS_TXT_H
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#if defined(__cplusplus) || defined(c_plusplus)
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extern "C" {
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#endif
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/*!
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* \brief Get the number of character strings in a TXT record
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* \since 16.10.0, 17.4.0
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*
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* \param record The DNS record
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*
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* \return the number of character strings in this TXT record
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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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* \brief Get the character strings from this TXT record
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* \since 16.10.0, 17.4.0
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*
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* \param record The DNS record
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*
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* \retval NULL Unable to allocate memory
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* \return Vector of strings. Free with ast_dns_txt_free_strings
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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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* \brief Free strings returned by ast_dns_txt_get_strings
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* \since 16.10.0, 17.4.0
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*
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* \param strings The vector to free
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*/
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void ast_dns_txt_free_strings(struct ast_vector_string *strings);
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#if defined(__cplusplus) || defined(c_plusplus)
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}
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#endif
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#endif /* ASTERISK_DNS_TXT_H */
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@ -516,8 +516,9 @@ static struct ast_dns_record *generic_record_alloc(struct ast_dns_query *query,
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typedef struct ast_dns_record *(*dns_alloc_fn)(struct ast_dns_query *query, const char *data, const size_t size);
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static dns_alloc_fn dns_alloc_table [] = {
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[T_TXT] = dns_txt_alloc,
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[T_NAPTR] = dns_naptr_alloc,
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[T_SRV] = dns_srv_alloc,
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[T_SRV] = dns_srv_alloc,
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};
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static struct ast_dns_record *allocate_dns_record(unsigned int rr_type, struct ast_dns_query *query, const char *data, const size_t size)
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@ -0,0 +1,126 @@
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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 <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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