[Asterisk-code-review] dns_txt: Add TXT record parsing support (asterisk[16])
Sean Bright
asteriskteam at digium.com
Wed Mar 11 15:32:37 CDT 2020
Sean Bright has uploaded this change for review. ( https://gerrit.asterisk.org/c/asterisk/+/13907 )
Change subject: dns_txt: Add TXT record parsing support
......................................................................
dns_txt: Add TXT record parsing support
Change-Id: Ie0eca23b8e6f4c7d9846b6013d79099314d90ef5
---
M include/asterisk/dns_internal.h
A include/asterisk/dns_txt.h
M main/dns_core.c
A main/dns_txt.c
4 files changed, 214 insertions(+), 1 deletion(-)
git pull ssh://gerrit.asterisk.org:29418/asterisk refs/changes/07/13907/1
diff --git a/include/asterisk/dns_internal.h b/include/asterisk/dns_internal.h
index 7ce0c28..3d2d0df 100644
--- a/include/asterisk/dns_internal.h
+++ b/include/asterisk/dns_internal.h
@@ -26,6 +26,9 @@
#ifndef _ASTERISK_DNS_INTERNAL_H
#define _ASTERISK_DNS_INTERNAL_H
+/*! \brief For AST_LIST */
+#include "asterisk/linkedlists.h"
+
/*! \brief For AST_VECTOR */
#include "asterisk/vector.h"
@@ -57,6 +60,16 @@
char data[0];
};
+/*! \brief A TXT record */
+struct ast_dns_txt_record {
+ /*! \brief Generic DNS record information */
+ struct ast_dns_record generic;
+ /*! \brief The number of character strings in the TXT record */
+ size_t count;
+ /*! \brief The raw DNS record */
+ char data[0];
+};
+
/*! \brief An SRV record */
struct ast_dns_srv_record {
/*! \brief Generic DNS record information */
@@ -200,6 +213,19 @@
struct ast_sched_context *ast_dns_get_sched(void);
/*!
+ * \brief Allocate and parse a DNS TXT record
+ * \since 16.10.0, 17.4.0
+ *
+ * \param query The DNS query
+ * \param data This specific TXT record
+ * \param size The size of the TXT record
+ *
+ * \retval non-NULL success
+ * \retval NULL failure
+ */
+struct ast_dns_record *dns_txt_alloc(struct ast_dns_query *query, const char *data, const size_t size);
+
+/*!
* \brief Allocate and parse a DNS NAPTR record
*
* \param query The DNS query
diff --git a/include/asterisk/dns_txt.h b/include/asterisk/dns_txt.h
new file mode 100644
index 0000000..3e12017
--- /dev/null
+++ b/include/asterisk/dns_txt.h
@@ -0,0 +1,64 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2020, Sean Bright
+ *
+ * Sean Bright <sean.bright at gmail.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+/*! \file
+ * \brief DNS TXT Record Parsing API
+ * \author Sean Bright <sean.bright at gmail.com>
+ */
+
+#ifndef ASTERISK_DNS_TXT_H
+#define ASTERISK_DNS_TXT_H
+
+#if defined(__cplusplus) || defined(c_plusplus)
+extern "C" {
+#endif
+
+/*!
+ * \brief Get the number of character strings in a TXT record
+ * \since 16.10.0, 17.4.0
+ *
+ * \param record The DNS record
+ *
+ * \return the number of character strings in this TXT record
+ */
+size_t ast_dns_txt_get_count(const struct ast_dns_record *record);
+
+/*!
+ * \brief Get the character strings from this TXT record
+ * \since 16.10.0, 17.4.0
+ *
+ * \param record The DNS record
+ *
+ * \retval NULL Unable to allocate memory
+ * \return Vector of strings. Free with ast_dns_txt_get_strings
+ */
+struct ast_vector_string *ast_dns_txt_get_strings(const struct ast_dns_record *record);
+
+/*!
+ * \brief Free strings returned by ast_dns_txt_get_strings
+ * \since 16.10.0, 17.4.0
+ *
+ * \param strings The vector to free
+ */
+void ast_dns_txt_free_strings(struct ast_vector_string *strings);
+
+#if defined(__cplusplus) || defined(c_plusplus)
+}
+#endif
+
+#endif /* ASTERISK_DNS_TXT_H */
diff --git a/main/dns_core.c b/main/dns_core.c
index f262d7d..0fb0731 100644
--- a/main/dns_core.c
+++ b/main/dns_core.c
@@ -516,8 +516,9 @@
typedef struct ast_dns_record *(*dns_alloc_fn)(struct ast_dns_query *query, const char *data, const size_t size);
static dns_alloc_fn dns_alloc_table [] = {
+ [T_TXT] = dns_txt_alloc,
[T_NAPTR] = dns_naptr_alloc,
- [T_SRV] = dns_srv_alloc,
+ [T_SRV] = dns_srv_alloc,
};
static struct ast_dns_record *allocate_dns_record(unsigned int rr_type, struct ast_dns_query *query, const char *data, const size_t size)
diff --git a/main/dns_txt.c b/main/dns_txt.c
new file mode 100644
index 0000000..bd1f3dd
--- /dev/null
+++ b/main/dns_txt.c
@@ -0,0 +1,122 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2020, Sean Bright
+ *
+ * Sean Bright <sean.bright at gmail.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+/*! \file
+ * \brief DNS TXT Record Parsing API
+ * \author Sean Bright <sean.bright at gmail.com>
+ */
+
+/*** MODULEINFO
+ <support_level>core</support_level>
+ ***/
+
+#include "asterisk.h"
+
+#include <resolv.h>
+
+#include "asterisk/dns_core.h"
+#include "asterisk/dns_txt.h"
+#include "asterisk/dns_internal.h"
+#include "asterisk/utils.h"
+
+struct ast_dns_record *dns_txt_alloc(struct ast_dns_query *query, const char *data, const size_t size)
+{
+ struct ast_dns_txt_record *txt;
+ const char *end_of_record = data + size;
+ size_t count = 0;
+
+ /* Because we can't allocate additional memory, the best we can do here is just
+ * validate that this confirms to a TXT record. */
+ while (data < end_of_record) {
+ uint8_t byte_count = (uint8_t) *data;
+ count++;
+ data += byte_count + 1;
+ }
+
+ if (data != end_of_record) {
+ /* This is not a valid TXT record, so we can bail out */
+ return NULL;
+ }
+
+ txt = ast_calloc(1, sizeof(*txt) + size);
+ txt->count = count;
+ txt->generic.data_ptr = txt->data;
+
+ return (struct ast_dns_record *) txt;
+}
+
+size_t ast_dns_txt_get_count(const struct ast_dns_record *record)
+{
+ struct ast_dns_txt_record *txt = (struct ast_dns_txt_record *) record;
+ ast_assert(ast_dns_record_get_rr_type(record) == T_TXT);
+ return txt->count;
+}
+
+struct ast_vector_string *ast_dns_txt_get_strings(const struct ast_dns_record *record)
+{
+ struct ast_vector_string *strings;
+
+ const size_t size = ast_dns_record_get_data_size(record);
+ const char *data = ast_dns_record_get_data(record);
+ const char *end_of_record = data + size;
+
+ ast_assert(ast_dns_record_get_rr_type(record) == T_TXT);
+
+ strings = ast_malloc(sizeof(struct ast_vector_const_string));
+ if (!strings) {
+ return NULL;
+ }
+
+ if (AST_VECTOR_INIT(strings, ast_dns_txt_get_count(record))) {
+ ast_free(strings);
+ return NULL;
+ }
+
+ while (data < end_of_record) {
+ char *s;
+ uint8_t bytes = (uint8_t) *data;
+
+ s = ast_malloc(bytes + 1);
+ if (!s) {
+ ast_dns_txt_free_strings(strings);
+ return NULL;
+ }
+
+ memcpy(s, &data[1], bytes);
+ s[bytes] = 0;
+
+ /* We've know the size in advance so this can't fail */
+ AST_VECTOR_APPEND(strings, s);
+
+ data += bytes + 1;
+ }
+
+ /* Sanity check */
+ if (data != end_of_record) {
+ ast_dns_txt_free_strings(strings);
+ return NULL;
+ }
+
+ return strings;
+}
+
+void ast_dns_txt_free_strings(struct ast_vector_string *strings)
+{
+ AST_VECTOR_CALLBACK_VOID(strings, ast_free);
+ AST_VECTOR_PTR_FREE(strings);
+}
--
To view, visit https://gerrit.asterisk.org/c/asterisk/+/13907
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Gerrit-Project: asterisk
Gerrit-Branch: 16
Gerrit-Change-Id: Ie0eca23b8e6f4c7d9846b6013d79099314d90ef5
Gerrit-Change-Number: 13907
Gerrit-PatchSet: 1
Gerrit-Owner: Sean Bright <sean.bright at gmail.com>
Gerrit-MessageType: newchange
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