Reduce duplication of common DNS code.

The NAPTR and SRV branches were worked on independently and
resulted in some code being duplicated in each. Since both
have been merged into trunk now, this patch reduces the
duplication by factoring out common code into its own
source files.



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@434490 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 109 insertions, 0 deletions

diff --git a/include/asterisk/dns_test.h b/include/asterisk/dns_test.h
new file mode 100644
index 000000000..0858bab33
--- /dev/null
+++ b/include/asterisk/dns_test.h
@@ -0,0 +1,109 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2015, Digium, Inc.
+ *
+ * Mark Michelson <mmichelson@digium.com>
+ *
+ * Includes code and algorithms from the Zapata library.
+ *
+ * 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.
+ */
+
+#ifndef DNS_TEST_H
+#define DNS_TEST_H
+
+/*!
+ * \brief Representation of a string in DNS
+ *
+ * In DNS, a string has a byte to indicate the length,
+ * followed by a series of bytes representing the string.
+ * DNS does not NULL-terminate its strings. However, the
+ * string stored in this structure is expected to be NULL-
+ * terminated.
+ */
+struct ast_dns_test_string {
+	uint8_t len;
+	const char *val;
+};
+
+/*!
+ * \brief Write a DNS string to a buffer
+ *
+ * This writes the DNS string to the buffer and returns the total
+ * number of bytes written to the buffer.
+ *
+ * There is no buffer size passed to this function. Tests are expected to
+ * use a buffer that is sufficiently large for their tests.
+ *
+ * \param string The string to write
+ * \param buf The buffer to write the string into
+ * \return The number of bytes written to the buffer
+ */
+int ast_dns_test_write_string(const struct ast_dns_test_string *string, char *buf);
+
+/*!
+ * \brief Write a DNS domain to a buffer
+ *
+ * A DNS domain consists of a series of labels separated
+ * by dots. Each of these labels gets written as a DNS
+ * string. A DNS domain ends with a NULL label, which is
+ * essentially a zero-length DNS string.
+ *
+ * There is no buffer size passed to this function. Tests are expected to
+ * use a buffer that is sufficiently large for their tests.
+ *
+ * \param string The DNS domain to write
+ * \param buf The buffer to write the domain into
+ * \return The number of bytes written to the buffer
+ */
+int ast_dns_test_write_domain(const char *string, char *buf);
+
+/*!
+ * \brief Callback to write specific DNS record to an answer
+ *
+ * When generating a DNS result, the type of DNS record being generated
+ * will need to be performed by individual test cases. This is a callback
+ * that tests can define to write a specific type of DNS record to the
+ * provided buffer.
+ *
+ * There is no buffer size passed to this function. Tests are expected to
+ * use a buffer that is sufficiently large for their tests.
+ *
+ * \param record Pointer to test-specific DNS record data
+ * \param buf The buffer into which to write the DNS record
+ * \return The number of bytes written to the buffer
+ */
+typedef int (*record_fn)(void *record, char *buf);
+
+/*!
+ * \brief Generate a full DNS response for the given DNS records.
+ *
+ * This function takes care of generating the DNS header, question, and
+ * answer sections of a DNS response. In order to place test-specific
+ * record data into the DNS answers, a callback is provided as a parameter
+ * to this function so that the necessary records can be encoded properly
+ * by the tests.
+ *
+ * There is no buffer size passed to this function. Tests are expected to
+ * use a buffer that is sufficiently large for their tests.
+ *
+ * \param query The DNS query that is being processed
+ * \param records An array of test-specific representations of DNS records
+ * \param num_records The number of elements in the records array
+ * \param record_size The size of each element in the records array
+ * \param generate The test-specific encoder for DNS records
+ * \param buffer The buffer into which to write the DNS response
+ */
+int ast_dns_test_generate_result(struct ast_dns_query *query, void *records, size_t num_records,
+		size_t record_size, record_fn generate, char *buffer);
+
+#endif /* DNS_TEST_H */