Add SDP translator and PJMEDIA implementation.

This creates the following:
* Asterisk's internal representation of an SDP
* An API for translating SDPs from one format to another
* An implementation of a translator for PJMEDIA

Change-Id: Ie2ecd3cbebe76756577be9b133e84d2ee356d46b

3 files changed, 234 insertions, 0 deletions

diff --git a/include/asterisk/sdp_options.h b/include/asterisk/sdp_options.h
index 52f6f5545..a5c2d084e 100644
--- a/include/asterisk/sdp_options.h
+++ b/include/asterisk/sdp_options.h
@@ -108,6 +108,8 @@ enum ast_sdp_options_repr {
 	AST_SDP_REPR_STRING,
 	/*! SDP is represented as a pjmedia_sdp_session */
 	AST_SDP_REPR_PJMEDIA,
+	/*! End of the list */
+	AST_SDP_REPR_END,
 };
 
 /*!
diff --git a/include/asterisk/sdp_priv.h b/include/asterisk/sdp_priv.h
new file mode 100644
index 000000000..000d11143
--- /dev/null
+++ b/include/asterisk/sdp_priv.h
@@ -0,0 +1,130 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2017, Digium, Inc.
+ *
+ * Mark Michelson <mmichelson@digium.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.
+ */
+
+/* NOTE: It is unlikely that you need to include this file. You probably will only need
+ * this if you are an SDP translator, or if you are an inner part of the SDP API
+ */
+
+#ifndef _SDP_PRIV_H
+#define _SDP_PRIV_H
+
+#include "asterisk/vector.h"
+
+/*!
+ * \brief Structure representing an SDP attribute
+ */
+struct ast_sdp_a_line {
+	/*! Attribute name */
+	char *name;
+	/*! Attribute value. For attributes that have no value, this will be an empty string */
+	char *value;
+};
+
+/*!
+ * \brief Structure representing an SDP connection
+ */
+struct ast_sdp_c_line {
+	/* IP family string (e.g. IP4 or IP6) */
+	char *family;
+	/* Connection address. Can be an IP address or FQDN */
+	char *addr;
+};
+
+/*!
+ * \brief A collection of SDP attributes
+ */
+AST_VECTOR(ast_sdp_a_line_vector, struct ast_sdp_a_line);
+
+/*!
+ * \brief An SDP media stream
+ *
+ * This contains both the m line, as well as its
+ * constituent a lines.
+ */
+struct ast_sdp_m_line {
+	/*! Media type (e.g. "audio" or "video") */
+	char *type;
+	/*! Port number in m line */
+	uint16_t port;
+	/*! Number of ports specified in m line */
+	uint16_t port_count;
+	/*! RTP profile string (e.g. "RTP/AVP") */
+	char *profile;
+	/*! RTP payloads */
+	AST_VECTOR(, char *) payloads;
+	/*! Connection information for this media stream */
+	struct ast_sdp_c_line c_line;
+	/*! The attributes for this media stream */
+	struct ast_sdp_a_line_vector a_lines;
+};
+
+/*!
+ * \brief SDP time information
+ */
+struct ast_sdp_t_line {
+	/*! Session start time */
+	uint32_t start;
+	/*! Session end time */
+	uint32_t end;
+};
+
+/*!
+ * \brief An SDP
+ */
+struct ast_sdp {
+	/*! SDP Origin line */
+	struct {
+		/*! Origin user name */
+		char *user;
+		/*! Origin id */
+		uint32_t id;
+		/*! Origin version */
+		uint32_t version;
+		/*! Origin IP address family (e.g. "IP4" or "IP6") */
+		char *family;
+		/*! Origin address. Can be an IP address or FQDN */
+		char *addr;
+	} o_line;
+	/*! SDP Session name */
+	char *s_line;
+	/*! SDP top-level connection information */
+	struct ast_sdp_c_line c_line;
+	/*! SDP timing information */
+	struct ast_sdp_t_line t_line;
+	/*! SDP top-level attributes */
+	struct ast_sdp_a_line_vector a_lines;
+	/*! SDP media streams */
+	AST_VECTOR(, struct ast_sdp_m_line) m_lines;
+};
+
+/*!
+ * \brief Allocate a new SDP.
+ *
+ * \note This does not perform any initialization.
+ *
+ * \retval NULL FAIL
+ * \retval non-NULL New SDP
+ */
+struct ast_sdp *ast_sdp_alloc(void);
+
+/*!
+ * \brief Free an SDP and all its constituent parts
+ */
+void ast_sdp_free(struct ast_sdp *dead);
+
+#endif /* _SDP_PRIV_H */
diff --git a/include/asterisk/sdp_translator.h b/include/asterisk/sdp_translator.h
new file mode 100644
index 000000000..62a875e0a
--- /dev/null
+++ b/include/asterisk/sdp_translator.h
@@ -0,0 +1,102 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2017, Digium, Inc.
+ *
+ * Mark Michelson <mmichelson@digium.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.
+ */
+
+#ifndef _ASTERISK_SDP_TRANSLATOR_H
+#define _ASTERISK_SDP_TRANSLATOR_H
+
+#include "asterisk/sdp_options.h"
+
+struct sdp;
+
+/*!
+ * \brief SDP translator operations
+ */
+struct ast_sdp_translator_ops {
+	/*! The SDP representation on which this translator operates */
+	enum ast_sdp_options_repr repr;
+	/*! Allocate new translator private data for a translator */
+	void *(*translator_new)(void);
+	/*! Free translator private data */
+	void (*translator_free)(void *translator_priv);
+	/*! Convert the channel-native SDP into an internal Asterisk SDP */
+	struct ast_sdp *(*to_sdp)(void *repr_sdp, void *translator_priv);
+	/*! Convert an internal Asterisk SDP into a channel-native SDP */
+	void *(*from_sdp)(struct ast_sdp *sdp, void *translator_priv);
+};
+
+/*!
+ * \brief An SDP translator
+ *
+ * An SDP translator is responsible for converting between Asterisk's internal
+ * representation of an SDP and the representation that is native to the channel
+ * driver. Translators are allocated per-use.
+ */
+struct ast_sdp_translator {
+	/*! The operations this translator uses */
+	struct ast_sdp_translator_ops *ops;
+	/*! Private data this translator uses */
+	void *translator_priv;
+};
+
+/*!
+ * \brief Register an SDP translator
+ * \param ops The SDP operations defined by this translator
+ * \retval 0 Success
+ * \retval -1 FAIL
+ */
+int ast_sdp_register_translator(struct ast_sdp_translator_ops *ops);
+
+/*!
+ * \brief Unregister an SDP translator
+ */
+void ast_sdp_unregister_translator(struct ast_sdp_translator_ops *ops);
+
+/*!
+ * \brief Allocate a new SDP translator
+ * \param Representation corresponding to the translator_ops to use
+ * \retval NULL FAIL
+ * \retval non-NULL New SDP translator
+ */
+struct ast_sdp_translator *ast_sdp_translator_new(enum ast_sdp_options_repr repr);
+
+/*!
+ * \brief Free an SDP translator
+ */
+void ast_sdp_translator_free(struct ast_sdp_translator *translator);
+
+/*!
+ * \brief Translate a native SDP to internal Asterisk SDP
+ *
+ * \param translator The translator to use when translating
+ * \param native_sdp The SDP from the channel driver
+ * \retval NULL FAIL
+ * \retval Non-NULL The translated SDP
+ */
+struct ast_sdp *ast_sdp_translator_to_sdp(struct ast_sdp_translator *translator, void *native_sdp);
+
+/*!
+ * \brief Translate an internal Asterisk SDP to a native SDP
+ *
+ * \param translator The translator to use when translating
+ * \param ast_sdp The Asterisk SDP to translate
+ * \retval NULL FAIL
+ * \retval non-NULL The translated SDP
+ */
+void *ast_sdp_translator_from_sdp(struct ast_sdp_translator *translator, struct ast_sdp *ast_sdp);
+
+#endif /* _ASTERISK_SDP_TRANSLATOR_H */