add full SDP codec information to the MNCC socket

This way osmo-msc can benefit from the complete codec information received via
SIP, which was so far terminated at osmo-sip-connector. osmo-sip-connector
could/should have translated the received SDP to MNCC bearer_cap, but this was
never implemented properly. Since osmo-msc already handles SDP towards the MGW,
it makes most sense to pass SDP to osmo-msc transparently.

To be able to send a valid RTP IP:port in the SDP upon the first MNCC_SETUP_IND
going out, move the CN side CRCX to the very start of establishing a voice
call. As a result, first create MGW conns for both RAN and CN before starting.

The voice_call_full.msc chart shows the change in message sequence for MO and
MT voice calls.

Implement cc_sdp.c, which accumulates codec information from various sources
(MS, BSS, Assignment, remote call leg) and provides filtering to get the
available set of codecs at any point in time.

Implement codec_sdp_cc_t9n.c, to translate between SDP and the various
libosmo-mgcp-client, CC and BSSMAP representations of codecs:
- Speech Version,
- Permitted Speech,
- Speech Codec Type,
- default Payload Type numbers,
- enum mgcp_codecs,
- FR/HR compatibility
- SDP audio codec names,
- various AMR configurations.
A codec_map lists these relations in one large data record.
Various functions provide conversions by traversing this map.

Add trans->cc.mnccc_release_sent: so far, avoiding to send an MNCC release
during trans_free() was done by setting the callref = 0. But that also skips CC
Release. On codec mismatch, we send a specific MNCC error code but still want a
normal CC Release: hence send the MNCC message, set mnccc_release_sent = true
and do normal CC Release in trans_free().
(A better way to do this would be to adopt the mncc_call FSM from inter-MSC
handover also for local voice calls, but that is out of scope for now. I want
to try that soon, as time permits.)

Change-Id: I8c3b2de53ffae4ec3a66b9dabf308c290a2c999f

1 files changed, 58 insertions, 0 deletions

diff --git a/include/osmocom/msc/codec_sdp_cc_t9n.h b/include/osmocom/msc/codec_sdp_cc_t9n.h
new file mode 100644
index 000000000..b082f159e
--- /dev/null
+++ b/include/osmocom/msc/codec_sdp_cc_t9n.h
@@ -0,0 +1,58 @@
+/* Routines for translation ("t9n") between SDP codec names and CC/BSSMAP codec constants */
+#pragma once
+
+#include <osmocom/gsm/protocol/gsm_04_08.h>
+#include <osmocom/gsm/protocol/gsm_08_08.h>
+#include <osmocom/mgcp_client/mgcp_client.h>
+#include <osmocom/msc/sdp_msg.h>
+#include <osmocom/gsm/mncc.h>
+
+#define NO_MGCP_CODEC 0xffffffff
+
+extern const struct gsm_mncc_bearer_cap bearer_cap_empty;
+
+enum codec_frhr {
+	CODEC_FRHR_NONE = 0,
+	CODEC_FRHR_FR,
+	CODEC_FRHR_HR,
+};
+
+struct codec_mapping {
+	struct sdp_audio_codec sdp;
+	enum mgcp_codecs mgcp;
+	unsigned int speech_ver_count;
+	enum gsm48_bcap_speech_ver speech_ver[8];
+	uint32_t mncc_payload_msg_type;
+	/* gsm0808_speech_codec_type corresponds to gsm0808_speech_codec[_list]->type */
+	bool has_gsm0808_speech_codec_type;
+	enum gsm0808_speech_codec_type gsm0808_speech_codec_type;
+	enum gsm0808_permitted_speech perm_speech;
+	enum codec_frhr frhr;
+};
+
+extern const struct codec_mapping codec_map[];
+#define foreach_codec_mapping(CODEC_MAPPING) \
+	for ((CODEC_MAPPING) = codec_map; (CODEC_MAPPING) < codec_map + ARRAY_SIZE(codec_map); (CODEC_MAPPING)++)
+
+const struct codec_mapping *codec_mapping_by_speech_ver(enum gsm48_bcap_speech_ver speech_ver);
+const struct codec_mapping *codec_mapping_by_gsm0808_speech_codec_type(enum gsm0808_speech_codec_type sct,
+								       uint16_t cfg);
+const struct codec_mapping *codec_mapping_by_perm_speech(enum gsm0808_permitted_speech perm_speech);
+const struct codec_mapping *codec_mapping_by_subtype_name(const char *subtype_name);
+const struct codec_mapping *codec_mapping_by_mgcp_codec(enum mgcp_codecs mgcp);
+
+int bearer_cap_add_speech_ver(struct gsm_mncc_bearer_cap *bearer_cap, enum gsm48_bcap_speech_ver speech_ver);
+int sdp_audio_codec_add_to_bearer_cap(struct gsm_mncc_bearer_cap *bearer_cap, const struct sdp_audio_codec *codec);
+int sdp_audio_codecs_to_bearer_cap(struct gsm_mncc_bearer_cap *bearer_cap, const struct sdp_audio_codecs *ac);
+int bearer_cap_set_radio(struct gsm_mncc_bearer_cap *bearer_cap);
+
+struct sdp_audio_codec *sdp_audio_codecs_add_speech_ver(struct sdp_audio_codecs *ac,
+							enum gsm48_bcap_speech_ver speech_ver);
+struct sdp_audio_codec *sdp_audio_codecs_add_mgcp_codec(struct sdp_audio_codecs *ac, enum mgcp_codecs mgcp_codec);
+void sdp_audio_codecs_from_bearer_cap(struct sdp_audio_codecs *ac, const struct gsm_mncc_bearer_cap *bc);
+
+void sdp_audio_codecs_from_speech_codec_list(struct sdp_audio_codecs *ac, const struct gsm0808_speech_codec_list *cl);
+
+int sdp_audio_codecs_to_gsm0808_channel_type(struct gsm0808_channel_type *ct, const struct sdp_audio_codecs *ac);
+
+enum mgcp_codecs sdp_audio_codec_to_mgcp_codec(const struct sdp_audio_codec *codec);