--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libervia/backend/plugins/plugin_xep_0339.py	Fri Jun 02 11:49:51 2023 +0200
@@ -0,0 +1,199 @@
+#!/usr/bin/env python3
+
+# Libervia plugin
+# Copyright (C) 2009-2023 Jérôme Poisson (goffi@goffi.org)
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from typing import List
+
+from twisted.words.protocols.jabber.xmlstream import XMPPHandler
+from twisted.words.xish import domish
+from wokkel import disco, iwokkel
+from zope.interface import implementer
+
+from libervia.backend.core import exceptions
+from libervia.backend.core.constants import Const as C
+from libervia.backend.core.core_types import SatXMPPEntity
+from libervia.backend.core.i18n import _
+from libervia.backend.core.log import getLogger
+from libervia.backend.tools import xml_tools
+
+log = getLogger(__name__)
+
+NS_JINGLE_RTP_SSMA = "urn:xmpp:jingle:apps:rtp:ssma:0"
+
+PLUGIN_INFO = {
+    C.PI_NAME: "Source-Specific Media Attributes in Jingle",
+    C.PI_IMPORT_NAME: "XEP-0339",
+    C.PI_TYPE: "XEP",
+    C.PI_MODES: C.PLUG_MODE_BOTH,
+    C.PI_PROTOCOLS: ["XEP-0339"],
+    C.PI_DEPENDENCIES: ["XEP-0092", "XEP-0167"],
+    C.PI_RECOMMENDATIONS: [],
+    C.PI_MAIN: "XEP_0339",
+    C.PI_HANDLER: "yes",
+    C.PI_DESCRIPTION: _("""Source-Specific Media Attributes in Jingle"""),
+}
+
+
+class XEP_0339:
+    def __init__(self, host):
+        log.info(f"plugin {PLUGIN_INFO[C.PI_NAME]!r} initialization")
+        self.host = host
+        host.trigger.add("XEP-0167_parse_sdp_a", self._parse_sdp_a_trigger)
+        host.trigger.add(
+            "XEP-0167_generate_sdp_content", self._generate_sdp_content_trigger
+        )
+        host.trigger.add("XEP-0167_parse_description", self._parse_description_trigger)
+        host.trigger.add("XEP-0167_build_description", self._build_description_trigger)
+
+    def get_handler(self, client):
+        return XEP_0339_handler()
+
+    def _parse_sdp_a_trigger(
+        self,
+        attribute: str,
+        parts: List[str],
+        call_data: dict,
+        metadata: dict,
+        media_type: str,
+        application_data: dict,
+        transport_data: dict,
+    ) -> None:
+        """Parse "ssrc" attributes"""
+        if attribute == "ssrc":
+            assert application_data is not None
+            ssrc_id = int(parts[0])
+
+            if len(parts) > 1:
+                name, *values = " ".join(parts[1:]).split(":", 1)
+                if values:
+                    value = values[0] or None
+                else:
+                    value = None
+                application_data.setdefault("ssrc", {}).setdefault(ssrc_id, {})[
+                    name
+                ] = value
+            else:
+                log.warning(f"no attribute in ssrc: {' '.join(parts)}")
+                application_data.setdefault("ssrc", {}).setdefault(ssrc_id, {})
+        elif attribute == "ssrc-group":
+            assert application_data is not None
+            semantics, *ssrc_ids = parts
+            ssrc_ids = [int(ssrc_id) for ssrc_id in ssrc_ids]
+            application_data.setdefault("ssrc-group", {})[semantics] = ssrc_ids
+        elif attribute == "msid":
+            assert application_data is not None
+            application_data["msid"] = " ".join(parts)
+
+
+    def _generate_sdp_content_trigger(
+        self,
+        session: dict,
+        local: bool,
+        idx: int,
+        content_data: dict,
+        sdp_lines: List[str],
+        application_data: dict,
+        app_data_key: str,
+        media_data: dict,
+        media: str
+    ) -> None:
+        """Generate "msid" and "ssrc" attributes"""
+        if "msid" in media_data:
+            sdp_lines.append(f"a=msid:{media_data['msid']}")
+
+        ssrc_data = media_data.get("ssrc", {})
+        ssrc_group_data = media_data.get("ssrc-group", {})
+
+        for ssrc_id, attributes in ssrc_data.items():
+            if not attributes:
+                # there are no attributes for this SSRC ID, we add a simple line with only
+                # the SSRC ID
+                sdp_lines.append(f"a=ssrc:{ssrc_id}")
+            else:
+                for attr_name, attr_value in attributes.items():
+                    if attr_value is not None:
+                        sdp_lines.append(f"a=ssrc:{ssrc_id} {attr_name}:{attr_value}")
+                    else:
+                        sdp_lines.append(f"a=ssrc:{ssrc_id} {attr_name}")
+        for semantics, ssrc_ids in ssrc_group_data.items():
+            ssrc_lines = " ".join(str(ssrc_id) for ssrc_id in ssrc_ids)
+            sdp_lines.append(f"a=ssrc-group:{semantics} {ssrc_lines}")
+
+    def _parse_description_trigger(
+        self, desc_elt: domish.Element, media_data: dict
+    ) -> bool:
+        """Parse the <source> and <ssrc-group> elements"""
+        for source_elt in desc_elt.elements(NS_JINGLE_RTP_SSMA, "source"):
+            try:
+                ssrc_id = int(source_elt["ssrc"])
+                media_data.setdefault("ssrc", {})[ssrc_id] = {}
+                for param_elt in source_elt.elements(NS_JINGLE_RTP_SSMA, "parameter"):
+                    name = param_elt["name"]
+                    value = param_elt.getAttribute("value")
+                    media_data["ssrc"][ssrc_id][name] = value
+                    if name == "msid" and "msid" not in media_data:
+                        media_data["msid"] = value
+            except (KeyError, ValueError) as e:
+                log.warning(f"Error while parsing <source>: {e}\n{source_elt.toXml()}")
+
+        for ssrc_group_elt in desc_elt.elements(NS_JINGLE_RTP_SSMA, "ssrc-group"):
+            try:
+                semantics = ssrc_group_elt["semantics"]
+                semantic_ids = media_data.setdefault("ssrc-group", {})[semantics] = []
+                for source_elt in ssrc_group_elt.elements(NS_JINGLE_RTP_SSMA, "source"):
+                    semantic_ids.append(
+                        int(source_elt["ssrc"])
+                    )
+            except (KeyError, ValueError) as e:
+                log.warning(
+                    f"Error while parsing <ssrc-group>: {e}\n{ssrc_group_elt.toXml()}"
+                )
+
+        return True
+
+    def _build_description_trigger(
+        self, desc_elt: domish.Element, media_data: dict, session: dict
+    ) -> bool:
+        """Build the <source> and <ssrc-group> elements if possible"""
+        for ssrc_id, parameters in media_data.get("ssrc", {}).items():
+            if "msid" not in parameters and "msid" in media_data:
+                parameters["msid"] = media_data["msid"]
+            source_elt = desc_elt.addElement((NS_JINGLE_RTP_SSMA, "source"))
+            source_elt["ssrc"] = str(ssrc_id)
+            for name, value in parameters.items():
+                param_elt = source_elt.addElement((NS_JINGLE_RTP_SSMA, "parameter"))
+                param_elt["name"] = name
+                if value is not None:
+                    param_elt["value"] = value
+
+        for semantics, ssrc_ids in media_data.get("ssrc-group", {}).items():
+            ssrc_group_elt = desc_elt.addElement((NS_JINGLE_RTP_SSMA, "ssrc-group"))
+            ssrc_group_elt["semantics"] = semantics
+            for ssrc_id in ssrc_ids:
+                source_elt = ssrc_group_elt.addElement((NS_JINGLE_RTP_SSMA, "source"))
+                source_elt["ssrc"] = str(ssrc_id)
+
+        return True
+
+
+@implementer(iwokkel.IDisco)
+class XEP_0339_handler(XMPPHandler):
+    def getDiscoInfo(self, requestor, target, nodeIdentifier=""):
+        return [disco.DiscoFeature(NS_JINGLE_RTP_SSMA)]
+
+    def getDiscoItems(self, requestor, target, nodeIdentifier=""):
+        return []