res_pjsip: Add 100rel option "peer_supported".

This patch adds a new option to the 100rel parameter for pjsip
endpoints called "peer_supported". When an endpoint with this option
receives an incoming request and the request indicated support for the
100rel extension, then Asterisk will send 1xx responses reliably. If
the request did not indicate 100rel support, Asterisk sends 1xx
responses normally.

ASTERISK-30158

Change-Id: Id6d95ffa8f00dab118e0b386146e99f254f287ad

contrib/ast-db-manage/config/versions/539f68bede2c_add_peer_supported_to_100rel.py

@@ -0,0 +1,57 @@
+"""Add peer_supported to 100rel
+
+Revision ID: 539f68bede2c
+Revises: 9f3692b1654b
+Create Date: 2022-08-10 09:36:16.576049
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '539f68bede2c'
+down_revision = '9f3692b1654b'
+
+from alembic import op
+from sqlalchemy.dialects.postgresql import ENUM
+import sqlalchemy as sa
+
+
+OLD_ENUM = ['no', 'required', 'yes']
+NEW_ENUM = ['no', 'required', 'peer_supported', 'yes']
+
+old_type = sa.Enum(*OLD_ENUM, name='pjsip_100rel_values')
+new_type = sa.Enum(*NEW_ENUM, name='pjsip_100rel_values_v2')
+
+def upgrade():
+    context = op.get_context()
+
+    # Upgrading to this revision WILL clear your directmedia values.
+    if context.bind.dialect.name != 'postgresql':
+        op.alter_column('ps_endpoints', '100rel',
+                        type_=new_type,
+                        existing_type=old_type)
+    else:
+        enum = ENUM(*NEW_ENUM, name='pjsip_100rel_values_v2')
+        enum.create(op.get_bind(), checkfirst=False)
+
+        op.execute('ALTER TABLE ps_endpoints ALTER COLUMN 100rel TYPE'
+                   ' pjsip_100rel_values_v2 USING'
+                   ' 100rel::text::pjsip_100rel_values_v2')
+
+        ENUM(name="pjsip_100rel_values").drop(op.get_bind(), checkfirst=False)
+
+def downgrade():
+    context = op.get_context()
+
+    if context.bind.dialect.name != 'postgresql':
+        op.alter_column('ps_endpoints', '100rel',
+                        type_=old_type,
+                        existing_type=new_type)
+    else:
+        enum = ENUM(*OLD_ENUM, name='pjsip_100rel_values')
+        enum.create(op.get_bind(), checkfirst=False)
+
+        op.execute('ALTER TABLE ps_endpoints ALTER COLUMN 100rel TYPE'
+                   ' pjsip_100rel_values USING'
+                   ' 100rel::text::pjsip_100rel_values')
+
+        ENUM(name="pjsip_100rel_values_v2").drop(op.get_bind(), checkfirst=False)

doc/CHANGES-staging/res_pjsip_100rel_option.txt

@@ -0,0 +1,6 @@
+Subject: res_pjsip
+
+A new option named "peer_supported" has been added to the endpoint option
+100rel. When set to this option, Asterisk sends provisional responses
+reliably if the peer supports it. If the peer does not support reliable
+provisional responses, Asterisk sends them normally.

include/asterisk/res_pjsip.h

@@ -449,6 +449,20 @@ struct ast_sip_contact_wrapper {
 	struct ast_sip_contact *contact;
 };
 
+/*!
+ * \brief 100rel modes for SIP endpoints
+ */
+enum ast_sip_100rel_mode {
+	/*! Do not support 100rel. (no) */
+	AST_SIP_100REL_UNSUPPORTED = 0,
+	/*! As UAC, indicate 100rel support in Supported header. (yes) */
+	AST_SIP_100REL_SUPPORTED,
+	/*! As UAS, send 1xx responses reliably, if the UAC indicated its support. Otherwise same as AST_SIP_100REL_SUPPORTED. (peer_supported) */
+	AST_SIP_100REL_PEER_SUPPORTED,
+	/*! Require the use of 100rel. (required) */
+	AST_SIP_100REL_REQUIRED,
+};
+
 /*!
  * \brief DTMF modes for SIP endpoints
  */
@@ -981,6 +995,8 @@ struct ast_sip_endpoint {
 	AST_STRING_FIELD_EXTENDED(geoloc_incoming_call_profile);
 	/*! The name of the geoloc profile to apply when Asterisk sends a call to this endpoint */
 	AST_STRING_FIELD_EXTENDED(geoloc_outgoing_call_profile);
+	/*! 100rel mode to use with this endpoint */
+	enum ast_sip_100rel_mode rel100;
 };
 
 /*! URI parameter for symmetric transport */

res/res_pjsip/pjsip_config.xml

@@ -32,9 +32,33 @@
 					<synopsis>Allow support for RFC3262 provisional ACK tags</synopsis>
 					<description>
 						<enumlist>
-							<enum name="no" />
-							<enum name="required" />
-							<enum name="yes" />
+							<enum name="no">
+							<para>If set to <literal>no</literal>, do not support transmission of
+							reliable provisional responses. As UAS, if an incoming request contains 100rel
+							in the Required header, it is rejected with 420 Bad Extension.</para>
+							</enum>
+							<enum name="required">
+							<para>If set to <literal>required</literal>, require provisional responses to
+							be sent and received reliably. As UAS, incoming requests without 100rel
+							in the Supported header are rejected with 421 Extension Required. As UAC,
+							outgoing requests will have 100rel in the Required header.</para>
+							</enum>
+							<enum name="peer_supported">
+							<para>If set to <literal>peer_supported</literal>, send provisional responses
+							reliably if the request by the peer contained 100rel in the Supported or
+							Require header. As UAS, if an incoming request contains 100rel in the Supported
+							header, send 1xx responses reliably. If the request by the peer does not contain 100rel
+							in the Supported and Require header, send responses normally. As UAC, outgoing requests
+							will contain 100rel in the Supported header.</para>
+							</enum>
+							<enum name="yes">
+							<para>If set to <literal>yes</literal>, indicate the support of reliable provisional
+							responses and PRACK them if required by the peer. As UAS, if the incoming request
+							contains 100rel in the Supported header but not in the Required header, send 1xx
+							responses normally. If the incoming request contains 100rel in the Required header,
+							send 1xx responses reliably. As UAC add 100rel to the Supported header and PRACK 1xx
+							responses if required.</para>
+							</enum>
 						</enumlist>
 					</description>
 				</configOption>

res/res_pjsip/pjsip_configuration.c

@@ -182,9 +182,16 @@ static int prack_handler(const struct aco_option *opt, struct ast_variable *var,
 
 	if (ast_true(var->value)) {
 		endpoint->extensions.flags |= PJSIP_INV_SUPPORT_100REL;
+		endpoint->rel100 = AST_SIP_100REL_SUPPORTED;
+	} else if (!strcasecmp(var->value, "peer_supported")) {
+		endpoint->extensions.flags |= PJSIP_INV_SUPPORT_100REL;
+		endpoint->rel100 = AST_SIP_100REL_PEER_SUPPORTED;
 	} else if (!strcasecmp(var->value, "required")) {
 		endpoint->extensions.flags |= PJSIP_INV_REQUIRE_100REL;
-	} else if (!ast_false(var->value)){
+		endpoint->rel100 = AST_SIP_100REL_REQUIRED;
+	} else if (ast_false(var->value)) {
+		endpoint->rel100 = AST_SIP_100REL_UNSUPPORTED;
+	} else {
 		return -1;
 	}
 
@@ -195,10 +202,12 @@ static int prack_to_str(const void *obj, const intptr_t *args, char **buf)
 {
 	const struct ast_sip_endpoint *endpoint = obj;
 
-	if (endpoint->extensions.flags & PJSIP_INV_REQUIRE_100REL) {
-		*buf = "required";
-	} else if (endpoint->extensions.flags & PJSIP_INV_SUPPORT_100REL) {
+	if (endpoint->rel100 == AST_SIP_100REL_SUPPORTED) {
 		*buf = "yes";
+	} else if (endpoint->rel100 == AST_SIP_100REL_PEER_SUPPORTED) {
+		*buf = "peer_supported";
+	} else if (endpoint->rel100 == AST_SIP_100REL_REQUIRED) {
+		*buf = "required";
 	} else {
 		*buf = "no";
 	}

res/res_pjsip_session.c

@@ -3789,8 +3789,23 @@ static pjsip_inv_session *pre_session_setup(pjsip_rx_data *rdata, const struct a
 	pjsip_dialog *dlg;
 	pjsip_inv_session *inv_session;
 	unsigned int options = endpoint->extensions.flags;
+	const pj_str_t STR_100REL = { "100rel", 6};
+	unsigned int i;
 	pj_status_t dlg_status = PJ_EUNKNOWN;
 
+	/*
+	 * If 100rel is set to "peer_supported" on the endpoint and the peer indicated support for 100rel
+	 * in the Supported header, send 1xx responses reliably by adding PJSIP_INV_REQUIRE_100REL to pjsip_inv_options flags.
+	 */
+	if (endpoint->rel100 == AST_SIP_100REL_PEER_SUPPORTED && rdata->msg_info.supported != NULL) {
+		for (i = 0; i < rdata->msg_info.supported->count; ++i) {
+			if (pj_stricmp(&rdata->msg_info.supported->values[i], &STR_100REL) == 0) {
+				options |= PJSIP_INV_REQUIRE_100REL;
+				break;
+			}
+		}
+	}
+
 	if (pjsip_inv_verify_request(rdata, &options, NULL, NULL, ast_sip_get_pjsip_endpoint(), &tdata) != PJ_SUCCESS) {
 		if (tdata) {
 			if (pjsip_endpt_send_response2(ast_sip_get_pjsip_endpoint(), rdata, tdata, NULL, NULL) != PJ_SUCCESS) {