res_pjsip_registrar: Remove unavailable contacts if exceeds max_contacts

The behavior of max_contacts and remove_existing are connected.  If
remove_existing is enabled, the soonest expiring contacts are removed.
This may occur when there is an unavailable contact.  Similarly,
when remove_existing is not enabled, registrations from good
endpoints are rejected in favor of retaining unavailable contacts.

This commit adds a new AOR option remove_unavailable, and the effect
of this setting will depend on remove_existing.  If remove_existing
is set to no, we will still remove unavailable contacts when they
exceed max_contacts, if there are any. If remove_existing is set to
yes, we will prioritize the removal of unavailable contacts before
those that are expiring soonest.

ASTERISK-29525

Change-Id: Ia2711b08f2b4d1177411b1be23e970d7fdff5784

configs/samples/pjsip.conf.sample

@@ -1109,6 +1109,16 @@
                         ; contact created by rewrite_contact that the device is
                         ; refreshing.
                         ; (default: "no")
+;remove_unavailable=no  ; If remove_existing is disabled, will allow a registration
+                        ; to succeed by removing only unavailable contacts when
+                        ; max_contacts is exceeded. This will reject a registration
+                        ; that exceeds max_contacts if no unavailable contacts are
+                        ; present to remove. If remove_existing is enabled, will
+                        ; prioritize removal of unavailable contacts before removing
+                        ; expiring soonest.  This tames the behavior of remove_existing
+                        ; to only remove an available contact if an unavailable one is
+                        ; not present.
+                        ; (default: "no")
 ;type=  ; Must be of type aor (default: "")
 ;qualify_frequency=0    ; Interval at which to qualify an AoR via OPTIONS requests.
                         ; (default: "0")

contrib/ast-db-manage/config/versions/f56d79a9f337_pjsip_create_remove_unavailable.py

@@ -0,0 +1,30 @@
+"""pjsip create remove_unavailable
+
+Revision ID: f56d79a9f337
+Revises: c20d6e3992f4
+Create Date: 2021-07-28 02:09:11.082061
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = 'f56d79a9f337'
+down_revision = 'c20d6e3992f4'
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects.postgresql import ENUM
+
+AST_BOOL_NAME = 'ast_bool_values'
+AST_BOOL_VALUES = [ '0', '1',
+                    'off', 'on',
+                    'false', 'true',
+                    'no', 'yes' ]
+
+def upgrade():
+    ast_bool_values = ENUM(*AST_BOOL_VALUES, name=AST_BOOL_NAME, create_type=False)
+    op.add_column('ps_aors', sa.Column('remove_unavailable', ast_bool_values))
+
+def downgrade():
+    op.drop_column('ps_aors', 'remove_unavailable')
+    pass
+

doc/CHANGES-staging/res_pjsip_registrar.txt

@@ -0,0 +1,7 @@
+Subject: res_pjsip_registrar
+
+Adds new PJSIP AOR option remove_unavailable to either
+remove unavailable contacts when a REGISTER exceeds
+max_contacts when remove_existing is disabled, or
+prioritize unavailable contacts over other existing
+contacts when remove_existing is enabled.

include/asterisk/res_pjsip.h

@@ -389,6 +389,8 @@ struct ast_sip_aor {
 	double qualify_timeout;
 	/*! Voicemail extension to set in Message-Account */
 	char *voicemail_extension;
+	/*! Whether to remove unavailable contacts over max_contacts at all or first if remove_existing is enabled */
+	unsigned int remove_unavailable;
 };
 
 /*!

res/res_pjsip.c

@@ -1997,8 +1997,9 @@
 						TLS.  Unfortunately, refreshing a registration may register a
 						different contact address and exceed
 						<replaceable>max_contacts</replaceable>.  The
-						<replaceable>remove_existing</replaceable> option can help by
+						<replaceable>remove_existing</replaceable> and
-						removing the soonest to expire contact(s) over
+						<replaceable>remove_unavailable</replaceable> options can help by
+						removing either the soonest to expire or unavailable contact(s) over
 						<replaceable>max_contacts</replaceable> which is likely the
 						old <replaceable>rewrite_contact</replaceable> contact source
 						address being refreshed.
@@ -2041,6 +2042,26 @@
 						</para></note>
 					</description>
 				</configOption>
+				<configOption name="remove_unavailable" default="no">
+					<synopsis>Determines whether new contacts should replace unavailable ones.</synopsis>
+					<description><para>
+						The effect of this setting depends on the setting of
+						<replaceable>remove_existing</replaceable>.</para>
+						<para>If <replaceable>remove_existing</replaceable> is set to
+						<literal>no</literal> (default), setting remove_unavailable to
+						<literal>yes</literal> will remove only unavailable contacts that exceed
+						<replaceable>max_contacts</replaceable>	to allow an incoming
+						REGISTER to complete sucessfully.</para>
+						<para>If <replaceable>remove_existing</replaceable> is set to
+						<literal>yes</literal>, setting remove_unavailable to
+						<literal>yes</literal> will prioritize unavailable contacts for removal
+						instead of just removing the contact that expires the soonest.</para>
+						<note><para>See <replaceable>remove_existing</replaceable> and
+						<replaceable>max_contacts</replaceable> for further information about how
+						these 3 settings interact.
+						</para></note>
+					</description>
+				</configOption>
 				<configOption name="type">
 					<synopsis>Must be of type 'aor'.</synopsis>
 				</configOption>
@@ -2444,6 +2465,9 @@
 				<parameter name="RemoveExisting">
 					<para><xi:include xpointer="xpointer(/docs/configInfo[@name='res_pjsip']/configFile[@name='pjsip.conf']/configObject[@name='aor']/configOption[@name='remove_existing']/synopsis/node())"/></para>
 				</parameter>
+				<parameter name="RemoveUnavailable">
+					<para><xi:include xpointer="xpointer(/docs/configInfo[@name='res_pjsip']/configFile[@name='pjsip.conf']/configObject[@name='aor']/configOption[@name='remove_unavailable']/synopsis/node())"/></para>
+				</parameter>
 				<parameter name="Mailboxes">
 					<para><xi:include xpointer="xpointer(/docs/configInfo[@name='res_pjsip']/configFile[@name='pjsip.conf']/configObject[@name='aor']/configOption[@name='mailboxes']/synopsis/node())"/></para>
 				</parameter>
@@ -2904,6 +2928,9 @@
 				<parameter name="RemoveExisting">
 					<para><xi:include xpointer="xpointer(/docs/configInfo[@name='res_pjsip']/configFile[@name='pjsip.conf']/configObject[@name='aor']/configOption[@name='remove_existing']/synopsis/node())"/></para>
 				</parameter>
+				<parameter name="RemoveUnavailable">
+					<para><xi:include xpointer="xpointer(/docs/configInfo[@name='res_pjsip']/configFile[@name='pjsip.conf']/configObject[@name='aor']/configOption[@name='remove_unavailable']/synopsis/node())"/></para>
+				</parameter>
 				<parameter name="Mailboxes">
 					<para><xi:include xpointer="xpointer(/docs/configInfo[@name='res_pjsip']/configFile[@name='pjsip.conf']/configObject[@name='aor']/configOption[@name='mailboxes']/synopsis/node())"/></para>
 				</parameter>

res/res_pjsip/location.c

@@ -1410,6 +1410,7 @@ int ast_sip_initialize_sorcery_location(void)
 	ast_sorcery_object_field_register(sorcery, "aor", "authenticate_qualify", "no", OPT_BOOL_T, 1, FLDSET(struct ast_sip_aor, authenticate_qualify));
 	ast_sorcery_object_field_register(sorcery, "aor", "max_contacts", "0", OPT_UINT_T, 0, FLDSET(struct ast_sip_aor, max_contacts));
 	ast_sorcery_object_field_register(sorcery, "aor", "remove_existing", "no", OPT_BOOL_T, 1, FLDSET(struct ast_sip_aor, remove_existing));
+	ast_sorcery_object_field_register(sorcery, "aor", "remove_unavailable", "no", OPT_BOOL_T, 1, FLDSET(struct ast_sip_aor, remove_unavailable));
 	ast_sorcery_object_field_register_custom(sorcery, "aor", "contact", "", permanent_uri_handler, contacts_to_str, contacts_to_var_list, 0, 0);
 	ast_sorcery_object_field_register(sorcery, "aor", "mailboxes", "", OPT_STRINGFIELD_T, 0, STRFLDSET(struct ast_sip_aor, mailboxes));
 	ast_sorcery_object_field_register_custom(sorcery, "aor", "voicemail_extension", "", voicemail_extension_handler, voicemail_extension_to_str, NULL, 0, 0);

res/res_pjsip_registrar.c

@@ -204,6 +204,7 @@ static int registrar_validate_contacts(const pjsip_rx_data *rdata, pj_pool_t *po
 enum contact_delete_type {
 	CONTACT_DELETE_ERROR,
 	CONTACT_DELETE_EXISTING,
+	CONTACT_DELETE_UNAVAILABLE,
 	CONTACT_DELETE_EXPIRE,
 	CONTACT_DELETE_REQUEST,
 	CONTACT_DELETE_SHUTDOWN,
@@ -448,6 +449,9 @@ static int registrar_contact_delete(enum contact_delete_type type, pjsip_transpo
 			case CONTACT_DELETE_EXISTING:
 				reason = "remove existing";
 				break;
+			case CONTACT_DELETE_UNAVAILABLE:
+				reason = "remove unavailable";
+				break;
 			case CONTACT_DELETE_EXPIRE:
 				reason = "expiration";
 				break;
@@ -483,7 +487,48 @@ static int vec_contact_cmp(struct ast_sip_contact *left, struct ast_sip_contact
 	struct ast_sip_contact *right_contact = right;
 
 	/* Sort from soonest to expire to last to expire */
-	return ast_tvcmp(left_contact->expiration_time, right_contact->expiration_time);
+	int time_sorted = ast_tvcmp(left_contact->expiration_time, right_contact->expiration_time);
+
+	struct ast_sip_aor *aor = ast_sip_location_retrieve_aor(left_contact->aor);
+	struct ast_sip_contact_status *left_status;
+	struct ast_sip_contact_status *right_status;
+	int remove_unavailable = 0;
+	int left_unreachable;
+	int right_unreachable;
+
+	if (aor) {
+		remove_unavailable = aor->remove_unavailable;
+		ao2_ref(aor, -1);
+	}
+
+	if (!remove_unavailable) {
+		return time_sorted;
+	}
+
+	/* Get contact status if available */
+	left_status = ast_sip_get_contact_status(left_contact);
+	if (!left_status) {
+		return time_sorted;
+	}
+
+	right_status = ast_sip_get_contact_status(right_contact);
+	if (!right_status) {
+		ao2_ref(left_status, -1);
+		return time_sorted;
+	}
+
+	left_unreachable = (left_status->status == UNAVAILABLE);
+	right_unreachable = (right_status->status == UNAVAILABLE);
+	ao2_ref(left_status, -1);
+	ao2_ref(right_status, -1);
+	if (left_unreachable != right_unreachable) {
+		/* Set unavailable contact to top of vector */
+		if (left_unreachable) return -1;
+		if (right_unreachable) return 1;
+	}
+
+	/* Either both available or both unavailable */
+	return time_sorted;
 }
 
 static int vec_contact_add(void *obj, void *arg, int flags)
@@ -512,7 +557,7 @@ static int vec_contact_add(void *obj, void *arg, int flags)
 
 /*!
  * \internal
- * \brief Remove excess existing contacts that expire the soonest.
+ * \brief Remove excess existing contacts that are unavailable or expire soonest.
  * \since 13.18.0
  *
  * \param contacts Container of unmodified contacts that could remove.
@@ -521,7 +566,7 @@ static int vec_contact_add(void *obj, void *arg, int flags)
  * \return Nothing
  */
 static void remove_excess_contacts(struct ao2_container *contacts, struct ao2_container *response_contacts,
-	unsigned int to_remove)
+	unsigned int to_remove, unsigned int remove_existing)
 {
 	struct excess_contact_vector contact_vec;
 
@@ -545,13 +590,17 @@ static void remove_excess_contacts(struct ao2_container *contacts, struct ao2_co
 	ast_assert(AST_VECTOR_SIZE(&contact_vec) == to_remove);
 	to_remove = AST_VECTOR_SIZE(&contact_vec);
 
-	/* Remove the excess contacts that expire the soonest */
+	/* Remove the excess contacts that are unavailable or expire the soonest */
 	while (to_remove--) {
 		struct ast_sip_contact *contact;
 
 		contact = AST_VECTOR_GET(&contact_vec, to_remove);
 
-		registrar_contact_delete(CONTACT_DELETE_EXISTING, NULL, contact, contact->aor);
+		if (!remove_existing) {
+			registrar_contact_delete(CONTACT_DELETE_UNAVAILABLE, NULL, contact, contact->aor);
+		} else {
+			registrar_contact_delete(CONTACT_DELETE_EXISTING, NULL, contact, contact->aor);
+		}
 
 		ao2_unlink(response_contacts, contact);
 	}
@@ -574,6 +623,29 @@ static int registrar_add_non_permanent(void *obj, void *arg, int flags)
 	return 0;
 }
 
+/*! \brief Internal callback function which adds any contact which is unreachable */
+static int registrar_add_unreachable(void *obj, void *arg, int flags)
+{
+	struct ast_sip_contact *contact = obj;
+	struct ao2_container *container = arg;
+	struct ast_sip_contact_status *status;
+	int unreachable;
+
+	status = ast_sip_get_contact_status(contact);
+	if (!status) {
+		return 0;
+	}
+
+	unreachable = (status->status == UNAVAILABLE);
+	ao2_ref(status, -1);
+
+	if (unreachable) {
+		ao2_link(container, contact);
+	}
+
+	return 0;
+}
+
 struct aor_core_response {
 	/*! Tx data to use for statefull response.  NULL for stateless response. */
 	pjsip_tx_data *tdata;
@@ -596,6 +668,7 @@ static void register_aor_core(pjsip_rx_data *rdata,
 	int permanent = 0;
 	int contact_count;
 	struct ao2_container *existing_contacts = NULL;
+	struct ao2_container *unavail_contacts = NULL;
 	pjsip_contact_hdr *contact_hdr = (pjsip_contact_hdr *)&rdata->msg_info.msg->hdr;
 	struct registrar_contact_details details = { 0, };
 	pjsip_tx_data *tdata;
@@ -666,6 +739,33 @@ static void register_aor_core(pjsip_rx_data *rdata,
 		/* Total contacts after this registration */
 		contact_count = ao2_container_count(contacts) - permanent + added - deleted;
 	}
+
+	if (contact_count > aor->max_contacts && aor->remove_unavailable) {
+		/* Get unavailable contact total */
+		int unavail_count = 0;
+
+		unavail_contacts = ao2_container_alloc_list(AO2_ALLOC_OPT_LOCK_NOLOCK, 0,
+			NULL, ast_sorcery_object_id_compare);
+		if (!unavail_contacts) {
+			response->code = 500;
+			pjsip_endpt_release_pool(ast_sip_get_pjsip_endpoint(), details.pool);
+			return;
+		}
+		ao2_callback(contacts, OBJ_NODATA, registrar_add_unreachable, unavail_contacts);
+		if (unavail_contacts) {
+			unavail_count = ao2_container_count(unavail_contacts);
+		}
+
+		/* Check to see if removing unavailable contacts will help */
+		if (contact_count - unavail_count <= aor->max_contacts) {
+			/* Remove any unavailable contacts */
+			remove_excess_contacts(unavail_contacts, contacts, contact_count - aor->max_contacts, aor->remove_existing);
+			ao2_cleanup(unavail_contacts);
+			/* We're only here if !aor->remove_existing so this count is correct */
+			contact_count = ao2_container_count(contacts) - permanent + added - deleted;
+		}
+	}
+
 	if (contact_count > aor->max_contacts) {
 		/* Enforce the maximum number of contacts */
 		ast_sip_report_failed_acl(endpoint, rdata, "registrar_attempt_exceeds_maximum_configured_contacts");
@@ -867,8 +967,9 @@ static void register_aor_core(pjsip_rx_data *rdata,
 		/* Total contacts after this registration */
 		contact_count = ao2_container_count(existing_contacts) + updated + added;
 		if (contact_count > aor->max_contacts) {
-			/* Remove excess existing contacts that expire the soonest */
+			/* Remove excess existing contacts that are unavailable or expire soonest */
-			remove_excess_contacts(existing_contacts, contacts, contact_count - aor->max_contacts);
+			remove_excess_contacts(existing_contacts, contacts, contact_count - aor->max_contacts,
+				aor->remove_existing);
 		}
 		ao2_ref(existing_contacts, -1);
 	}