res_pjsip: Split type=identify to IP address and SIP header matching priorities

The type=identify endpoint identification method can match by IP address
and by SIP header.  However, the SIP header matching has limited
usefulness because you cannot specify the SIP header matching priority
relative to the IP address matching.  All the matching happens at the same
priority and the order of evaluating the identify sections is
indeterminate.  e.g., If you had two type=identify sections where one
matches by IP address for endpoint alice and the other matches by SIP
header for endpoint bob then you couldn't predict which endpoint is
matched when a request comes in that matches both.

* Extract the SIP header matching criteria into its own "header" endpoint
identification method so the user can specify the relative priority of the
SIP header and the IP address matching criteria in the global
endpoint_identifier_order option.  The "ip" endpoint identification method
now only matches by IP address.

ASTERISK-27491

Change-Id: I9df142a575b7e1e3471b7cda5d3ea156cef08095

contrib/ast-db-manage/config/versions/52798ad97bdf_add_pjsip_identify_by_header.py

@@ -0,0 +1,57 @@
+"""add pjsip identify by header
+
+Revision ID: 52798ad97bdf
+Revises: 20abce6d1e3c
+Create Date: 2018-01-08 12:16:02.782277
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '52798ad97bdf'
+down_revision = '20abce6d1e3c'
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def column_upgrade(table_name, column_name, enum_name):
+    if op.get_context().bind.dialect.name != 'postgresql':
+        if op.get_context().bind.dialect.name == 'mssql':
+            op.drop_constraint('ck_ps_endpoints_identify_by_pjsip_identify_by_values',
+                               table_name)
+        op.alter_column(table_name, column_name, type_=sa.String(80))
+        return
+
+    # Postgres requires a few more steps
+    op.execute('ALTER TABLE ' + table_name + ' ALTER COLUMN ' + column_name +
+               ' TYPE varchar(80) USING identify_by::text::' + enum_name)
+
+    op.execute('DROP TYPE ' + enum_name)
+
+
+def column_downgrade(table_name, column_name, enum_name, enum_values):
+    if op.get_context().bind.dialect.name != 'postgresql':
+        op.alter_column(table_name, column_name,
+                        type_=sa.Enum(*enum_values, name=enum_name))
+        return
+
+    # Postgres requires a few more steps
+    updated = sa.Enum(*enum_values, name=enum_name)
+    updated.create(op.get_bind(), checkfirst=False)
+
+    op.execute('ALTER TABLE ' + table_name + ' ALTER COLUMN ' + column_name +
+               ' TYPE ' + enum_name + ' USING identify_by::text::' + enum_name)
+
+
+def upgrade():
+    # The ps_endpoints identify_by column has always been a comma separated
+    # list of enum values.  This is better represented as a string anyway to
+    # avoid database compatibility issues.  Also future changes are likely
+    # to allow loadable endpoint identifier names and negating fixed enum
+    # benefits.
+    column_upgrade('ps_endpoints', 'identify_by', 'pjsip_identify_by_values')
+
+
+def downgrade():
+    column_downgrade('ps_endpoints', 'identify_by', 'pjsip_identify_by_values',
+                     ['username', 'auth_username', 'ip'])