Commond utility functions for bridge/port mapping (#14)

Author: prsunny

src/swsssdk/port_util.py

@@ -0,0 +1,68 @@
+"""
+Bridge/Port mapping utility library.
+"""
+import swsssdk
+import re
+
+SONIC_ETHERNET_RE_PATTERN = "^Ethernet(\d+)$"
+SONIC_PORTCHANNEL_RE_PATTERN = "^PortChannel(\d+)$"
+
+def get_index(if_name):
+    """
+    OIDs are 1-based, interfaces are 0-based, return the 1-based index
+    Ethernet N = N + 1
+    PortChannel N = N + 1000
+    """
+    return get_index_from_str(if_name.decode())
+
+
+def get_index_from_str(if_name):
+    """
+    OIDs are 1-based, interfaces are 0-based, return the 1-based index
+    Ethernet N = N + 1
+    PortChannel N = N + 1000
+    """
+    patterns = {
+        SONIC_ETHERNET_RE_PATTERN: 1,
+        SONIC_PORTCHANNEL_RE_PATTERN: 1000
+    }
+
+    for pattern, baseidx in patterns.items():
+        match = re.match(pattern, if_name)
+        if match:
+            return int(match.group(1)) + baseidx
+
+def get_interface_oid_map(db):
+    """
+        Get the Interface names from Counters DB
+    """
+    db.connect('COUNTERS_DB')
+    if_name_map = db.get_all('COUNTERS_DB', 'COUNTERS_PORT_NAME_MAP', blocking=True)
+    if_id_map = {sai_oid: if_name for if_name, sai_oid in if_name_map.items()
+                 # only map the interface if it's a style understood to be a SONiC interface.
+                 if get_index(if_name) is not None}
+
+    return if_name_map, if_id_map
+
+def get_bridge_port_map(db):
+    """
+        Get the Bridge port mapping from ASIC DB
+    """
+    db.connect('ASIC_DB')
+    if_br_oid_map = {}
+    br_port_str = db.keys('ASIC_DB', "ASIC_STATE:SAI_OBJECT_TYPE_BRIDGE_PORT:*")
+    if not br_port_str:
+        return
+
+    offset = len("ASIC_STATE:SAI_OBJECT_TYPE_BRIDGE_PORT:")
+    oid_pfx = len("oid:0x")
+    for br_s in br_port_str:
+        # Example output: ASIC_STATE:SAI_OBJECT_TYPE_BRIDGE_PORT:oid:0x3a000000000616
+        br_port_id = br_s[(offset + oid_pfx):]
+        ent = db.get_all('ASIC_DB', br_s, blocking=True)
+        if b"SAI_BRIDGE_PORT_ATTR_PORT_ID" in ent:
+            port_id = ent[b"SAI_BRIDGE_PORT_ATTR_PORT_ID"][oid_pfx:]
+            if_br_oid_map[br_port_id] = port_id
+
+    return if_br_oid_map
+