Add rtnetlink api's for link creates

Ticket: CM-3346
Reviewed By:
Testing Done:

ifupdown/netlink.py

@@ -0,0 +1,242 @@
+#!/usr/bin/env python
+#
+# Copyright 2014 Cumulus Networks, Inc. All rights reserved.
+# Author: Scott Feldman, sfeldma@cumulusnetworks.com
+#
+
+from os import strerror
+import select
+from time import time
+import socket
+from ctypes import *
+from errno import *
+import logging
+
+logger = logging.getLogger(__name__)
+
+#
+# from /usr/include/linux/netlink.h
+#
+
+NETLINK_ROUTE = 0            # Routing/device hook
+NETLINK_UNUSED = 1           # Unused number
+NETLINK_USERSOCK = 2         # Reserved for user mode socket protocols 
+NETLINK_FIREWALL = 3         # Firewalling hook
+NETLINK_INET_DIAG = 4        # INET socket monitoring
+NETLINK_NFLOG = 5            # netfilter/iptables ULOG 
+NETLINK_XFRM = 6             # ipsec 
+NETLINK_SELINUX = 7          # SELinux event notifications 
+NETLINK_ISCSI = 8            # Open-iSCSI 
+NETLINK_AUDIT = 9            # auditing 
+NETLINK_FIB_LOOKUP = 10	
+NETLINK_CONNECTOR = 11
+NETLINK_NETFILTER = 12       # netfilter subsystem 
+NETLINK_IP6_FW = 13
+NETLINK_DNRTMSG = 14         # DECnet routing messages 
+NETLINK_KOBJECT_UEVENT = 15  # Kernel messages to userspace 
+NETLINK_GENERIC = 16
+NETLINK_SCSITRANSPORT = 18   # SCSI Transports 
+NETLINK_ECRYPTFS = 19
+NETLINK_RDMA = 20
+NETLINK_CRYPTO = 21          # Crypto layer 
+
+NLMSG_NOOP = 1        # Nothing.
+NLMSG_ERROR = 2       # Error
+NLMSG_DONE = 3        # End of a dump
+NLMSG_OVERRUN = 4     # Data lost
+
+NETLINK_NO_ENOBUFS = 5
+
+SOL_NETLINK = 270
+
+class Nlmsghdr(Structure):
+
+    _fields_ = [
+        ('nlmsg_len', c_uint32),
+        ('nlmsg_type', c_uint16),
+        ('nlmsg_flags', c_uint16),
+        ('nlmsg_seq', c_uint32),
+        ('nlmsg_pid', c_uint32)
+    ]
+
+    def dump(self):
+        print 'nlmsg_len', self.nlmsg_len
+        print 'nlmsg_type', self.nlmsg_type
+        print 'nlmsg_flags 0x%04x' % self.nlmsg_flags
+        print 'nlmsg_seq', self.nlmsg_seq
+        print 'nlmsg_pid', self.nlmsg_pid
+
+# Flags values
+
+NLM_F_REQUEST = 1          # It is request message.
+NLM_F_MULTI = 2            # Multipart message, terminated by NLMSG_DONE
+NLM_F_ACK = 4              # Reply with ack, with zero or error code
+NLM_F_ECHO = 8             # Echo this request
+NLM_F_DUMP_INTR = 16       # Dump was inconsistent due to sequence change
+
+# Modifiers to GET request
+NLM_F_ROOT = 0x100         # specify tree root
+NLM_F_MATCH = 0x200        # return all matching
+NLM_F_ATOMIC = 0x400       # atomic GET
+NLM_F_DUMP = (NLM_F_ROOT|NLM_F_MATCH)
+
+# Modifiers to NEW request
+NLM_F_REPLACE = 0x100      # Override existing
+NLM_F_EXCL = 0x200         # Do not touch, if it exists
+NLM_F_CREATE = 0x400       # Create, if it does not exist
+NLM_F_APPEND = 0x800       # Add to end of list
+
+NLMSG_ALIGNTO = 4
+def NLMSG_ALIGN(len):
+    return (len + NLMSG_ALIGNTO - 1) & ~(NLMSG_ALIGNTO - 1)
+def NLMSG_HDRLEN():
+    return NLMSG_ALIGN(sizeof(Nlmsghdr))
+def NLMSG_LENGTH(len):
+    return len + NLMSG_ALIGN(NLMSG_HDRLEN())
+def NLMSG_SPACE(len):
+    return NLMSG_ALIGN(NLMSG_LENGTH(len))
+def NLMSG_DATA(nlh):
+    return addressof(nlh) + NLMSG_LENGTH(0)
+def NLMSG_NEXT(nlh, len):
+    cur = NLMSG_ALIGN(nlh.nlmsg_len)
+    nlh = Nlmsghdr.from_address(addressof(nlh) + cur)
+    return len - cur, nlh
+def NLMSG_OK(nlh, len):
+    return len >= sizeof(Nlmsghdr) and \
+        nlh.nlmsg_len >= sizeof(Nlmsghdr) and \
+        nlh.nlmsg_len <= len
+
+class Nlmsgerr(Structure):
+
+    _fields_ = [
+        ('error', c_int),
+        ('msg', Nlmsghdr),
+    ]
+
+class NetlinkError(Exception):
+
+    def __init__(self, message):
+        Exception.__init__(self, message)
+        #logger.error(message)
+        print(message)
+
+class Netlink(socket.socket):
+
+    def __init__(self, pid, proto):
+
+        self.pid = pid
+        self.recvbuf = bytearray(8 * 1024)
+        self.sendbuf = bytearray(8 * 1024)
+        self.seq = int(time())
+
+        try:
+
+            socket.socket.__init__(self, socket.AF_NETLINK, \
+                socket.SOCK_RAW, proto)
+            self.setblocking(0)
+
+            # Need to turn off ENOBUFS for netlink socket otherwise
+            # in a kernel overrun situation, the socket will return
+            # ENOBUFS on socket recv and be stuck for future recvs.
+
+            self.setsockopt(SOL_NETLINK, NETLINK_NO_ENOBUFS, 1)
+
+        except socket.error as (errno, string):
+            raise NetlinkError("open: socket err[%d]: %s" % \
+                (errno, string))
+
+    def bind(self, groups, cb):
+
+        self._nl_cb = cb
+
+        try:
+            socket.socket.bind(self, (self.pid, groups))
+
+        except socket.error as (errno, string):
+            raise NetlinkError("bind: socket err[%d]: %s" % \
+                (errno, string))
+
+    def sendall(self, string):
+        try:
+            socket.socket.sendall(self, string)
+        except socket.error as (errno, string):
+            raise NetlinkError("send: socket err[%d]: %s" % \
+                (errno, string))
+
+    def _process_nlh(self, recv, nlh):
+        while NLMSG_OK(nlh, recv):
+            yield recv, nlh
+            recv, nlh = NLMSG_NEXT(nlh, recv)
+
+    def process(self, tokens=[]):
+
+        found_done = False
+
+        try:
+            recv, src_addr = self.recvfrom_into(self.recvbuf)
+            if not recv:
+                # EOF
+                print "EOF"
+                return False
+
+        except socket.error as (errno, string):
+            if errno in [EINTR, EAGAIN]:
+                return False
+            raise NetlinkError("process: socket err[%d]: %s" % \
+                (errno, string))
+
+        nlh = Nlmsghdr.from_buffer(self.recvbuf)
+        for recv, nlh in self._process_nlh(recv, nlh):
+
+#            print "type %u, seq %u, pid %u" % \
+#                (nlh.nlmsg_type, nlh.nlmsg_seq, nlh.nlmsg_pid)
+
+            l = nlh.nlmsg_len - sizeof(Nlmsghdr)
+
+            if l < 0 or nlh.nlmsg_len > recv:
+                raise NetlinkError("process: malformed msg: len %d" % \
+                    nlh.nlmsg_len)
+
+            if tokens:
+                current = (nlh.nlmsg_pid, nlh.nlmsg_seq)
+                if current not in tokens:
+                    continue
+
+            if nlh.nlmsg_type == NLMSG_DONE:
+                found_done = True
+                break
+
+            if nlh.nlmsg_type == NLMSG_ERROR:
+                err = Nlmsgerr.from_address(NLMSG_DATA(nlh))
+                if err.error == 0:
+                    return False
+                raise NetlinkError("process: %s" % strerror(abs(err.error)))
+
+            if self._nl_cb:
+                self._nl_cb(nlh)
+
+        if found_done:
+            return False 
+
+        remnant = recv - NLMSG_ALIGN(nlh.nlmsg_len) > 0
+        if remnant:
+            raise NetlinkError("process: remnant of size %d" % \
+                remnant)
+
+        return True
+
+    def process_wait(self, tokens):
+        while self.process(tokens):
+            pass
+
+    def process_forever(self):
+        epoll = select.epoll()
+        epoll.register(self.fileno(), select.EPOLLIN)
+        while True:
+            events = epoll.poll()
+            for fileno, event in events:
+                if fileno == self.fileno():
+                    self.process()
+
+    def process_event(self, event):
+        return self.process()