openstack/os-ken
Code Issues Proposed changes

rest_router: Ensure that usage of icmp.dest_unreach and icmp.TimeExceeded complies with RFC 4884

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When using the icmp.dest_unreach and icmp.TimeExceeded classes, we
should ensure that it is in compliance with RFC 4884.  As such, the
data_len parameter passed to the constructor of each should be
interpreted in 32 bit units.  Furthermore - any data that is passed in
must be zero padded to a 32 bit boundary.

The only sample application known to use either of these types is rest_router.
This patch corrects its use of these classes.

Signed-off-by: Victor J. Orlikowski <vjo@duke.edu>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
This commit is contained in:
Victor Orlikowski 2016-01-31 14:36:45 +00:00 committed by FUJITA Tomonori
parent 8f7d302fd5
commit 28cb1d59d9
1 changed files with 23 additions and 4 deletions
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27
ryu/app/rest_router.py
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@ -1523,18 +1523,37 @@ class OfCtl(object):
eth = protocol_list[ETHERNET]
e = ethernet.ethernet(eth.src, eth.dst, ether_proto)
ip = protocol_list[IPV4]
if icmp_data is None and msg_data is not None:
ip_datagram = msg_data[offset:]
# RFC 4884 says that we should send "at least 128 octets"
# if we are using the ICMP Extension Structure.
# We're not using the extension structure, but let's send
# up to 128 bytes of the original msg_data.
#
# RFC 4884 also states that the length field is interpreted in
# 32 bit units, so the length calculated in bytes needs to first
# be divided by 4, then increased by 1 if the modulus is non-zero.
#
# Finally, RFC 4884 says, if we're specifying the length, we MUST
# zero pad to the next 32 bit boundary.
end_of_data = offset + len(ip) + 128
ip_datagram = bytearray()
ip_datagram += msg_data[offset:end_of_data]
data_len = int(len(ip_datagram) / 4)
length_modulus = int(len(ip_datagram) % 4)
if length_modulus:
data_len += 1
ip_datagram += bytearray([0] * (4 - length_modulus))
if icmp_type == icmp.ICMP_DEST_UNREACH:
icmp_data = icmp.dest_unreach(data_len=len(ip_datagram),
icmp_data = icmp.dest_unreach(data_len=data_len,
data=ip_datagram)
elif icmp_type == icmp.ICMP_TIME_EXCEEDED:
icmp_data = icmp.TimeExceeded(data_len=len(ip_datagram),
icmp_data = icmp.TimeExceeded(data_len=data_len,
data=ip_datagram)
ic = icmp.icmp(icmp_type, icmp_code, csum, data=icmp_data)
ip = protocol_list[IPV4]
if src_ip is None:
src_ip = ip.dst
ip_total_length = ip.header_length * 4 + ic._MIN_LEN