net/icmp: Support icmp timestamp request

[wenquan2015]

When received a icmp timestamp request, send a icmp timestamp reply.

Summary

When received a icmp timestamp request, send a icmp timestamp reply.

Impact

icmp

Testing

from scapy.all import *

icmp_pkt = IP(src="10.0.1.3", dst="10.0.1.2") / ICMP(type=13, id=124, seq=567)

send(icmp_pkt, verbose=1)
send(icmp_pkt, verbose=1)

test result:

15:02:54.140070 ARP, Request who-has 10.0.1.3 tell 10.0.1.2, length 28
15:02:54.140089 ARP, Reply 10.0.1.3 is-at 52:1c:16:3d:b4:c8, length 28
15:02:54.153566 IP 10.0.1.3 > 10.0.1.2: ICMP time stamp query id 124 seq 567, length 20
15:02:54.160108 IP 10.0.1.2 > 10.0.1.3: ICMP time stamp reply id 124 seq 567: org 07:02:54.067, recv 00:00:21.390, xmit 00:00:21.390, length 20