Bug 1757247

Description of problem:
When trying to use ICS dhcrelay (or dnsmasq itself) to relay DHCPv6 info-req to a dnsmasq DHCP server the relay-fwd packages are ignored by dnsmasq.

Version-Release number of selected component (if applicable):
dnsmasq-2.76-9.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Install DHCP server with ipv6 address on eth1, and below dnsmasq.conf

[root@pxe-server ~]# ip6tables -F  # Drop the firewall, alternative open udp ports 546 and 547.

[root@pxe-server ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth1 
DEVICE=eth1
NAME=eth1
TYPE=Ethernet
ONBOOT=yes
NM_CONTROLLED=no
HOTPLUG=no
PEERDNS=no
IPV6INIT=yes
IPV6_AUTOCONF=no
IPV6ADDR=fd12:3456:789a:1::1/64

[root@pxe-server ~]# cat /etc/dnsmasq.conf 
port=0
interface=eth1

dhcp-range=set:ctlplane-subnet,fd12:3456:789a:1::aaaa,fd12:3456:789a:1::ffff,64,10m
dhcp-range=set:ctlplane-subnet2,fd12:3456:789a:2::aaaa,fd12:3456:789a:2::ffff,64,10m
# dhcp-option=tag:ctlplane-subnet,option6:3,[fd12:3456:789a:1::fffe]
dhcp-match=set:ipv6,option6:1
dhcp-userclass=set:ipxe6,iPXE
dhcp-option=tag:ipxe6,option6:bootfile-url,http://[fd12:3456:789a:1::1]:8000/inspector.ipxe
dhcp-option=tag:ipv6,option6:bootfile-url,tftp://[fd12:3456:789a:1::1]/ipxe.efi
dhcp-sequential-ip

2. Install radvd and dhcrelay node with ipv6 on eth1 and eth2. eth1 is on same L2 segment as eth1 on the dhcp server.

[root@dhcp6-relay ~]# ip6tables -F  # Drop the firewall, alternative open udp ports 546 and 547.

[root@dhcp6-relay ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth1 
DEVICE=eth1
NAME=eth1
TYPE=Ethernet
ONBOOT=yes
NM_CONTROLLED=no
HOTPLUG=no
PEERDNS=no
IPV6INIT=yes
IPV6_AUTOCONF=no
IPV6ADDR=fd12:3456:789a:1::2/64

[root@dhcp6-relay ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth2
DEVICE=eth2
NAME=eth2
TYPE=Ethernet
ONBOOT=yes
NM_CONTROLLED=no
HOTPLUG=no
PEERDNS=no
IPV6INIT=yes
IPV6_AUTOCONF=no
IPV6ADDR=fd12:3456:789a:2::1/64

[root@dhcp6-relay ~]# cat /etc/radvd.conf 
interface eth1 {
  AdvSendAdvert on;
  AdvRASolicitedUnicast on;
  AdvManagedFlag off;
  AdvOtherConfigFlag on;
  prefix fd12:3456:789a:1::/64 {
  };
};

interface eth2 {
  AdvSendAdvert on;
  AdvRASolicitedUnicast on;
  AdvManagedFlag off;
  AdvOtherConfigFlag on;
  prefix fd12:3456:789a:2::/64 {
  };
};

[root@dhcp6-relay ~]# sysctl net.ipv6.conf.eth1.forwarding=1
[root@dhcp6-relay ~]# sysctl net.ipv6.conf.eth2.forwarding=1

[root@dhcp6-relay ~]# systemctl restart radvd

2.1. Start the DHCPv6 relay ...

[root@dhcp6-relay ~]#  dhcrelay -6 -d --no-pid -u eth1 -l eth2  

Actual results:
Dropped all unnecessary capabilities.
Internet Systems Consortium DHCP Relay Agent 4.2.5
Copyright 2004-2013 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/
Bound to *:547
Listening on Socket/eth2
Sending on   Socket/eth2
Listening on Socket/eth1
Sending on   Socket/eth1
Setting hop count limit to 32 for interface eth1
Dropped all capabilities.
Relaying Solicit from fe80::5054:ff:fe50:f586 port 546 going up.
Relaying Information-request from fe80::5054:ff:fe50:f586 port 546 going up.
Relaying Solicit from fe80::5054:ff:fe50:f586 port 546 going up.
Relaying Information-request from fe80::5054:ff:fe50:f586 port 546 going up.
Relaying Solicit from fe80::5054:ff:fe50:f586 port 546 going up.
Relaying Information-request from fe80::5054:ff:fe50:f586 port 546 going up.

++ dnsmasq logs: (Nothing is logged)


Expected results:
Dropped all unnecessary capabilities.
Internet Systems Consortium DHCP Relay Agent 4.2.5
Copyright 2004-2013 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/
Bound to *:547
Listening on Socket/eth2
Sending on   Socket/eth2
Listening on Socket/eth1
Sending on   Socket/eth1
Setting hop count limit to 32 for interface eth1
Dropped all capabilities.
Relaying Information-request from fe80::5054:ff:fe50:f586 port 546 going up.
Relaying Reply to fe80::5054:ff:fe50:f586 port 546 down.
Relaying Solicit from fe80::5054:ff:fe50:f586 port 546 going up.
Relaying Advertise to fe80::5054:ff:fe50:f586 port 546 down.
Relaying Request from fe80::5054:ff:fe50:f586 port 546 going up.
Relaying Reply to fe80::5054:ff:fe50:f586 port 546 down.
Relaying Release from fe80::5054:ff:fe50:f586 port 546 going up.
Relaying Reply to fe80::5054:ff:fe50:f586 port 546 down.


++ dnsmasq logs:
dnsmasq-dhcp: DHCPINFORMATION-REQUEST(eth1) 00:04:c4:4d:7a:ed:13:a4:ad:49:ba:27:61:7c:ff:09:d1:b2 
dnsmasq-dhcp: DHCPSOLICIT(eth1) 00:04:c4:4d:7a:ed:13:a4:ad:49:ba:27:61:7c:ff:09:d1:b2 
dnsmasq-dhcp: DHCPADVERTISE(eth1) fd12:3456:789a:2::aaab 00:04:c4:4d:7a:ed:13:a4:ad:49:ba:27:61:7c:ff:09:d1:b2 
dnsmasq-dhcp: DHCPREQUEST(eth1) 00:04:c4:4d:7a:ed:13:a4:ad:49:ba:27:61:7c:ff:09:d1:b2 
dnsmasq-dhcp: DHCPREPLY(eth1) fd12:3456:789a:2::aaab 00:04:c4:4d:7a:ed:13:a4:ad:49:ba:27:61:7c:ff:09:d1:b2 
dnsmasq-dhcp: DHCPRELEASE(eth1) 00:04:c4:4d:7a:ed:13:a4:ad:49:ba:27:61:7c:ff:09:d1:b2 


Additional info:
Compiling dnsmask from git, 2.80-75-ge710c34 fixes the problem.

git clone git://thekelleys.org.uk/dnsmasq.git 
cd dnsmasq/
make PREFIX=$HOME install