support redistribute vrf function

[zice312963205]

bgpd: Add support for BGP vrf route copying

Example configuration:
router bgp 100 vrf vrf-1
address-family ipv4 unicast
rd vpn export 1:1
rt vpn both 1:1
export vpn
import vpn
redistribute vrf vrf-2
exit-address-family
!
!
router bgp 100 vrf vrf-2
neighbor 2.2.2.2 remote-as 1
address-family ipv4 unicast
rd vpn export 2:2
rt vpn both 2:2
neighbor 2.2.2.2 activate
exit-address-family
!
BGP routes learned from the neighbor 2.2.2.2 under VRF-1 can be directly copied to the BGP under VRF-1 without carrying the RD and RT attributes of VRF-1. After being copied to VRF-1, the routes will be sent to VPN with the RD 1:1 and RT 1:1 attributes, forming BGP-VPN routes.

[cscarpitta]

Just a few things we should do before submitting the code:

• Add documentation to the bgp docs for the new command redistribute vrf that you added. This should go in a separate commit.
• Write test cases for the new functionality and add them to the tests folder. This should go in a separate commit.
• Format the code according to the FRR style guidelines. We can use the clang-format source formatter tool to automatically format code according to the guidelines.
• Format the commit messages according to the guidelines described here, here, and here.

I can help with all the above items.

[cscarpitta]

I suggest to replace these lines with something like this:

afi = bgp_node_afi(vty);
safi = bgp_node_safi(vty);
if ((SAFI_UNICAST != safi) || ((AFI_IP != afi) && (AFI_IP6 != afi))) {
	vty_out(vty, "%% redistribute vrf is valid only for unicast ipv4|ipv6\n");
	return CMD_WARNING_CONFIG_FAILED;
}

and leave the vpn_policy_getafi function unchanged.

This should be equivalent to your implementation, but it doesn't change the vpn_policy_getafi function which is used in some other places.

[zice312963205]

Done for this. Thanks for your comments.

[cscarpitta]

Now the function vpn_policy_getafi() is never called from your code, right?

I think there is no reason to change it. Can we remove the #if 0 directive and leave vpn_policy_getafi() unchanged?

[zice312963205]

Ok... I'm sorry, I forgot to restore it.