Subject: Re: [PATCH] vxlan: force user to set port value

From: Sridhar Samudrala <[email-masked]>
Date: Wed, 15 May 2013 14:57:54 -0700

On 5/15/2013 1:48 PM, Stephen Hemminger wrote:
> This change shifts burden onto the users to choose the UDP port value.
> There is no default value, the destination port must be specified.
>
> This is a migration compromise. The initial development of VXLAN
> used UDP port 5287 but now there is an official assigned port for
The original and current kernel default is 8472.
> VXLAN.  The kernel can't change because of legacy compatibility
> but new deployments should not use the legacy port value.
>
> ---
>   ip/iplink_vxlan.c |   13 ++++++++++++-
>   1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/ip/iplink_vxlan.c b/ip/iplink_vxlan.c
> index 2d93ee2..263feca 100644
> --- a/ip/iplink_vxlan.c
> +++ b/ip/iplink_vxlan.c
> @@ -53,7 +53,8 @@ static int vxlan_parse_opt(struct link_util *lu, int argc, char **argv,
>   	__u8 noage = 0;
>   	__u32 age = 0;
>   	__u32 maxaddr = 0;
> -	__u16 dstport = 4789;
> +	__u16 dstport = 0;
> +	int dst_port_set = 0;
>   	struct ifla_vxlan_port_range range = { 0, 0 };
>   
>   	while (argc > 0) {
> @@ -131,6 +132,7 @@ static int vxlan_parse_opt(struct link_util *lu, int argc, char **argv,
>   			NEXT_ARG();
>   			if (get_u16(&dstport, *argv, 0))
>   				invarg("dst port", *argv);
> +			dst_port_set = 1;
>   		} else if (!matches(*argv, "nolearning")) {
>   			learning = 0;
>   		} else if (!matches(*argv, "learning")) {
> @@ -161,10 +163,18 @@ static int vxlan_parse_opt(struct link_util *lu, int argc, char **argv,
>   		}
>   		argc--, argv++;
>   	}
> +
>   	if (!vni_set) {
>   		fprintf(stderr, "vxlan: missing virtual network identifier\n");
>   		return -1;
>   	}
> +
> +	if (!dst_port_set) {
> +		fprintf(stderr, "vxlan: destination port not specified\n"
> +			"Use 'dstport 4789' to get the IANA assigned value\n");
> +		return -1;
> +	}
Just setting the dstport 4789 is not enough. The user has to make sure 
that the
vxlan module is loaded with a module  parameter 'udp_port' set to 4789.

Thanks
Sridhar
> +
>   	addattr32(n, 1024, IFLA_VXLAN_ID, vni);
>   	if (gaddr)
>   		addattr_l(n, 1024, IFLA_VXLAN_GROUP, &gaddr, 4);
> @@ -179,6 +189,7 @@ static int vxlan_parse_opt(struct link_util *lu, int argc, char **argv,
>   	addattr8(n, 1024, IFLA_VXLAN_RSC, rsc);
>   	addattr8(n, 1024, IFLA_VXLAN_L2MISS, l2miss);
>   	addattr8(n, 1024, IFLA_VXLAN_L3MISS, l3miss);
> +
>   	if (noage)
>   		addattr32(n, 1024, IFLA_VXLAN_AGEING, 0);
>   	else if (age)