Ask for help about the change of libnl 3.2.16 or newer version

[Andy Wang]

Hi friends of Libnl organization:

I am a Watchguard employee and quite new to Libnl framework. In about Jan 5th we upgraded to the new version 3.2.16 . The new version is good ,but we found we cannot add the IPV6 address in the new version.


Function "rtnl_link_name2i" in this version always return integer value 0 which means it fails to get a valid interface index from cache. I also tried the newest version 3.2.20, it has the same problem.

I copied the function of our company in which it called Libnl function to add IPV6 address. It works well in the past version before 3.2.16, but it failed in the line which is drawn as green after it.
-------------------------
/* This adds single address to interface */
int wgnet_add_addr(const char * ifname,struct if_addr * ip) {
    struct nl_cache *link_cache = NULL;
    struct nl_addr   *n_addr = NULL;
    struct rtnl_addr *r_addr = NULL;
    int ifindex;
    int ret=-1;

    if (!ip || !ifname) {
        return EINVAL;
    }

    if (!handle && (ret=wgnet_init()) != 0 ) {
        return ret;
    }

    rtnl_link_alloc_cache(handle,ip->ipaddr.sa_family,&link_cache);
    r_addr = rtnl_addr_alloc();
    /* FIXME we can use local version at some point */
    n_addr=nl_addr_alloc(sizeof(ip->ipaddr.ip6));

    if (!link_cache || !r_addr || !n_addr) {
        ret   = ENOMEM;
        goto error;
    }

    ifindex = rtnl_link_name2i(link_cache, ifname);
    if (!ifindex) {
        ret   = ENOENT;
        goto error;
    }

    /* Copy data from provided data */
    nl_addr_set_family(n_addr,ip->ipaddr.sa_family);
    nl_addr_set_binary_addr(n_addr,ip->ipaddr.addr,ip->ipaddr.sa_family==AF_INET ? sizeof(ip->ipaddr.ip): sizeof(ip->ipaddr.ip6)) ;
    nl_addr_set_prefixlen(n_addr,ip->ipaddr.prefix);

    /* set netlink message and sent it out */
    rtnl_addr_set_local(r_addr,n_addr);
    rtnl_addr_set_ifindex(r_addr, ifindex);
    if ( ip->scope ) {
        rtnl_addr_set_scope(r_addr,ip->scope);
    }
    if ( ip->flags ) {
        rtnl_addr_set_flags(r_addr,ip->flags);
    }
    ret=rtnl_addr_add(handle, r_addr, 0);

error:
    *****
    return ret;
}

-------------------------

I compared the source code of the past version 3.2.13 and the current version 3.2.16 , and found there are the following modification in function "rtnl_link_get_by_name" which "rtnl_link_name2i" calls.

[cid:image001.png at 01CDFCEF.21316140]



Then I comment this new-added code and build the newlibnl* .so files, and use them again. Then the IPV6 address could be added rightly like before.
I think there should have some reasons why the new code is added, but I can't understand more. So I ask help from you and expect to make it more clear.
My questions is :

1.       Does my change of rolling back this line reasonable? Will it affect other fiends?

2.       If my change is not reasonable, is it possible to change Watchguard code to adapt the new version of Libnl. My current purpose is to let the adding of IPV6 address work rightly.

Thanks again for your time to read my long Email. Expecting for any comments!

Thanks & Regards!
YuTong Wang

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.infradead.org/pipermail/libnl/attachments/20130127/280755d9/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 37679 bytes
Desc: image001.png
URL: <http://lists.infradead.org/pipermail/libnl/attachments/20130127/280755d9/attachment-0001.png>