On Wed, Oct 28, 2015 at 4:41 PM, Baptiste <[email protected]> wrote: > So, when you write > if (cname && memcmp(ptr, cname, cnamelen)) > return DNS_UPD_NAME_ERROR; > else if (memcmp(ptr, dn_name, dn_name_len)) > return DNS_UPD_NAME_ERROR; > > your compare cname againt name in current record only if cname is set. > In Ben's case, cname is set and ptr and cname comparison was true, > hence memcmp returned 0. > Since memcmp returns 0, then HAProxy checks the next condition and > compare ptr to dn_name, which lead to return the DNS_UPD_NAME_ERROR > since we're evaluating a cname and ptr points to the CNAME while > dn_name points to the queried name. > > Basically, the code parsed the first response record, the CNAME, then > returned an error because the value of the cname does not match > anymore the name in the A record. > > With the code below, when cname is set, there is no chance you compare > ptr and dn_name... > if (cname) { > if (memcmp(ptr, cname, cnamelen)) { > return DNS_UPD_NAME_ERROR; > } > } > else if (memcmp(ptr, dn_name, dn_name_len)) > return DNS_UPD_NAME_ERROR;
Thank you for the careful explanation Baptiste, that riddle was confounding our understanding.
