static DNS_RR *smtp_addr_list(DNS_RR *mx_names, DSN_BUF *why)
{
DNS_RR *addr_list = 0;
DNS_RR *rr;
/*
* As long as we are able to look up any host address, we ignore problems
* with DNS lookups (except if we're backup MX, and all the better MX
* hosts can't be found).
*
* XXX 2821: update the error status (0->FAIL upon unrecoverable lookup
* error, any->RETRY upon temporary lookup error) so that we can
* correctly handle the case of no resolvable MX host. Currently this is
* always treated as a soft error. RFC 2821 wants a more precise
* response.
*
* XXX dns_lookup() enables RES_DEFNAMES. This is wrong for names found in
* MX records - we should not append the local domain to dot-less names.
*
* XXX However, this is not the only problem. If we use the native name
* service for host lookup, then it will usually enable RES_DNSRCH which
* appends local domain information to all lookups. In particular,
* getaddrinfo() may invoke a resolver that runs in a different process
* (NIS server, nscd), so we can't even reliably turn this off by
* tweaking the in-process resolver flags.
*/
for (rr = mx_names; rr; rr = rr->next) {
if (rr->type != T_MX)
msg_panic("smtp_addr_list: bad resource type: %d", rr->type);
addr_list = smtp_addr_one(addr_list, (char *) rr->data, rr->pref, why);
}
return (addr_list);
}
DNS_RR *smtp_host_addr(const char *host, int misc_flags, DSN_BUF *why)
{
DNS_RR *addr_list;
dsb_reset(why); /* Paranoia */
/*
* If the host is specified by numerical address, just convert the
* address to internal form. Otherwise, the host is specified by name.
*/
#define PREF0 0
addr_list = smtp_addr_one((DNS_RR *) 0, host, PREF0, why);
if (addr_list
&& (misc_flags & SMTP_MISC_FLAG_LOOP_DETECT)
&& smtp_find_self(addr_list) != 0) {
dns_rr_free(addr_list);
dsb_simple(why, "5.4.6", "mail for %s loops back to myself", host);
return (0);
}
if (addr_list && addr_list->next) {
if (var_smtp_rand_addr)
addr_list = dns_rr_shuffle(addr_list);
/* The following changes the order of equal-preference hosts. */
if (inet_proto_info()->ai_family_list[1] != 0)
addr_list = dns_rr_sort(addr_list, SMTP_COMPARE_ADDR(misc_flags));
}
if (msg_verbose)
smtp_print_addr(host, addr_list);
return (addr_list);
}
DNS_RR *smtp_host_addr(const char *host, int misc_flags, DSN_BUF *why)
{
DNS_RR *addr_list;
int res_opt = 0;
const char *ahost;
dsb_reset(why); /* Paranoia */
if (smtp_dns_support == SMTP_DNS_DNSSEC)
res_opt |= RES_USE_DNSSEC;
/*
* IDNA support.
*/
#ifndef NO_EAI
if (!allascii(host) && (ahost = midna_domain_to_ascii(host)) != 0) {
if (msg_verbose)
msg_info("%s asciified to %s", host, ahost);
} else
#endif
ahost = host;
/*
* If the host is specified by numerical address, just convert the
* address to internal form. Otherwise, the host is specified by name.
*/
#define PREF0 0
addr_list = smtp_addr_one((DNS_RR *) 0, ahost, res_opt, PREF0, why);
if (addr_list
&& (misc_flags & SMTP_MISC_FLAG_LOOP_DETECT)
&& smtp_find_self(addr_list) != 0) {
dns_rr_free(addr_list);
dsb_simple(why, "5.4.6", "mail for %s loops back to myself", host);
return (0);
}
if (addr_list && addr_list->next) {
if (var_smtp_rand_addr)
addr_list = dns_rr_shuffle(addr_list);
/* The following changes the order of equal-preference hosts. */
if (inet_proto_info()->ai_family_list[1] != 0)
addr_list = dns_rr_sort(addr_list, SMTP_COMPARE_ADDR(misc_flags));
}
if (msg_verbose)
smtp_print_addr(host, addr_list);
return (addr_list);
}
