void
res_print (const struct res *res, bool backward)
{
if (!backward && res->parent) res_print (res->parent, backward);
printf ("-> Port: %d", res->port);
printf ("\n");
printf ("-> HS: \n");
hs_print (&res->hs);
if (res->rules.cur) {
printf (", Rules: ");
for (int i = 0; i < res->rules.cur; i++) {
if (i) printf (", ");
const struct res_rule *r = &res->rules.arr[i];
printf ("%s_%d", r->tf ? r->tf : "", r->rule);
printf ("\n");
rule_print (r->tf_rule, r->tf_tf);
}
}
printf ("\n");
if (backward && res->parent) res_print (res->parent, backward);
}
void
list_res_print (const struct list_res *l, bool backward)
{
int count = 0;
for (const struct res *res = l->head; res; res = res->next, count++) {
res_print (res, backward);
printf (" HS: ");
hs_print (&res->hs);
hs_print_json (&res->hs);
printf ("-----\n");
}
printf ("Count: %d\n", count);
}
// Perform a DNS query and parse the results. Follows CNAME records.
void SipSrvLookup::res_query_and_parse(const char* in_name,
int type,
res_response* in_response,
const char*& out_name,
res_response*& out_response
)
{
OsSysLog::add(FAC_SIP, PRI_DEBUG,
"SipSrvLookup::res_query_and_parse in_name = '%s', "
"type = %d (%s)",
in_name,type,
type == T_CNAME ? "CNAME" :
type == T_SRV ? "SRV" :
type == T_A ? "A" :
type == T_NAPTR ? "NAPTR" :
"unknown");
// The number of CNAMEs we have followed.
int cname_count = 0;
// The response currently being examined.
res_response* response = in_response;
// The name currently being examined.
const char* name = in_name;
// TRUE if 'response' was a lookup for 'name' and 'type'.
UtlBoolean response_for_this_name = FALSE;
// Buffer into which to read DNS replies.
char answer[DNS_RESPONSE_SIZE];
union u_rdata* p;
// Loop until we find a reason to exit. Each turn around the loop does
// another DNS lookup.
while (1)
{
// While response != NULL and there is a CNAME record for name
// in response.
while (response != NULL &&
(p = look_for(response, name, T_CNAME)) != NULL)
{
cname_count++;
if (cname_count > SipSrvLookup::getOption(SipSrvLookup::OptionCodeCNAMELimit))
{
break;
}
// If necessary, free the current 'name'.
if (name != in_name)
{
free((void*) name);
}
// Copy the canonical name from the CNAME record into 'name', so
// we can still use it after freeing 'response'.
name = strdup(p->string);
// Remember that we are now looking for a name that was not the one
// that we searched for to produce this response. Hence, if we don't
// find any RRs for it, that is not authoritative and we have to do
// another DNS query.
response_for_this_name = FALSE;
// Go back and check whether the result name of the CNAME is listed
// in this response.
}
// This response does not contain a CNAME for 'name'. So it is either
// a final response that gives us the RRs we are looking for, or
// we need to do a lookup on 'name'.
// Check whether the response was for this name, or contains records
// of the type we are looking for. If either, then any records we
// are looking for are in this response, so we can return.
if (response_for_this_name ||
(response != NULL && look_for(response, name, type) != NULL))
{
break;
}
// We must do another lookup.
// Start by freeing 'response' if we need to.
if (response != in_response)
{
res_free(response);
}
response = NULL;
// Now, 'response' will be from a query for 'name'.
response_for_this_name = TRUE;
// Debugging print.
if (SipSrvLookup::getOption(SipSrvLookup::OptionCodePrintAnswers))
{
printf("res_nquery(\"%s\", class = %d, type = %d)\n",
name, C_IN, type);
}
// Initialize the res state struct and set the timeout to
// 3 secs and retries to 2
struct __res_state res;
res_ninit(&res);
res.retrans = mTimeout;
res.retry = mRetries;
if (!mNameserverIP.isNull())
{
res.nscount = 1;
inet_aton(mNameserverIP.data(), &res.nsaddr_list[0].sin_addr);
if (mNameserverPort > 1)
{
res.nsaddr_list[0].sin_port = htons(mNameserverPort);
}
}
// Use res_nquery, not res_search or res_query, so defaulting rules are not
// applied to the domain, and so that the query is thread-safe.
int r = res_nquery(&res, name, C_IN, type,
(unsigned char*) answer, sizeof (answer));
// Done with res state struct, so cleanup.
// Must close once and only once per res_ninit, after res_nquery.
res_nclose(&res);
if (r == -1)
{
// res_query failed, return.
OsSysLog::add(FAC_SIP, PRI_WARNING,
"DNS query for name '%s', "
"type = %d (%s): returned error",
name, type,
type == T_CNAME ? "CNAME" :
type == T_SRV ? "SRV" :
type == T_A ? "A" :
type == T_NAPTR ? "NAPTR" :
"unknown");
break;
}
response = res_parse((char*) &answer);
if (response == NULL)
{
// res_parse failed, return.
OsSysLog::add(FAC_SIP, PRI_WARNING,
"DNS query for name '%s', "
"type = %d (%s): response could not be parsed",
name, type,
type == T_CNAME ? "CNAME" :
type == T_SRV ? "SRV" :
type == T_A ? "A" :
type == T_NAPTR ? "NAPTR" :
"unknown");
break;
}
// If requested for testing purposes, sort the query and print it.
// Sort first, so we see how sorting came out.
if (SipSrvLookup::getOption(SipSrvLookup::OptionCodeSortAnswers))
{
sort_answers(response);
}
if (SipSrvLookup::getOption(SipSrvLookup::OptionCodePrintAnswers))
{
res_print(response);
}
// Now that we have a fresh DNS query to analyze, go back and check it
// for a CNAME for 'name' and then for records of the requested type.
}
// Final processing: Copy the working name and response to the output
// variables.
out_name = name;
out_response = response;
OsSysLog::add(FAC_SIP, PRI_DEBUG,
"SipSrvLookup::res_query_and_parse out_name = '%s', out_response = %p",
out_name, out_response);
}
