check_curl fix: populate the dns cache when hostname gets resolved locally (#2280)

* check_curl fix: populate the dns cache when hostname gets resolved locally

due to a previous refactor, it would populate it when hostname wasnt getting resolved locally

hostname_gets_resolved locally now assumes that resolving is local if proxy was unknown. previously was returning 0 instead of true, contradicting what it says

fix a memory leak. server_address_clean was being assigned to another strndup result before being freed

fix another memory leak, one path to return in hostname_gets_resolved_locally was not freeing up two variables

improve logs and comments around hostname_gets_resolved_locally

clang-format is applied

* check_curl: fix typo in comment

---------

Co-authored-by: Ahmet Oeztuerk <Ahmet.Oeztuerk@consol.de>

1 files changed, 4 insertions, 3 deletions

diff --git a/plugins/check_curl.d/check_curl_helpers.h b/plugins/check_curl.d/check_curl_helpers.h
index 55df9bc1..2f9b0d1c 100644
--- a/plugins/check_curl.d/check_curl_helpers.h
+++ b/plugins/check_curl.d/check_curl_helpers.h
@@ -127,9 +127,10 @@ mp_subcheck check_curl_certificate_checks(CURL *curl, X509 *cert, int warn_days_
                                                                                   int crit_days_till_exp);
 char *fmt_url(check_curl_working_state workingState);
 
-/* determine_hostname_resolver determines if the host or the proxy resolves the target hostname
-returns RESOLVE_LOCALLY if requester resolves the hostname locally, RESOLVE_REMOTELY if proxy
-resolves the hostname */
+/* hostname_gets_resolved_locally determines if the host or the proxy resolves the target hostname.
+This depends on proxy schema, forced proxy and noproxy hostnames, wildcarded hostnames, IP addresses
+and IP CIDRs. Returns true if the host resolves the hostname locally, and false if proxy resolves
+the hostname */
 bool hostname_gets_resolved_locally(const check_curl_working_state working_state);
 
 /* Checks if an IP is inside given CIDR region. Using /protocol_size or not specifying the prefix