[monitoring-plugins] check_curl: host_name may be null

[Sven Nierlein]

 Module: monitoring-plugins
 Branch: feature_check_curl
 Commit: 772fb233b92d4ad5fc87f30a8efee5c9bb295d1d
 Author: Sven Nierlein <sven at nierlein.de>
   Date: Mon May 18 14:08:45 2020 +0200
    URL: https://www.monitoring-plugins.org/repositories/monitoring-plugins/commit/?id=772fb23

check_curl: host_name may be null

for example when using like: ./check_curl localhost

---

 plugins/check_curl.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/plugins/check_curl.c b/plugins/check_curl.c
index 2b0e378..2d69b31 100644
--- a/plugins/check_curl.c
+++ b/plugins/check_curl.c
@@ -127,8 +127,8 @@ int cflags = REG_NOSUB | REG_EXTENDED | REG_NEWLINE;
 int errcode;
 int invert_regex = 0;
 
-char *server_address;
-char *host_name;
+char *server_address = NULL;
+char *host_name = NULL;
 char *server_url = 0;
 char server_ip[DEFAULT_BUFFER_SIZE];
 struct curl_slist *server_ips = NULL;
@@ -367,7 +367,7 @@ check_http (void)
   handle_curl_option_return_code (curl_easy_setopt (curl, CURLOPT_TIMEOUT, socket_timeout), "CURLOPT_TIMEOUT");
 
   // fill dns resolve cache to make curl connect to the given server_address instead of the host_name, only required for ssl, because we use the host_name later on to make SNI happy
-  if(use_ssl) {
+  if(use_ssl && host_name != NULL) {
       struct curl_slist *host = NULL;
       char dnscache[DEFAULT_BUFFER_SIZE];
       snprintf (dnscache, DEFAULT_BUFFER_SIZE, "%s:%d:%s", host_name, server_port, server_address);
@@ -380,7 +380,7 @@ check_http (void)
   /* compose URL: use the address we want to connect to, set Host: header later */
   snprintf (url, DEFAULT_BUFFER_SIZE, "%s://%s:%d%s",
       use_ssl ? "https" : "http",
-      use_ssl ? host_name : server_address,
+      use_ssl & host_name != NULL ? host_name : server_address,
       server_port,
       server_url
   );