apache: warn about possible misconfiguration

When the server doesn't return `Content-Type: text-plain`, it's a strong
hint that we're not querying the right URL.

Fixes #1170

diff --git a/src/apache.c b/src/apache.c
index 13c8db6..ee06220 100644 (file)
--- a/src/apache.c
+++ b/src/apache.c
@@ -596,13 +596,16 @@ static int apache_read_host (user_data_t *user_data) /* {{{ */
 
        st = user_data->data;
 
+       int status;
+
+       char *content_type;
+       static const char *text_plain = "text/plain";
+
        assert (st->url != NULL);
        /* (Assured by `config_add') */
 
        if (st->curl == NULL)
        {
-               int status;
-
                status = init_host (st);
                if (status != 0)
                        return (-1);
@@ -625,6 +628,16 @@ static int apache_read_host (user_data_t *user_data) /* {{{ */
                st->server_type = APACHE;
        }
 
+       status = curl_easy_getinfo (st->curl, CURLINFO_CONTENT_TYPE, &content_type);
+       if ((status == CURLE_OK) && (content_type != NULL) &&
+           (strncasecmp (content_type, text_plain, strlen (text_plain)) != 0))
+       {
+               WARNING ("apache plugin: `Content-Type' response header is not `%s' "
+                       "(received: `%s'). Expecting unparseable data. Please check `URL' "
+                       "parameter (missing `?auto' suffix ?)",
+                       text_plain, content_type);
+       }
+
        ptr = st->apache_buffer;
        saveptr = NULL;
        while ((line = strtok_r (ptr, "\n\r", &saveptr)) != NULL)