tls-store: avoid log flooding

In case we can't write in the certs directory, this is possible
we flood the log for each TLS session or even worse each TLS
packet.  So this patch puts a limit in the number of logged
messages related to file creation.

src/log-tlsstore.c

@@ -57,6 +57,9 @@
 
 static char tls_logfile_base_dir[PATH_MAX] = "/tmp";
 SC_ATOMIC_DECLARE(unsigned int, cert_id);
+static char logging_dir_not_writable;
+
+#define LOGGING_WRITE_ISSUE_LIMIT 6
 
 typedef struct LogTlsStoreLogThread_ {
     uint32_t tls_cnt;
@@ -112,7 +115,12 @@ static void LogTlsLogPem(LogTlsStoreLogThread *aft, const Packet *p, SSLState *s
 
     fp = fopen(filename, "w");
     if (fp == NULL) {
-        SCLogWarning(SC_ERR_FOPEN, "Can't create PEM file: %s", filename);
+        if (logging_dir_not_writable < LOGGING_WRITE_ISSUE_LIMIT) {
+            SCLogWarning(SC_ERR_FOPEN,
+                         "Can't create PEM file '%s' in '%s' directory",
+                         filename, tls_logfile_base_dir);
+            logging_dir_not_writable++;
+        }
         SCReturn;
     }
 
@@ -199,8 +207,12 @@ static void LogTlsLogPem(LogTlsStoreLogThread *aft, const Packet *p, SSLState *s
 
         fclose(fpmeta);
     } else {
-        SCLogWarning(SC_ERR_FOPEN, "Can't open meta file: %s",
-                     filename);
+        if (logging_dir_not_writable < LOGGING_WRITE_ISSUE_LIMIT) {
+            SCLogWarning(SC_ERR_FOPEN,
+                         "Can't create meta file '%s' in '%s' directory",
+                         filename, tls_logfile_base_dir);
+            logging_dir_not_writable++;
+        }
         SCReturn;
     }
 
@@ -210,11 +222,17 @@ static void LogTlsLogPem(LogTlsStoreLogThread *aft, const Packet *p, SSLState *s
 
 end_fwrite_fp:
     fclose(fp);
-    SCLogWarning(SC_ERR_FWRITE, "Unable to write certificate");
+    if (logging_dir_not_writable < LOGGING_WRITE_ISSUE_LIMIT) {
+        SCLogWarning(SC_ERR_FWRITE, "Unable to write certificate");
+        logging_dir_not_writable++;
+    }
 end_fwrite_fpmeta:
     if (fpmeta) {
         fclose(fpmeta);
-        SCLogWarning(SC_ERR_FWRITE, "Unable to write certificate metafile");
+        if (logging_dir_not_writable < LOGGING_WRITE_ISSUE_LIMIT) {
+            SCLogWarning(SC_ERR_FWRITE, "Unable to write certificate metafile");
+            logging_dir_not_writable++;
+        }
     }
     SCReturn;
 end_fp: