Fix memory leak in proto - name mapping

==15745== 3 bytes in 1 blocks are definitely lost in loss record 5 of 615
==15745==    at 0x4C2A2DB: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==15745==    by 0x71858C1: strdup (strdup.c:42)
==15745==    by 0xA20814: SCProtoNameInit (util-proto-name.c:75)
==15745==    by 0x952D1B: PostConfLoadedSetup (suricata.c:1983)
==15745==    by 0x9537CD: main (suricata.c:2112)

Also, clean up and add a check to make sure it's initialized only once.

src/util-proto-name.c

@@ -27,12 +27,18 @@
 #include "suricata-common.h"
 #include "util-proto-name.h"
 
+static int init_once = 0;
+
 /**
  *  \brief  Function to load the protocol names from the specified protocol
  *          file.
  */
 void SCProtoNameInit()
 {
+    BUG_ON(init_once);
+    init_once++;
+    memset(known_proto, 0x00, sizeof(known_proto));
+
     /* Load the known protocols name from the /etc/protocols file */
     FILE *fp = fopen(PROTO_FILE,"r");
     if (fp != NULL) {
@@ -71,6 +77,10 @@ void SCProtoNameInit()
             char *cname = strtok_r(NULL, " \t", &ptr);
 #endif /* __WIN32 */
 
+            if (known_proto[proto] != NULL) {
+                SCFree(known_proto[proto]);
+            }
+
             if (cname != NULL) {
                 known_proto[proto] = SCStrdup(cname);
             } else {
@@ -111,8 +121,9 @@ uint8_t SCProtoNameValid(uint16_t proto)
  */
 void SCProtoNameDeInit()
 {
+    int cnt;
     /* clears the memory of loaded protocol names */
-    for (uint8_t cnt=0;cnt < 255;cnt++) {
+    for (cnt = 0; cnt < 255; cnt++) {
         if (known_proto[cnt] != NULL)
             SCFree(known_proto[cnt]);
     }