Add error handling

When /etc/hosts isn't present, the hostname
lookup does not crash the redis-server

src/ipmodule.c

@@ -3,26 +3,36 @@
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <netdb.h>
-
+#include<string.h>
 #include "redismodule.h"
 
 int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
     char hostbuffer[256];
-    char *IPbuffer;
+    char IPbuffer[50];
     struct hostent *host_entry;
     int hostname;
+    struct in_addr **addr_list;
+    int i;
 
     if (RedisModule_Init(ctx,"RedisIP",1,REDISMODULE_APIVER_1)
             == REDISMODULE_ERR) return REDISMODULE_ERR;
 
     hostname = gethostname(hostbuffer, sizeof(hostbuffer));
 
-    // checks /etc/hosts (needs error handling for if hostname isn't present)
-    host_entry = gethostbyname(hostbuffer);
+    // checks /etc/hosts
+    if ((host_entry = gethostbyname(hostbuffer)) == NULL) {
+        RedisModule_Log(ctx, "warning", "Hostname: NOTFOUND");
+        return REDISMODULE_OK;
+    }
 
-    IPbuffer = inet_ntoa(*((struct in_addr*)
-                           host_entry->h_addr_list[0]));
+    addr_list = (struct in_addr **) host_entry->h_addr_list;
 
+    for(i = 0; addr_list[i] != NULL; i++)
+    {
+        //Return the first one;
+        strcpy(IPbuffer , inet_ntoa(*addr_list[i]) );
+        break;
+    }
     RedisModule_Log(ctx, "warning", "Hostname: %s", hostbuffer);
     RedisModule_Log(ctx, "warning", "IP: %s", IPbuffer);