Add function to validate ip address

src/ui/util.c

@@ -120,3 +120,34 @@ else {
     }
 
 }
+
+int isValidIPaddress(const char * ip){
+
+
+     /* Compile regular expression */
+    reti = regcomp(&regex, 
+        "^([0-9]|[1-9][0-9]|1([0-9][0-9])|2([0-4][0-9]|5[0-5]))."
+         "([0-9]|[1-9][0-9]|1([0-9][0-9])|2([0-4][0-9]|5[0-5]))."
+         "([0-9]|[1-9][0-9]|1([0-9][0-9])|2([0-4][0-9]|5[0-5]))."
+         "([0-9]|[1-9][0-9]|1([0-9][0-9])|2([0-4][0-9]|5[0-5]))$", REG_EXTENDED);
+    if (reti) {
+        //printf( "Could not compile regex\n");
+        return -1;
+    }
+
+    /* Execute regular expression */
+    reti = regexec(&regex, ip, 0, NULL, 0);
+    if (!reti) {
+        return 0;
+    }
+    else if (reti == REG_NOMATCH) {
+        //puts("Invalid ip addresses");
+        return -1;
+    }
+    else {
+        regerror(reti, &regex, msgbuf, sizeof(msgbuf));
+        //printf("Regex match failed: %s\n", msgbuf);
+        return -1;
+    }
+
+}