Add is_valid_hostname()

common/fko_util.c

@@ -175,6 +175,68 @@ is_valid_ipv4_addr(const char * const ip_str, const int len)
     return(res);
 }
 
+/* Validate a hostname
+*/
+int
+is_valid_hostname(const char * const hostname_str, const int len)
+{
+    int                 label_size = 0, total_size = 0;
+    const char         *ndx     = hostname_str;
+
+    if (hostname_str == NULL)
+        return 0;
+
+    if (len > 254)
+        return 0;
+
+    while(total_size < len)
+    {
+        if (*ndx == '\0')
+            return 0;
+
+        if (label_size == 0) //More restrictions on first character of a label
+        {
+            if (!isalnum(*ndx))
+                return 0;
+        }
+        else if (!(isalnum(*ndx) | (*ndx == '.') | (*ndx == '-')))
+            return 0;
+
+        if (*ndx == '.')
+        {
+            if (label_size > 63)
+                return 0;
+            if (!isalnum(*(ndx-1)))  //checks that previous character was not a . or -
+                return 0;
+
+            label_size = 0;
+        }
+        else
+        {
+            label_size++;
+        }
+
+        total_size++;
+
+        ndx++; //move to next character
+    }
+    /* At this point, we're pointing at the null.  Decrement ndx for simplicity
+    */
+    ndx--;
+    if (*ndx == '-')
+        return 0;
+
+    if (*ndx == '.')
+        total_size--;
+
+    if (label_size > 63)
+        return 0;
+
+    /* By now we've bailed if invalid
+    */
+    return 1;
+}
+
 /* Convert a digest_type string to its integer value.
 */
 short

common/fko_util.h

@@ -41,6 +41,7 @@
 int     is_valid_encoded_msg_len(const int len);
 int     is_valid_pt_msg_len(const int len);
 int     is_valid_ipv4_addr(const char * const ip_str, const int len);
+int     is_valid_hostname(const char * const hostname_str, const int len);
 int     is_base64(const unsigned char * const buf, const unsigned short int len);
 void    hex_dump(const unsigned char *data, const int size);
 int     enc_mode_strtoint(const char *enc_mode_str);