public static string InvertHost(string host)
{
if (HostUtils.IsNumeric(host))
{
return(host);
}
else
{
int n = host.Length;
char[] res = new char[n];
int a = 0;
while (a < n)
{
int c = a;
while (c < n && host[c] != '.')
{
c++;
}
int d = n - c;
while (a < c)
{
res[d++] = host[a++];
}
res[d++] = '.';
a = c + 1;
}
return(new string(res));
}
}
public static string DomainOf(string host)
{
if (HostUtils.IsNumeric(host))
{
return(host);
}
int n = host.Length;
for (int i = 0; i < suffix.Length; i++)
{
if (host.EndsWith(suffix[i]))
{
int p = LastDotBefore(host, n - suffix[i].Length);
if (p == -1)
{
return(host);
}
return(host.Substring(p + 1));
}
}
int q = LastDotBefore(host, n);
if (q == -1)
{
return(host);
}
int r = LastDotBefore(host, q);
if (r == -1)
{
return(host);
}
return(host.Substring(r + 1));
}