private static PublicSuffixRule FindMatchingRule(List <string> domainLabels, PublicSuffixRuleCache ruleCache)
{
var ruleMatches = ruleCache.PublicSuffixRules.Where(r => r.AppliesTo(domainLabels)).ToList();
// If there is only one match, return it.
if (ruleMatches.Count() == 1)
{
return(ruleMatches[0]);
}
// If more than one rule matches, the prevailing rule is the one which is an exception rule.
var exceptionRules = ruleMatches.Where(r => r.Type == PublicSuffixRule.RuleType.Exception).ToList();
if (exceptionRules.Count() == 1)
{
return(exceptionRules[0]);
}
if (exceptionRules.Count() > 1)
{
throw new ApplicationException("Unexpectedly found multiple matching exception rules.");
}
// If there is no matching exception rule, the prevailing rule is the one with the most labels.
var prevailingRule = ruleMatches.OrderByDescending(r => r.Labels.Count).Take(1).SingleOrDefault();
return(prevailingRule);
}
public static bool TryParse(string rawDomainName, PublicSuffixRuleCache ruleCache, out DomainName domainName)
{
if (string.IsNullOrEmpty(rawDomainName) || !rawDomainName.Contains('.') || rawDomainName.StartsWith("."))
{
domainName = new DomainName(rawDomainName, null, null);
return(true);
}
try
{
rawDomainName = rawDomainName.ToLower();
// Split our domain into parts (based on the '.')
// We'll be checking rules from the right-most part of the domain
var domainLabels = rawDomainName.Trim().Split('.').ToList();
domainLabels.Reverse();
// If no rules match, the prevailing rule is "*"
var prevailingRule = FindMatchingRule(domainLabels, ruleCache) ?? new PublicSuffixRule("*");
// If the prevailing rule is an exception rule, modify it by removing the leftmost label.
if (prevailingRule.Type == PublicSuffixRule.RuleType.Exception)
{
var labels = prevailingRule.Labels;
labels.Reverse();
labels.RemoveAt(0);
prevailingRule = new PublicSuffixRule(string.Join(".", labels));
}
// The public suffix is the set of labels from the domain which directly match the labels of the prevailing rule (joined by dots).
var publicSuffix = Enumerable.Range(0, prevailingRule.Labels.Count).Aggregate(string.Empty, (current, i) => string.Format("{0}.{1}", domainLabels[i], current).Trim('.'));
// The registered or registrable domain is the public suffix plus one additional label.
var registrableDomain = string.Format("{0}.{1}", domainLabels[prevailingRule.Labels.Count], publicSuffix);
domainName = new DomainName(rawDomainName, publicSuffix, registrableDomain);
return(true);
}
catch
{
domainName = null;
return(false);
}
}
