/// <summary>
/// Adds dns records to cache. If old entry exists, it is replaced.
/// </summary>
/// <param name="qname">Query name.</param>
/// <param name="qtype">Query type.</param>
/// <param name="response">DNS server response.</param>
/// <exception cref="ArgumentNullException">Is raised when <b>qname</b> or <b>response</b> is null reference.</exception>
/// <exception cref="ArgumentException">Is raised when any of the arguments has invalid value.</exception>
public void AddToCache(string qname,int qtype,DnsServerResponse response)
{
if(qname == null){
throw new ArgumentNullException("qname");
}
if(qname == string.Empty){
throw new ArgumentException("Argument 'qname' value must be specified.","qname");
}
if(response == null){
throw new ArgumentNullException("response");
}
lock(m_pCache){
// Remove old cache entry, if any.
if(m_pCache.ContainsKey(qname + qtype)){
m_pCache.Remove(qname + qtype);
}
if(response.ResponseCode == DNS_RCode.NO_ERROR){
int ttl = m_MaxCacheTtl;
// Search smallest DNS record TTL and use it.
foreach(DNS_rr rr in response.AllAnswers){
if(rr.TTL < ttl){
ttl = rr.TTL;
}
}
m_pCache.Add(qname + qtype,new CacheEntry(response,DateTime.Now.AddSeconds(ttl)));
}
else{
m_pCache.Add(qname + qtype,new CacheEntry(response,DateTime.Now.AddSeconds(m_MaxNegativeCacheTtl)));
}
}
}
/// <summary>
/// Default constructor.
/// </summary>
/// <param name="answers">Dns answers.</param>
/// <param name="addTime">Entry add time.</param>
public DnsCacheEntry(DnsServerResponse answers,DateTime addTime)
{
m_pResponse = answers;
m_Time = addTime;
}
/// <summary>
/// Adds dns records to cache. If old entry exists, it is replaced.
/// </summary>
/// <param name="qname"></param>
/// <param name="qtype"></param>
/// <param name="answers"></param>
public static void AddToCache(string qname,int qtype,DnsServerResponse answers)
{
if(answers == null){
return;
}
try{
lock(m_pCache){
// Remove old cache entry, if any.
if(m_pCache.Contains(qname + qtype)){
m_pCache.Remove(qname + qtype);
}
m_pCache.Add(qname + qtype,new DnsCacheEntry(answers,DateTime.Now));
}
}
catch{
}
}
/// <summary>
/// Gets A and AAAA records from DNS server additional responses section.
/// </summary>
/// <param name="name">Host name.</param>
/// <param name="response">DNS server response.</param>
/// <returns>Returns A and AAAA records from DNS server additional responses section.</returns>
/// <exception cref="ArgumentNullException">Is raised when <b>name</b> or <b>response</b> is null reference.</exception>
private IPAddress[] Get_A_or_AAAA_FromResponse(string name,DnsServerResponse response)
{
if(name == null){
throw new ArgumentNullException("name");
}
if(response == null){
throw new ArgumentNullException("response");
}
List<IPAddress> aList = new List<IPAddress>();
List<IPAddress> aaaaList = new List<IPAddress>();
foreach(DNS_rr rr in response.AdditionalAnswers){
if(string.Equals(name,rr.Name,StringComparison.InvariantCultureIgnoreCase)){
if(rr is DNS_rr_A){
aList.Add(((DNS_rr_A)rr).IP);
}
else if(rr is DNS_rr_AAAA){
aaaaList.Add(((DNS_rr_AAAA)rr).IP);
}
}
}
// We list IPv4 first and then IPv6 addresses.
aList.AddRange(aaaaList);
return aList.ToArray();
}
/// <summary>
/// Default constructor.
/// </summary>
/// <param name="response">DNS server response.</param>
/// <param name="expires">Time when cache entry expires.</param>
/// <exception cref="ArgumentNullException">Is raised when <b>response</b> is null reference.</exception>
public CacheEntry(DnsServerResponse response,DateTime expires)
{
if(response == null){
throw new ArgumentNullException("response");
}
m_pResponse = response;
m_Expires = expires;
}
