/// <summary>
/// Returns the textual representation of the SenderID record
/// </summary>
/// <returns> Textual representation </returns>
public override string ToString()
{
StringBuilder res = new StringBuilder();
if (Version == 1)
{
res.Append("v=spf1");
}
else
{
res.Append("v=spf");
res.Append(Version);
res.Append(".");
res.Append(MinorVersion);
res.Append("/");
res.Append(String.Join(",", Scopes.Where(s => s != SenderIDScope.Unknown).Select(s => EnumHelper <SenderIDScope> .ToString(s).ToLower()).ToArray()));
}
if ((Terms != null) && (Terms.Count > 0))
{
foreach (SpfTerm term in Terms)
{
SpfModifier modifier = term as SpfModifier;
if ((modifier == null) || (modifier.Type != SpfModifierType.Unknown))
{
res.Append(" ");
res.Append(term.ToString());
}
}
}
return(res.ToString());
}
/// <summary>
/// Returns the textual representation of a SPF record
/// </summary>
/// <returns> Textual representation </returns>
public override string ToString()
{
StringBuilder res = new StringBuilder();
res.Append("v=spf1");
if ((Terms != null) && (Terms.Count > 0))
{
foreach (SpfTerm term in Terms)
{
SpfModifier modifier = term as SpfModifier;
if ((modifier == null) || (modifier.Type != SpfModifierType.Unknown))
{
res.Append(" ");
res.Append(term.ToString());
}
}
}
return(res.ToString());
}
private SpfQualifier CheckHostInternal(IPAddress ip, string sender, string domain, bool expandExplanation, out string explanation)
{
explanation = String.Empty;
if (String.IsNullOrEmpty(domain))
{
return(SpfQualifier.None);
}
if (String.IsNullOrEmpty(sender))
{
sender = "postmaster@unknown";
}
else if (!sender.Contains('@'))
{
sender = "postmaster@" + sender;
}
SpfQualifier result;
T record;
if (!TryLoadRecords(domain, out record, out result))
{
return(result);
}
if ((record.Terms == null) || (record.Terms.Count == 0))
{
return(SpfQualifier.Neutral);
}
if (record.Terms.OfType <SpfModifier>().GroupBy(m => m.Type).Where(g => (g.Key == SpfModifierType.Exp) || (g.Key == SpfModifierType.Redirect)).Any(g => g.Count() > 1))
{
return(SpfQualifier.PermError);
}
#region Evaluate mechanism
foreach (SpfMechanism mechanism in record.Terms.OfType <SpfMechanism>())
{
if (LookupCount > DnsLookupLimit)
{
return(SpfQualifier.PermError);
}
SpfQualifier qualifier = CheckMechanism(mechanism, ip, sender, domain);
if (qualifier != SpfQualifier.None)
{
result = qualifier;
break;
}
}
#endregion
#region Evaluate modifiers
if (result == SpfQualifier.None)
{
SpfModifier redirectModifier = record.Terms.OfType <SpfModifier>().FirstOrDefault(m => m.Type == SpfModifierType.Redirect);
if (redirectModifier != null)
{
string redirectDomain = ExpandDomain(redirectModifier.Domain ?? String.Empty, ip, sender, domain);
if (String.IsNullOrEmpty(redirectDomain) || (redirectDomain.Equals(domain, StringComparison.InvariantCultureIgnoreCase)))
{
result = SpfQualifier.PermError;
}
else
{
result = CheckHostInternal(ip, sender, redirectDomain, expandExplanation, out explanation);
if (result == SpfQualifier.None)
{
result = SpfQualifier.PermError;
}
}
}
}
else if ((result == SpfQualifier.Fail) && expandExplanation)
{
SpfModifier expModifier = record.Terms.OfType <SpfModifier>().Where(m => m.Type == SpfModifierType.Exp).FirstOrDefault();
if (expModifier != null)
{
string target = ExpandDomain(expModifier.Domain, ip, sender, domain);
if (String.IsNullOrEmpty(target))
{
explanation = String.Empty;
}
else
{
DnsMessage dnsMessage = ResolveDns(target, RecordType.Txt);
if ((dnsMessage != null) && (dnsMessage.ReturnCode == ReturnCode.NoError))
{
TxtRecord txtRecord = dnsMessage.AnswerRecords.OfType <TxtRecord>().FirstOrDefault();
if (txtRecord != null)
{
explanation = ExpandDomain(txtRecord.TextData, ip, sender, domain);
}
}
}
}
}
#endregion
return((result != SpfQualifier.None) ? result : SpfQualifier.Neutral);
}
internal static bool TryParse(string s, out SpfTerm value)
{
if (String.IsNullOrEmpty(s))
{
value = null;
return(false);
}
#region Parse Mechanism
Regex regex = new Regex(@"^(\s)*(?<qualifier>[~+?-]?)(?<type>[a-z0-9]+)(:(?<domain>[^/]+))?(/(?<prefix>[0-9]+)(/(?<prefix6>[0-9]+))?)?(\s)*$", RegexOptions.Compiled | RegexOptions.IgnoreCase);
Match match = regex.Match(s);
if (match.Success)
{
SpfMechanism mechanism = new SpfMechanism();
switch (match.Groups["qualifier"].Value)
{
case "+":
mechanism.Qualifier = SpfQualifier.Pass;
break;
case "-":
mechanism.Qualifier = SpfQualifier.Fail;
break;
case "~":
mechanism.Qualifier = SpfQualifier.SoftFail;
break;
case "?":
mechanism.Qualifier = SpfQualifier.Neutral;
break;
default:
mechanism.Qualifier = SpfQualifier.Pass;
break;
}
SpfMechanismType type;
mechanism.Type = EnumHelper <SpfMechanismType> .TryParse(match.Groups["type"].Value, true, out type) ? type : SpfMechanismType.Unknown;
mechanism.Domain = match.Groups["domain"].Value;
string tmpPrefix = match.Groups["prefix"].Value;
int prefix;
if (!String.IsNullOrEmpty(tmpPrefix) && Int32.TryParse(tmpPrefix, out prefix))
{
mechanism.Prefix = prefix;
}
tmpPrefix = match.Groups["prefix6"].Value;
if (!String.IsNullOrEmpty(tmpPrefix) && Int32.TryParse(tmpPrefix, out prefix))
{
mechanism.Prefix6 = prefix;
}
value = mechanism;
return(true);
}
#endregion
#region Parse Modifier
regex = new Regex(@"^(\s)*(?<type>[a-z]+)=(?<domain>[^\s]+)(\s)*$", RegexOptions.Compiled | RegexOptions.IgnoreCase);
match = regex.Match(s);
if (match.Success)
{
SpfModifier modifier = new SpfModifier();
SpfModifierType type;
modifier.Type = EnumHelper <SpfModifierType> .TryParse(match.Groups["type"].Value, true, out type) ? type : SpfModifierType.Unknown;
modifier.Domain = match.Groups["domain"].Value;
value = modifier;
return(true);
}
#endregion
value = null;
return(false);
}