/// <summary>
/// Checks if the mechamism matches the current request.
/// </summary>
/// <returns>Match result</returns>
public override async Task <SpfResult> Matches()
{
try
{
if (this.term.dnsLookupsLeft-- <= 0)
{
throw new Exception("DNS Lookup maximum reached.");
}
string TargetDomain = this.TargetDomain;
string[] DomainNames = await DnsResolver.LookupDomainName(this.term.ip);
// First check if domain is found.
foreach (string DomainName in DomainNames)
{
if (string.Compare(DomainName, TargetDomain, true) == 0 &&
await this.MatchReverseIp(DomainName))
{
return(SpfResult.Pass);
}
}
// Second, check if sub-domain is found.
foreach (string DomainName in DomainNames)
{
if (DomainName.EndsWith("." + TargetDomain, StringComparison.CurrentCultureIgnoreCase) &&
await this.MatchReverseIp(DomainName))
{
return(SpfResult.Pass);
}
}
}
catch (Exception)
{
// Fail
}
return(SpfResult.Fail);
}
/// <summary>
/// Expands any macros in the domain specification.
/// </summary>
public override async Task Expand()
{
if (this.expanded)
{
return;
}
this.expanded = true;
this.term.Reset(this.domain);
StringBuilder sb = new StringBuilder();
char ch;
while ((ch = this.term.PeekNextChar()) > ' ')
{
this.term.pos++;
if (ch == '%')
{
switch (ch = this.term.PeekNextChar())
{
case (char)0:
sb.Append('%');
break;
case '%':
this.term.pos++;
sb.Append('%');
break;
case '_':
this.term.pos++;
sb.Append(' ');
break;
case '-':
this.term.pos++;
sb.Append("%20");
break;
case '{':
this.term.pos++;
char MacroLetter = char.ToLower(this.term.NextChar());
int? Digit;
bool Reverse;
if (char.IsDigit(this.term.PeekNextChar()))
{
Digit = this.term.NextInteger();
if (Digit == 0)
{
throw new Exception("Invalid number of digits.");
}
}
else
{
Digit = null;
}
if (char.ToLower(this.term.PeekNextChar()) == 'r')
{
this.term.pos++;
Reverse = true;
}
else
{
Reverse = false;
}
int Start = this.term.pos;
while ((ch = this.term.PeekNextChar()) == '.' || ch == '-' || ch == '+' ||
ch == ',' || ch == '/' || ch == '_' || ch == '=')
{
this.term.pos++;
}
string Delimiter = this.term.s.Substring(Start, this.term.pos - Start);
ch = this.term.NextChar();
if (ch != '}')
{
throw new Exception("Expected }");
}
string s;
switch (MacroLetter)
{
case 's': // sender
s = this.term.sender;
break;
case 'l': // local-part of sender
s = this.term.sender;
int i = s.IndexOf('@');
if (i < 0)
{
s = string.Empty;
}
else
{
s = s.Substring(0, i);
}
break;
case 'o': // domain of sender
s = this.term.sender;
i = s.IndexOf('@');
if (i >= 0)
{
s = s.Substring(i + 1);
}
break;
case 'd': // domain
s = this.term.domain;
break;
case 'i':
switch (this.term.ip.AddressFamily)
{
case AddressFamily.InterNetwork:
s = this.term.ip.ToString();
break;
case AddressFamily.InterNetworkV6:
byte[] Bin = this.term.ip.GetAddressBytes();
StringBuilder sb2 = new StringBuilder();
byte b, b2;
for (i = 0; i < 16; i++)
{
b = Bin[i];
b2 = (byte)(b >> 4);
if (b2 < 10)
{
sb2.Append((char)('0' + b2));
}
else
{
sb2.Append((char)('a' + b2 - 10));
}
sb2.Append('.');
b2 = (byte)(b & 15);
if (b2 < 10)
{
sb2.Append((char)('0' + b2));
}
else
{
sb2.Append((char)('a' + b2 - 10));
}
if (i < 15)
{
sb2.Append('.');
}
}
s = sb2.ToString();
break;
default:
throw new Exception("Invalid client address.");
}
break;
case 'p':
try
{
if (this.term.dnsLookupsLeft-- <= 0)
{
throw new Exception("DNS Lookup maximum reached.");
}
string[] DomainNames = await DnsResolver.LookupDomainName(this.term.ip);
// First check if domain is found.
s = null;
foreach (string DomainName in DomainNames)
{
if (string.Compare(DomainName, this.term.domain, true) == 0 &&
await this.MatchReverseIp(DomainName))
{
s = DomainName;
break;
}
}
if (s is null)
{
// Second, check if sub-domain is found.
foreach (string DomainName in DomainNames)
{
if (DomainName.EndsWith("." + this.term.domain, StringComparison.CurrentCultureIgnoreCase) &&
await this.MatchReverseIp(DomainName))
{
s = DomainName;
break;
}
}
if (s is null)
{
if (DomainNames.Length == 0)
{
s = "unknown";
}
else
{
s = DomainNames[DnsResolver.Next(DomainNames.Length)];
}
}
}
}
catch (ArgumentException)
{
s = "unknown";
}
catch (TimeoutException)
{
s = "unknown";
}
break;
case 'v':
switch (this.term.ip.AddressFamily)
{
case AddressFamily.InterNetwork:
s = "in-addr";
break;
case AddressFamily.InterNetworkV6:
s = "ip6";
break;
default:
throw new Exception("Invalid client address.");
}
break;
case 'h':
s = this.term.helloDomain;
break;
case 'c':
this.AssertExp();
s = this.term.ip.ToString();
break;
case 'r':
this.AssertExp();
s = this.term.hostDomain;
break;
case 't':
this.AssertExp();
int Seconds = (int)Math.Round((DateTime.UtcNow - UnixEpoch).TotalSeconds);
s = Seconds.ToString();
break;
default:
throw new Exception("Unknown macro.");
}
if (Reverse || Digit.HasValue || !string.IsNullOrEmpty(Delimiter))
{
if (string.IsNullOrEmpty(Delimiter))
{
Delimiter = ".";
}
string[] Parts = s.Split(new string[] { Delimiter }, StringSplitOptions.None);
int i = Parts.Length;
if (Reverse)
{
Array.Reverse(Parts);
}
if (Digit.HasValue && Digit.Value < i)
{
i = Digit.Value;
}
bool First = true;
int j = Parts.Length - i;
while (i-- > 0)
{
if (First)
{
First = false;
}
else
{
sb.Append('.');
}
sb.Append(Parts[j++]);
}
}
else
{
sb.Append(s);
}
break;
default:
this.term.pos++;
sb.Append('%');
sb.Append(ch);
break;
}
}
else
{
sb.Append(ch);
}
}
this.domain = sb.ToString();
}