// TODO: maintain a list of token types provided by parser so that scanner can remain unbiased
// TODO: maintain a list of special token types
public Token GetToken()
{
SkipWhitespace();
if (currType == CharType.Alpha)
{
WordToken token = WordToken.GetToken(this);
// TODO: check for reserved words
return(token);
}
else if (currType == CharType.Numeric)
{
return(NumberToken.GetToken(this));
}
else if (currType == CharType.Quote)
{
return(StringToken.GetToken(this));
}
else if (currType == CharType.EOF)
{
return(new EndOfFileToken());
}
else if (currType == CharType.Special)
{
SpecialToken token = SpecialToken.GetToken(this);
// TODO: check for special token types
return(token);
}
return(null);
}
public static NumberToken GetToken(Scanner scanner)
{
NumberToken t = new NumberToken();
t.stringBuilder = new StringBuilder();
t.sc = scanner.col;
t.sr = scanner.row;
t.AccumulateValue(scanner, ref t._value);
t.wholePlaces = t.digitCount;
if (scanner.curr == '.')
{
t.stringBuilder.Append(scanner.curr);
scanner.Next();
t.real = true;
t.AccumulateValue(scanner, ref t._value);
t.decimalPlaces = t.digitCount - t.wholePlaces;
}
if (scanner.curr == 'e' || scanner.curr == 'E')
{
t.real = true;
t.stringBuilder.Append(scanner.curr);
scanner.Next();
if (scanner.curr == '+' || scanner.curr == '-')
{
t.exponentSign = scanner.curr;
t.stringBuilder.Append(scanner.curr);
scanner.Next();
}
t.digitCount = 0;
t.AccumulateValue(scanner, ref t.eValue);
if (t.exponentSign == '-')
{
t.eValue = -t.eValue;
}
}
t.ec = scanner.col;
t.er = scanner.row;
var exponent = t.eValue - t.decimalPlaces;
if (exponent != 0)
{
t.Value *= Math.Pow(10, exponent);
}
t.String = t.stringBuilder.ToString();
return(t);
}
public static NumberToken GetToken(Scanner scanner)
{
NumberToken t = new NumberToken();
t.stringBuilder = new StringBuilder();
t.sc = scanner.col;
t.sr = scanner.row;
t.AccumulateValue(scanner, ref t._value);
t.wholePlaces = t.digitCount;
// no dealing with real values, just integers
// if (scanner.curr == '.')
// {
// t.stringBuilder.Append(scanner.curr);
// scanner.Next();
// t.real = true;
// t.AccumulateValue(scanner, ref t._value);
// t.decimalPlaces = t.digitCount - t.wholePlaces;
// }
// if (scanner.curr == 'e' || scanner.curr == 'E')
// {
// t.real = true;
// t.stringBuilder.Append(scanner.curr);
// scanner.Next();
// if (scanner.curr == '+' || scanner.curr == '-')
// {
// t.exponentSign = scanner.curr;
// t.stringBuilder.Append(scanner.curr);
// scanner.Next();
// }
// t.digitCount = 0;
// t.AccumulateValue(scanner, ref t.eValue);
// if (t.exponentSign == '-')
// {
// t.eValue = -t.eValue;
// }
// }
t.ec = scanner.col;
t.er = scanner.row;
// var exponent = t.eValue - t.decimalPlaces;
// if (exponent != 0)
// {
// t.Value *= Math.Pow(10, exponent);
// }
t.String = t.stringBuilder.ToString();
return(t);
}
public override void Parse(string filename)
{
FileStream fs = File.OpenRead(filename);
StreamReader sr = new StreamReader(fs);
scanner = new Scanner(sr);
// Getting the first token will skip whitespace, so I will have either a comment, a RR or a control block
GetToken();
do
{
if (token.Type == tokenControl)
{
// get the next token which should be a string containing
// ORIGIN, INCLUDE or TTL
GetToken();
if (token.Type == tokenOrigin)
{
origin = ParseOrigin();
owner = origin;
}
else if (token.Type == tokenTTL)
{
GetToken();
if (token.Type == TokenType.Numeric)
{
NumberToken nt = token as NumberToken;
ttl = (int)nt.Value;
}
GetToken();
}
else if (token.Type == tokenInclude)
{
GetToken();
// TODO: finish this
// will it be a filename, need to process dots and slashes??
// there could be a domain name - how to know?
// there could be a comment - how to know?
}
}
else
{
ParseResourceRecord();
}
}while (!(token.Type == TokenType.EndOfFile));
}
// TODO: maintain a list of token types provided by parser so that scanner can remain unbiased
// TODO: maintain a list of special token types
public Token GetToken(bool skipWhitespace = true)
{
if (skipWhitespace)
{
SkipWhitespace();
}
if (currType == CharType.Whitespace)
{
return(new Token()
{
Type = TokenType.Whitespace
});
}
else if (currType == CharType.Alpha)
{
WordToken token = WordToken.GetToken(this);
// TODO: check for reserved words
return(token);
}
else if (currType == CharType.Numeric)
{
// TODO: need a scanner options class that lets me specify things like
// skipping whitespace, treating numbers etc.
// because here an IP address will be treated as a decimal number
// 192.0[.2.1]
return(NumberToken.GetToken(this));
}
else if (currType == CharType.Quote)
{
return(StringToken.GetToken(this));
}
else if (currType == CharType.EOF)
{
return(new EndOfFileToken());
}
else if (currType == CharType.Special)
{
SpecialToken token = SpecialToken.GetToken(this);
// TODO: check for special token types
return(token);
}
return(null);
}
protected override void ParseFactor()
{
if (token.Type == TokenType.Identifier)
{
WordToken wt = token as WordToken;
var node = SearchAll(wt.Word);
if (node == null)
{
throw new InvalidOperationException("Unknown identifier");
}
else
{
runtimeStack.Push(node.Value);
}
GetToken();
}
else if (token.Type == tokenPi)
{
runtimeStack.Push(Math.PI);
GetToken();
}
else if (token.Type == TokenType.Numeric)
{
NumberToken nt = token as NumberToken;
runtimeStack.Push(nt.Value);
GetToken();
}
else if (token.Type == tokenOpenParentheses)
{
GetToken();
ParseExpression();
if (token.Type == tokenCloseParentheses)
{
GetToken();
}
else
{
throw new InvalidOperationException("No closing parentheses");
}
}
}
public Token Get()
{
int tokenCode = -1;
do
{
tokenCode = code[index++];
if (tokenCode == TokenType.LineMarker)
{
// TODO: replicate the global currentLineNumber from book
int lineNumber = code[index++];
}
}while (tokenCode == TokenType.LineMarker);
if (tokenCode == TokenType.Numeric)
{
var token = new NumberToken();
var node = GetSymbolTableNode();
token.Value = node.Value;
return(token);
}
if (tokenCode == TokenType.String)
{
var token = new StringToken();
var node = GetSymbolTableNode();
token.Value = node.Symbol;
return(token);
}
if (tokenCode == TokenType.Identifier)
{
var token = new WordToken();
var node = GetSymbolTableNode();
token.Word = node.Symbol;
return(token);
}
var defaultToken = new WordToken();
defaultToken.Word = "";
return(defaultToken);
}
protected void ParseResourceRecord()
{
bool haveType = false;
MasterFileEntry entry = new MasterFileEntry();
while (haveType == false && token.Type != TokenType.EndOfFile)
{
if (token.Type == TokenType.Numeric)
{
// most likely a <rr> beginning with TTL
// [<TTL>] [<class>] <type> <RDATA>
NumberToken nt = token as NumberToken;
entry.TTL = (int)nt.Value;
GetToken();
}
else if (token.IsInList(tokensQueryClass))
{
// most likely a <rr> beginning with class
// [<class>] [<TTL>] <type> <RDATA>
WordToken wt = token as WordToken;
entry.Class = wt.Word;
GetToken();
}
else if (token.IsInList(tokensQueryType))
{
haveType = true;
WordToken wt = token as WordToken;
entry.Type = wt.Word;
// prepare to parse the data
if (token.Type == tokenCanonicalName)
{
// name string - probably fqdn
GetToken();
entry.Data = ParseDomainName();
}
else if (token.Type == tokenHostInfo)
{
// CPU string
GetToken();
// OS string
GetToken();
GetToken();
}
else if (token.Type == tokenMailExchange)
{
GetToken();
NumberToken nt = token as NumberToken;
entry.Priority = (int)nt.Value;
GetToken();
entry.Data = ParseDomainName();
}
else if (token.Type == tokenNameServer)
{
GetToken();
entry.Data = ParseDomainName();
}
else if (token.Type == tokenPointer)
{
GetToken();
entry.Data = ParseDomainName();
}
else if (token.Type == tokenAuthority)
{
// name server
GetToken();
// TODO: if token is open parentheses then loop until close parentheses (and stop scanner from swallowing parentheses)
entry.NameServer = ParseDomainName();
// mailbox of responsible person
entry.Responsible = ParseDomainName();
// serial number
NumberToken nt = token as NumberToken;
entry.SerialNumber = (int)nt.Value;
// refresh interval
GetToken();
nt = token as NumberToken;
entry.RefreshInterval = (int)nt.Value;
// retry interval
GetToken();
nt = token as NumberToken;
entry.RetryInterval = (int)nt.Value;
// expiry timeout
GetToken();
nt = token as NumberToken;
entry.ExpiryTimeout = (int)nt.Value;
// minimum ttl
GetToken();
nt = token as NumberToken;
entry.MinimumTTL = (int)nt.Value;
GetToken();
}
else if (token.Type == tokenText)
{
GetToken();
// TODO: this is wrong and probably needs additional parsing
entry.Data = ((WordToken)token).Word;
GetToken();
}
else if (token.Type == tokenHostAddress)
{
GetToken();
entry.Data = ParseIPv4Address();
}
else if (token.Type == tokenHostIPv6Address)
{
GetToken();
entry.Data = ParseIPv6Address();
}
else if (token.Type == tokenWellKnownService)
{
// address
GetToken();
string address = ParseIPv4Address();
string protocol = ((WordToken)token).Word;
// TODO: open parentheses, loop until close
}
}
else
{
// most likely a <rr> beginning with <owner>
// <domain-name> [<class>] [<TTL>] <type> <RDATA>
entry.Owner = ParseDomainName();
if (entry.Owner != "@")
{
// set default owner in case we reach another record that doesn't have an owner
// see section 5.1
owner = entry.Owner;
}
}
}
if (entry.Owner == null)
{
entry.Owner = owner;
}
if (entry.Owner == "@")
{
entry.Owner = origin;
}
else if (entry.Owner.EndsWith(".") == false)
{
entry.Owner += "." + origin;
}
// add to the running list of entries found
Entries.Add(entry);
Console.WriteLine($"Parsed resource record: {entry.Owner}\t{entry.Type}\t{entry.Class}\t{entry.Data}");
}