DomainLiteralReader.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Net / System / Net / Mail / DomainLiteralReader.cs / 1305376 / DomainLiteralReader.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Net.Mail{ 
 
    using System.Net.Mime;
    using System.Diagnostics; 
    using System.Text;

    //
    // RFC 2822 Section 3.4.1 - Addr-Spec, Domain-Literals 
    // A domain literal is a domain identifier that does not conform to the dot-atom format (Section 3.2.4) and must be
    // enclosed in brackets '[' ']'.  Domain literals may contain quoted-pairs. 
    // 
    internal static class DomainLiteralReader
    { 
        //
        // Reads a domain literal in reverse
        //
        // Preconditions: 
        //  - Index must be within the bounds of the data string.
        //  - The char at the given index is the initial bracket. (data[index] == EndSquareBracket) 
        // 
        // Return value:
        // - The next index past the terminating bracket (data[index + 1] == StartSquareBracket). 
        //   e.g. In (user@[domain]), starting at index=12 (]) returns index=4 (@).
        //
        // A FormatException will be thrown if:
        // - A non-escaped character is encountered that is not valid in a domain literal, including Unicode. 
        // - The final bracket is not found.
        // 
        internal static int ReadReverse(string data, int index) 
        {
            Debug.Assert(0 <= index && index < data.Length, "index was outside the bounds of the string: " + index); 
            Debug.Assert(data[index] == MailBnfHelper.EndSquareBracket, "data did not end with a square bracket");

            // Skip the end bracket
            index--; 

            do 
            { 
                // Check for valid whitespace
                index = WhitespaceReader.ReadFwsReverse(data, index); 
                if (index < 0)
                {
                    break;
                } 
                // Check for escaped characters
                int quotedCharCount = QuotedPairReader.CountQuotedChars(data, index, false); 
                if (quotedCharCount > 0) 
                {
                    // Skip quoted pairs 
                    index = index - quotedCharCount;
                }
                // Check for the terminating bracket
                else if (data[index] == MailBnfHelper.StartSquareBracket) 
                {
                    // We're done parsing 
                    return index - 1; 
                }
                // Check for invalid characters 
                else if (data[index] > MailBnfHelper.Ascii7bitMaxValue || !MailBnfHelper.Dtext[data[index]])
                {
                    throw new FormatException(SR.GetString(SR.MailHeaderFieldInvalidCharacter, data[index]));
                } 
                // Valid char
                else 
                { 
                    index--;
                } 
            }
            while (index >= 0);

            // We didn't find a matching '[', throw. 
            throw new FormatException(SR.GetString(SR.MailHeaderFieldInvalidCharacter,
                MailBnfHelper.EndSquareBracket)); 
        } 
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.

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