MailBnfHelper.cs

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using System.Text;
 
namespace System.Net.Mime;
 
internal static class MailBnfHelper
{
    internal static readonly bool[] Atext = CreateCharactersAllowedInAtoms();
 
    internal static readonly bool[] Qtext = CreateCharactersAllowedInQuotedStrings();
 
    internal static readonly bool[] Dtext = CreateCharactersAllowedInDomainLiterals();
 
    internal static readonly bool[] Ftext = CreateCharactersAllowedInHeaderNames();
 
    internal static readonly bool[] Ttext = CreateCharactersAllowedInTokens();
 
    internal static readonly bool[] Ctext = CreateCharactersAllowedInComments();
 
    private static readonly string[] s_months = new string[13]
    {
        null, "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep",
        "Oct", "Nov", "Dec"
    };
 
    private static bool[] CreateCharactersAllowedInAtoms()
    {
        bool[] array = new bool[128];
        for (int i = 48; i <= 57; i++)
        {
            array[i] = true;
        }
        for (int j = 65; j <= 90; j++)
        {
            array[j] = true;
        }
        for (int k = 97; k <= 122; k++)
        {
            array[k] = true;
        }
        array[33] = true;
        array[35] = true;
        array[36] = true;
        array[37] = true;
        array[38] = true;
        array[39] = true;
        array[42] = true;
        array[43] = true;
        array[45] = true;
        array[47] = true;
        array[61] = true;
        array[63] = true;
        array[94] = true;
        array[95] = true;
        array[96] = true;
        array[123] = true;
        array[124] = true;
        array[125] = true;
        array[126] = true;
        return array;
    }
 
    private static bool[] CreateCharactersAllowedInQuotedStrings()
    {
        bool[] array = new bool[128];
        for (int i = 1; i <= 9; i++)
        {
            array[i] = true;
        }
        array[11] = true;
        array[12] = true;
        for (int j = 14; j <= 33; j++)
        {
            array[j] = true;
        }
        for (int k = 35; k <= 91; k++)
        {
            array[k] = true;
        }
        for (int l = 93; l <= 127; l++)
        {
            array[l] = true;
        }
        return array;
    }
 
    private static bool[] CreateCharactersAllowedInDomainLiterals()
    {
        bool[] array = new bool[128];
        for (int i = 1; i <= 8; i++)
        {
            array[i] = true;
        }
        array[11] = true;
        array[12] = true;
        for (int j = 14; j <= 31; j++)
        {
            array[j] = true;
        }
        for (int k = 33; k <= 90; k++)
        {
            array[k] = true;
        }
        for (int l = 94; l <= 127; l++)
        {
            array[l] = true;
        }
        return array;
    }
 
    private static bool[] CreateCharactersAllowedInHeaderNames()
    {
        bool[] array = new bool[128];
        for (int i = 33; i <= 57; i++)
        {
            array[i] = true;
        }
        for (int j = 59; j <= 126; j++)
        {
            array[j] = true;
        }
        return array;
    }
 
    private static bool[] CreateCharactersAllowedInTokens()
    {
        bool[] array = new bool[128];
        for (int i = 33; i <= 126; i++)
        {
            array[i] = true;
        }
        array[40] = false;
        array[41] = false;
        array[60] = false;
        array[62] = false;
        array[64] = false;
        array[44] = false;
        array[59] = false;
        array[58] = false;
        array[92] = false;
        array[34] = false;
        array[47] = false;
        array[91] = false;
        array[93] = false;
        array[63] = false;
        array[61] = false;
        return array;
    }
 
    private static bool[] CreateCharactersAllowedInComments()
    {
        bool[] array = new bool[128];
        for (int i = 1; i <= 8; i++)
        {
            array[i] = true;
        }
        array[11] = true;
        array[12] = true;
        for (int j = 14; j <= 31; j++)
        {
            array[j] = true;
        }
        for (int k = 33; k <= 39; k++)
        {
            array[k] = true;
        }
        for (int l = 42; l <= 91; l++)
        {
            array[l] = true;
        }
        for (int m = 93; m <= 127; m++)
        {
            array[m] = true;
        }
        return array;
    }
 
    internal static bool SkipCFWS(string data, ref int offset)
    {
        int num = 0;
        while (offset < data.Length)
        {
            if (data[offset] > '\u007f')
            {
                throw new FormatException(System.SR.Format(System.SR.MailHeaderFieldInvalidCharacter, data[offset]));
            }
            if (data[offset] == '\\' && num > 0)
            {
                offset += 2;
            }
            else if (data[offset] == '(')
            {
                num++;
            }
            else if (data[offset] == ')')
            {
                num--;
            }
            else if (data[offset] != ' ' && data[offset] != '\t' && num == 0)
            {
                return true;
            }
            if (num < 0)
            {
                throw new FormatException(System.SR.Format(System.SR.MailHeaderFieldInvalidCharacter, data[offset]));
            }
            offset++;
        }
        return false;
    }
 
    internal static void ValidateHeaderName(string data)
    {
        int i;
        for (i = 0; i < data.Length; i++)
        {
            if (data[i] > Ftext.Length || !Ftext[(uint)data[i]])
            {
                throw new FormatException(System.SR.InvalidHeaderName);
            }
        }
        if (i == 0)
        {
            throw new FormatException(System.SR.InvalidHeaderName);
        }
    }
 
    internal static string ReadQuotedString(string data, ref int offset, StringBuilder builder)
    {
        return ReadQuotedString(data, ref offset, builder, doesntRequireQuotes: false, permitUnicodeInDisplayName: false);
    }
 
    internal static string ReadQuotedString(string data, ref int offset, StringBuilder builder, bool doesntRequireQuotes, bool permitUnicodeInDisplayName)
    {
        if (!doesntRequireQuotes)
        {
            offset++;
        }
        int num = offset;
        StringBuilder stringBuilder = ((builder != null) ? builder : new StringBuilder());
        while (offset < data.Length)
        {
            if (data[offset] == '\\')
            {
                stringBuilder.Append(data, num, offset - num);
                num = ++offset;
            }
            else
            {
                if (data[offset] == '"')
                {
                    stringBuilder.Append(data, num, offset - num);
                    offset++;
                    if (builder == null)
                    {
                        return stringBuilder.ToString();
                    }
                    return null;
                }
                if (data[offset] == '=' && data.Length > offset + 3 && data[offset + 1] == '\r' && data[offset + 2] == '\n' && (data[offset + 3] == ' ' || data[offset + 3] == '\t'))
                {
                    offset += 3;
                }
                else if (permitUnicodeInDisplayName)
                {
                    if (data[offset] <= '\u007f' && !Qtext[(uint)data[offset]])
                    {
                        throw new FormatException(System.SR.Format(System.SR.MailHeaderFieldInvalidCharacter, data[offset]));
                    }
                }
                else if (data[offset] > '\u007f' || !Qtext[(uint)data[offset]])
                {
                    throw new FormatException(System.SR.Format(System.SR.MailHeaderFieldInvalidCharacter, data[offset]));
                }
            }
            offset++;
        }
        if (doesntRequireQuotes)
        {
            stringBuilder.Append(data, num, offset - num);
            if (builder == null)
            {
                return stringBuilder.ToString();
            }
            return null;
        }
        throw new FormatException(System.SR.MailHeaderFieldMalformedHeader);
    }
 
    internal static string ReadParameterAttribute(string data, ref int offset, StringBuilder builder)
    {
        if (!SkipCFWS(data, ref offset))
        {
            return null;
        }
        return ReadToken(data, ref offset, null);
    }
 
    internal static string ReadToken(string data, ref int offset, StringBuilder builder)
    {
        int num = offset;
        while (offset < data.Length)
        {
            if (data[offset] > '\u007f')
            {
                throw new FormatException(System.SR.Format(System.SR.MailHeaderFieldInvalidCharacter, data[offset]));
            }
            if (!Ttext[(uint)data[offset]])
            {
                break;
            }
            offset++;
        }
        if (num == offset && offset < data.Length)
        {
            throw new FormatException(System.SR.Format(System.SR.MailHeaderFieldInvalidCharacter, data[offset]));
        }
        return data.Substring(num, offset - num);
    }
 
    internal static string GetDateTimeString(DateTime value, StringBuilder builder)
    {
        StringBuilder stringBuilder = ((builder != null) ? builder : new StringBuilder());
        stringBuilder.Append(value.Day);
        stringBuilder.Append(' ');
        stringBuilder.Append(s_months[value.Month]);
        stringBuilder.Append(' ');
        stringBuilder.Append(value.Year);
        stringBuilder.Append(' ');
        if (value.Hour <= 9)
        {
            stringBuilder.Append('0');
        }
        stringBuilder.Append(value.Hour);
        stringBuilder.Append(':');
        if (value.Minute <= 9)
        {
            stringBuilder.Append('0');
        }
        stringBuilder.Append(value.Minute);
        stringBuilder.Append(':');
        if (value.Second <= 9)
        {
            stringBuilder.Append('0');
        }
        stringBuilder.Append(value.Second);
        string text = TimeZoneInfo.Local.GetUtcOffset(value).ToString();
        if (text[0] != '-')
        {
            stringBuilder.Append(" +");
        }
        else
        {
            stringBuilder.Append(' ');
        }
        string[] array = text.Split(':');
        stringBuilder.Append(array[0]);
        stringBuilder.Append(array[1]);
        if (builder == null)
        {
            return stringBuilder.ToString();
        }
        return null;
    }
 
    internal static void GetTokenOrQuotedString(string data, StringBuilder builder, bool allowUnicode)
    {
        int i = 0;
        int num = 0;
        for (; i < data.Length; i++)
        {
            if (CheckForUnicode(data[i], allowUnicode) || (Ttext[(uint)data[i]] && data[i] != ' '))
            {
                continue;
            }
            builder.Append('"');
            for (; i < data.Length; i++)
            {
                if (!CheckForUnicode(data[i], allowUnicode))
                {
                    if (IsFWSAt(data, i))
                    {
                        i += 2;
                    }
                    else if (!Qtext[(uint)data[i]])
                    {
                        builder.Append(data, num, i - num);
                        builder.Append('\\');
                        num = i;
                    }
                }
            }
            builder.Append(data, num, i - num);
            builder.Append('"');
            return;
        }
        if (data.Length == 0)
        {
            builder.Append("\"\"");
        }
        builder.Append(data);
    }
 
    private static bool CheckForUnicode(char ch, bool allowUnicode)
    {
        if (ch < '\u007f')
        {
            return false;
        }
        if (!allowUnicode)
        {
            throw new FormatException(System.SR.Format(System.SR.MailHeaderFieldInvalidCharacter, ch));
        }
        return true;
    }
 
    internal static bool IsAllowedWhiteSpace(char c)
    {
        if (c != '\t' && c != ' ' && c != '\r')
        {
            return c == '\n';
        }
        return true;
    }
 
    internal static bool HasCROrLF(string data)
    {
        for (int i = 0; i < data.Length; i++)
        {
            if (data[i] == '\r' || data[i] == '\n')
            {
                return true;
            }
        }
        return false;
    }
 
    internal static bool IsFWSAt(string data, int index)
    {
        if (data[index] == '\r' && index + 2 < data.Length && data[index + 1] == '\n')
        {
            if (data[index + 2] != ' ')
            {
                return data[index + 2] == '\t';
            }
            return true;
        }
        return false;
    }
}