_UncName.cs source code in C# .NET

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Code:

                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Net / System / _UncName.cs / 1 / _UncName.cs
                        

                        
                            #if !PLATFORM_UNIX 
//------------------------------------------------------------------------------
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
//  
//-----------------------------------------------------------------------------
using System.Globalization; 
 
namespace System {
 
    // The class designed as to keep minimal the working set of Uri class.
    // The idea is to stay with static helper methods and strings
    internal class UncNameHelper {
 
    // fields
 
        internal const int MaximumInternetNameLength = 256; 

        private UncNameHelper() { 
        }


    // properties 

    // methods 
        internal static string ParseCanonicalName(string str, int start, int end, ref bool loopback) { 
            return DomainNameHelper.ParseCanonicalName(str, start, end, ref loopback);
        } 

        //
        // IsValid
        // 
        //
        //   ATTN: This class has been re-designed as to conform to XP+ UNC hostname format 
        //         It is now similar to DNS name but can contain Unicode characters as well 
        //         This class will be removed and replaced by IDN specification later,
        //         but for now we violate URI RFC cause we never escape Unicode characters on the wire 
        //         For the same reason we never unescape UNC host names since we never accept
        //         them in escaped format.
        //
        // 
        //      Valid UNC server name chars:
        //          a Unicode Letter    (not allowed as the only in a segment) 
        //          a Latin-1 digit 
        //          '-'    45 0x2D
        //          '.'    46 0x2E    (only as a host domain delimiter) 
        //          '_'    95 0x5F
        //
        //
        // Assumption is the caller will check on the resulting name length 
        // Remarks:  MUST NOT be used unless all input indexes are are verified and trusted.
        internal unsafe static bool IsValid(char* name, ushort start, ref int returnedEnd, bool notImplicitFile) { 
            ushort end = (ushort) returnedEnd; 

            if (start==end) 
                return false;
            //
            // First segment could consist of only '_' or '-' but it cannot be all digits or empty
            // 
            bool validShortName = false;
            ushort i = start; 
            for (; i < end; ++i) 
            {
                if (name[i] == '/' || name[i] == '\\' || (notImplicitFile && (name[i] == ':' || name[i] == '?' || name[i] == '#'))) 
                {
                    end = i;
                    break;
                } 
                else if (name[i] == '.')
                { 
                    ++i; 
                    break;
                } 
                if (Char.IsLetter(name[i]) || name[i] == '-' || name[i] == '_')
                {
                    validShortName = true;
                } 
                else if (name[i] < '0' || name[i] > '9')
                    return false; 
            } 

            if (!validShortName) 
                return false;

            //
            // Subsequent segments must start with a letter or a digit 
            //
 
            for (; i < end; ++i) 
            {
                if (name[i] == '/' || name[i] == '\\' || (notImplicitFile && (name[i] == ':' || name[i] == '?' || name[i] == '#'))) 
                {
                    end = i;
                    break;
                } 
                else if (name[i] == '.')
                { 
                    if (!validShortName || ((i-1) >= start && name[i-1] == '.')) 
                        return false;
 
                    validShortName = false;
                }
                else if (name[i] == '-' || name[i] == '_')
                { 
                    if (!validShortName)
                        return false; 
                } 
                else if (Char.IsLetter(name[i]) || (name[i] >= '0' && name[i] <= '9'))
                { 
                    if (!validShortName)
                        validShortName = true;
                }
                else 
                    return false;
            } 
 
            // last segment can end with the dot
            if (((i-1) >= start && name[i-1] == '.')) 
                validShortName = true;

            if (!validShortName)
                return false; 

            //  caller must check for (end - start <= MaximumInternetNameLength) 
 
            returnedEnd = end;
            return true; 
        }
    }
}
#endif // !PLATFORM_UNIX

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