Generate Unique Namespace (in DNS Name Format)

originally posted 2014-08-06

1	originally posted 2014-08-06

Generates a unique namespace that conforms to DNS name format from the input.

Releated: Validate Format of a Domain Name post

Input formats:

If email address, the host part is used.

If URI, the primary domain name is used.

If neither of the above formats then uses the input as is.

Looks in the [Subscription] table of the specified database table for the [Namespace] column to determine uniqueness.

//LinqPad Query, Language = "C# Program"
void Main()
{
  string value = "justin@elementalp.com";
  GenerateNamespace(value).Dump(value + " becomes...");
  
  value = "The ABC Company!";
  GenerateNamespace(value).Dump(value + " becomes...");
  
  value = "Foo";
  GenerateNamespace(value).Dump(value + " becomes...");	
}

/// &amp;lt;summary&amp;gt;
/// Uses an input value as the basis for generating a unique namespace
/// If the formatted input name is already in use, a number will be appended to it until a unique namespace results.
/// Input value defaults to "ORG"
/// Output is made to confirm to DNS name requirements.
/// Examines the SQL object "[npt_cloud].[dbo].[Subscription].[Namespace]" to check for uniqueness.
/// &amp;lt;/summary&amp;gt;
public string GenerateNamespace(string value)
{

  //string value = "https://this.that.these.those.elementalp.com";
  //string value = "----= The-ElementalP-Company =----";
  string result = null;
  
  const string sql =
  @"declare @pattern nvarchar(100) = '%[^0-9A-Za-z\-]%' --filter chars that are not alpha, numerics, or dashes
  declare @defaultName nvarchar(100) = 'ORG'; --the default namespace name
  declare @try nvarchar(100) = null

  	if(@ns is null or len(@ns)=0) goto thenext;

  --remove characters not in the pattern
  while patindex(@pattern, @ns) &amp;gt; 0 set @ns = stuff(@ns, patindex(@pattern, @ns), 1, '');
  set @ns = ltrim(rtrim(@ns));
  if(@ns is null or len(@ns)=0) goto thenext;
  
  --remove leading dashes
  while (patindex('-%', @ns) = 1) set @ns = substring(@ns,2,len(@ns));
  
  --remove trailing dashes
  while (patindex('%-', @ns) = len(@ns)) set @ns = substring(@ns,1,len(@ns)-1);
  
  --shorten to 63 chars, make upper case, and trim                   
  set @ns = ltrim(rtrim(upper(substring(@ns,1,63))));
    
  thenext:
  
  --default empty namespace
  if(@ns is null or len(@ns)=0) set @ns = @defaultName  --goto theend;
    
  set @try = @ns
  
  declare @num int = 0;
  while (1=1)
  begin
    if exists (select [Namespace] from [dbo].[Subscription] where [Namespace] like @try)
    begin
      set @num = @num + 1;
      set @try = @ns + convert(nvarchar(10),@num)
    end
  else break;
  
  end
  theend:
  select [Namespace] = @try;";

  System.Diagnostics.Debug.WriteLine(string.Format("Input: {0}",  value!=null ? string.Format("\"{0}\"",value) : "null"));
    
  //parse host name from namespace
  if(!string.IsNullOrWhiteSpace(value))value = ParseNamespace(value);
  
  if(value==null) value = string.Empty;

  using (var connection = new SqlConnection("Data Source=.;Initial Catalog=npt_cloud;Application Name=npt;Integrated Security=true;"))
  {
    connection.Open();
    using (var command = new SqlCommand(sql, connection))
    {
      var param = new SqlParameter("@ns", System.Data.SqlDbType.NVarChar);
      param.Value = value;
      command.Parameters.Add(param);
    
      result = command.ExecuteScalar() as string;
      connection.Close();
      return result;
    }
  }
}

/// &amp;lt;summary&amp;gt;
/// Parses a namespace from input value.
/// If the input value is an email address, the output will be the host name.
/// If the input value is a URL, the output is the primary domain name.
/// If the input value is not one of the above formats, the input text before the first period (if any) is returned.
/// &amp;lt;/summary&amp;gt;
public static string ParseNamespace(string text)
{
  string ns = null;
  try
  {
      //try get domain as email address
      var addr = new MailAddress(text);
      ns = addr.Host;
  }
  catch (System.FormatException ex1)
  {
      try
      {
          //try get domain as uri
          var uri = new Uri(text);
          string[] hostParts = uri.Host.Split(new string[1] { "." }, StringSplitOptions.RemoveEmptyEntries);
          ns = hostParts[hostParts.Length-2];
      }
      catch (System.UriFormatException ex2)
      {
          //use id as the domain
          ns = text;
      }
  }

  if (ns != null) ns = ns.Split(new char[] { '.' }, 2)[0];
  
  return ns;
}

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//LinqPad Query, Language = "C# Program"

void Main()

{

string value = "justin@elementalp.com";

GenerateNamespace(value).Dump(value + " becomes...");

value = "The ABC Company!";

GenerateNamespace(value).Dump(value + " becomes...");

value = "Foo";

GenerateNamespace(value).Dump(value + " becomes...");

}

/// &lt;summary&gt;

/// Uses an input value as the basis for generating a unique namespace

/// If the formatted input name is already in use, a number will be appended to it until a unique namespace results.

/// Input value defaults to "ORG"

/// Output is made to confirm to DNS name requirements.

/// Examines the SQL object "[npt_cloud].[dbo].[Subscription].[Namespace]" to check for uniqueness.

/// &lt;/summary&gt;

public string GenerateNamespace(string value)

{

//string value = "https://this.that.these.those.elementalp.com";

//string value = "----= The-ElementalP-Company =----";

string result = null;

const string sql =

@"declare @pattern nvarchar(100) = '%[^0-9A-Za-z\-]%' --filter chars that are not alpha, numerics, or dashes

declare @defaultName nvarchar(100) = 'ORG'; --the default namespace name

declare @try nvarchar(100) = null

if(@ns is null or len(@ns)=0) goto thenext;

--remove characters not in the pattern

while patindex(@pattern, @ns) &gt; 0 set @ns = stuff(@ns, patindex(@pattern, @ns), 1, '');

set @ns = ltrim(rtrim(@ns));

if(@ns is null or len(@ns)=0) goto thenext;

--remove leading dashes

while (patindex('-%', @ns) = 1) set @ns = substring(@ns,2,len(@ns));

--remove trailing dashes

while (patindex('%-', @ns) = len(@ns)) set @ns = substring(@ns,1,len(@ns)-1);

--shorten to 63 chars, make upper case, and trim

set @ns = ltrim(rtrim(upper(substring(@ns,1,63))));

thenext:

--default empty namespace

if(@ns is null or len(@ns)=0) set @ns = @defaultName --goto theend;

set @try = @ns

declare @num int = 0;

while (1=1)

begin

if exists (select [Namespace] from [dbo].[Subscription] where [Namespace] like @try)

begin

set @num = @num + 1;

set @try = @ns + convert(nvarchar(10),@num)

end

else break;

end

theend:

select [Namespace] = @try;";

System.Diagnostics.Debug.WriteLine(string.Format("Input: {0}", value!=null ? string.Format("\"{0}\"",value) : "null"));

//parse host name from namespace

if(!string.IsNullOrWhiteSpace(value))value = ParseNamespace(value);

if(value==null) value = string.Empty;

using (var connection = new SqlConnection("Data Source=.;Initial Catalog=npt_cloud;Application Name=npt;Integrated Security=true;"))

{

connection.Open();

using (var command = new SqlCommand(sql, connection))

{

var param = new SqlParameter("@ns", System.Data.SqlDbType.NVarChar);

param.Value = value;

command.Parameters.Add(param);

result = command.ExecuteScalar() as string;

connection.Close();

return result;

}

/// &lt;summary&gt;

/// Parses a namespace from input value.

/// If the input value is an email address, the output will be the host name.

/// If the input value is a URL, the output is the primary domain name.

/// If the input value is not one of the above formats, the input text before the first period (if any) is returned.

/// &lt;/summary&gt;

public static string ParseNamespace(string text)

{

string ns = null;

try

{

//try get domain as email address

var addr = new MailAddress(text);

ns = addr.Host;

}

catch (System.FormatException ex1)

{

try

{

//try get domain as uri

var uri = new Uri(text);

string[] hostParts = uri.Host.Split(new string[1] { "." }, StringSplitOptions.RemoveEmptyEntries);

ns = hostParts[hostParts.Length-2];

}

catch (System.UriFormatException ex2)

{

//use id as the domain

ns = text;

}

if (ns != null) ns = ns.Split(new char[] { '.' }, 2)[0];

return ns;

}