docker setup

util/Setup/Helpers.cs

@@ -0,0 +1,91 @@
+using System;
+using System.Security.Cryptography;
+using System.Text;
+
+namespace Setup
+{
+    public static class Helpers
+    {
+        public static string SecureRandomString(int length, bool alpha = true, bool upper = true, bool lower = true,
+            bool numeric = true, bool special = false)
+        {
+            return SecureRandomString(length, RandomStringCharacters(alpha, upper, lower, numeric, special));
+        }
+
+        // ref https://stackoverflow.com/a/8996788/1090359 with modifications
+        public static string SecureRandomString(int length, string characters)
+        {
+            if(length < 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(length), "length cannot be less than zero.");
+            }
+
+            if((characters?.Length ?? 0) == 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(characters), "characters invalid.");
+            }
+
+            const int byteSize = 0x100;
+            if(byteSize < characters.Length)
+            {
+                throw new ArgumentException(
+                    string.Format("{0} may contain no more than {1} characters.", nameof(characters), byteSize),
+                    nameof(characters));
+            }
+
+            var outOfRangeStart = byteSize - (byteSize % characters.Length);
+            using(var rng = RandomNumberGenerator.Create())
+            {
+                var sb = new StringBuilder();
+                var buffer = new byte[128];
+                while(sb.Length < length)
+                {
+                    rng.GetBytes(buffer);
+                    for(var i = 0; i < buffer.Length && sb.Length < length; ++i)
+                    {
+                        // Divide the byte into charSet-sized groups. If the random value falls into the last group and the
+                        // last group is too small to choose from the entire allowedCharSet, ignore the value in order to
+                        // avoid biasing the result.
+                        if(outOfRangeStart <= buffer[i])
+                        {
+                            continue;
+                        }
+
+                        sb.Append(characters[buffer[i] % characters.Length]);
+                    }
+                }
+
+                return sb.ToString();
+            }
+        }
+
+        private static string RandomStringCharacters(bool alpha, bool upper, bool lower, bool numeric, bool special)
+        {
+            var characters = string.Empty;
+            if(alpha)
+            {
+                if(upper)
+                {
+                    characters += "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+                }
+
+                if(lower)
+                {
+                    characters += "abcdefghijklmnopqrstuvwxyz";
+                }
+            }
+
+            if(numeric)
+            {
+                characters += "0123456789";
+            }
+
+            if(special)
+            {
+                characters += "!@#$%^*&";
+            }
+
+            return characters;
+        }
+    }
+}