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Refactor C# sample / fix generation fail on some url supplied with queries parameters (#515)

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Co-authored-by: REY Nicolas <nicolas.rey@interflora.fr>
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Nicolas REY 2020-12-02 09:19:17 +01:00 committed by GitHub
parent dd6bac73cc
commit fe333f6487
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 31 additions and 23 deletions
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54
examples/signature.cs
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@ -1,6 +1,6 @@
using System; using System;
using System.Collections.Generic; using System.Collections.Generic;
using System.Linq; using System.IO;
using System.Security.Cryptography; using System.Security.Cryptography;
using System.Text; using System.Text;
@ -21,40 +21,48 @@ namespace ImgProxy.Examples
const int Enlarge = 1; const int Enlarge = 1;
const string Extension = "png"; const string Extension = "png";
var url = GenerateUrl(Key, Salt, Url, Resize, Width, Height, Gravity, Enlarge, Extension); var url = SignerHelper.GenerateUrl(Key, Salt, Url, Resize, Width, Height, Gravity, Enlarge, Extension);
Console.WriteLine(url); Console.WriteLine(url);
} }
}
static string GenerateUrl(string key, string salt, string url, string resize, int width, int height, string gravity, int enlarge, string extension) public static class SignerHelper
{
public static string GenerateUrl(string key, string salt, string url, string resize, int width, int height, string gravity, int enlarge, string extension)
{ {
var keybin = StringToByteArray(key); var keybin = HexadecimalStringToByteArray(key);
var saltBin = StringToByteArray(salt); var saltBin = HexadecimalStringToByteArray(salt);
var encodedUrl = string.Join("/", WholeChunks(Convert.ToBase64String(Encoding.UTF8.GetBytes(url)).TrimEnd('='), 16));
var encodedUrl = EncodeBase64URLSafeString(url);
var path = $"/{resize}/{width}/{height}/{gravity}/{enlarge}/{encodedUrl}.{extension}"; var path = $"/{resize}/{width}/{height}/{gravity}/{enlarge}/{encodedUrl}.{extension}";
using (var hmac = new HMACSHA256(keybin)) var passwordWithSaltBytes = new List<byte>();
passwordWithSaltBytes.AddRange(saltBin);
passwordWithSaltBytes.AddRange(Encoding.UTF8.GetBytes(path));
using var hmac = new HMACSHA256(keybin);
byte[] digestBytes = hmac.ComputeHash(passwordWithSaltBytes.ToArray());
var urlSafeBase64 = EncodeBase64URLSafeString(digestBytes);
return $"/{urlSafeBase64}{path}";
}
static byte[] HexadecimalStringToByteArray(string input)
{
var outputLength = input.Length / 2;
var output = new byte[outputLength];
using (var sr = new StringReader(input))
{ {
var hash = hmac.ComputeHash(saltBin.Concat(Encoding.UTF8.GetBytes(path)).ToArray()); for (var i = 0; i < outputLength; i++)
var urlSafeBase64 = Convert.ToBase64String(hash).TrimEnd('=').Replace('+', '-').Replace('/', '_'); output[i] = Convert.ToByte(new string(new char[2] { (char)sr.Read(), (char)sr.Read() }), 16);
return $"/{urlSafeBase64}{path}";
} }
return output;
} }
static byte[] StringToByteArray(string hex) static string EncodeBase64URLSafeString(this byte[] stream)
{ => Convert.ToBase64String(stream).TrimEnd('=').Replace('+', '-').Replace('/', '_');
return Enumerable.Range(0, hex.Length)
.Where(x => x % 2 == 0)
.Select(x => Convert.ToByte(hex.Substring(x, 2), 16))
.ToArray();
}
static IEnumerable<string> WholeChunks(string str, int maxChunkSize) static string EncodeBase64URLSafeString(this string str)
{ => EncodeBase64URLSafeString(Encoding.ASCII.GetBytes(str));
for (int i = 0; i < str.Length; i += maxChunkSize)
yield return str.Substring(i, Math.Min(maxChunkSize, str.Length - i));
}
} }
} }