Pkpass Generator for Wallet

PkpassGenerator3000.cs

using System;
using System.Configuration;
using System.IO;
using System.IO.Compression;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Security.Cryptography;
using System.Security.Cryptography.Pkcs;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.Azure.WebJobs.Host;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

namespace WalletPassGenerator
{
	public static class Generator
	{
		private const string ForegroundColor = "rgb(255,255,255)";
		private const string BackgroundColor = "rgb(35,37,51)";
		private const string LabelColor = "rgb(112,95,173)";
		private const string AppleOid = "1.2.840.113635.100.4.14";

		[FunctionName("GeneratePass")]
		public static async Task<HttpResponseMessage> Run([HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = "pass/{eventId}")]HttpRequestMessage req, string eventId, TraceWriter log, ExecutionContext executionContext)
		{
			try
			{
				var eventData = FetchEventData(eventId);
				var attendee = await req.Content.ReadAsAsync<Attendee>() ?? new Attendee {Email = "toto@toto.com", Name = "Toto Leheros"};
				var signatureData = CreateSignatureData(executionContext);

				var memoryStream = new MemoryStream();

				using (var pkpass = new ZipArchive(memoryStream, ZipArchiveMode.Create, true))
				{
					var passJson = pkpass.CreateEntry("pass.json");
					var passJsonHash = await CreatePassJsonAsync(passJson, signatureData, eventData, attendee);
					var manifest = new JObject(new JProperty("pass.json", passJsonHash));

					async Task AddImageAsync(string path)
					{
						var hash = await ConvertFileToEntryAsync(pkpass.CreateEntry(path), Path.Combine(executionContext.FunctionAppDirectory, "Assets", path));
						manifest.Add(new JProperty(path, hash));
					}

					await AddImageAsync("strip.png");
					await AddImageAsync("strip@2x.png");
					await AddImageAsync("icon.png");
					await AddImageAsync("icon@2x.png");
					await AddImageAsync("logo.png");
					await AddImageAsync("logo@2x.png");

					var manifestEntry = pkpass.CreateEntry("manifest.json");
					var dataToSign = await CreateManifestJsonAsync(manifestEntry, manifest);

					await CreateSignatureAsync(pkpass.CreateEntry("signature"), signatureData, dataToSign);
				}

				memoryStream.Position = 0;

				return new HttpResponseMessage(HttpStatusCode.OK)
				{
					Content = new StreamContent(memoryStream)
					{
						Headers =
						{
							ContentType = new MediaTypeHeaderValue("application/vnd.apple.pkpass"),
							ContentDisposition = new ContentDispositionHeaderValue("attachment") {FileName = $"pass-{eventId}.pkpass"}
						}
					}
				};
			}
			catch (Exception ex)
			{
				log.Error("An error occured", ex);
				throw;
			}
		}

		private static SignatureData CreateSignatureData(ExecutionContext executionContext)
		{
			var signingCertificate = new X509Certificate2(Path.Combine(executionContext.FunctionAppDirectory, ConfigurationManager.AppSettings["CertificatePath"]), ConfigurationManager.AppSettings["PrivateKeyPassword"]);
			var teamIdentifier = Regex.Match(signingCertificate.Subject, @"OU=(?<teamId>\w+),").Groups["teamId"].Value;
			return new SignatureData
			{
				SigningCertificate = signingCertificate,
				Authority = new X509Certificate2(Path.Combine(executionContext.FunctionAppDirectory, ConfigurationManager.AppSettings["CertificateAuthorityPath"])),
				TeamIdentifier = teamIdentifier,
				PassTypeIdentifier = ConfigurationManager.AppSettings["PassTypeIdentifier"]
			};
		}

		private static EventData FetchEventData(string eventId)
		{
			return new EventData
			{
				Id = "matinaleserverless052018",
				Organizer = "Cellenza",
				Type = "Matinale Cellenza",
				Link = "http://click.cellenza.com/inscription-matinale-31-mai-architectures-modernes",
				DateTime = new DateTimeOffset(2018, 05, 29, 09, 00, 00, TimeSpan.FromHours(2)),
				Title = "Matinale Serverless",
				SubTitle = "Serverless, microservices et containers",
				Speaker = "Marius Zaharia, Michel Hubert",
				Location = new EventLocation
				{
					Address = "City Chateauform, 2 Avenue Vélasquez, 75008 PARIS",
					Phone = "+33145631429",
					Email = "contact@cellenza.com"
				}
			};
		}

		private static async Task<string> CreatePassJsonAsync(ZipArchiveEntry archiveEntry, SignatureData signatureData, EventData eventData, Attendee attendee)
		{
			var serial = string.Join(":", eventData.Id, GetHashForBytes(Encoding.UTF8.GetBytes(attendee.Email.ToLowerInvariant())));
			var passTemplate = new
			{
				FormatVersion = 1,
				PassTypeIdentifier = signatureData.PassTypeIdentifier,
				SerialNumber = serial,
				TeamIdentifier = signatureData.TeamIdentifier,
				OrganizationName = eventData.Organizer,
				Description = eventData.Type,
				ForegroundColor = ForegroundColor,
				BackgroundColor = BackgroundColor,
				LabelColor = LabelColor,
				Barcode = new
				{
					Message = serial,
					Format = "PKBarcodeFormatQR",
					messageEncoding = "iso-8859-1"
				},
				EventTicket = new
				{
					HeaderFields = new object[]
					{
						new
						{
							Key = "date",
							Label = "Date",
							IsRelative = true,
							Value = eventData.DateTime.ToString("yyyy-MM-ddTHH:mm:sszzz"),
							DateStyle = "PKDateStyleShort",
							TimeStyle = "PKDateStyleShort",
						}
					},
					PrimaryFields = new object[]
					{
						new
						{
							Key = "title",
							Label = string.Empty,
							Value = eventData.Title
						}
					},
					SecondaryFields = new object[]
					{
						new
						{
							Key = "subtitle",
							Label = string.Empty,
							Value = eventData.SubTitle,
							TextAlignment = "PKTextAlignmentLeft"
						}
					},
					AuxiliaryFields = new object[]
					{
						new
						{
							Key = "speaker",
							Label = "PRESENTE PAR",
							Value = eventData.Speaker,
							TextAlignment = "PKTextAlignmentLeft"
						}
					},
					BackFields = new object[]
					{
						new
						{
							Key = "site",
							Label = "PLUS D'INFOS",
							Value = eventData.Link
						},
						new
						{
							Key = "address",
							Label = "ADRESSE",
							Value = eventData.Location.Address
						},
						new
						{
							Key = "phone",
							Label = "TELEPHONE",
							Value = eventData.Location.Phone
						},
						new
						{
							Key = "email",
							Label = "EMAIL",
							Value = eventData.Location.Email
						}
					}
				}
			};

			var serializer = JsonSerializer.CreateDefault(new JsonSerializerSettings { ContractResolver = new Newtonsoft.Json.Serialization.CamelCasePropertyNamesContractResolver(), Formatting = Formatting.Indented });

			using (var entryStream = archiveEntry.Open())
			using (var memoryStream = new MemoryStream())
			using (var writer = new StreamWriter(memoryStream) { AutoFlush = true })
			{
				serializer.Serialize(writer, passTemplate);
				memoryStream.Position = 0;
				var hash = GetHashForStream(memoryStream);
				memoryStream.Position = 0;
				await memoryStream.CopyToAsync(entryStream);
				return hash;
			}
		}

		private static async Task<string> ConvertFileToEntryAsync(ZipArchiveEntry archiveEntry, string filePath)
		{
			using (var fileStream = File.OpenRead(filePath))
			using (var entryStream = archiveEntry.Open())
			{
				var hash = GetHashForStream(fileStream);
				fileStream.Position = 0;
				await fileStream.CopyToAsync(entryStream);
				return hash;
			}
		}

		private static async Task<byte[]> CreateManifestJsonAsync(ZipArchiveEntry archiveEntry, JToken manifest)
		{
			using (var memoryStream = new MemoryStream())
			using (var entryStream = archiveEntry.Open())
			using (var streamWriter = new StreamWriter(memoryStream) { AutoFlush = true })
			{
				await streamWriter.WriteAsync(manifest.ToString(Formatting.Indented));
				memoryStream.Position = 0;
				await memoryStream.CopyToAsync(entryStream);
				return memoryStream.ToArray();
			}
		}

		private static string GetHashForBytes(byte[] bytes)
		{
			using (var sha1 = new SHA1Managed())
			{
				return string.Concat(sha1.ComputeHash(bytes).Select(x => x.ToString("x2")));
			}
		}

		private static string GetHashForStream(Stream stream)
		{
			using (var sha1 = new SHA1Managed())
			{
				return string.Concat(sha1.ComputeHash(stream).Select(x => x.ToString("x2")));
			}
		}

		private static async Task CreateSignatureAsync(ZipArchiveEntry entry, SignatureData signatureData, byte[] dataToSign)
		{
			var signedCms = new SignedCms(new ContentInfo(new Oid(AppleOid), dataToSign), true);
			var cmsSigner = new CmsSigner(SubjectIdentifierType.SubjectKeyIdentifier, signatureData.SigningCertificate) { IncludeOption = X509IncludeOption.None };
			cmsSigner.SignedAttributes.Add(new Pkcs9SigningTime());
			cmsSigner.Certificates.Add(signatureData.SigningCertificate);
			cmsSigner.Certificates.Add(signatureData.Authority);
			signedCms.ComputeSignature(cmsSigner);
			var bytes = signedCms.Encode();
			using (var stream = entry.Open())
			{
				await stream.WriteAsync(bytes, 0, bytes.Length);
			}
		}
	}

	public class SignatureData
	{
		public X509Certificate2 SigningCertificate { get; set; }
		public X509Certificate2 Authority { get; set; }
		public string TeamIdentifier { get; set; }
		public string PassTypeIdentifier { get; set; }
	}

	public class EventData
	{
		public string Organizer { get; set; }
		public string Type { get; set; }
		public string Link { get; set; }
		public DateTimeOffset DateTime { get; set; }
		public string Title { get; set; }
		public string SubTitle { get; set; }
		public string Speaker { get; set; }
		public EventLocation Location { get; set; }
		public string Id { get; set; }
	}

	public class EventLocation
	{
		public string Address { get; set; }
		public string Phone { get; set; }
		public string Email { get; set; }
	}

	public class Attendee
	{
		public string Name { get; set; }
		public string Email { get; set; }
	}
}