bitwarden/src/Billing/Utilities/PayPalIpnClient.cs

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Net.Http;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Web;
using Microsoft.Extensions.Options;

namespace Bit.Billing.Utilities
{
    public class PayPalIpnClient
    {
        private readonly HttpClient _httpClient = new HttpClient();
        private readonly Uri _ipnUri;

        public PayPalIpnClient(IOptions<BillingSettings> billingSettings)
        {
            var bSettings = billingSettings?.Value;
            _ipnUri = new Uri(bSettings.PayPal.Production ? "https://www.paypal.com/cgi-bin/webscr" :
                "https://www.sandbox.paypal.com/cgi-bin/webscr");
        }

        public async Task<bool> VerifyIpnAsync(string ipnBody)
        {
            if(ipnBody == null)
            {
                throw new ArgumentException("No IPN body.");
            }

            var request = new HttpRequestMessage
            {
                Method = HttpMethod.Post,
                RequestUri = _ipnUri
            };
            var cmdIpnBody = string.Concat("cmd=_notify-validate&", ipnBody);
            request.Content = new StringContent(cmdIpnBody, Encoding.UTF8, "application/x-www-form-urlencoded");
            var response = await _httpClient.SendAsync(request);
            if(!response.IsSuccessStatusCode)
            {
                throw new Exception("Failed to verify IPN, status: " + response.StatusCode);
            }
            var responseContent = await response.Content.ReadAsStringAsync();
            if(responseContent.Equals("VERIFIED"))
            {
                return true;
            }
            else if(responseContent.Equals("INVALID"))
            {
                return false;
            }
            else
            {
                throw new Exception("Failed to verify IPN.");
            }
        }

        public class IpnTransaction
        {
            private string[] _dateFormats = new string[]
            {
                "HH:mm:ss dd MMM yyyy PDT", "HH:mm:ss dd MMM yyyy PST", "HH:mm:ss dd MMM, yyyy PST",
                "HH:mm:ss dd MMM, yyyy PDT","HH:mm:ss MMM dd, yyyy PST", "HH:mm:ss MMM dd, yyyy PDT"
            };

            public IpnTransaction(string ipnFormData)
            {
                if(string.IsNullOrWhiteSpace(ipnFormData))
                {
                    return;
                }

                var qsData = HttpUtility.ParseQueryString(ipnFormData);
                var dataDict = qsData.Keys.Cast<string>().ToDictionary(k => k, v => qsData[v].ToString());

                TxnId = GetDictValue(dataDict, "txn_id");
                TxnType = GetDictValue(dataDict, "txn_type");
                ParentTxnId = GetDictValue(dataDict, "parent_txn_id");
                PaymentStatus = GetDictValue(dataDict, "payment_status");
                PaymentType = GetDictValue(dataDict, "payment_type");
                McCurrency = GetDictValue(dataDict, "mc_currency");
                Custom = GetDictValue(dataDict, "custom");
                ItemName = GetDictValue(dataDict, "item_name");
                ItemNumber = GetDictValue(dataDict, "item_number");
                PayerId = GetDictValue(dataDict, "payer_id");
                PayerEmail = GetDictValue(dataDict, "payer_email");
                ReceiverId = GetDictValue(dataDict, "receiver_id");
                ReceiverEmail = GetDictValue(dataDict, "receiver_email");

                PaymentDate = ConvertDate(GetDictValue(dataDict, "payment_date"));

                var mcGrossString = GetDictValue(dataDict, "mc_gross");
                if(!string.IsNullOrWhiteSpace(mcGrossString) && decimal.TryParse(mcGrossString, out var mcGross))
                {
                    McGross = mcGross;
                }
                var mcFeeString = GetDictValue(dataDict, "mc_fee");
                if(!string.IsNullOrWhiteSpace(mcFeeString) && decimal.TryParse(mcFeeString, out var mcFee))
                {
                    McFee = mcFee;
                }
            }

            public string TxnId { get; set; }
            public string TxnType { get; set; }
            public string ParentTxnId { get; set; }
            public string PaymentStatus { get; set; }
            public string PaymentType { get; set; }
            public decimal McGross { get; set; }
            public decimal McFee { get; set; }
            public string McCurrency { get; set; }
            public string Custom { get; set; }
            public string ItemName { get; set; }
            public string ItemNumber { get; set; }
            public string PayerId { get; set; }
            public string PayerEmail { get; set; }
            public string ReceiverId { get; set; }
            public string ReceiverEmail { get; set; }
            public DateTime PaymentDate { get; set; }

            public Tuple<Guid?, Guid?> GetIdsFromCustom()
            {
                Guid? orgId = null;
                Guid? userId = null;

                if(!string.IsNullOrWhiteSpace(Custom) && Custom.Contains(":"))
                {
                    var mainParts = Custom.Split(',');
                    foreach(var mainPart in mainParts)
                    {
                        var parts = mainPart.Split(':');
                        if(parts.Length > 1 && Guid.TryParse(parts[1], out var id))
                        {
                            if(parts[0] == "user_id")
                            {
                                userId = id;
                            }
                            else if(parts[0] == "organization_id")
                            {
                                orgId = id;
                            }
                        }
                    }
                }

                return new Tuple<Guid?, Guid?>(orgId, userId);
            }

            public bool IsAccountCredit()
            {
                return !string.IsNullOrWhiteSpace(Custom) && Custom.Contains("account_credit:1");
            }

            private string GetDictValue(IDictionary<string, string> dict, string key)
            {
                return dict.ContainsKey(key) ? dict[key] : null;
            }

            private DateTime ConvertDate(string dateString)
            {
                if(!string.IsNullOrWhiteSpace(dateString))
                {
                    var parsed = DateTime.TryParseExact(dateString, _dateFormats,
                        CultureInfo.InvariantCulture, DateTimeStyles.None, out var paymentDate);
                    if(parsed)
                    {
                        var pacificTime = RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ?
                            TimeZoneInfo.FindSystemTimeZoneById("Pacific Standard Time") :
                            TimeZoneInfo.FindSystemTimeZoneById("America/Los_Angeles");
                        return TimeZoneInfo.ConvertTimeToUtc(paymentDate, pacificTime);
                    }
                }
                return default(DateTime);
            }
        }
    }
}