79h1sM2Y

1using System;
2using System.Collections.Generic;
3using System.IO;
4using System.Linq;
5using System.Net.Sockets;
6using System.Text;
7using System.Threading.Tasks;
8
9namespace Lab_SMTP
10{
11    public class SMTPClient
12    {
13        private bool _authRequest = false;
14        private Socket _socket;
15
16        public bool AuthRequest => _authRequest;
17
18        public async Task<bool> Connect(string serverDomain)
19        {
20            Socket s = GetSocket(serverDomain, 25);
21            if (s == null) return false;
22            _socket = s;
23            string hsResponse = await SendRequestWithResponse(_socket, "EHLO yandex.ru \r\n");
24            _authRequest = hsResponse.Contains("AUTH LOGIN");
25            return hsResponse.Contains("250");
26        }
27
28        public async Task<bool> SendAuth(string username, string password)
29        {
30            if (_socket == null || !_socket.Connected) return false;
31            string response = await SendRequestWithResponse(_socket, "AUTH LOGIN\r\n");
32            if (!response.Contains("334")) return false;
33            string encodedUsername = Convert.ToBase64String(Encoding.UTF8.GetBytes(username));
34            string encodedPassword = Convert.ToBase64String(Encoding.UTF8.GetBytes(password));
35            response = await SendRequestWithResponse(_socket, $"{encodedUsername}\r\n");
36            if (!response.Contains("334")) return false;
37            response = await SendRequestWithResponse(_socket, $"{encodedPassword}\r\n");
38            return response.Contains("235");
39        }
40
41        public async Task<bool> SendFrom(string from) {
42            if (_socket == null || !_socket.Connected) return false;
43            string response = await SendRequestWithResponse(_socket, $"MAIL FROM:<{from}>\r\n");
44            return response.Contains("250");
45        }
46
47        public async Task<bool> SendTo(string to) {
48            if (_socket == null || !_socket.Connected) return false;
49            string response = await SendRequestWithResponse(_socket, $"RCPT TO:<{to}>\r\n");
50            return response.Contains("250");
51        }
52
53        public async Task<bool> SendData(string data) {
54            if (_socket == null || !_socket.Connected) return false;
55            string response = await SendRequestWithResponse(_socket, "DATA \r\n");
56            if (!response.Contains("354")) return false;
57            StringReader reader = new StringReader(data);
58            while (true)
59            {
60                string str = reader.ReadLine();
61                if (str == null) break;
62                await SendRequest(_socket, $"{str}\r\n");
63            }
64            response = await SendRequestWithResponse(_socket, ".\r\n");
65            return response.Contains("250");
66        }
67
68        public async Task<bool> SendQuit(string to) {
69            if (_socket == null || !_socket.Connected) return false;
70            string response = await SendRequestWithResponse(_socket, $"QUIT\r\n");
71            return response.Contains("250");
72        }
73
74        public static Socket GetSocket(string host, int port) {
75            Socket s = null;
76            var tempSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
77            try {
78                tempSocket.Connect(host, port);
79            }
80            catch (SocketException ex) {
81                return null;
82            }
83            if (tempSocket.Connected)
84                s = tempSocket;
85            return s;
86        }
87
88        public static Task<int> ReceiveAsync(Socket socket, byte[] buffer, int offset, int size, SocketFlags socketFlags) {
89            var tcs = new TaskCompletionSource<int>(socket);
90            socket.BeginReceive(buffer, offset, size, socketFlags, iar =>
91            {
92                var t = (TaskCompletionSource<int>)iar.AsyncState;
93                var s = (Socket)t.Task.AsyncState;
94                try { t.TrySetResult(s.EndReceive(iar)); }
95                catch (Exception exc) { t.TrySetException(exc); }
96            }, tcs);
97            return tcs.Task;
98        }
99
100        public static async Task SendRequest(Socket socket, string request) {
101            Byte[] bytesSent = Encoding.Default.GetBytes(request);
102            socket.Send(bytesSent, bytesSent.Length, 0);
103            await Task.Delay(100);
104        }
105
106        public static async Task<string> SendRequestWithResponse(Socket socket, string request) {
107            return await SendRequestWithResponse(socket, socket, request);
108        }
109
110        public static async Task<string> SendRequestWithResponse(Socket socketToSend, Socket socketToRecieve, string request) {
111            Byte[] bytesReceived = new Byte[256];
112            int bytes;
113            string response = "";
114
115            await SendRequest(socketToSend, request);
116
117            do {
118                bytes = await ReceiveAsync(socketToRecieve, bytesReceived, 0, bytesReceived.Length, 0);
119                response = response + Encoding.Default.GetString(bytesReceived, 0, bytes);
120                if (bytes < 255) break;
121            }
122            while (bytes > 0);
123            return response;
124        }
125    }
126}