# < Summary

Information

Class: | Renci.SshNet.Connection.ProtocolVersionExchange
Assembly: | Renci.SshNet
File(s): | \home\appveyor\projects\ssh-net\src\Renci.SshNet\Connection\ProtocolVersionExchange.cs

Line coverage
90%

Covered lines: | 109
Uncovered lines: | 11
Coverable lines: | 120
Total lines: | 266
Line coverage: | 90.8%

Branch coverage
76%

Covered branches: | 26
Total branches: | 34
Branch coverage: | 76.4%

Method coverage

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# Metrics

Method | Branch coverage | Cyclomatic complexity | Line coverage
--- | --- | --- | ---
.cctor() | 100% | 1 | 100%
Start(...) | 100% | 6 | 100%
StartAsync() | 33.33% | 6 | 70%
GetGroupValue(...) | 100% | 2 | 100%
SocketReadLine(...) | 100% | 10 | 100%
SocketReadLineAsync() | 60% | 10 | 77.27%
CreateConnectionLostException() | 100% | 1 | 100%
CreateServerResponseContainsNullCharacterException(...) | 100% | 1 | 100%
CreateServerResponseDoesNotContainIdentification(...) | 100% | 1 | 100%

# File(s)

## \home\appveyor\projects\ssh-net\src\Renci.SshNet\Connection\ProtocolVersionExchange.cs

| # | Line |  | Line coverage
--- | --- | --- | --- | ---
|  | `1` |  | `using System;`
|  | `2` |  | `using System.Collections.Generic;`
|  | `3` |  | `using System.Globalization;`
|  | `4` |  | `using System.Net.Sockets;`
|  | `5` |  | `using System.Text;`
|  | `6` |  | `using System.Text.RegularExpressions;`
|  | `7` |  | `using System.Threading;`
|  | `8` |  | `using System.Threading.Tasks;`
|  | `9` |  | ``
|  | `10` |  | `using Renci.SshNet.Abstractions;`
|  | `11` |  | `using Renci.SshNet.Common;`
|  | `12` |  | `using Renci.SshNet.Messages.Transport;`
|  | `13` |  | ``
|  | `14` |  | `namespace Renci.SshNet.Connection`
|  | `15` |  | `{`
|  | `16` |  | `/// <summary>`
|  | `17` |  | `/// Handles the SSH protocol version exchange.`
|  | `18` |  | `/// </summary>`
|  | `19` |  | `/// <remarks>`
|  | `20` |  | `/// https://tools.ietf.org/html/rfc4253#section-4.2.`
|  | `21` |  | `/// </remarks>`
|  | `22` |  | `internal sealed class ProtocolVersionExchange : IProtocolVersionExchange`
|  | `23` |  | `{`
|  | `24` |  | `private const byte Null = 0x00;`
|  | `25` |  | ``
| 4 | `26` |  | `private static readonly Regex ServerVersionRe = new Regex("^SSH-(?<protoversion>[^-]+)-(?<softwareversion>.+?)([`
|  | `27` |  | ``
|  | `28` |  | `/// <summary>`
|  | `29` |  | `/// Performs the SSH protocol version exchange.`
|  | `30` |  | `/// </summary>`
|  | `31` |  | `/// <param name="clientVersion">The identification string of the SSH client.</param>`
|  | `32` |  | `/// <param name="socket">A <see cref="Socket"/> connected to the server.</param>`
|  | `33` |  | `/// <param name="timeout">The maximum time to wait for the server to respond.</param>`
|  | `34` |  | `/// <returns>`
|  | `35` |  | `/// The SSH identification of the server.`
|  | `36` |  | `/// </returns>`
|  | `37` |  | `public SshIdentification Start(string clientVersion, Socket socket, TimeSpan timeout)`
| 1272 | `38` |  | `{`
|  | `39` |  | `// Immediately send the identification string since the spec states both sides MUST send an identification s`
|  | `40` |  | `// when the connection has been established`
| 1272 | `41` |  | `SocketAbstraction.Send(socket, Encoding.UTF8.GetBytes(clientVersion + "\x0D\x0A"));`
|  | `42` |  | ``
| 1272 | `43` |  | `var bytesReceived = new List<byte>();`
|  | `44` |  | ``
|  | `45` |  | `// Get server version from the server,`
|  | `46` |  | `// ignore text lines which are sent before if any`
| 1374 | `47` |  | `while (true)`
| 1374 | `48` |  | `{`
| 1374 | `49` |  | `var line = SocketReadLine(socket, timeout, bytesReceived);`
| 1353 | `50` |  | `if (line is null)`
| 18 | `51` |  | `{`
| 18 | `52` |  | `if (bytesReceived.Count == 0)`
| 9 | `53` |  | `{`
| 9 | `54` |  | `throw CreateConnectionLostException();`
|  | `55` |  | `}`
|  | `56` |  | ``
| 9 | `57` |  | `throw CreateServerResponseDoesNotContainIdentification(bytesReceived);`
|  | `58` |  | `}`
|  | `59` |  | ``
| 1335 | `60` |  | `var identificationMatch = ServerVersionRe.Match(line);`
| 1335 | `61` |  | `if (identificationMatch.Success)`
| 1233 | `62` |  | `{`
| 1233 | `63` |  | `return new SshIdentification(GetGroupValue(identificationMatch, "protoversion"),`
| 1233 | `64` |  | `GetGroupValue(identificationMatch, "softwareversion"),`
| 1233 | `65` |  | `GetGroupValue(identificationMatch, "comments"));`
|  | `66` |  | `}`
| 102 | `67` |  | `}`
| 1233 | `68` |  | `}`
|  | `69` |  | ``
|  | `70` |  | `/// <summary>`
|  | `71` |  | `/// Asynchronously performs the SSH protocol version exchange.`
|  | `72` |  | `/// </summary>`
|  | `73` |  | `/// <param name="clientVersion">The identification string of the SSH client.</param>`
|  | `74` |  | `/// <param name="socket">A <see cref="Socket"/> connected to the server.</param>`
|  | `75` |  | `/// <param name="cancellationToken">The token to monitor for cancellation requests.</param>`
|  | `76` |  | `/// <returns>`
|  | `77` |  | `/// A task that represents the SSH protocol version exchange. The value of its`
|  | `78` |  | `/// <see cref="Task{Task}.Result"/> contains the SSH identification of the server.`
|  | `79` |  | `/// </returns>`
|  | `80` |  | `public async Task<SshIdentification> StartAsync(string clientVersion, Socket socket, CancellationToken cancellat`
| 2 | `81` |  | `{`
|  | `82` |  | `// Immediately send the identification string since the spec states both sides MUST send an identification s`
|  | `83` |  | `// when the connection has been established`
| 2 | `84` |  | `SocketAbstraction.Send(socket, Encoding.UTF8.GetBytes(clientVersion + "\x0D\x0A"));`
|  | `85` |  | ``
| 2 | `86` |  | `var bytesReceived = new List<byte>();`
|  | `87` |  | ``
|  | `88` |  | `// Get server version from the server,`
|  | `89` |  | `// ignore text lines which are sent before if any`
| 2 | `90` |  | `while (true)`
| 2 | `91` |  | `{`
| 2 | `92` |  | `var line = await SocketReadLineAsync(socket, bytesReceived, cancellationToken).ConfigureAwait(false);`
| 2 | `93` |  | `if (line is null)`
| 0 | `94` |  | `{`
| 0 | `95` |  | `if (bytesReceived.Count == 0)`
| 0 | `96` |  | `{`
| 0 | `97` |  | `throw CreateConnectionLostException();`
|  | `98` |  | `}`
|  | `99` |  | ``
| 0 | `100` |  | `throw CreateServerResponseDoesNotContainIdentification(bytesReceived);`
|  | `101` |  | `}`
|  | `102` |  | ``
| 2 | `103` |  | `var identificationMatch = ServerVersionRe.Match(line);`
| 2 | `104` |  | `if (identificationMatch.Success)`
| 2 | `105` |  | `{`
| 2 | `106` |  | `return new SshIdentification(GetGroupValue(identificationMatch, "protoversion"),`
| 2 | `107` |  | `GetGroupValue(identificationMatch, "softwareversion"),`
| 2 | `108` |  | `GetGroupValue(identificationMatch, "comments"));`
|  | `109` |  | `}`
| 0 | `110` |  | `}`
| 2 | `111` |  | `}`
|  | `112` |  | ``
|  | `113` |  | `private static string GetGroupValue(Match match, string groupName)`
| 3705 | `114` |  | `{`
| 3705 | `115` |  | `var commentsGroup = match.Groups[groupName];`
| 3705 | `116` |  | `if (commentsGroup.Success)`
| 2482 | `117` |  | `{`
| 2482 | `118` |  | `return commentsGroup.Value;`
|  | `119` |  | `}`
|  | `120` |  | ``
| 1223 | `121` |  | `return null;`
| 3705 | `122` |  | `}`
|  | `123` |  | ``
|  | `124` |  | `/// <summary>`
|  | `125` |  | `/// Performs a blocking read on the socket until a line is read.`
|  | `126` |  | `/// </summary>`
|  | `127` |  | `/// <param name="socket">The <see cref="Socket"/> to read from.</param>`
|  | `128` |  | `/// <param name="timeout">A <see cref="TimeSpan"/> that represents the time to wait until a line is read.</param`
|  | `129` |  | `/// <param name="buffer">A <see cref="List{Byte}"/> to which read bytes will be added.</param>`
|  | `130` |  | `/// <exception cref="SshOperationTimeoutException">The read has timed-out.</exception>`
|  | `131` |  | `/// <exception cref="SocketException">An error occurred when trying to access the socket.</exception>`
|  | `132` |  | `/// <returns>`
|  | `133` |  | `/// The line read from the socket, or <see langword="null"/> when the remote server has shutdown and all data ha`
|  | `134` |  | `/// </returns>`
|  | `135` |  | `private static string SocketReadLine(Socket socket, TimeSpan timeout, List<byte> buffer)`
| 1374 | `136` |  | `{`
| 1374 | `137` |  | `var data = new byte[1];`
|  | `138` |  | ``
| 1374 | `139` |  | `var startPosition = buffer.Count;`
|  | `140` |  | ``
|  | `141` |  | `// Read data one byte at a time to find end of line and leave any unhandled information in the buffer`
|  | `142` |  | `// to be processed by subsequent invocations.`
| 27411 | `143` |  | `while (true)`
| 27411 | `144` |  | `{`
| 27411 | `145` |  | `var bytesRead = SocketAbstraction.Read(socket, data, 0, data.Length, timeout);`
| 27402 | `146` |  | `if (bytesRead == 0)`
| 18 | `147` |  | `{`
|  | `148` |  | `// The remote server shut down the socket.`
| 18 | `149` |  | `break;`
|  | `150` |  | `}`
|  | `151` |  | ``
| 27384 | `152` |  | `var byteRead = data[0];`
| 27384 | `153` |  | `buffer.Add(byteRead);`
|  | `154` |  | ``
|  | `155` |  | `// The null character MUST NOT be sent`
| 27384 | `156` |  | `if (byteRead is Null)`
| 12 | `157` |  | `{`
| 12 | `158` |  | `throw CreateServerResponseContainsNullCharacterException(buffer);`
|  | `159` |  | `}`
|  | `160` |  | ``
| 27372 | `161` |  | `if (byteRead == Session.LineFeed)`
| 1335 | `162` |  | `{`
| 1335 | `163` |  | `if (buffer.Count > startPosition + 1 && buffer[buffer.Count - 2] == Session.CarriageReturn)`
| 1299 | `164` |  | `{`
|  | `165` |  | `// Return current line without CRLF`
| 1299 | `166` |  | `return Encoding.UTF8.GetString(buffer.ToArray(), startPosition, buffer.Count - (startPosition +`
|  | `167` |  | `}`
|  | `168` |  | ``
|  | `169` |  | `// Even though RFC4253 clearly indicates that the identification string should be terminated`
|  | `170` |  | `// by a CR LF we also support banners and identification strings that are terminated by a LF`
|  | `171` |  | ``
|  | `172` |  | `// Return current line without LF`
| 36 | `173` |  | `return Encoding.UTF8.GetString(buffer.ToArray(), startPosition, buffer.Count - (startPosition + 1));`
|  | `174` |  | `}`
| 26037 | `175` |  | `}`
|  | `176` |  | ``
| 18 | `177` |  | `return null;`
| 1353 | `178` |  | `}`
|  | `179` |  | ``
|  | `180` |  | `private static async Task<string> SocketReadLineAsync(Socket socket, List<byte> buffer, CancellationToken cancel`
| 2 | `181` |  | `{`
| 2 | `182` |  | `var data = new byte[1];`
|  | `183` |  | ``
| 2 | `184` |  | `var startPosition = buffer.Count;`
|  | `185` |  | ``
|  | `186` |  | `// Read data one byte at a time to find end of line and leave any unhandled information in the buffer`
|  | `187` |  | `// to be processed by subsequent invocations.`
| 42 | `188` |  | `while (true)`
| 42 | `189` |  | `{`
| 42 | `190` |  | `var bytesRead = await SocketAbstraction.ReadAsync(socket, data, 0, data.Length, cancellationToken).Confi`
| 42 | `191` |  | `if (bytesRead == 0)`
| 0 | `192` |  | `{`
| 0 | `193` |  | `throw new SshConnectionException("The connection was closed by the remote host.");`
|  | `194` |  | `}`
|  | `195` |  | ``
| 42 | `196` |  | `var byteRead = data[0];`
| 42 | `197` |  | `buffer.Add(byteRead);`
|  | `198` |  | ``
|  | `199` |  | `// The null character MUST NOT be sent`
| 42 | `200` |  | `if (byteRead is Null)`
| 0 | `201` |  | `{`
| 0 | `202` |  | `throw CreateServerResponseContainsNullCharacterException(buffer);`
|  | `203` |  | `}`
|  | `204` |  | ``
| 42 | `205` |  | `if (byteRead == Session.LineFeed)`
| 2 | `206` |  | `{`
| 2 | `207` |  | `if (buffer.Count > startPosition + 1 && buffer[buffer.Count - 2] == Session.CarriageReturn)`
| 2 | `208` |  | `{`
|  | `209` |  | `// Return current line without CRLF`
| 2 | `210` |  | `return Encoding.UTF8.GetString(buffer.ToArray(), startPosition, buffer.Count - (startPosition +`
|  | `211` |  | `}`
|  | `212` |  | ``
|  | `213` |  | `// Even though RFC4253 clearly indicates that the identification string should be terminated`
|  | `214` |  | `// by a CR LF we also support banners and identification strings that are terminated by a LF`
|  | `215` |  | ``
|  | `216` |  | `// Return current line without LF`
| 0 | `217` |  | `return Encoding.UTF8.GetString(buffer.ToArray(), startPosition, buffer.Count - (startPosition + 1));`
|  | `218` |  | `}`
| 40 | `219` |  | `}`
| 2 | `220` |  | `}`
|  | `221` |  | ``
|  | `222` |  | `private static SshConnectionException CreateConnectionLostException()`
| 9 | `223` |  | `{`
|  | `224` |  | `#pragma warning disable SA1118 // Parameter should not span multiple lines`
| 9 | `225` |  | `var message = string.Format(CultureInfo.InvariantCulture,`
| 9 | `226` |  | `"The server response does not contain an SSH identification string.{0}" +`
| 9 | `227` |  | `"The connection to the remote server was closed before any data was received.{0}`
| 9 | `228` |  | `"More information on the Protocol Version Exchange is available here:{0}" +`
| 9 | `229` |  | `"https://tools.ietf.org/html/rfc4253#section-4.2",`
| 9 | `230` |  | `Environment.NewLine);`
|  | `231` |  | `#pragma warning restore SA1118 // Parameter should not span multiple lines`
|  | `232` |  | ``
| 9 | `233` |  | `return new SshConnectionException(message, DisconnectReason.ConnectionLost);`
| 9 | `234` |  | `}`
|  | `235` |  | ``
|  | `236` |  | `private static SshConnectionException CreateServerResponseContainsNullCharacterException(List<byte> buffer)`
| 12 | `237` |  | `{`
|  | `238` |  | `#pragma warning disable SA1118 // Parameter should not span multiple lines`
| 12 | `239` |  | `var message = string.Format(CultureInfo.InvariantCulture,`
| 12 | `240` |  | `"The server response contains a null character at position 0x{0:X8}:{1}{1}{2}{1}`
| 12 | `241` |  | `"A server must not send a null character before the Protocol Version Exchange is`
| 12 | `242` |  | `"More information is available here:{1}" +`
| 12 | `243` |  | `"https://tools.ietf.org/html/rfc4253#section-4.2",`
| 12 | `244` |  | `buffer.Count,`
| 12 | `245` |  | `Environment.NewLine,`
| 12 | `246` |  | `PacketDump.Create(buffer.ToArray(), 2));`
|  | `247` |  | `#pragma warning restore SA1118 // Parameter should not span multiple lines`
|  | `248` |  | ``
| 12 | `249` |  | `throw new SshConnectionException(message);`
|  | `250` |  | `}`
|  | `251` |  | ``
|  | `252` |  | `private static SshConnectionException CreateServerResponseDoesNotContainIdentification(List<byte> bytesReceived)`
| 9 | `253` |  | `{`
|  | `254` |  | `#pragma warning disable SA1118 // Parameter should not span multiple lines`
| 9 | `255` |  | `var message = string.Format(CultureInfo.InvariantCulture,`
| 9 | `256` |  | `"The server response does not contain an SSH identification string:{0}{0}{1}{0}{`
| 9 | `257` |  | `"More information on the Protocol Version Exchange is available here:{0}" +`
| 9 | `258` |  | `"https://tools.ietf.org/html/rfc4253#section-4.2",`
| 9 | `259` |  | `Environment.NewLine,`
| 9 | `260` |  | `PacketDump.Create(bytesReceived, 2));`
|  | `261` |  | `#pragma warning restore SA1118 // Parameter should not span multiple lines`
|  | `262` |  | ``
| 9 | `263` |  | `throw new SshConnectionException(message, DisconnectReason.ProtocolError);`
|  | `264` |  | `}`
|  | `265` |  | `}`
|  | `266` |  | `}`

# Methods/Properties

.cctor()
Start(System.String,System.Net.Sockets.Socket,System.TimeSpan)
StartAsync()
GetGroupValue(System.Text.RegularExpressions.Match,System.String)
SocketReadLine(System.Net.Sockets.Socket,System.TimeSpan,System.Collections.Generic.List`1<System.Byte>)
SocketReadLineAsync()
CreateConnectionLostException()
CreateServerResponseContainsNullCharacterException(System.Collections.Generic.List`1<System.Byte>)
CreateServerResponseDoesNotContainIdentification(System.Collections.Generic.List`1<System.Byte>)