Synapse

│ English (en) │ polski (pl) │ русский (ru) │

Synapse provides an easy to use serial port and synchronous TCP/IP library.

Overview

Synapse offers serial port and TCP/IP connectivity. It differs from other libraries that you only require to add some Synapse Pascal source code files to your code; no need for installing packages etc. The only exception is that you will need an external crypto library if you want to use encryption such as SSL/TLS/SSH.

See the documentation on the official site (link below) for more details.

Installation

Installation can be as simple as simply copying over all files to your application directory and adding the relevant Synapse units to your uses clause.

A more elegant and recommended way is compiling the laz_synapse.lpk package so you can use the same units in all your projects.

Synapse download / Wiki info page: Download and Wiki

Support and bug reporting

The Synapse project has a mailing list where support is given and patches can be submitted.

Bug reports can also be mailed to the mailing list.

See the Synapse support page and some well presented on line help

SSL/TLS support

You can use OpenSSL, CryptLib, StreamSecII or OpenStreamSecII SSL support with Synapse. By default, no SSL support is used.

The support is activated by putting the chosen unit name in the uses section in your project. You also have to put the binary library file in your project path (Windows), or install it into your library search path (Linux, macOS, FreeBSD).

Synapse loads SSL library files in runtime as dynamic libraries.

For detailed information refer to SSL/TLS Plugin Architecture
Some crypt libraries can be obtained from: http://synapse.ararat.cz/files/crypt/

Missing library

On Linux you need to make sure the required dynamic library is present/installed on your system. In case of cryptlib if the library is not present on the system, an error message appears during linking:

/usr/bin/ld: cannot find -lcl

A similar message will be displayed when using other dynamic libraries.

Web server example

See the Webserver example.

QOTD server query example

See the Quote of the Day server query example.

Sending email

Refer to the Synapse - Email Examples article.

Downloading files

From an FTP server

Given an URL and a (path and) file name, this will download it from an FTP server. It's mostly a wrapper around the Synapse code meant to make downloading easier when handling arbitrary files. If you know exactly what you're going to download where, just a call to Synapse:

FtpGetFile

will get you very far.

function DownloadFTP(URL, TargetFile: string): boolean;
const
  FTPPort=21;
  FTPScheme='ftp://'; //URI scheme name for FTP URLs
var
  Host: string;
  Port: integer;
  Source: string;
  FoundPos: integer;
begin
  // Strip out scheme info:
  if LeftStr(URL, length(FTPScheme))=FTPScheme then URL:=Copy(URL, length(FTPScheme)+1, length(URL));

  // Crude parsing; could have used URI parsing code in FPC packages...
  FoundPos:=pos('/', URL);
  Host:=LeftStr(URL, FoundPos-1);
  Source:=Copy(URL, FoundPos+1, Length(URL));

  //Check for port numbers:
  FoundPos:=pos(':', Host);
  Port:=FTPPort;
  if FoundPos>0 then
  begin
    Host:=LeftStr(Host, FoundPos-1);
    Port:=StrToIntDef(Copy(Host, FoundPos+1, Length(Host)),21);
  end;
  Result:=FtpGetFile(Host, IntToStr(Port), Source, TargetFile, 'anonymous', 'fpc@example.com');
  if result=false then writeln('DownloadFTP: error downloading '+URL+'. Details: host: '+Host+'; port: '+Inttostr(Port)+'; remote path: '+Source+' to '+TargetFile);
end;

Example to get list of files in given path

//Use ftpsend unit

function FtpGetDir(const IP, Port, Path, User, Pass: string; DirList: TStringList): Boolean;
var
  i: Integer;
  s: string;
begin
  Result := False;
  with TFTPSend.Create do
  try
    Username := User;
    Password := Pass;
    TargetHost := IP;
    TargetPort := Port;
    if not Login then
      Exit;
    Result := List(Path, False);
    for i := 0 to FtpList.Count -1 do
    begin
      s := FTPList[i].FileName;
      DirList.Add(s);
    end;
    Logout;
  finally
    Free;
  end;
end;

From an HTTP server

Given an URL and a (path and) file name, this will download it from an HTTP server. Note that this code checks the HTTP status code (like 200, 404) to see if the document we got back from the server is the desired file or an error page.

Simple version

...
uses httpsend,
...
function DownloadHTTP(URL, TargetFile: string): Boolean;
var
  HTTPGetResult: Boolean;
  HTTPSender: THTTPSend;
begin
  Result := False;
  HTTPSender := THTTPSend.Create;
  try
    HTTPGetResult := HTTPSender.HTTPMethod('GET', URL);
    if (HTTPSender.ResultCode >= 100) and (HTTPSender.ResultCode<=299) then begin
      HTTPSender.Document.SaveToFile(TargetFile);
      Result := True;
    end; 
  finally
    HTTPSender.Free;
  end;
end;

Advanced version

...
uses httpsend
...
function DownloadHTTP(URL, TargetFile: string): Boolean;
// Download file; retry if necessary.
// Could use Synapse HttpGetBinary, but that doesn't deal
// with result codes (i.e. it happily downloads a 404 error document)
const
  MaxRetries = 3;
var
  HTTPGetResult: Boolean;
  HTTPSender: THTTPSend;
  RetryAttempt: Integer;
begin
  Result := False;
  RetryAttempt := 1;
  HTTPSender := THTTPSend.Create;
  try
    try
      // Try to get the file
      HTTPGetResult := HTTPSender.HTTPMethod('GET', URL);
      while (HTTPGetResult = False) and (RetryAttempt < MaxRetries) do
      begin
        Sleep(500 * RetryAttempt);
        HTTPSender.Clear;
        HTTPGetResult := HTTPSender.HTTPMethod('GET', URL);
        RetryAttempt := RetryAttempt + 1;
      end;
      // If we have an answer from the server, check if the file
      // was sent to us.
      case HTTPSender.Resultcode of
        100..299:
          begin
            HTTPSender.Document.SaveToFile(TargetFile);
            Result := True;
          end; //informational, success
        300..399: Result := False; // redirection. Not implemented, but could be.
        400..499: Result := False; // client error; 404 not found etc
        500..599: Result := False; // internal server error
        else Result := False; // unknown code
      end;
    except
      // We don't care for the reason for this error; the download failed.
      Result := False;
    end;
  finally
    HTTPSender.Free;
  end;
end;

Simple version with progress

The following example shows how to get progress information from the HTTP download, as well as the file size. The file size is retrieved from the header information.

unit uhttpdownloader;

// Essential to change this. The default is {$mode objfpc}{$H+} and does not work.
{$mode Delphi}

interface

uses
  Classes, SysUtils, httpsend, blcksock, typinfo;

type
  IProgress = interface
    procedure ProgressNotification(Text: String; CurrentProgress : integer; MaxProgress : integer);
  end;

type
  { THttpDownloader }

  THttpDownloader = class
  public
    function DownloadHTTP(URL, TargetFile: string; ProgressMonitor : IProgress): Boolean;
  private
    Bytes : Integer;
    MaxBytes : Integer;
    HTTPSender: THTTPSend;
    ProgressMonitor : IProgress;
    procedure Status(Sender: TObject; Reason: THookSocketReason; const Value: String);
    function GetSizeFromHeader(Header: String):integer;
  end;

implementation

function THttpDownloader.DownloadHTTP(URL, TargetFile: string; ProgressMonitor : IProgress): Boolean;
var
  HTTPGetResult: Boolean;
begin
  Result := False;
  Bytes:= 0;
  MaxBytes:= -1;
  Self.ProgressMonitor:= ProgressMonitor;

  HTTPSender := THTTPSend.Create;
  try
    HTTPSender.Sock.OnStatus:= Status;
    HTTPGetResult := HTTPSender.HTTPMethod('GET', URL);
    if (HTTPSender.ResultCode >= 100) and (HTTPSender.ResultCode<=299) then begin
      HTTPSender.Document.SaveToFile(TargetFile);
      Result := True;
    end;
  finally
    HTTPSender.Free;
  end;
end;

procedure THttpDownloader.Status(Sender: TObject; Reason: THookSocketReason; const Value: String);
var
  V, currentHeader: String;
  i: integer;
begin
  //try to get filesize from headers
  if (MaxBytes = -1) then
  begin
    for i:= 0 to HTTPSender.Headers.Count - 1 do
    begin
      currentHeader:= HTTPSender.Headers[i];
      MaxBytes:= GetSizeFromHeader(currentHeader);
      if MaxBytes <> -1 then break;
    end;
  end;

  V := GetEnumName(TypeInfo(THookSocketReason), Integer(Reason)) + ' ' + Value;

  if Reason = THookSocketReason.HR_ReadCount then
  begin
    Bytes:= Bytes + StrToInt(Value);
    ProgressMonitor.ProgressNotification(V, Bytes, MaxBytes);
  end;
end;

function THttpDownloader.GetSizeFromHeader(Header: String): integer;
var
  item : TStringList;
begin
  Result:= -1;

  if Pos('Content-Length:', Header) <> 0 then
  begin
    item:= TStringList.Create();
    item.Delimiter:= ':';
    item.StrictDelimiter:=true;
    item.DelimitedText:=Header;
    if item.Count = 2 then
    begin
      Result:= StrToInt(Trim(item[1]));
    end;
  end;
end;

end.

What are we doing here?

First of all we look into the headers to get the file size. We have to wait and check if the header is there. The first events do not contain the Content-Length: information.

Once found, we extract that information. There are several events popping up here, which you can react to. But we only check for THookSocketReason.HR_ReadCount in that example.

"HR_ReadCount" provides us with the information how many bytes where read since the last event.

The progress is then reported to the UI:

procedure TMainForm.ProgressNotification(Text: String; CurrentProgress: integer; MaxProgress: integer);
begin
  if (MaxProgress <> -1) then
  begin
    ProgressBar.Max:= MaxProgress;
  end;

  ProgressBar.Position:= CurrentProgress;
  memoStatus.Lines.Add(Text);
  Application.ProcessMessages;
end;

So, the final main unit will be:

unit uMain;

{$mode Delphi}

interface

uses
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls, ComCtrls, httpsend, blcksock, typinfo,
  uhttpdownloader;

type

  { TMainForm }

  TMainForm = class(TForm, IProgress)
    btnStartDownload: TButton;
    edtUrl: TEdit;
    labelUrl: TLabel;
    memoStatus: TMemo;
    ProgressBar: TProgressBar;
    SaveDialog: TSaveDialog;
    procedure btnStartDownloadClick(Sender: TObject);
  private
    { private declarations }
    function GetFileNameFromURL(url: String):string;
  public
    { public declarations }
    procedure ProgressNotification(Text: String; CurrentProgress : integer; MaxProgress : integer);
  end;

var
  MainForm: TMainForm;

implementation

{$R *.lfm}

{ TMainForm }

procedure TMainForm.btnStartDownloadClick(Sender: TObject);
var
  fileName: String;
  downloader: THttpDownloader;
  success: boolean;
begin
  fileName:= GetFileNameFromURL(edtUrl.Text);
  SaveDialog.FileName:=fileName;
  if (SaveDialog.Execute) then
  begin
    memoStatus.Lines.Clear;
    ProgressBar.Position:=0;
    downloader:= THttpDownloader.Create();
    success:= downloader.DownloadHTTP(edtUrl.Text, SaveDialog.FileName, Self);

    ProgressBar.Position:=0;
    if Success then
      memoStatus.Lines.Add('Download successful')
    else
      memoStatus.Lines.Add('Error during download');

  end;
end;

function TMainForm.GetFileNameFromURL(url: String): string;
var i, l : integer;
    fileName, current : String;
begin
  fileName:= '';
  l:= Length(url);
  for i:= l downto 0 do begin
    current:= url[i];
    if current <> '/' then
    begin
      fileName:= current + fileName;
    end else begin
      Result:= fileName;
      break;
    end;
  end;
end;

procedure TMainForm.ProgressNotification(Text: String; CurrentProgress: integer; MaxProgress: integer);
begin
  if (MaxProgress <> -1) then ProgressBar.Max:= MaxProgress;
  ProgressBar.Position:= CurrentProgress;
  memoStatus.Lines.Add(Text);
  Application.ProcessMessages;
end;

end.

Reference: https://andydunkel.net/2015/09/09/lazarus_synapse_progress/

From an HTTP server by parsing URLs: Sourceforge

Please see Download from SourceForge for an example of downloading from sourceforge.net.

From an HTTPS server

This is similar to downloading from an HTTP server. In addition you need to activate SSL/TLS support and obtain the binary file(s) for the needed library. Then you can use the same DownloadHTTP function for downloading a file from a URL starting with https://.

SSH/Telnet client sample program

Below you will find a unit that allows you to use telnet/SSH client functionality that uses the synapse tlntsend.pas unit. An example program shows how to use this. A different, simpler way is illustrated by Leonardo Ramé at [1]. His example cannot use telnet and only sends one command, though.

Requirements

Apart from the Synapse sources (of which you only need a couple), if you want to use SSH functionality, you will need an encryption library that Synapse uses. If you only use Telnet, you don't need this.

There are 2 choices:

Cryptlib library. Advantage: stable. Apparently able to use private keys but these are in some format that is not widely supported.
LibSSH2 library. Pascal bindings still in development, but you can use a file with your private key (in OpenSSH format) to authenticate.

Cryptlib

On Windows, download a binary version of the cryptlib DLL (CL32.DLL) and put it in your source directory. If you compile to a different directory or distribute your program, you will need to distribute the DLL as well.
On Linux and OSX, install cryptlib via your package manager/other means. When distributing your application, mark cryptlib as a requirement in your .deb/.rpm/whatever package.

You will also need the bindings (cryptlib.pas), present in the source distribution of cryptlib.

The versions of the cryptlib binary and the bindings must match.

  Note: It seems that cryptlib is not suitable to connect to linux machines, though AIX works. Use SSH2 instead.

LibSSH2

On Windows, download a binary version of the libssh2 DLL (LIBSSH2.DLL) and put it in your source directory. If you compile to a different directory or distribute your program, you will need to distribute the DLL as well.
On Linux and macOS, install libssh2 via your package manager/other means. When distributing your application:
- Linux: mark libssh2 as a requirement in your .deb/.rpm/whatever package.
- macOS: include libssh2 in your Application Bundle's Resources directory.

You will also need ssl_libssh2.pas (see below) and the bindings: (libssh2.pas, see this forum post). The libssh2 binary and the bindings must match.

Synapse libssh2 SSL plugin

  Note: plugin is not completed.

{
  ssl_libssh2.pas version 0.2

  SSH2 support (draft) plugin for Synapse Library (http://www.ararat.cz/synapse) by LibSSH2 (http://libssh2.org)
  Requires: libssh2 pascal interface - http://www.lazarus.freepascal.org/index.php/topic,15935.msg86465.html#msg86465 and
  libssh2.dll with OpenSSL.

  (С) Alexey Suhinin http://x-alexey.narod.ru
}

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$H+}

unit ssl_libssh2;

interface

uses
  SysUtils,
  blcksock, synsock,
  libssh2;

type
  {:@abstract(class implementing CryptLib SSL/SSH plugin.)
   Instance of this class will be created for each @link(TTCPBlockSocket).
   You not need to create instance of this class, all is done by Synapse itself!}
  TSSLLibSSH2 = class(TCustomSSL)
  protected
    FSession: PLIBSSH2_SESSION;
    FChannel: PLIBSSH2_CHANNEL;
    function SSHCheck(Value: integer): Boolean;
    function DeInit: Boolean;
  public
    {:See @inherited}
    constructor Create(const Value: TTCPBlockSocket); override;
    destructor Destroy; override;
    function Connect: boolean; override;
    function LibName: String; override;
    function Shutdown: boolean; override;
    {:See @inherited}
    function BiShutdown: boolean; override;
    {:See @inherited}
    function SendBuffer(Buffer: TMemory; Len: Integer): Integer; override;
    {:See @inherited}
    function RecvBuffer(Buffer: TMemory; Len: Integer): Integer; override;
    {:See @inherited}
    function WaitingData: Integer; override;
    {:See @inherited}
    function GetSSLVersion: string; override;
  published
  end;

implementation

{==============================================================================}
function TSSLLibSSH2.SSHCheck(Value: integer): Boolean;
var
  PLastError: PAnsiChar;
  ErrMsgLen: Integer;
begin
  Result := true;
  FLastError := 0;
  FLastErrorDesc := '';
  if Value<0 then
  begin
    FLastError := libssh2_session_last_error(FSession, PLastError, ErrMsglen, 0);
    FLastErrorDesc := PLastError;
    Result := false;
  end;
end;


function TSSLLibSSH2.DeInit: Boolean;
begin
  if Assigned(FChannel) then
  begin
    libssh2_channel_free(FChannel);
    FChannel := nil;
  end;
  if Assigned(FSession) then
  begin
    libssh2_session_disconnect(FSession,'Goodbye');
    libssh2_session_free(FSession);
    FSession := nil;
  end;
  FSSLEnabled := False;
  Result := true;
end;

constructor TSSLLibSSH2.Create(const Value: TTCPBlockSocket);
begin
  inherited Create(Value);
  FSession := nil;
  FChannel := nil;
end;

destructor TSSLLibSSH2.Destroy;
begin
  DeInit;
  inherited Destroy;
end;

function TSSLLibSSH2.Connect: boolean;
begin
  Result := False;
  if SSLEnabled then DeInit;
  if (FSocket.Socket <> INVALID_SOCKET) and (FSocket.SSL.SSLType = LT_SSHv2) then
    begin
      FSession := libssh2_session_init();
      if not Assigned(FSession) then
      begin
        FLastError := -999;
        FLastErrorDesc := 'Cannot initialize SSH session';
        exit;
      end;
      if not SSHCheck(libssh2_session_startup(FSession, FSocket.Socket)) then
        exit;
      if (FSocket.SSL.PrivateKeyFile<>'') then
      begin
        if (not SSHCheck(libssh2_userauth_publickey_fromfile(FSession, PChar(FSocket.SSL.Username), nil, PChar(FSocket.SSL.PrivateKeyFile), PChar(FSocket.SSL.KeyPassword)))) then
          exit;
      end
      else
      if (FSocket.SSL.Username<>'') and (FSocket.SSL.Password<>'') then
      begin
        if (not SSHCheck(libssh2_userauth_password(FSession, PChar(FSocket.SSL.Username), PChar(FSocket.SSL.Password)))) then
          exit;
      end;
      FChannel := libssh2_channel_open_session(FSession);
      if not assigned(FChannel) then
      begin
        SSHCheck(-1); // get error
        if FLastError = 0 then
        begin
          FLastError := -999; // unknown error
          FLastErrorDesc := 'Cannot open session';
        end;
        exit;
      end;
      if not SSHCheck(libssh2_channel_request_pty(FChannel, 'vanilla')) then
        exit;
      if not SSHCheck(libssh2_channel_shell(FChannel)) then
        exit;
      FSSLEnabled := True;
      Result := True;
    end;
end;

function TSSLLibSSH2.LibName: String;
begin
  Result := 'ssl_libssh2';
end;

function TSSLLibSSH2.Shutdown: boolean;
begin
  Result := DeInit;
end;


function TSSLLibSSH2.BiShutdown: boolean;
begin
  Result := DeInit;
end;

function TSSLLibSSH2.SendBuffer(Buffer: TMemory; Len: Integer): Integer;
begin
  Result:=libssh2_channel_write(FChannel, PChar(Buffer), Len);
  SSHCheck(Result);
end;

function TSSLLibSSH2.RecvBuffer(Buffer: TMemory; Len: Integer): Integer;
begin
  result:=libssh2_channel_read(FChannel, PChar(Buffer), Len);
  SSHCheck(Result);
end;

function TSSLLibSSH2.WaitingData: Integer;
begin
  if libssh2_poll_channel_read(FChannel, Result) <> 1 then Result := 0;
end;

function TSSLLibSSH2.GetSSLVersion: string;
begin
  Result:=libssh2_version(0);
end;

initialization
  if libssh2_init(0)=0 then
				SSLImplementation := TSSLLibSSH2;

finalization
  libssh2_exit;

end.

Terminal client class

The telnetsshclient.pas unit below wraps around the Synapse tlntsend.pas unit and abstracts logging in, sending commands and receiving output and logging out.

If you only need a telnet client and can live without SSH support, comment out {$DEFINE HAS_SSH_SUPPORT} below so you don't need to have the libssh2 dll.

This unit has been lightly tested on a Linux ssh/telnet server. Additional tests welcome.

unit telnetsshclient;
 
{ Wrapper around Synapse libraries and SSL library (libssh2+libssl
is used right now)
Download compiled Windows dll from e.g.
http://alxdm.dyndns-at-work.com:808/files/windll_libssh2.zip
Download FreePascal interface files:
http://www.lazarus.freepascal.org/index.php/topic,15935.msg86465.html#msg86465

This unit allows the user to send Telnet or SSH commands and get the output
Thanks to Leonardo Rame
http://leonardorame.blogspot.com/2010/01/synapse-based-ssh-client.html
and Ludo Brands.
 
Written by Reinier Olislagers 2011.
Modified for libssh2 by Alexey Suhinin 2012.

License of code:
* MIT
* LGPLv2 or later (with FreePascal static linking exception)
* GPLv2 or later
according to your choice.
Free use allowed but please don't sue or blame me.
 
Uses other libraries/components; different licenses may apply that also can influence the combined/compiled work.
}
 
{$mode objfpc}{$H+}
{$DEFINE HAS_SSH_SUPPORT} //comment out if only telnet support required
{$DEFINE LIBSSH2}
 
interface
 
uses
  Classes, SysUtils,
  tlntsend
  {$IFDEF HAS_SSH_SUPPORT}
  {ssl - or actually ssh - libs required by tlntsend}
    {$IFDEF LIBSSH2}
      ssl_libssh2
    {$ELSE}
      ssl_cryptlib
  {$ENDIF}
  {$ENDIF HAS_SSH_SUPPORT}  ;
 
type
  TProtocolType = (Telnet, SSH); //Different means of connecting
  TServerType = (Unix, Windows); //line endings, mostly
  { TelnetSSHClient }
 
  { TTelnetSSHClient }
 
  TTelnetSSHClient = class(TTelnetSend)
  protected
    FConnected: boolean;
    FOutputPosition: integer; //Keeps track of position in output stream
    FProtocolType: TProtocolType;
    FServerLineEnding: string; //depends on FServerType
    FServerType: TServerType;
    FWelcomeMessage, FTelnetLoginPrompt, FTelnetPasswordPrompt: string;
    procedure SetPrivateKeyFile(Value: string);
    function GetPrivateKeyFile: string;
    { Based on protocol and servertype, set expected serverside line ending}
    procedure DetermineLineEnding;
    { Sets port if no explicit port set. Uses protocol type: SSH or telnet}
    procedure DeterminePort;
    function GetSessionLog: string;
    procedure ProtocolTypeChange(Value: TProtocolType);
    function ReceiveData: string; //Can be used to get welcome message etc.
    procedure SendData(Data: string);
    procedure ServerTypeChange(Value: TServerType);
  public
    {All output generated during the entire session up to now}
    property AllOutput: string read GetSessionLog;
    {True if connected to server}
    property Connected: boolean read FConnected;
    {Name or IP address of host to connect to}
    property HostName: string read FTargetHost write FTargetHost;
    {Port on host used for connection. If left as 0, it will be determined by protocol type (22 for SSH, 23 for Telnet}
    property Port: String read FTargetPort write FTargetPort;
    {Location of private key file.}
    property PrivateKeyFile: string read GetPrivateKeyFile write SetPrivateKeyFile;
    {Telnet login prompt}
    property TelnetLoginPrompt: string read FTelnetLoginPrompt write FTelnetLoginPrompt;
    {Telnet password prompt}
    property TelnetPasswordPrompt: string read FTelnetPasswordPrompt write FTelnetPasswordPrompt;
    {Username used when connecting}
    property UserName: string read FUserName write FUserName;
    {Password used when connecting. Used as passphrase if PrivateKey is used}
    property Password: string read FPassword write FPassword;
    {Should we talk Telnet or SSH to the server? Defaults to SSH.}
    property ProtocolType: TProtocolType read FProtocolType write ProtocolTypeChange;
    {Windows or Unix/Linux server? Has effect on line endings. Defaults to Unix. NOTE: untested}
    property Servertype: TServerType read FServerType write ServerTypeChange;
    {Initial message displayed on logon}
    property WelcomeMessage: string read FWelcomeMessage;
    {Connect/logon to server. Requires that all authentication, protocol and hostname/port options are correct
    Returns descriptive result. You can then use the Connected property.}
    function Connect: string;
    {If connected, logoff from server}
    procedure Disconnect;
    {Send command to server and receive result}
    function CommandResult(Command: string): string; //Send command and get results
    constructor Create;
    destructor Destroy; override;
  end;
 
implementation
 
 
{ TelnetSSHClient }
procedure TTelnetSSHClient.SetPrivateKeyFile(value: string);
begin
  Sock.SSL.PrivateKeyFile := value;
end;

function TTelnetSSHClient.GetPrivateKeyFile: string;
begin
  Result := Sock.SSL.PrivateKeyFile;
end;

procedure TTelnetSSHClient.DetermineLineEnding;
begin
  case FProtocolType of
    SSH:
    begin
      if FServerType = Unix then
        FServerLineEnding := #10 //Unix
      else
        FServerLineEnding := #13 + #10; //windows
    end;
    Telnet:
    begin
      if FServerType = Unix then
        FServerLineEnding := #10 //Unix
      else
        FServerLineEnding := #13 + #10; //windows
    end;
    else
      raise Exception.Create('Unknown protocol type');
  end;
end;
 
procedure Ttelnetsshclient.DeterminePort;
begin
  if FTargetPort = '' then
    //Set default port for protocol
  begin
    case FProtocolType of
      Telnet: FTargetPort := '23';
      SSH: FTargetPort := '22';
      else
        raise Exception.Create('Unknown protocol type.');
    end;
 
  end;
end;
 
procedure TTelnetSSHClient.ServerTypeChange(Value: Tservertype);
begin
  FServerType := Value;
  DetermineLineEnding;
end;
 
function TTelnetSSHClient.Connect: string;
var
  Received: string;
begin
  result:='Unknown error while connecting';
  FOutputPosition := 1; //First character in output stream
  FWelcomeMessage := '';
  //Just to make sure:
  DetermineLineEnding;
  DeterminePort;
  if FTargetPort='0' then
  begin
   result:='Port may not be 0.';
   exit; //jump out of function
  end;
  case FProtocolType of
    Telnet:
    begin
      try
        if Login then
          begin
            FConnected := True;
            result:='Connected to telnet server.';
          end
        else
          if Sock.LastError<>0 then raise Exception.Create(Sock.LastErrorDesc);
      except
        on E: Exception do
        begin
          FConnected:=false;
          result:='Error connecting to telnet server '+FTargetHost+':'+
          FTargetPort+' as user ' + FUserName +
          '. Technical details: '+E.Message;
        end;
      end;
    end;
    SSH:
    begin
      {$IFNDEF HAS_SSH_SUPPORT}
      raise Exception.Create(
        'SSH support has not been compiled into the telnetsshclient library.');
      {$ENDIF HAS_SSH_SUPPORT}
      try
        if (PrivateKeyFile <> '') and (FPassword <> '') then
          Sock.SSL.KeyPassword:=FPassword;
        if SSHLogin then
          begin
            FConnected := True;
            result:='Connected to SSH server.';
          end
        else
          begin
            if Sock.LastError<>0 then raise Exception.Create(Sock.LastErrorDesc);
            if Sock.SSL.LastError<0 then raise Exception.Create(Sock.SSL.LastErrorDesc);
          end;
      except
        on E: Exception do
        begin
          FConnected:=false;
          result:='Error connecting to SSH server '+FTargetHost+':'+
          FTargetPort+' as user ' + FUserName +
          '. Technical details: '+E.Message;
        end;
      end;
    end;
    else
      raise Exception.Create('Unknown protocol type');
  end;
  if FConnected = True then
  begin
    FWelcomeMessage := ReceiveData;
    if FProtocolType=Telnet then
    begin
      //Unfortunately, we'll have to extract login ourselves
      //Hope it applies to all server types.
      if (AnsiPos(AnsiLowerCase(FTelnetLoginPrompt),AnsiLowerCase(FWelcomeMessage))>0) then
      begin
        SendData(UserName);
      end;
      Received:=ReceiveData;
      if (AnsiPos(AnsiLowerCase(FTelnetPasswordPrompt),AnsiLowerCase(Received))>0) then
      begin
        SendData(Password);
      end;
      //Receive additional welcome message/message of the day
      FWelcomeMessage:=FWelcomeMessage+LineEnding+ReceiveData;
    end;
  end;
end;
 
procedure TTelnetSSHClient.Disconnect;
begin
  Logout;
  FConnected := False;
end;
 
function TTelnetSSHClient.ReceiveData: string;
begin
  Result := '';
  while Sock.CanRead(1000) or (Sock.WaitingData > 0) do
  begin
    Sock.RecvPacket(1000);
    Result := Result + Copy(SessionLog, FOutputPosition,
      Length(SessionLog));
    FOutputPosition := Length(SessionLog) + 1;
  end;
end;
 
procedure Ttelnetsshclient.SendData(Data: String);
begin
  Data := Data + FServerLineEnding; //Could be linux, could be Windows
  Send(Data);
end;
 
function TTelnetSSHClient.GetSessionLog: string;
begin
  // Gets complete output up to now
  Result := SessionLog;
end;
 
procedure TTelnetSSHClient.ProtocolTypeChange(Value: Tprotocoltype);
begin
  FProtocolType := Value;
  //Auto-determine port and line ending, if necessary
  DeterminePort;
  DetermineLineEnding;
end;
 
function TTelnetSSHClient.CommandResult(Command: string): string;
begin
  Result := '';
  if FConnected then
  begin
    SendData(Command);
    Result := ReceiveData; //gets too much
  end
  else
  begin
    //raise exception
    Result := '';
    raise Exception.Create('Can only run command when connected');
  end;
end;
 
constructor TTelnetSSHClient.Create;
begin
  inherited;
  FConnected := False;
  FProtocolType := SSH; //Could be telnet, too
  FServerType := Unix; //Probably a safe default.
  FTelnetLoginPrompt := 'login:';
  FTelnetPasswordPrompt := 'password:';
  DetermineLineEnding;
  DeterminePort;
end;
 
destructor TTelnetSSHClient.Destroy;
begin
  if FConnected then
    Disconnect;
  inherited Destroy;
end;
 
end.

Example client code

To use the TTelnetSSHClient class we just made, you can use this example application, sshtest.lpr. Note that it needs to be compiled by Lazarus as it needs the LCL components to work with Synapse:

program sshtest;

{Test program for telnetsshclient

Written by Reinier Olislagers 2011.
Modified for libssh2 by Alexey Suhinin 2012.

License of code:
* MIT
* LGPLv2 or later (with FreePascal static linking exception)
* GPLv2 or later
according to your choice.
Free use allowed but please don't sue or blame me.

Uses other libraries/components; different licenses may apply that also can influence the combined/compiled work.

Run: sshtest <serverIPorhostname> [PrivateKeyFile]
}
{$mode objfpc}{$H+}
{$APPTYPE CONSOLE}

uses
  telnetsshclient;
var
  comm: TTelnetSSHClient;
  Command: string;
begin
  writeln('Starting.');
  comm:=TTelnetSSHClient.Create;
  comm.HostName:= ParamStr(1); //First argument on command line
  if comm.HostName='' then
  begin
    writeln('Please specify hostname on command line.');
    halt(1);
  end;

  comm.PrivateKeyFile := ParamStr(2);

  comm.TargetPort:='0'; //auto determine based on protocoltype
  comm.UserName:='root'; //change to your situation
  comm.Password:='password'; //change to your situation
  comm.ProtocolType:=SSH; //Telnet or SSH
  writeln(comm.Connect); //Show result of connection
  if comm.Connected then
  begin
    writeln('Server: ' + comm.HostName + ':'+comm.TargetPort+', user: '+comm.UserName);
    writeln('Welcome message:');
    writeln(comm.WelcomeMessage);
    Command:='ls -al';
    writeln('*** Sending ' + Command);
    writeln('*** Begin result****');
    writeln(comm.CommandResult(Command));
    writeln('*** End result****');
    writeln('');
    writeln('');
    Command:='df -h';
    writeln('*** Sending ' + Command);
    writeln('*** Begin result****');
    writeln(comm.CommandResult(Command));
    writeln('*** End result****');
    writeln('');
    writeln('');
    writeln('All output:');
    writeln('*** Begin result****');
    writeln(comm.AllOutput);
    writeln('*** End result****');
    comm.Disconnect;
  end
  else
  begin
    writeln('Connection to ' +
      comm.HostName + ':' +
      comm.TargetPort + ' failed.');
  end;
  comm.Free;
end.

OAuth v1/Twitter/Plurk integration

An OAuth v1 library written in FPC that uses Synapse (and is ready for other network libraries like lNet) is available in fpctwit. FPCtwit also contains FPC Twitter and Plurk example client programs and a Lazarus Twitter client.

External links