SSH package for U++
--------------------

SSH package is a libssh2 wrapper for Ultimate++.
It aims to be a complete secure shell client solution. (SFtp, Scp, Exec, Terminal, X11Exec, KnownHosts)
Currently it is at a technical preview stage, which means it is a work-in-progress, and subject to change.

Requirements:

- A C++ compiler with at least C++11 support.
- libssh2 ssh library (https://www.libssh2.org/)

Features and Highlights:

- Tight integration with U++.
- Support for both synchronous and asynchronous operations  with both high level and low level methods.
- Allows using U++ style memory [de/re]allocators with libssh2.
- Ssh subsystems support RTTI, and share a common interface for polymorphism. 
  Namely, it is possible to store different subsystems in the same U++ container. 
  (e.g. SFtp, Exec, Scp, Shell can be all stored in the same Array.)

Todo:

- Add known hosts and ssh agents support.
- Add more high level methods.
- Add ssh X11 support.
- Ship libssh2 library with the package.
- Documentation.

History:
-----------------

2017-06-28:  EAGAIN is now properly handled across the subsystems.
             WhenWrite and WhenRead callbacks are removed in favour of parametrized gates.
2017-06-27:  SFtp::StartStop: fixed.
2017-06-27:  CleanUp() methods are added to the classes Ssh, SFtp, and Channel.
             This method utilizes JobQueue's WhenCleanup event.
2017-06-26:  U++ memory [de/re]allocators added and made default.
             initial support for ssh shell, and terminal added.
             Subsystems now perform a clean up on failure to prevent possible heap leaks.          
2017-06-22:  Initial release.

[
Ssh           -> Main session class (system). Provides connection and authentication mechanism. Although known Hosts support not added yet, it will be available in the following versions.

SshSubsystem  -> SshSubsystem is base of all SSH protocol based communication subsystems.
--------------
SFtp          -> Complete, but I'm planning to further enhance it with more high level commannds, once the api stabilized.
Channel       -> Mostly done.
Scp           -> Complete.
Exec          -> Complete.
Shell         -> Not added yet. Besic support is present. And will be developed durther.
Terminal      -> Not added yet. Basic support is present. And will be developed further.
X11Exec       -> Not added yet. Will be added incrementally.

#include <Core/Core.h>
#include <SSH/SSH.h>

using namespace Upp;

// SshExec.cpp: 
// Demonstrates remote command execution on an ssh channel.

// A popular public test server:
// -----------------------------
// Host:     test.rebex.net
// User:     user
// Password: password
// Command:  ls -l

CONSOLE_APP_MAIN
{
	Ssh session;
	Cout() << "Hostname: ";
	auto host = ReadStdIn();
	Cout() << "Username: ";
	auto user = ReadStdIn();
	Cout() << "Password: ";
	auto pass = ReadStdIn();
	const int port = 22;

	if(session.Connect(host, port, user, pass)) {
		Cout() << "Command: ";
		auto cmd = ReadStdIn();
		Exec xc(session);
		auto rc = xc(cmd, Cout(), Cerr());
		if(xc.IsFailure()) Cerr() << Format("Exec failed. %s", xc.GetErrorDesc());
		else Cout() << Format("Remote program exited with code: %d\n", rc);
	}
	else Cerr() << session.GetErrorDesc() << '\n';
}

#include <Core/Core.h>
#include <SSH/SSH.h>

using namespace Upp;

// SFtpDir.cpp: 
// Demonstrates remote directory listing via an sftp channel.

// A popular public test server:
// -----------------------------
// Host:     test.rebex.net
// User:     user
// Password: password
// Path:     pub/examples

CONSOLE_APP_MAIN
{
	Ssh session;
	Cout() << "Hostname: ";
	auto host = ReadStdIn();
	Cout() << "Username: ";
	auto user = ReadStdIn();
	Cout() << "Password: ";
	auto pass = ReadStdIn();
	Cout() << "Path: ";
	auto path = ReadStdIn();
	const int port = 22;

	if(session.Connect(host, port, user, pass)) {
		SFtp sftp(session);
		SFtp::DirList ls;
		if(!sftp.ListDir(path, ls)) Exit(sftp.GetError());
		for(auto& e : ls)  Cout() << e.GetEntry() << "\n";
	}
	else Cerr() << session.GetErrorDesc() << '\n';
}