tdelibs/kdesu/ssh.cpp

/* vi: ts=8 sts=4 sw=4
*
* $Id$
*
* This file is part of the KDE project, module kdesu.
* Copyright (C) 2000 Geert Jansen <jansen@kde.org>
*
* This is free software; you can use this library under the GNU Library
* General Public License, version 2. See the file "COPYING.LIB" for the
* exact licensing terms.
*
* ssh.cpp: Execute a program on a remote machine using ssh.
*/

#include <config.h>

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <errno.h>
#include <string.h>
#include <ctype.h>
#include <signal.h>
#include <time.h>

#include <sys/types.h>
#include <sys/stat.h>

#include <tqglobal.h>
#include <tqcstring.h>

#include <kdebug.h>
#include <klocale.h>
#include <kstandarddirs.h>

#include "ssh.h"
#include "kcookie.h"


SshProcess::SshProcess(const TQCString &host, const TQCString &user, const TQCString &command)
{
    m_Host = host;
    m_User = user;
    m_Command = command;
    m_Stub = "kdesu_stub";
    srand(time(0L));
}


SshProcess::~SshProcess()
{
}


void SshProcess::setStub(const TQCString &stub)
{
    m_Stub = stub;
}


int SshProcess::checkInstall(const char *password)
{
    return exec(password, 1);
}


int SshProcess::checkNeedPassword()
{
    return exec(0L, 2);
}


int SshProcess::exec(const char *password, int check)
{
    if (check)
    setTerminal(true);

    QCStringList args;
    args += "-l"; args += m_User;
    args += "-o"; args += "StrictHostKeyChecking=no";
    args += m_Host; args += m_Stub;

    if (StubProcess::exec("ssh", args) < 0)
    {
        return check ? SshNotFound : -1;
    }

    int ret = ConverseSsh(password, check);
    if (ret < 0)
    {
        if (!check)
            kdError(900) << k_lineinfo << "Conversation with ssh failed\n";
        return ret;
    }
    if (check == 2)
    {
        if (ret == 1)
        {
            kill(m_Pid, SIGTERM);
            waitForChild();
        }
        return ret;
    }

    if (m_bErase && password)
    {
        char *ptr = const_cast<char *>(password);
        const uint plen = strlen(password);
        for (unsigned i=0; i < plen; i++)
            ptr[i] = '\000';
    }

    ret = ConverseStub(check);
    if (ret < 0)
    {
        if (!check)
            kdError(900) << k_lineinfo << "Converstation with kdesu_stub failed\n";
        return ret;
    }
    else if (ret == 1)
    {
        kill(m_Pid, SIGTERM);
        waitForChild();
        ret = SshIncorrectPassword;
    }

    if (check == 1)
    {
        waitForChild();
        return 0;
    }

    setExitString("Waiting for forwarded connections to terminate");
    ret = waitForChild();
    return ret;
}

/*
* Create a port forwarding for DCOP. For the remote port, we take a pseudo
* random number between 10k and 50k. This is not ok, of course, but I see
* no other way. There is, afaik, no security issue involved here. If the port
* happens to be occupied, ssh will refuse to start.
*
* 14/SEP/2000: DCOP forwarding is not used anymore.
*/

TQCString SshProcess::dcopForward()
{
    TQCString result;

    setDcopTransport("tcp");

    TQCString srv = StubProcess::dcopServer();
    if (srv.isEmpty())
        return result;

    int i = srv.find('/');
    if (i == -1)
        return result;
    if (srv.left(i) != "tcp")
        return result;
    int j = srv.find(':', ++i);
    if (j == -1)
        return result;
    TQCString host = srv.mid(i, j-i);
    bool ok;
    int port = srv.mid(++j).toInt(&ok);
    if (!ok)
        return result;

    m_dcopPort = 10000 + (int) ((40000.0 * rand()) / (1.0 + RAND_MAX));
    result.sprintf("%d:%s:%d", m_dcopPort, host.data(), port);
    return result;
}


/*
* Conversation with ssh.
* If check is 0, this waits for either a "Password: " prompt,
* or the header of the stub. If a prompt is received, the password is
* written back. Used for running a command.
* If check is 1, operation is the same as 0 except that if a stub header is
* received, the stub is stopped with the "stop" command. This is used for
* checking a password.
* If check is 2, operation is the same as 1, except that no password is
* written. The prompt is saved to m_Prompt. Used for checking the need for
* a password.
*/

int SshProcess::ConverseSsh(const char *password, int check)
{
    unsigned i, j, colon;

    TQCString line;
    int state = 0;

    while (state < 2)
    {
        line = readLine();
        const uint len = line.length();
        if (line.isNull())
            return -1;

        switch (state) {
        case 0:
            // Check for "kdesu_stub" header.
            if (line == "kdesu_stub")
            {
                unreadLine(line);
                return 0;
            }
    
            // Match "Password: " with the regex ^[^:]+:[\w]*$.
            for (i=0,j=0,colon=0; i<len; i++)
            {
                if (line[i] == ':')
                {
                    j = i; colon++;
                    continue;
                }
                if (!isspace(line[i]))
                    j++;
            }
            if ((colon == 1) && (line[j] == ':'))
            {
                if (check == 2)
                {
                    m_Prompt = line;
                    return SshNeedsPassword;
                }
                WaitSlave();
                write(m_Fd, password, strlen(password));
                write(m_Fd, "\n", 1);
                state++;
                break;
            }
    
            // Warning/error message.
            m_Error += line; m_Error += "\n";
            if (m_bTerminal)
                fprintf(stderr, "ssh: %s\n", line.data());
            break;
    
        case 1:
            if (line.isEmpty())
            {
                state++;
                break;
            }
            return -1;
        }
    }
    return 0;
}


// Display redirection is handled by ssh natively.
TQCString SshProcess::display()
{
    return "no";
}


TQCString SshProcess::displayAuth()
{
    return "no";
}


// Return the remote end of the forwarded connection.
TQCString SshProcess::dcopServer()
{
    return TQCString().sprintf("tcp/localhost:%d", m_dcopPort);
}

void SshProcess::virtual_hook( int id, void* data )
{ StubProcess::virtual_hook( id, data ); }