ssh.cpp

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/* vi: ts=8 sts=4 sw=4
*
* 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 "ssh.h"
#include "kcookie.h"

#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 <time.h>

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

#include <QtCore/QBool>

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

extern int kdesuDebugArea();

namespace KDESu {

using namespace KDESuPrivate;

class SshProcess::SshProcessPrivate
{
public:
    SshProcessPrivate(const QByteArray &host)
        : m_Host( host )
        , m_Stub( "kdesu_stub" )
    {}
    QByteArray m_Prompt;
    QByteArray m_Host;
    QByteArray m_Error;
    QByteArray m_Stub;
};


SshProcess::SshProcess(const QByteArray &host, const QByteArray &user, const QByteArray &command)
    : d( new SshProcessPrivate(host) )
{
    m_User = user;
    m_Command = command;
    srand(time(0L));
}


SshProcess::~SshProcess()
{
    delete d;
}

void SshProcess::setHost(const QByteArray &host)
{
    d->m_Host = host;
}


void SshProcess::setStub(const QByteArray &stub)
{
    d->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);

    QList<QByteArray> args;
    args += "-l"; args += m_User;
    args += "-o"; args += "StrictHostKeyChecking=no";
    args += d->m_Host; args += d->m_Stub;

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

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

    if (m_bErase && password)
        memset(const_cast<char *>(password), 0, qstrlen(password));

    ret = ConverseStub(check);
    if (ret < 0)
    {
        if (!check)
            kError(kdesuDebugArea()) << k_lineinfo << "Conversation with kdesu_stub failed.";
        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;
}

QByteArray SshProcess::prompt() const
{
    return d->m_Prompt;
}

QByteArray SshProcess::error() const
{
    return d->m_Error;
}


/*
* 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;

    QByteArray 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)
                {
                    d->m_Prompt = line;
                    return SshNeedsPassword;
                }
                if (WaitSlave())
                    return -1;
                write(fd(), password, strlen(password));
                write(fd(), "\n", 1);
                state++;
                break;
            }

            // Warning/error message.
            d->m_Error += line; d->m_Error += '\n';
            if (m_bTerminal)
                fprintf(stderr, "ssh: %s\n", line.constData());
            break;

        case 1:
            if (line.isEmpty())
            {
                state++;
                break;
            }
            return -1;
        }
    }
    return 0;
}


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


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

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

}