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home » brain » inspircd-cvs » inspircd » src » modules » m_spanningtree

hmac.cpp

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/*       +------------------------------------+
 *       | Inspire Internet Relay Chat Daemon |
 *       +------------------------------------+
 *
 *  InspIRCd: (C) 2002-2008 InspIRCd Development Team
 * See: http://www.inspircd.org/wiki/index.php/Credits
 *
 * This program is free but copyrighted software; see
 *            the file COPYING for details.
 *
 * ---------------------------------------------------
 */

#include "inspircd.h"
#include "commands/cmd_whois.h"
#include "commands/cmd_stats.h"
#include "socket.h"
#include "xline.h"
#include "transport.h"
#include "m_hash.h"
#include "socketengine.h"

#include "m_spanningtree/main.h"
#include "m_spanningtree/utils.h"
#include "m_spanningtree/treeserver.h"
#include "m_spanningtree/link.h"
#include "m_spanningtree/treesocket.h"
#include "m_spanningtree/resolvers.h"
#include "m_spanningtree/handshaketimer.h"

/* $ModDep: m_spanningtree/resolvers.h m_spanningtree/main.h m_spanningtree/utils.h m_spanningtree/treeserver.h m_spanningtree/link.h m_spanningtree/treesocket.h m_hash.h */

const std::string& TreeSocket::GetOurChallenge()
{
        return this->ourchallenge;
}

void TreeSocket::SetOurChallenge(const std::string &c)
{
        this->ourchallenge = c;
}

const std::string& TreeSocket::GetTheirChallenge()
{
        return this->theirchallenge;
}

void TreeSocket::SetTheirChallenge(const std::string &c)
{
        this->theirchallenge = c;
}

std::string TreeSocket::MakePass(const std::string &password, const std::string &challenge)
{
        /* This is a simple (maybe a bit hacky?) HMAC algorithm, thanks to jilles for
         * suggesting the use of HMAC to secure the password against various attacks.
         *
         * Note: If m_sha256.so is not loaded, we MUST fall back to plaintext with no
         *       HMAC challenge/response.
         */
        Module* sha256 = ServerInstance->Modules->Find("m_sha256.so");
        if (Utils->ChallengeResponse && sha256 && !challenge.empty())
        {
                /* XXX: This is how HMAC is supposed to be done:
                 *
                 * sha256( (pass xor 0x5c) + sha256((pass xor 0x36) + m) )
                 *
                 * Note that we are encoding the hex hash, not the binary
                 * output of the hash which is slightly different to standard.
                 *
                 * Don't ask me why its always 0x5c and 0x36... it just is.
                 */
                std::string hmac1, hmac2;

                for (size_t n = 0; n < password.length(); n++)
                {
                        hmac1 += static_cast<char>(password[n] ^ 0x5C);
                        hmac2 += static_cast<char>(password[n] ^ 0x36);
                }

                hmac2 += challenge;
                HashResetRequest(Utils->Creator, sha256).Send();
                hmac2 = HashSumRequest(Utils->Creator, sha256, hmac2).Send();

                HashResetRequest(Utils->Creator, sha256).Send();
                std::string hmac = hmac1 + hmac2;
                hmac = HashSumRequest(Utils->Creator, sha256, hmac).Send();

                return "HMAC-SHA256:"+ hmac;
        }
        else if (!challenge.empty() && !sha256)
                ServerInstance->Logs->Log("m_spanningtree",DEFAULT,"Not authenticating to server using SHA256/HMAC because we don't have m_sha256 loaded!");

        return password;
}

std::string TreeSocket::RandString(unsigned int ilength)
{
        char* randombuf = new char[ilength+1];
        std::string out;
#ifdef WINDOWS
        int f = -1;
#else
        int f = open("/dev/urandom", O_RDONLY, 0);
#endif

        if (f >= 0)
        {
#ifndef WINDOWS
                if (read(f, randombuf, ilength) < 1)
                        ServerInstance->Logs->Log("m_spanningtree", DEFAULT, "There are crack smoking monkeys in your kernel (in other words, nonblocking /dev/urandom blocked.)");
                close(f);
#endif
        }
        else
        {
                for (unsigned int i = 0; i < ilength; i++)
                        randombuf[i] = rand();
        }

        for (unsigned int i = 0; i < ilength; i++)
        {
                char randchar = static_cast<char>((randombuf[i] & 0x7F) | 0x21);
                out += (randchar == '=' ? '_' : randchar);
        }

        delete[] randombuf;
        return out;
}

bool TreeSocket::ComparePass(const std::string &ours, const std::string &theirs)
{
        if ((!strncmp(ours.c_str(), "HMAC-SHA256:", 12)) || (!strncmp(theirs.c_str(), "HMAC-SHA256:", 12)))
        {
                /* One or both of us specified hmac sha256, but we don't have sha256 module loaded!
                 * We can't allow this password as valid.
                  */
                if (!ServerInstance->Modules->Find("m_sha256.so") || !Utils->ChallengeResponse)
                        return false;
                else
                        /* Straight string compare of hashes */
                        return ours == theirs;
        }
        else
                /* Straight string compare of plaintext */
                return ours == theirs;
}