/*  Starshatter OpenSource Distribution
    Copyright (c) 1997-2004, Destroyer Studios LLC.
    All Rights Reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice,
      this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright notice,
      this list of conditions and the following disclaimer in the documentation
      and/or other materials provided with the distribution.
    * Neither the name "Destroyer Studios" nor the names of its contributors
      may be used to endorse or promote products derived from this software
      without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
    AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
    ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
    LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
    CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
    SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
    INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
    CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
    ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.

    SUBSYSTEM:    Stars.exe
    FILE:         NetAuth.cpp
    AUTHOR:       John DiCamillo


    OVERVIEW
    ========
    This class represents a user connecting to the multiplayer lobby
*/


#include "MemDebug.h"
#include "NetAuth.h"
#include "NetLobby.h"
#include "NetUser.h"
#include "ModConfig.h"
#include "ModInfo.h"
#include "Random.h"
#include "Sha1.h"

static int auth_level = NetAuth::NET_AUTH_MINIMAL;

// +-------------------------------------------------------------------+

int
NetAuth::AuthLevel()
{
    return auth_level;
}


void
NetAuth::SetAuthLevel(int n)
{
    if (n >= NET_AUTH_MINIMAL && n <= NET_AUTH_SECURE)
    auth_level = n;
}

// +-------------------------------------------------------------------+

Text
NetAuth::CreateAuthRequest(NetUser* u)
{
    Text request;

    if (u) {
        u->SetAuthLevel(auth_level);

        if (auth_level == NET_AUTH_MINIMAL) {
            u->SetAuthState(NET_AUTH_OK);
            u->SetSalt("Very Low Sodium");
        }

        else if (auth_level == NET_AUTH_STANDARD) {
            u->SetAuthState(NET_AUTH_INITIAL);
            u->SetSalt("Very Low Sodium");

            request = "level 1";
        }

        else {
            char salt[33];

            for (int i = 0; i < 32; i++)
            salt[i] = (char) ('0' + (int) Random(0, 9.4));

            salt[32] = 0;
            u->SetSalt(salt);
            u->SetAuthState(NET_AUTH_INITIAL);

            request = "level 2 salt ";
            request += salt;
        }
    }

    return request;
}

// +-------------------------------------------------------------------+

static Text Digest(const char* salt, const char* file)
{
    int  length = 0;
    int  offset = 0;
    char block[4096];
    char digest[64];

    ZeroMemory(digest, sizeof(digest));

    if (file) {
        FILE* f;
        fopen_s(&f, file, "rb");

        if (f) {
            SHA1 sha1;

            if (salt) {
                sha1.Input(salt, strlen(salt));
            }

            fseek(f, 0, SEEK_END);
            length = ftell(f);
            fseek(f, 0, SEEK_SET);

            while (offset < length) {
                int n = fread(block, sizeof(char), 4096, f);
                sha1.Input(block, n);
                offset += n;
            }

            fclose(f);

            unsigned result[5];
            if (sha1.Result(result)) {
                sprintf_s(digest, "SHA1_%08X_%08X_%08X_%08X_%08X",
                result[0], result[1], result[2], result[3], result[4]);
            }
        }
    }

    return digest;
}

// +-------------------------------------------------------------------+

Text
NetAuth::CreateAuthResponse(int level, const char* salt)
{
    Text        response;
    ModConfig*  config = ModConfig::GetInstance();

    if (level == NET_AUTH_SECURE) {
        response += "exe ";
        response += Digest(salt, "stars.exe");    // XXX should look up name of this exe
        response += " ";

        response += "dat ";
        response += Digest(salt, "shatter.dat");
        response += " ";

        response += "etc ";
        response += Digest(salt, "start.dat");
        response += " ";
    }

    if (level >= NET_AUTH_STANDARD) {
        List<ModInfo>&    mods     = config->GetModInfoList();
        ListIter<ModInfo> mod_iter = mods;

        char buffer[32];
        sprintf_s(buffer, "num %d ", mods.size());
        response += buffer;

        while (++mod_iter) {
            ModInfo* info = mod_iter.value();

            response += "mod \"";
            response += info->Name();
            response += "\" ver \"";
            response += info->Version();
            response += "\" ";

            if (level == NET_AUTH_SECURE) {
                response += "sha ";
                response += Digest(salt, info->Filename());
                response += " ";
            }
        }
    }

    return response;
}

// +-------------------------------------------------------------------+

bool
NetAuth::AuthUser(NetUser* u, Text response)
{
    bool authentic = false;

    if (auth_level == NET_AUTH_MINIMAL) {  // (this case should not occur)
        if (u) {
            u->SetAuthLevel(auth_level);
            u->SetAuthState(NET_AUTH_OK);
        }

        authentic = (u != 0);
    }

    else if (u) {
        Text expected_response = CreateAuthResponse(auth_level, u->Salt());
        if (expected_response == response)
        authentic = true;

        u->SetAuthState(authentic ? NET_AUTH_OK : NET_AUTH_FAILED);
    }

    return authentic;
}

// +-------------------------------------------------------------------+