//
// ZoneMinder RTSP Authentication Class Implementation, $Date$, $Revision$
// 
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
// 

#include "zm.h"
#include "zm_utils.h"
#include "zm_rtsp_auth.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

Authenticator::Authenticator(std::string &username, std::string password) {
#ifdef HAVE_GCRYPT_H
    // Special initialisation for libgcrypt
    if ( !gcry_check_version( GCRYPT_VERSION ) )
    {
        Fatal( "Unable to initialise libgcrypt" );
    }
    gcry_control( GCRYCTL_DISABLE_SECMEM, 0 );
    gcry_control( GCRYCTL_INITIALIZATION_FINISHED, 0 );
#endif // HAVE_GCRYPT_H
    
    fAuthMethod = AUTH_UNDEFINED;
    fUsername = username;
    fPassword = password;
}

Authenticator::~Authenticator() {
	reset();
}

void Authenticator::reset() {
	fRealm.clear(); 
	fNonce.clear();
	fUsername.clear(); 
	fPassword.clear();
	fAuthMethod = AUTH_UNDEFINED;
}

void Authenticator::authHandleHeader(std::string headerData) 
{
    const char* basic_match = "Basic ";
    const char* digest_match = "Digest ";
    size_t digest_match_len = strlen(digest_match);
    
    // Check if basic auth
    if (strncasecmp(headerData.c_str(),basic_match,strlen(basic_match)) == 0)
    {
        fAuthMethod = AUTH_BASIC;
        Debug( 2, "Set authMethod to Basic");
    } 
    // Check if digest auth
    else if (strncasecmp( headerData.c_str(),digest_match,digest_match_len ) == 0)
    {
        fAuthMethod = AUTH_DIGEST;
        Debug( 2, "Set authMethod to Digest");
        StringVector subparts = split(headerData.substr(digest_match_len, headerData.length() - digest_match_len), ",");
        // subparts are key="value"
        for ( size_t i = 0; i < subparts.size(); i++ )
        {
            StringVector kvPair = split( trimSpaces( subparts[i] ), "=" );
            std::string key = trimSpaces( kvPair[0] );
            if (key == "realm") {
                fRealm = trimSet( kvPair[1], "\"");
                continue;
            }
            if (key == "nonce") {
                fNonce = trimSet( kvPair[1], "\"");
                continue;
            }
        }
        Debug( 2, "Auth data completed. User: %s, realm: %s, nonce: %s", username().c_str(), fRealm.c_str(), fNonce.c_str());
    }
}

std::string Authenticator::quote(std::string src)
{
    return replaceAll(replaceAll(src, "\\", "\\\\"), "\"", "\\\"");
}

std::string Authenticator::getAuthHeader(std::string method, std::string uri) 
{
    std::string result = "Authorization: ";
    if (fAuthMethod == AUTH_BASIC) 
    {
        result += "Basic " + base64Encode( username() + ":" + password() );
    }
    else if (fAuthMethod == AUTH_DIGEST)
    {
        result += std::string("Digest ") + 
        		  "username=\"" + quote(username()) + "\", realm=\"" + quote(realm()) + "\", " +
                  "nonce=\"" + quote(nonce()) + "\", uri=\"" + quote(uri) + "\", " + 
                  "response=\"" + computeDigestResponse(method, uri) + "\"";
                  
        //Authorization: Digest username="zm",
        //                      realm="NC-336PW-HD-1080P",
        //                      nonce="de8859d97609a6fcc16eaba490dcfd80",
        //                      uri="rtsp://10.192.16.8:554/live/0/h264.sdp",
        //                      response="4092120557d3099a163bd51a0d59744d",
        //                      algorithm=MD5,
        //                      opaque="5ccc069c403ebaf9f0171e9517f40e41",
        //                      qop="auth",
        //                      cnonce="c8051140765877dc",
        //                      nc=00000001
        
    }
    result += "\r\n";
    return result;
}

std::string Authenticator::computeDigestResponse(std::string &method, std::string &uri) {
#if HAVE_DECL_MD5 || HAVE_DECL_GNUTLS_FINGERPRINT
    // The "response" field is computed as:
    //    md5(md5(<username>:<realm>:<password>):<nonce>:md5(<cmd>:<url>))
    size_t md5len = 16;
    unsigned char md5buf[md5len];
    char md5HexBuf[md5len*2+1];
    
    // Step 1: md5(<username>:<realm>:<password>)
    std::string ha1Data = username() + ":" + realm() + ":" + password();
#if HAVE_DECL_MD5
    MD5((unsigned char*)ha1Data.c_str(), ha1Data.length(), md5buf);
#elif HAVE_DECL_GNUTLS_FINGERPRINT
    gnutls_datum_t md5dataha1 = { (unsigned char*)ha1Data.c_str(), ha1Data.length() };
    gnutls_fingerprint( GNUTLS_DIG_MD5, &md5dataha1, md5buf, &md5len );
#endif
    for ( unsigned int j = 0; j < md5len; j++ )
    {
        sprintf(&md5HexBuf[2*j], "%02x", md5buf[j] );
    }
    md5HexBuf[md5len*2]='\0';
    std::string ha1Hash = md5HexBuf;
    
    // Step 2: md5(<cmd>:<url>)
    std::string ha2Data = method + ":" + uri;
#if HAVE_DECL_MD5
    MD5((unsigned char*)ha2Data.c_str(), ha2Data.length(), md5buf );
#elif HAVE_DECL_GNUTLS_FINGERPRINT
    gnutls_datum_t md5dataha2 = { (unsigned char*)ha2Data.c_str(), ha2Data.length() };
    gnutls_fingerprint( GNUTLS_DIG_MD5, &md5dataha2, md5buf, &md5len );
#endif
    for ( unsigned int j = 0; j < md5len; j++ )
    {
        sprintf( &md5HexBuf[2*j], "%02x", md5buf[j] );
    }
    md5HexBuf[md5len*2]='\0';
    std::string ha2Hash = md5HexBuf;

    // Step 3: md5(ha1:<nonce>:ha2)
    std::string digestData = ha1Hash + ":" + nonce() + ":" + ha2Hash;
#if HAVE_DECL_MD5
    MD5((unsigned char*)digestData.c_str(), digestData.length(), md5buf);
#elif HAVE_DECL_GNUTLS_FINGERPRINT
    gnutls_datum_t md5datadigest = { (unsigned char*)digestData.c_str(), digestData.length() };
    gnutls_fingerprint( GNUTLS_DIG_MD5, &md5datadigest, md5buf, &md5len );
#endif
    for ( unsigned int j = 0; j < md5len; j++ )
    {
        sprintf( &md5HexBuf[2*j], "%02x", md5buf[j] );
    }
    md5HexBuf[md5len*2]='\0';
   
    return md5HexBuf;
#else // HAVE_DECL_MD5
	Error( "You need to build with gnutls or openssl installed to use digest authentication" );
#endif // HAVE_DECL_MD5
    return( 0 );
}