/*
  *  OpenVPN -- An application to securely tunnel IP networks
  *             over a single TCP/UDP port, with support for SSL/TLS-based
  *             session authentication and key exchange,
  *             packet encryption, packet authentication, and
  *             packet compression.
  *

  *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>

  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License version 2
  *  as published by the Free Software Foundation.
  *
  *  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.,
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

  */
 

 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #elif defined(_MSC_VER)
 #include "config-msvc.h"
 #endif
 

 #include "syshead.h"
 
 #if PROXY_DIGEST_AUTH
 
 #include "crypto.h"
 #include "httpdigest.h"
 
 static void
 CvtHex(

     IN HASH Bin,
     OUT HASHHEX Hex
     )

 {

     unsigned short i;
     unsigned char j;

     for (i = 0; i < HASHLEN; i++)
     {

         j = (Bin[i] >> 4) & 0xf;
         if (j <= 9)
         {
             Hex[i*2] = (j + '0');
         }
         else
         {
             Hex[i*2] = (j + 'a' - 10);
         }
         j = Bin[i] & 0xf;
         if (j <= 9)
         {
             Hex[i*2+1] = (j + '0');
         }
         else
         {
             Hex[i*2+1] = (j + 'a' - 10);
         }
     }
     Hex[HASHHEXLEN] = '\0';
 }

 
 /* calculate H(A1) as per spec */
 void
 DigestCalcHA1(

     IN char *pszAlg,
     IN char *pszUserName,
     IN char *pszRealm,
     IN char *pszPassword,
     IN char *pszNonce,
     IN char *pszCNonce,
     OUT HASHHEX SessionKey
     )

 {

     HASH HA1;

     md_ctx_t *md5_ctx = md_ctx_new();

     const md_kt_t *md5_kt = md_kt_get("MD5");

     md_ctx_init(md5_ctx, md5_kt);
     md_ctx_update(md5_ctx, (const uint8_t *) pszUserName, strlen(pszUserName));
     md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
     md_ctx_update(md5_ctx, (const uint8_t *) pszRealm, strlen(pszRealm));
     md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
     md_ctx_update(md5_ctx, (const uint8_t *) pszPassword, strlen(pszPassword));
     md_ctx_final(md5_ctx, HA1);

     if (pszAlg && strcasecmp(pszAlg, "md5-sess") == 0)

     {

         md_ctx_init(md5_ctx, md5_kt);
         md_ctx_update(md5_ctx, HA1, HASHLEN);
         md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
         md_ctx_update(md5_ctx, (const uint8_t *) pszNonce, strlen(pszNonce));
         md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
         md_ctx_update(md5_ctx, (const uint8_t *) pszCNonce, strlen(pszCNonce));
         md_ctx_final(md5_ctx, HA1);

     }

     md_ctx_cleanup(md5_ctx);
     md_ctx_free(md5_ctx);

     CvtHex(HA1, SessionKey);

 }
 
 /* calculate request-digest/response-digest as per HTTP Digest spec */
 void
 DigestCalcResponse(

     IN HASHHEX HA1,                          /* H(A1) */
     IN char *pszNonce,                       /* nonce from server */
     IN char *pszNonceCount,                  /* 8 hex digits */
     IN char *pszCNonce,                      /* client nonce */
     IN char *pszQop,                         /* qop-value: "", "auth", "auth-int" */
     IN char *pszMethod,                      /* method from the request */
     IN char *pszDigestUri,                   /* requested URL */
     IN HASHHEX HEntity,                      /* H(entity body) if qop="auth-int" */
     OUT HASHHEX Response                     /* request-digest or response-digest */
     )

 {

     HASH HA2;
     HASH RespHash;
     HASHHEX HA2Hex;

     md_ctx_t *md5_ctx = md_ctx_new();

     const md_kt_t *md5_kt = md_kt_get("MD5");

     /* calculate H(A2) */

     md_ctx_init(md5_ctx, md5_kt);
     md_ctx_update(md5_ctx, (const uint8_t *) pszMethod, strlen(pszMethod));
     md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
     md_ctx_update(md5_ctx, (const uint8_t *) pszDigestUri, strlen(pszDigestUri));

     if (strcasecmp(pszQop, "auth-int") == 0)

     {

         md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
         md_ctx_update(md5_ctx, HEntity, HASHHEXLEN);

     }

     md_ctx_final(md5_ctx, HA2);

     CvtHex(HA2, HA2Hex);

     /* calculate response */

     md_ctx_init(md5_ctx, md5_kt);
     md_ctx_update(md5_ctx, HA1, HASHHEXLEN);
     md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
     md_ctx_update(md5_ctx, (const uint8_t *) pszNonce, strlen(pszNonce));
     md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);

     if (*pszQop)

     {

         md_ctx_update(md5_ctx, (const uint8_t *) pszNonceCount, strlen(pszNonceCount));
         md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
         md_ctx_update(md5_ctx, (const uint8_t *) pszCNonce, strlen(pszCNonce));
         md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
         md_ctx_update(md5_ctx, (const uint8_t *) pszQop, strlen(pszQop));
         md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);

     }

     md_ctx_update(md5_ctx, HA2Hex, HASHHEXLEN);
     md_ctx_final(md5_ctx, RespHash);
     md_ctx_cleanup(md5_ctx);
     md_ctx_free(md5_ctx);

     CvtHex(RespHash, Response);

 }
 

 #endif /* if PROXY_DIGEST_AUTH */