text: /* The source in this file is derived from the reference implementation
   * in RFC 2617.
   * RFC 2617 is Copyright (C) The Internet Society (1999).  All Rights Reserved.
   *
   * The following copyright and licence statement covers all changes made to the
   * reference implementation.
   *
   * Key changes were: alteration to a plain C layout.
   * Create CvtBin function
   * Allow CalcHA1 to make use of precaculated username:password:realm hash's
   * to prevent squid knowing the users password (idea suggested in RFC 2617).
   */
  
  /*
   * DEBUG:
   * AUTHOR: RFC 2617 & Robert Collins
   *
   * SQUID Internet Object Cache  http://squid.nlanr.net/Squid/
   * ----------------------------------------------------------
   *
   *  Squid is the result of efforts by numerous individuals from the
   *  Internet community.  Development is led by Duane Wessels of the
   *  National Laboratory for Applied Network Research and funded by the
   *  National Science Foundation.  Squid is Copyrighted (C) 1998 by
   *  the Regents of the University of California.  Please see the
   *  COPYRIGHT file for full details.  Squid incorporates software
   *  developed and/or copyrighted by other sources.  Please see the
   *  CREDITS file for full details.
   *
   *  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, USA.
   *
   */
  
  #include "squid.h"
  #include <string.h>
  #include "rfc2617.h"
  #include "md5.h"
  
  void
  CvtHex(const HASH Bin, 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';
  }
  
  void
  CvtBin(const HASHHEX Hex, HASH Bin)
  {
      unsigned short i;
      unsigned char j;
  
      for (i = 0; i < HASHHEXLEN; i++) {
          unsigned char n;
          j = Hex[i];
          if (('0' <= j) && (j <= '9'))
              n = j - '0';
          else if (('a' <= j) && (j <= 'f'))
              n = j - 'a' + 10;
          else if (('A' <= j) && (j <= 'F'))
              n = j - 'A' + 10;
          else
              continue;
          if (i % 2 == 0)
              Bin[i / 2] = n << 4;
          else
              Bin[i / 2] |= n;
      }
      /* FIXME: Coverity detects the below as dead code.
        Why? :: right here i == 32
          which means the first step of the for loop makes i==16
          and cannot be < HASHLEN (which is also 16)
      */
      for (i = i / 2; i < HASHLEN; i++) {
          Bin[i] = '\0';
      }
  }
  
  /* calculate H(A1) as per spec */
  void
  DigestCalcHA1(
      const char *pszAlg,
      const char *pszUserName,
      const char *pszRealm,
      const char *pszPassword,
      const char *pszNonce,
      const char *pszCNonce,
      HASH HA1,
      HASHHEX SessionKey
  )
  {
      SquidMD5_CTX Md5Ctx;
  
      if (pszUserName) {
          SquidMD5Init(&Md5Ctx);
          SquidMD5Update(&Md5Ctx, pszUserName, strlen(pszUserName));
          SquidMD5Update(&Md5Ctx, ":", 1);
          SquidMD5Update(&Md5Ctx, pszRealm, strlen(pszRealm));
          SquidMD5Update(&Md5Ctx, ":", 1);
          SquidMD5Update(&Md5Ctx, pszPassword, strlen(pszPassword));
          SquidMD5Final((unsigned char *) HA1, &Md5Ctx);
      }
      if (strcasecmp(pszAlg, "md5-sess") == 0) {
          HASHHEX HA1Hex;
          CvtHex(HA1, HA1Hex);	/* RFC2617 errata */
          SquidMD5Init(&Md5Ctx);
          SquidMD5Update(&Md5Ctx, HA1Hex, HASHHEXLEN);
          SquidMD5Update(&Md5Ctx, ":", 1);
          SquidMD5Update(&Md5Ctx, pszNonce, strlen(pszNonce));
          SquidMD5Update(&Md5Ctx, ":", 1);
          SquidMD5Update(&Md5Ctx, pszCNonce, strlen(pszCNonce));
          SquidMD5Final((unsigned char *) HA1, &Md5Ctx);
      }
      CvtHex(HA1, SessionKey);
  }
  
  /* calculate request-digest/response-digest as per HTTP Digest spec */
  void
  DigestCalcResponse(
      const HASHHEX HA1,		/* H(A1) */
      const char *pszNonce,	/* nonce from server */
      const char *pszNonceCount,	/* 8 hex digits */
      const char *pszCNonce,	/* client nonce */
      const char *pszQop,		/* qop-value: "", "auth", "auth-int" */
      const char *pszMethod,	/* method from the request */
      const char *pszDigestUri,	/* requested URL */
      const HASHHEX HEntity,	/* H(entity body) if qop="auth-int" */
      HASHHEX Response		/* request-digest or response-digest */
  )
  {
      SquidMD5_CTX Md5Ctx;
      HASH HA2;
      HASH RespHash;
      HASHHEX HA2Hex;
  
      /*  calculate H(A2)
       */
      SquidMD5Init(&Md5Ctx);
      SquidMD5Update(&Md5Ctx, pszMethod, strlen(pszMethod));
      SquidMD5Update(&Md5Ctx, ":", 1);
      SquidMD5Update(&Md5Ctx, pszDigestUri, strlen(pszDigestUri));
      if (pszQop && strcasecmp(pszQop, "auth-int") == 0) {
          SquidMD5Update(&Md5Ctx, ":", 1);
          SquidMD5Update(&Md5Ctx, HEntity, HASHHEXLEN);
      }
      SquidMD5Final((unsigned char *) HA2, &Md5Ctx);
      CvtHex(HA2, HA2Hex);
  
      /* calculate response
       */
      SquidMD5Init(&Md5Ctx);
      SquidMD5Update(&Md5Ctx, HA1, HASHHEXLEN);
      SquidMD5Update(&Md5Ctx, ":", 1);
      SquidMD5Update(&Md5Ctx, pszNonce, strlen(pszNonce));
      SquidMD5Update(&Md5Ctx, ":", 1);
      if (pszQop) {
          SquidMD5Update(&Md5Ctx, pszNonceCount, strlen(pszNonceCount));
          SquidMD5Update(&Md5Ctx, ":", 1);
          SquidMD5Update(&Md5Ctx, pszCNonce, strlen(pszCNonce));
          SquidMD5Update(&Md5Ctx, ":", 1);
          SquidMD5Update(&Md5Ctx, pszQop, strlen(pszQop));
          SquidMD5Update(&Md5Ctx, ":", 1);
      }
      SquidMD5Update(&Md5Ctx, HA2Hex, HASHHEXLEN);
      SquidMD5Final((unsigned char *) RespHash, &Md5Ctx);
      CvtHex(RespHash, Response);
  }
  