/*
 *  sha.cpp
 *
 *  Copyright (C) 1998, 2009
 *  Paul E. Jones <paulej@packetizer.com>
 *  All Rights Reserved
 *
 *****************************************************************************
 *  $Id: sha.c 12 2009-06-22 19:34:25Z paulej $
 *****************************************************************************
 *
 *  Description:
 *      This utility will display the message digest (fingerprint) for
 *      the specified file(s).
 *
 *  Portability Issues:
 *      None.
 */

#include <stdio.h>
#include <string.h>
#ifdef WIN32
#include <io.h>
#endif
#include <fcntl.h>
#include <string/stdstring.h>
/*#include "sha1.h"*/

/*
 *  Function prototype
 */
void usage(void);

/*
 *  main
 *
 *  Description:
 *      This is the entry point for the program
 *
 *  Parameters:
 *      argc: [in]
 *          This is the count of arguments in the argv array
 *      argv: [in]
 *          This is an array of filenames for which to compute message
 *          digests
 *
 *  Returns:
 *      Nothing.
 *
 *  Comments:
 *
 */
typedef struct SHA1Context
{
   unsigned Message_Digest[5]; /* Message Digest (output)          */

   unsigned Length_Low;        /* Message length in bits           */
   unsigned Length_High;       /* Message length in bits           */

   unsigned char Message_Block[64]; /* 512-bit message blocks      */
   int Message_Block_Index;    /* Index into message block array   */

   int Computed;               /* Is the digest computed?          */
   int Corrupted;              /* Is the message digest corruped?  */
} SHA1Context;

int main(int argc, char *argv[])
{
   struct SHA1Context sha;         /* SHA-1 context                 */
   FILE        *fp;                /* File pointer for reading files*/
   char        c;                  /* Character read from file      */
   int         i;                  /* Counter                       */
   int         reading_stdin;      /* Are we reading standard in?   */
   int         read_stdin = 0;     /* Have we read stdin?           */

   /*
    *  Check the program arguments and print usage information if -?
    *  or --help is passed as the first argument.
    */
   if (argc > 1 && (string_is_equal(argv[1],"-?") ||
            string_is_equal(argv[1],"--help")))
   {
      usage();
      return 1;
   }

   /*
    *  For each filename passed in on the command line, calculate the
    *  SHA-1 value and display it.
    */
   for(i = 0; i < argc; i++)
   {
      /*
       *  We start the counter at 0 to guarantee entry into the for
       *  loop. So if 'i' is zero, we will increment it now.  If there
       *  is no argv[1], we will use STDIN below.
       */
      if (i == 0)
         i++;

      if (argc == 1 || string_is_equal(argv[i],"-"))
      {
#ifdef WIN32
         setmode(fileno(stdin), _O_BINARY);
#endif
         fp = stdin;
         reading_stdin = 1;
      }
      else
      {
         if (!(fp = fopen(argv[i],"rb")))
         {
            fprintf(stderr,
                  "sha: unable to open file %s\n",
                  argv[i]);
            return 2;
         }
         reading_stdin = 0;
      }

      /*
       *  We do not want to read STDIN multiple times
       */
      if (reading_stdin)
      {
         if (read_stdin)
            continue;

         read_stdin = 1;
      }

      /*
       *  Reset the SHA-1 context and process input
       */
      SHA1Reset(&sha);

      c = fgetc(fp);
      while(!feof(fp))
      {
         SHA1Input(&sha, &c, 1);
         c = fgetc(fp);
      }

      if (!reading_stdin)
         fclose(fp);

      if (!SHA1Result(&sha))
      {
         fprintf(stderr,
               "sha: could not compute message digest for %s\n",
               reading_stdin?"STDIN":argv[i]);
      }
      else
      {
         printf( "%08X %08X %08X %08X %08X - %s\n",
               sha.Message_Digest[0],
               sha.Message_Digest[1],
               sha.Message_Digest[2],
               sha.Message_Digest[3],
               sha.Message_Digest[4],
               reading_stdin?"STDIN":argv[i]);
      }
   }

   return 0;
}

/*
 *  usage
 *
 *  Description:
 *      This function will display program usage information to the
 *      user.
 *
 *  Parameters:
 *      None.
 *
 *  Returns:
 *      Nothing.
 *
 *  Comments:
 *
 */
void usage(void)
{
   printf("usage: sha <file> [<file> ...]\n");
   printf("\tThis program will display the message digest\n");
   printf("\tfor files using the Secure Hashing Algorithm (SHA-1).\n");
}
