source: zcrypt.c @ 49bc81e

/* zcrypt.c -- Read in a data stream from stdin & dump a decrypted/encrypted *
 *   datastream.  Reads the string to make the key from from the first       *
 *   parameter.  Encrypts or decrypts according to -d or -e flag.  (-e is    *
 *   default.)  Will invoke zwrite if the -c option is provided for          *
 *   encryption.  If a zephyr class is specified & the keyfile name omitted  *
 *   the ~/.crypt-table will be checked for "crypt-classname" and then       *
 *   "crypt-default" for the keyfile name.                                   */

#include <stdio.h>


#include <unistd.h>
#include <sys/types.h>
#include <zephyr/zephyr.h>
#include <glib.h>

#ifdef HAVE_KERBEROS_IV
#include <kerberosIV/des.h>
#else
#include <openssl/des.h>
#endif

#define MAX_KEY 128

#ifndef TRUE
#define TRUE -1
#endif
#ifndef FALSE
#define FALSE 0
#endif

#define ZWRITE_OPT_NOAUTH     (1<<0)
#define ZWRITE_OPT_SIGNATURE  (1<<1)
#define ZWRITE_OPT_IGNOREVARS (1<<2)
#define ZWRITE_OPT_VERBOSE    (1<<3)
#define ZWRITE_OPT_QUIET      (1<<4)
#define ZCRYPT_OPT_MESSAGE    (1<<5)
#define ZCRYPT_OPT_IGNOREDOT  (1<<6)

typedef struct
{
  int flags;
  char *signature;
  char *message;
} ZWRITEOPTIONS;

char *GetZephyrVarKeyFile(char *whoami, char *class, char *instance);
char *BuildArgString(char **argv, int start, int end);
int do_encrypt(char *keystring, int zephyr, char *class, char *instance,
          ZWRITEOPTIONS *zoptions, char* keyfile);
int do_decrypt(char *keystring);

#define M_NONE            0
#define M_ZEPHYR_ENCRYPT  1
#define M_DECRYPT         2
#define M_ENCRYPT         3
#define M_RANDOMIZE       4
#define M_SETKEY          5

main(int argc, char *argv[])
{
  char *fname = NULL;
  int error = FALSE;
  int zephyr = FALSE;
  char *class = NULL, *instance = NULL;
  int mode = M_NONE;

  extern int optind, opterr;
  extern char *optarg;
  char c;

  int messageflag = FALSE;
  ZWRITEOPTIONS zoptions;
  zoptions.flags = 0;

  while ((c = getopt(argc, argv, "ZDERSF:c:i:advqtluons:f:m")) != (char)EOF)
  {
    switch(c)
    {
      case 'Z':
        /* Zephyr encrypt */
        mode = M_ZEPHYR_ENCRYPT;
        break;
      case 'D':
        /* Decrypt */
        mode = M_DECRYPT;
        break;
      case 'E':
        /* Encrypt */
        mode = M_ENCRYPT;
        break;
      case 'R':
        /* Randomize the keyfile */
        mode = M_RANDOMIZE;
        break;
      case 'S':
        /* Set a new key value from stdin */
        mode = M_SETKEY;
        break;
      case 'F':
        /* Specify the keyfile explicitly */
        if (fname != NULL) error = TRUE;
        fname = optarg;
        break;
      case 'c':
        /* Zwrite/zcrypt: class name */
        if (class != NULL) error = TRUE;
        class = optarg;
        break;
      case 'i':
        /* Zwrite/zcrypt: instance name */
        if (instance != NULL) error = TRUE;
        instance = optarg;
        break;
      case 'a':
        /* Zwrite: authenticate (default) */
        zoptions.flags &= ~ZWRITE_OPT_NOAUTH;
        break;
      case 'd':
        /* Zwrite: do not authenticate */
        zoptions.flags |= ZWRITE_OPT_NOAUTH;
        break;
      case 'v':
        /* Zwrite: verbose */
        zoptions.flags |= ZWRITE_OPT_VERBOSE;
        break;
      case 'q':
        /* Zwrite: quiet */
        zoptions.flags |= ZWRITE_OPT_QUIET;
        break;
      case 't':
        /* Zwrite: no expand tabs (ignored) */
        break;
      case 'l':
        /* Zwrite: ignore '.' on a line by itself (ignored) */
        zoptions.flags |= ZCRYPT_OPT_IGNOREDOT;
        break;
      case 'u':
        /* Zwrite: urgent message */
        instance = "URGENT";
        break;
      case 'o':
        /* Zwrite: ignore zephyr variables zwrite-class, zwrite-inst, */
        /*         zwrite-opcode */
        zoptions.flags |= ZWRITE_OPT_IGNOREVARS;
        break;
      case 'n':
        /* Zwrite: prevent PING message (always used) */
        break;
      case 's':
        /* Zwrite: signature */
        zoptions.flags |= ZWRITE_OPT_SIGNATURE;
        zoptions.signature = optarg;
        break;
      case 'f':
        /* Zwrite: file system specification (ignored) */
        break;
      case 'm':
        /* Message on rest of line*/
        messageflag = TRUE;
        break;
      case '?':
        error = TRUE;
        break;
    }
    if (error || messageflag)
      break;
  }

  if (class != NULL || instance != NULL)
    zephyr = TRUE;

  if (messageflag)
  {
    zoptions.flags |= ZCRYPT_OPT_MESSAGE;
    zoptions.message = BuildArgString(argv, optind, argc);
    if (!zoptions.message)
    {
      printf("Memory allocation error.\n");
      error = TRUE;
    }
  }
  else if (optind < argc)
  {
    error = TRUE;
  }

  if (mode == M_NONE)
    mode = (zephyr?M_ZEPHYR_ENCRYPT:M_ENCRYPT);

  if (mode == M_ZEPHYR_ENCRYPT && !zephyr)
    error = TRUE;

  if (!error && fname == NULL && (class != NULL || instance != NULL))
    fname = GetZephyrVarKeyFile(argv[0], class, instance);
  
  if (error || fname == NULL)
  {
    printf("Usage: %s [-Z|-D|-E|-R|-S] [-F Keyfile] [-c class] [-i instance]\n", argv[0]);
    printf("       [-advqtluon] [-s signature] [-f arg] [-m message]\n");
    printf("  One or more of class, instance, and keyfile must be specified.\n");
  }
  else
  {
    if (mode == M_RANDOMIZE)
    {
      /* Choose a new, random key */
/*
      FILE *fkey = fopen(fname, "w");
      if (!fkey)
        printf("Could not open key file for writing: %s\n", fname);
      else
      {
        char string[100];
        fputs(fkey, string);
        fclose(fkey);
        }
 */
      printf("Feature not yet implemented.\n");
    }
    else if (mode == M_SETKEY)
    {
      /* Set a new, user-entered key */
      char newkey[MAX_KEY];
      FILE *fkey;

      if (isatty(0))
      {
        printf("Enter new key: ");
        /* Really should read without echo!!! */
        fgets(newkey, MAX_KEY - 1, stdin);
      }
      else
        fgets(newkey, MAX_KEY - 1, stdin);

      fkey = fopen(fname, "w");
      if (!fkey)
        printf("Could not open key file for writing: %s\n", fname);
      else
      {
        if (fputs(newkey, fkey) != strlen(newkey) || putc('\n', fkey) != '\n')
        {
          printf("Error writing to key file.\n");
          fclose(fkey);
        }
        else
        {
          fclose(fkey);
          printf("Key update complete.\n");
        }
      }
    }
    else
    {
      /* Encrypt/decrypt */
      FILE *fkey = fopen(fname, "r");
      if (!fkey)
        printf("Could not open key file: %s\n", fname);
      else
      {
        char keystring[MAX_KEY];
        fgets(keystring, MAX_KEY-1, fkey);
        if (mode == M_ZEPHYR_ENCRYPT || mode == M_ENCRYPT)
          do_encrypt(keystring, (mode == M_ZEPHYR_ENCRYPT), class, instance,
                     &zoptions, fname);
        else
          do_decrypt(keystring);
        fclose(fkey);
      }
    }
  }

  /* Always print the **END** message if -D is specified. */
  if (mode == M_DECRYPT)
    printf("**END**\n");
}

/* Build a space-separated string from argv from elements between start  *
 * and end - 1.  malloc()'s the returned string. */
char *BuildArgString(char **argv, int start, int end)
{
  int len = 1;
  int i;
  char *result;

  /* Compute the length of the string.  (Plus 1 or 2) */
  for (i = start; i < end; i++)
    len += strlen(argv[i]) + 1;

  /* Allocate memory */
  result = (char *)malloc(len);
  if (result)
  {
    /* Build the string */
    char *ptr = result;
    /* Start with an empty string, in case nothing is copied. */
    *ptr = '\0';
    /* Copy the arguments */
    for (i = start; i < end; i++)
    {
      char *temp = argv[i];
      /* Add a space, if not the first argument */
      if (i != start)
        *ptr++ = ' ';
      /* Copy argv[i], leaving ptr pointing to the '\0' copied from temp */
      while (*ptr = *temp++)
        ptr++;
    }
  }

  return result;
}

#define MAX_BUFF 258
#define MAX_SEARCH 3
/* Find the class/instance in the .crypt-table */
char *GetZephyrVarKeyFile(char *whoami, char *class, char *instance)
{
  int retval;
  char *keyfile;
  char *varname[MAX_SEARCH];
  int length[MAX_SEARCH], i;
  char buffer[MAX_BUFF];
  char *filename;
  char result[MAX_SEARCH][MAX_BUFF];
  int numsearch = 0;
  FILE *fsearch;

  memset(varname, 0, sizeof(varname));

  /* Determine names to look for in .crypt-table */
  if (instance)
    varname[numsearch++] = g_strdup_printf("crypt-%s-%s:", (class?class:"message"), instance);
  if (class)
    varname[numsearch++] = g_strdup_printf("crypt-%s:", class);
  varname[numsearch++] = g_strdup("crypt-default:");

  /* Setup the result array, and determine string lengths */
  for (i = 0; i < numsearch; i++)
  {
    result[i][0] = '\0';
    length[i] = strlen(varname[i]);
  }

  /* Open~/.crypt-table */
  filename = g_strdup_printf("%s/.crypt-table", getenv("HOME"));
  fsearch = fopen(filename, "r");
  if (fsearch)
  {
    /* Scan file for a match */
    while (!feof(fsearch))
    {
      fgets(buffer, MAX_BUFF - 3, fsearch);
      for (i = 0; i < numsearch; i++)
        if (strncasecmp(varname[i], buffer, length[i]) == 0)
        {
          int j;
          for (j = length[i]; buffer[j] == ' '; j++)
            ;
          strcpy(result[i], &buffer[j]);
          if (*result[i])
            if (result[i][strlen(result[i])-1] == '\n')
              result[i][strlen(result[i])-1] = '\0';
        }
    }

    /* Pick the "best" match found */
    keyfile = NULL;
    for (i = 0; i < numsearch; i++)
      if (*result[i])
      {
        keyfile = result[i];
        break;
      }

    if (keyfile == NULL)
    {
      printf("Could not find key table entry.\n");
    }
    else
    {
      /* Prepare result to be returned */
      char *temp = keyfile;
      keyfile = (char *)malloc(strlen(temp) + 1);
      if (keyfile)
        strcpy(keyfile, temp);
      else
        printf("Memory allocation error.\n");
    }
    
    fclose(fsearch);
  }
  else
    printf("Could not open key table file: %s\n", filename);

  for(i = 0; i < MAX_SEARCH; i++) {
    if(varname[i] != NULL) {
      g_free(varname[i]);
    }
  }

  if(filename != NULL) {
    g_free(filename);
  }

  return keyfile;
}

static pid_t zephyrpipe_pid = 0;

/* Open a pipe to zwrite */
FILE *GetZephyrPipe(char *class, char *instance, ZWRITEOPTIONS *zoptions)
{
  int fildes[2];
  pid_t pid;
  FILE *result;
  char *argv[20], argc = 0;

  if (pipe(fildes) < 0)
    return NULL;
  pid = fork();

  if (pid < 0)
  {
    /* Error: clean up */
    close(fildes[0]);
    close(fildes[1]);
    result = NULL;
  }
  else if (pid == 0)
  {
    /* Setup child process */
    argv[argc++] = "zwrite";
    argv[argc++] = "-n";     /* Always send without ping */
    if (class)
    {
      argv[argc++] = "-c";
      argv[argc++] = class;
    }
    if (instance)
    {
      argv[argc++] = "-i";
      argv[argc++] = instance;
    }
    if (zoptions->flags & ZWRITE_OPT_NOAUTH)
      argv[argc++] = "-d";
    if (zoptions->flags & ZWRITE_OPT_QUIET)
      argv[argc++] = "-q";
    if (zoptions->flags & ZWRITE_OPT_VERBOSE)
      argv[argc++] = "-v";
    if (zoptions->flags & ZWRITE_OPT_SIGNATURE)
    {
      argv[argc++] = "-s";
      argv[argc++] = zoptions->signature;
    }
    argv[argc++] = "-O";
    argv[argc++] = "crypt";
    argv[argc] = NULL;
    close(fildes[1]);
    if (fildes[0] != STDIN_FILENO)
    {
      if (dup2(fildes[0], STDIN_FILENO) != STDIN_FILENO)
        exit(0);
      close(fildes[0]);
    }
    close(fildes[0]);
    execvp(argv[0], argv);
    printf("Exec error: could not run zwrite\n");
    exit(0);
  }
  else
  {
    close(fildes[0]);
    /* Create a FILE * for the zwrite pipe */
    result = (FILE *)fdopen(fildes[1], "w");
    zephyrpipe_pid = pid;
  }

  return result;
}

/* Close the pipe to zwrite */
CloseZephyrPipe(FILE *pipe)
{
  fclose(pipe);
  waitpid(zephyrpipe_pid, NULL, 0);
  zephyrpipe_pid = 0;
}

#define MAX_RESULT 2048

#define BASE_CODE 70
#define LAST_CODE (BASE_CODE + 15)
#define OUTPUT_BLOCK_SIZE 16

block_to_ascii(char *output, FILE *outfile)
{
  int i;
  for (i = 0; i < 8; i++)
  {
    putc(((output[i] & 0xf0) >> 4) + BASE_CODE, outfile);
    putc( (output[i] & 0x0f)       + BASE_CODE, outfile);
  }
}

#define MAX_LINE 128

/* Encrypt stdin, with prompt if isatty, and send to stdout, or to zwrite
   if zephyr is set. */
int do_encrypt(char *keystring, int zephyr, char *class, char *instance,
          ZWRITEOPTIONS *zoptions, char* keyfile)
{
  des_cblock key;
  des_key_schedule schedule;
  char input[8], output[8];
  int size;
  int save_result = zephyr && isatty(0);
  FILE *outfile = stdout;
  int error = FALSE;
  char *inbuff = NULL, *inptr;
  int freein = FALSE;
  int use_buffer = FALSE;
  int num_blocks, last_block_size;

  des_string_to_key(keystring, key);
  des_key_sched(key, schedule);

  if (zephyr)
  {
    if (zoptions->flags & ZCRYPT_OPT_MESSAGE)
    {
      /* Use the -m message */
      int length;
      inbuff = zoptions->message;      
      length = strlen(inbuff);
      num_blocks = (length + 7) / 8;
      last_block_size = ((length + 7) % 8) + 1;
      use_buffer = TRUE;
    }
    else if (isatty(0))
    {
      /* tty input, so show the "Type your message now..." message */
      if (zoptions->flags & ZCRYPT_OPT_IGNOREDOT)
        printf("Type your message now.  End with the end-of-file character.\n");
      else
        printf("Type your message now.  End with control-D or a dot on a line by itself.\n");
      use_buffer = TRUE;
      if ((inptr = inbuff = (char *)malloc(MAX_RESULT)) == NULL)
      {
        printf("Memory allocation error\n");
        return FALSE;
      }
      while (inptr - inbuff < MAX_RESULT - MAX_LINE - 20)
      {
        fgets(inptr, MAX_LINE, stdin);
        if (inptr[0])
        {
          if (inptr[0] == '.' && inptr[1] == '\n' && 
              !(zoptions->flags & ZCRYPT_OPT_IGNOREDOT))
          {
            inptr[0] = '\0';
            break;
          }
          else
            inptr += strlen(inptr);
        }
        else
          break;
      }
      num_blocks = (inptr - inbuff + 7) / 8;
      last_block_size = ((inptr - inbuff + 7) % 8) + 1;
      freein = TRUE;
    }

    /* if (zephyr) */
    outfile = GetZephyrPipe(class, instance, zoptions);
    if (!outfile)
    {
      printf("Could not run zwrite\n");
      if (freein && inbuff)
        free(inbuff);
      return FALSE;
    }
  }

  inptr = inbuff;

  /* Encrypt the input (inbuff or stdin) and send it to outfile */
  while (TRUE)
  {
    if (use_buffer)
    {
      /* Get 8 bytes from buffer */
      if (num_blocks > 1)
      {
        size = 8;
        memcpy(input, inptr, size);
        inptr += 8;
        num_blocks--;
      }
      else if (num_blocks == 1)
      {
        size = last_block_size;
        memcpy(input, inptr, size);
        num_blocks--;
      }
      else
        size = 0;
    }
    else
      /* Get 8 bytes from stdin */
      size = fread(input, 1, 8, stdin);

    /* Check for EOF and pad the string to 8 chars, if needed */
    if (size == 0)
      break;                      /* END OF INPUT: BREAK FROM while LOOP! */
    if (size < 8)
      memset(input + size, 0, 8 - size);

    /* Encrypt and output the block */
    des_ecb_encrypt(input, output, schedule, TRUE);
    block_to_ascii(output, outfile);

    if (size < 8)
      break;
  }

  /* Close out the output */
  if (!error)
    putc('\n', outfile);
  if (zephyr)
    CloseZephyrPipe(outfile);

  /* Free the input buffer, if necessary */
  if (freein && inbuff)
    free(inbuff);

  return !error;
}

/* Read a half-byte from stdin, skipping invalid characters.  Returns -1
   if at EOF or file error */
int read_ascii_nybble()
{
  char c;

  while (TRUE)
  {
    if (fread(&c, 1, 1, stdin) == 0)
      return -1;
    else if (c >= BASE_CODE && c <= LAST_CODE)
      return c - BASE_CODE;
  }
}

/* Read both halves of the byte and return the single byte.  Returns -1
   if at EOF or file error. */
int read_ascii_byte()
{
  int c1, c2;
  c1 = read_ascii_nybble();
  if (c1 >= 0)
  {
    c2 = read_ascii_nybble();
    if (c2 >= 0)
    {
      return c1 * 0x10 + c2;
    }
  }
  return -1;
}

/* Read an 8-byte DES block from stdin */
int read_ascii_block(char *input)
{
  int c;

  int i;
  for (i = 0; i < 8; i++)
  {
    c = read_ascii_byte();
    if (c < 0)
      return FALSE;

    input[i] = c;
  }

  return TRUE;
}

/* Decrypt stdin */
int do_decrypt(char *keystring)
{
  des_cblock key;
  des_key_schedule schedule;
  char input[8], output[9];
  int size;

  output[0] = '\0';    /* In case no message at all                 */
  output[8] = '\0';    /* NULL at end will limit string length to 8 */

  des_string_to_key(keystring, key);
  des_key_sched(key, schedule);

  while (read_ascii_block(input))
  {
    des_ecb_encrypt(input, output, schedule, FALSE);
    printf("%s", output);
  }

  if (output[0])
  {
    if (output[strlen(output)-1] != '\n')
      printf("\n");
  }
  else
    printf("\n");
}