granicus.if.org Git - linux-pam/blob - modules/pam_filter/upperLOWER/upperLOWER.c

   1 /*
   2  * $Id$
   3  *
   4  * This is a sample filter program, for use with pam_filter (a module
   5  * provided with Linux-PAM). This filter simply transposes upper and
   6  * lower case letters, it is intended for demonstration purposes and
   7  * it serves no purpose other than to annoy the user...
   8  */
   9
  10 #include "config.h"
  11
  12 #ifdef MEMORY_DEBUG
  13 # undef exit
  14 #endif /* MEMORY_DEBUG */
  15
  16 #include <stdio.h>
  17 #include <stdlib.h>
  18 #include <syslog.h>
  19 #include <sys/time.h>
  20 #include <sys/types.h>
  21 #include <unistd.h>
  22
  23 #include <security/pam_filter.h>
  24 #include <security/pam_modules.h>
  25 #include <security/_pam_macros.h>
  26 #include <security/_pam_modutil.h>
  27
  28 /* ---------------------------------------------------------------- */
  29
  30 #include <stdarg.h>
  31 #ifdef hpux
  32 # define log_this syslog
  33 #else
  34 static void log_this(int err, const char *format, ...)
  35 {
  36     va_list args;
  37
  38     va_start(args, format);
  39     openlog("upperLOWER", LOG_CONS|LOG_PID, LOG_AUTH);
  40     vsyslog(err, format, args);
  41     va_end(args);
  42     closelog();
  43 }
  44 #endif
  45
  46 #include <ctype.h>
  47
  48 static void do_transpose(char *buffer,int len)
  49 {
  50      int i;
  51      for (i=0; i<len; ++i) {
  52           if (islower(buffer[i])) {
  53                buffer[i] = toupper(buffer[i]);
  54           } else {
  55                buffer[i] = tolower(buffer[i]);
  56           }
  57      }
  58 }
  59
  60 extern char **environ;
  61
  62 int main(int argc, char **argv)
  63 {
  64      char buffer[BUFSIZ];
  65      fd_set readers;
  66      void (*before_user)(char *,int);
  67      void (*before_app)(char *,int);
  68
  69 #ifdef DEBUG
  70      {
  71           int i;
  72
  73           fprintf(stderr,"environment :[\r\n");
  74           for (i=0; environ[i]; ++i) {
  75                fprintf(stderr,"-> %s\r\n",environ[i]);
  76           }
  77           fprintf(stderr,"]: end\r\n");
  78      }
  79 #endif
  80
  81      if (argc != 1) {
  82 #ifdef DEBUG
  83           fprintf(stderr,"filter invoked as conventional executable\n");
  84 #else
  85           log_this(LOG_ERR, "filter invoked as conventional executable");
  86 #endif
  87           exit(1);
  88      }
  89
  90      before_user = before_app = do_transpose;   /* assign filter functions */
  91
  92      /* enter a loop that deals with the input and output of the
  93         user.. passing it to and from the application */
  94
  95      FD_ZERO(&readers);                    /* initialize reading mask */
  96
  97      for (;;) {
  98
  99           FD_SET(APPOUT_FILENO, &readers);              /* wake for output */
 100           FD_SET(APPERR_FILENO, &readers);               /* wake for error */
 101           FD_SET(STDIN_FILENO, &readers);                /* wake for input */
 102
 103           if ( select(APPTOP_FILE,&readers,NULL,NULL,NULL) < 0 ) {
 104 #ifdef DEBUG
 105                fprintf(stderr,"select failed\n");
 106 #else
 107                log_this(LOG_WARNING,"select failed");
 108 #endif
 109                break;
 110           }
 111
 112           /* application errors */
 113
 114           if ( FD_ISSET(APPERR_FILENO,&readers) ) {
 115                int got = _pammodutil_read(APPERR_FILENO, buffer, BUFSIZ);
 116                if (got <= 0) {
 117                     break;
 118                } else {
 119                     /* translate to give to real terminal */
 120                     if (before_user != NULL)
 121                          before_user(buffer, got);
 122                     if (_pammodutil_write(STDERR_FILENO, buffer, got) != got ) {
 123                          log_this(LOG_WARNING,"couldn't write %d bytes?!",got);
 124                          break;
 125                     }
 126                }
 127           } else if ( FD_ISSET(APPOUT_FILENO,&readers) ) {    /* app output */
 128                int got = _pammodutil_read(APPOUT_FILENO, buffer, BUFSIZ);
 129                if (got <= 0) {
 130                     break;
 131                } else {
 132                     /* translate to give to real terminal */
 133                     if (before_user != NULL)
 134                          before_user(buffer, got);
 135                     if (_pammodutil_write(STDOUT_FILENO, buffer, got) != got ) {
 136                          log_this(LOG_WARNING,"couldn't write %d bytes!?",got);
 137                          break;
 138                     }
 139                }
 140           }
 141
 142           if ( FD_ISSET(STDIN_FILENO, &readers) ) {  /* user input */
 143                int got = _pammodutil_read(STDIN_FILENO, buffer, BUFSIZ);
 144                if (got < 0) {
 145                     log_this(LOG_WARNING,"user input junked");
 146                     break;
 147                } else if (got) {
 148                     /* translate to give to application */
 149                     if (before_app != NULL)
 150                          before_app(buffer, got);
 151                     if (_pammodutil_write(APPIN_FILENO, buffer, got) != got ) {
 152                          log_this(LOG_WARNING,"couldn't pass %d bytes!?",got);
 153                          break;
 154                     }
 155                } else {
 156                     /* nothing received -- an error? */
 157                     log_this(LOG_WARNING,"user input null?");
 158                     break;
 159                }
 160           }
 161      }
 162
 163      exit(0);
 164 }
 165
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