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 <security/_pam_aconf.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
  25 /* ---------------------------------------------------------------- */
  26
  27 #include <stdarg.h>
  28 #ifdef hpux
  29 # define log_this syslog
  30 #else
  31 static void log_this(int err, const char *format, ...)
  32 {
  33     va_list args;
  34
  35     va_start(args, format);
  36     openlog("upperLOWER", LOG_CONS|LOG_PID, LOG_AUTH);
  37     vsyslog(err, format, args);
  38     va_end(args);
  39     closelog();
  40 }
  41 #endif
  42
  43 #include <ctype.h>
  44
  45 static void do_transpose(char *buffer,int len)
  46 {
  47      int i;
  48      for (i=0; i<len; ++i) {
  49           if (islower(buffer[i])) {
  50                buffer[i] = toupper(buffer[i]);
  51           } else {
  52                buffer[i] = tolower(buffer[i]);
  53           }
  54      }
  55 }
  56
  57 extern char **environ;
  58
  59 int main(int argc, char **argv)
  60 {
  61      char buffer[BUFSIZ];
  62      fd_set readers;
  63      void (*before_user)(char *,int);
  64      void (*before_app)(char *,int);
  65
  66 #ifdef DEBUG
  67      {
  68           int i;
  69
  70           fprintf(stderr,"environment :[\r\n");
  71           for (i=0; environ[i]; ++i) {
  72                fprintf(stderr,"-> %s\r\n",environ[i]);
  73           }
  74           fprintf(stderr,"]: end\r\n");
  75      }
  76 #endif
  77
  78      if (argc != 1) {
  79 #ifdef DEBUG
  80           fprintf(stderr,"filter invoked as conventional executable\n");
  81 #else
  82           log_this(LOG_ERR, "filter invoked as conventional executable");
  83 #endif
  84           exit(1);
  85      }
  86
  87      before_user = before_app = do_transpose;   /* assign filter functions */
  88
  89      /* enter a loop that deals with the input and output of the
  90         user.. passing it to and from the application */
  91
  92      FD_ZERO(&readers);                    /* initialize reading mask */
  93
  94      for (;;) {
  95
  96           FD_SET(APPOUT_FILENO, &readers);              /* wake for output */
  97           FD_SET(APPERR_FILENO, &readers);               /* wake for error */
  98           FD_SET(STDIN_FILENO, &readers);                /* wake for input */
  99
 100           if ( select(APPTOP_FILE,&readers,NULL,NULL,NULL) < 0 ) {
 101 #ifdef DEBUG
 102                fprintf(stderr,"select failed\n");
 103 #else
 104                log_this(LOG_WARNING,"select failed");
 105 #endif
 106                break;
 107           }
 108
 109           /* application errors */
 110
 111           if ( FD_ISSET(APPERR_FILENO,&readers) ) {
 112                int got = read(APPERR_FILENO, buffer, BUFSIZ);
 113                if (got <= 0) {
 114                     break;
 115                } else {
 116                     /* translate to give to real terminal */
 117                     if (before_user != NULL)
 118                          before_user(buffer, got);
 119                     if ( write(STDERR_FILENO, buffer, got) != got ) {
 120                          log_this(LOG_WARNING,"couldn't write %d bytes?!",got);
 121                          break;
 122                     }
 123                }
 124           } else if ( FD_ISSET(APPOUT_FILENO,&readers) ) {    /* app output */
 125                int got = read(APPOUT_FILENO, buffer, BUFSIZ);
 126                if (got <= 0) {
 127                     break;
 128                } else {
 129                     /* translate to give to real terminal */
 130                     if (before_user != NULL)
 131                          before_user(buffer, got);
 132                     if ( write(STDOUT_FILENO, buffer, got) != got ) {
 133                          log_this(LOG_WARNING,"couldn't write %d bytes!?",got);
 134                          break;
 135                     }
 136                }
 137           }
 138
 139           if ( FD_ISSET(STDIN_FILENO, &readers) ) {  /* user input */
 140                int got = read(STDIN_FILENO, buffer, BUFSIZ);
 141                if (got < 0) {
 142                     log_this(LOG_WARNING,"user input junked");
 143                     break;
 144                } else if (got) {
 145                     /* translate to give to application */
 146                     if (before_app != NULL)
 147                          before_app(buffer, got);
 148                     if ( write(APPIN_FILENO, buffer, got) != got ) {
 149                          log_this(LOG_WARNING,"couldn't pass %d bytes!?",got);
 150                          break;
 151                     }
 152                } else {
 153                     /* nothing received -- an error? */
 154                     log_this(LOG_WARNING,"user input null?");
 155                     break;
 156                }
 157           }
 158      }
 159
 160      exit(0);
 161 }
 162
 163
 164